Forests are essential for maintaining the living conditions on Earth, providing livelihoods and wellbeing for a significant proportion of humanity, while also having the potential to address the existential challenges we are facing. This study explored the composition of the Finnish forest policy subsystem and analyzed the type of policies it has produced under different national and international political influences within a 22-year time frame, from 1994 to 2015. The main aims were to identify the predominant coalitions involved in the policy processes and to analyze the role of international influences and discourses in the Finnish forest policy subsystem. Furthermore, the study examines the related sustainability framings and discusses the implications of the analyzed forest policies for the sustainability of forestry and social equity.
The analytical approach was guided by three main policy process-related theories. Firstly, the Advocacy Coalition Framework (ACF) was used to unpack and critically examine the composition and value basis of the Finnish forest policy subsystem. Secondly, the ACF was combined with the Four Pathways of International Influences framework to analyze and identify how international influences affect the Finnish policy subsystem. Finally, Critical Discourse Analysis was applied to discover how Finnish forest policies are formulated, which influences guide them, and how international sustainability discourses are reflected in them. These theories also guided the data collection and analysis. The data consisted of expert interviews and policy documents and was examined using qualitative content analysis.
Based on the analysis, the Finnish forest policy subsystem consists of three coalitions: the private forestry coalition, the forestry administration coalition, and the environmental coalition. The first two derive their policy core beliefs from the forestry paradigm and promote the economic utilization of timber, whereas the environmental coalition derives its beliefs from the environmental paradigm and promotes the safeguarding of forest nature. The results of the dissertation indicate that Finnish forest policy has been inclined to favor the approach adopted by the private forestry and forestry administration coalitions by emphasizing the economic utilization of timber resources. This approach seems to stem from the importance of the export-dependent Finnish forest industry to the national economy. In addition, the results show that international influences have diffused into the Finnish forest policy development process through three different pathways, namely international rules, international norms and discourse, and markets. More specifically, legally binding international rules and non-legally binding international norms and discourse were regarded as equally important. In the 1990s, the rise of environmental consciousness and related regulation gave the environmental coalition the leverage to influence Finnish forest policy. However, the influence of the environmental coalition was only temporary. In the 2010s, the bioeconomy narrative applied by the private forestry coalition and the forestry administration coalition re-emphasized the economic utilization of forests to the detriment of environmental aspects.
The future of the Finnish forest sector depends on how it will reconcile – or fail to reconcile – the contradictory paradigms of environmental protection and forest utilization. Policy changes toward a sustainable future would require changes in the discourse and the discursive space, together with more open public discussion.
Stomata are a pivotal nexus between tree physiology and the environment, and thus modelling stomatal behaviour is critical for understanding tree growth and functioning. One of such models that have been widely tested is based on Lagrangian optimality analysis of gas exchange. The objectives of the present study were expanding the optimal stomata model to the whole-tree scale and coupling it with a model of cambial growth. The coupled model connects stomatal behaviour with non-stomatal limitation on photosynthesis, waterlogging effects, and the enzymatic activities and phenology of cambial growth. It requires commonplace inputs of meteorology, photosynthetic photon flux density (PPFD) and soil water conditions and can output transpiration, assimilation and cambial growth rates simultaneously at 30-minute resolution. The model was parameterized using Bayesian statistics and tested against observations on Pinus sylvestris and Picea abies from boreal forest sites in Finland of peatland and mineral soils. The model performance on simulating transpiration rate and stem radial dimension was good. Statistical analyses of model parameters showed that young/short trees almost always had higher stomatal conductance than old/tall trees under typical vapour pressure deficit (VPD) and PPFD. Also, maximum soil-to-root hydraulic conductance and minimum marginal water use efficiency (MWUE) of the trees were positively correlated with their leaf-to-sapwood area ratio. The modelled cambial growth duration was positively correlated with leaf-specific photosynthetic production (P) of the growing season at the moister peatland but not at the dryer mineral-soil site, and otherwise phenological traits of cambial growth were not significantly correlated with P at either site, suggesting P is not sufficient for determining the growth phenology of boreal trees. The model provides an easy-to-use tool for coupled tree eco-physiological and growth simulation and insights into larger-scale sink-driven vegetation modelling.
Seedling stands are areas in forest landscapes where young trees, typically from newly planted or naturally regenerated seedlings, grow. These stands are in the early stages of forest development and are crucial for the renewal and future growth of the forest. They represent a vital phase in the forest's lifecycle, for which careful management is often employed to ensure the successful establishment and growth of young crop trees.
To address the data-gathering requirements of forest management, seedling stands are typically assessed through field visits, a process that is considered time-consuming, expensive, and labor-intensive. As trees in the seedling stands are small and often densely stocked, they are difficult to assess in operational remote sensing-based forest inventories. However, recent developments in remote sensing, especially in laser scanning and the use of drones, could open new pathways to developing methods for the spatially explicit and timely inventorying of seedling stands; such methods could complement or even replace field visits.
The aim here was to develop and assess remote sensing methods of estimating the tree density, mean tree height, and species of seedling stands, which are the key characteristics supporting forest management. For this purpose, new remote sensing techniques–namely drone photogrammetric point clouds, hyper- and multi-spectral imagery (studies I and IV), and multi-spectral and single-photon airborne laser scanning (ALS; studies II and III) data–were investigated over seedling stands located in three study sites in the boreal forests of Finland. Performance of leaf-off and leaf-on hyper-spectral drone imagery and multi-spectral ALS data was explored in seedling stands in studies I and II. A canopy-thresholding method (Cth) was also optimized to minimize the interference of understory vegetation (study II), and the performance of single-photon ALS was examined in study III. In that study, an area-based approach (ABA) that included single-tree features and corrected the effect of edge trees (ABAEdgeITD) was developed and compared to conventional ABA. In study IV, a new approach for feeding multispectral drone images to convolutional neural networks was proposed and validated for the classification of seedling tree species.
The findings of this thesis demonstrated that drone imagery yielded more accurate tree density estimates, while dense multispectral ALS data outperformed other tested methods of tree height estimation (both when using leaf-on data). The use of ABAEdgeITD improved the tree density and height estimates compared to conventional ABA, although it was less accurate than the individual tree-based methods used in studies I and II. Characterization of advanced seedling stands was more accurate than that of early-growth stage stands (mean height < 1.3 m), which remained challenging. Finally, the image pre-processing approach, together with the convolutional neural network, used in study IV improved the species classification accuracy of seedlings. This thesis shows that the remote sensing methods used can be applied in operational forest inventories to complement or replace field visits. These new technologies are valuable approaches to increasing the efficiency and sustainability of forest management.
The sustainable utilisation of Non-Timber Forest Products (NTFPs) holds significant promise for livelihood improvement within forest fringe communities in Ghana. While local communities benefit from NTFPs, there is limited understanding of the locals' perceptions with regard to the potential of NTFPs to alleviate poverty. This research evaluated the intricate interplay of local perceptions with regard to climate change, value addition and the multiple uses of NTFPs, and their influence on livelihood improvement. The study employed a multidimensional approach, incorporating quantitative, qualitative and systematic review methodologies. Surveys and interviews were conducted to gather data on the perceptions of local communities of climate change, value addition to NTFPs and the multiple uses of NTFPs, as well as social factors that influence their perception. In addition, a systematic review using the PRISMA method was used to assess the potential of NTFPs to alleviate poverty. The findings underscored the significance of education, religion and gender, which are pivotal in shaping local perceptions of NTFPs and their potential to improve livelihoods. The systematic review showed the potential of NTFPs to alleviate poverty in Ghana and in other parts of the world. Initiatives that enhance market accessibility and create value-addition opportunities should be considered to uplift communities economically. Furthermore, policy frameworks and institutional support can emerge as essential elements in shaping local perceptions. In conclusion, this research elucidated the vital role of local perceptions for the sustainable utilisation of NTFPs to improve livelihoods within Ghana's forest fringe communities.
The Namibian savannah ecosystem has experienced considerable anthropogenic pressures, which have resulted in the disruption of key ecological processes, and consequently, the proliferation of a dense vegetation structure, commonly known as bush encroachment. Approximately 45 million hectares of land have been affected, which has caused a significant decline in the grazing capacity, poor economic returns for the farmers, and loss of suitable wildlife habitat. Restoration thinning, a method that involves the selective removal of excess trees/shrubs, has been applied to counteract the negative effects associated with this phenomenon.
This thesis aimed to assess the effect of thinning on (a) the activity patterns of local ungulates and predators, (b) the encroaching woody vegetation in terms of (i) regeneration, and (ii) structure, abundance, and habitat sighting lines, in a savannah habitat in the north-central region. Generalised linear mixed-effects models (GLMM) and linear mixed-effects models (LME) were used for statistical analysis. Results showed that thinned areas had overall greater wildlife activity. Thinned areas also had reduced tree/shrub abundance, which was significant for the mature height classes. Natural regeneration was rapid in thinned areas, where the abundance of young cohorts was 34% greater than non-thinned areas. In the thinned areas, red umbrella thorn (Vachellia reficiens) was significantly reduced but umbrella thorn (Vachellia tortilis) numbers increased. Tree/shrub densities in the thinned areas fell within the commonly accepted range for a 400 mm rainfall area (600–750 tree equivalents (TE) ha–1). Thinning significantly modified the dense thornbush to an open vegetation structure with a low woody canopy cover that favours grass growth and provides greater sighting lines for open savannah wildlife. This thesis demonstrated that thinning was effective in controlling bush encroachment and could be used as a method to restore other affected areas. However, periodic post-thinning management is recommended to control the established samplings.
Consumers globally have a long history engaging with edible non-wood forest products in both rural and urban settings, and involving diverse consumption practices. While edible non-wood forest products offer critical provisioning and cultural ecosystem services, current literature primarily emphasizes the conventional economic significance in rural areas, neglecting urban consumption patterns.
This thesis aims to investigate the forms and drivers behind urban consumers’ experience and consumption behavior with edible non-wood forest products in the regional Chinese market. It explores urban consumer behavior around three key aspects: consumer purchasing, foraging, and pro-environmental consumption behavior of wild/cultivated non-wood forest products. Building upon the theoretical background of ecosystem services and the Motivation–Opportunity–Ability model, supported by the Theory of Planned Behavior model, this thesis lays out a conceptual framework of the driving factors of the consumption behavior. A mixed methods approach was employed methodologically, including the logistic regression analysis, a qualitative thematic analysis, and the structural equation model.
The findings reported in three articles I-III reveal diverse patterns in urban consumer consumption behavior concerning edible non-wood forest products, emphasizing the urban-rural nexus around these products. Motivation, opportunities, and abilities emerge as key drivers of consumption behavior. Pragmatism and sustainability dominate self-consumption purchases for tea, while Chinese mianzi and renqing motives prevail in gift-giving (I). A greater diversity of motivation exists in berry-picking, particularly among younger urban families (II). Social norms and culture are influential in shaping consumer attitudes (I, II, III). High-quality product availabilities, convenience, services, and social media marketing channels offered by producers and distributors constitute vital consumption opportunities (II, III). Additional actors such as local networks will be supportive (II). Personal knowledge and consumer habits also shape consumption behavior (III). These findings provide managerial implications for farmers, marketers, and policy makers, encouraging further research in this area.
The aim of this thesis was to evaluate the survival, growth, and phytoremediation potential of Populus and Salix seedlings grown in polluted soils. More specifically, the following topics were studied: (1) the survival and growth of two European aspen clones and four hybrid aspen clones grown in control soil (pristine), old creosote soil polluted with hydrocarbons, and pristine soil spiked with fresh diesel oil at three different planting densities in a greenhouse over two growing seasons (Article I); (2) the survival, growth, and hydrocarbon removal of three European aspen clones and seven hybrid aspen clones grown in hydrocarbon-contaminated soil (including polycyclic aromatic hydrocarbons (PAHs) and total petroleum hydrocarbons (TPHs)) under field conditions over 4 years (Article II); and (3) the growth and metal accumulation ability of Salix psammophila seedlings with bamboo biochar (BBC) amendment at ratios of 0–7% in soils heavily contaminated by Cd and Zn in a pot experiment over 180 days (Article III).
In study I (Article I), the survival rates of European aspen and hybrid aspen clone seedlings were 70–100% in control soil, 99% in the old creosote-contaminated soil, and 22–59% in the diesel-contaminated soil across all planting densities. The heights of aspen seedlings were 5–44% and 9–38% lower and the stem dry biomass was 9–93% and 34–63% lower in diesel-contaminated and creosote-contaminated soils, respectively, compared to the control. Low plant density increased survival rates and growth compared to higher density treatments. Of all the clones, hybrid aspen clones 14 and 291 and European aspen clone R3 showed reasonable survival and growth across all treatments. Soil treatment, planting density, and clone type significantly affected survival rate, height, and stem dry biomass (p < 0.05).
In study II (Article II), the highest survival rates in old creosote-contaminated soils were in clone 291 (72%) among hybrid aspen clones and clone R3 (70%) among European aspen clones. Hybrid aspen clones 14 and 34 had 16–211% greater heights than other hybrid aspen clones. The height of European aspen clone R3 was also 25‒35% greater than that of other European aspen clones. However, clone type did not significantly affect seedling survival or height (p > 0.05). Among hybrid aspen clones, clone 134 had the largest hydrocarbon removal at a depth of 5–10 cm and clone 191 at a depth of 10–50 cm. Clone 14 also showed potential for removing hydrocarbons at both soil depths. In European aspen clones, clone R2 had the highest hydrocarbon removal at both soil depths. However, all clones showed an ability to remove total PAHs and TPHs from the soil (but p < 0.05 only at a soil depth of 5–10 cm). The reduction in hydrocarbon levels in the soil was more prominent at a soil depth of 5–10 cm than at a depth of 10–50 cm. Based on studies I and II, European aspen and hybrid aspen clones can be considered candidates for the remediation of soils polluted with PAHs and TPHs.
In study III (Article III), BBC ratios of 1% and 5% resulted in only slight decreases in characteristics, especially height (0.6‒1.3%) but also total dry biomass (2‒10%), of S. psammophila seedlings compared to the control, whereas BBC 3% increased these measurements slightly (2% increase). BBC 7% reduced the height (16%) and total dry biomass (26%) of seedlings compared to the control. BBC amendment increased the accumulation of Cu, Cd, and Zn in different plant tissues, especially Cd and Zn accumulation (23‒30% and 13‒24%, respectively), in the BBC 3% treatment compared to the control. Based on these findings, S. psammophila with BBC amendment can be considered a candidate for phytoremediation. However, metal accumulation in the roots, stems, and leaves was not significantly affected by the BBC 1‒7% treatments (p > 0.05), except for Pb accumulation in the roots and Cu accumulation in the stem (p < 0.05).
Overall, hybrid aspen, European aspen, and S. psammophila seedlings showed reasonable survival and growth, photosynthetic activity, efficient hydrocarbon removal from soil and metal accumulation ability both under greenhouse conditions and in a field experiment. Therefore, these species could be used to depollute areas affected by a range of hydrocarbons or Cd and Zn. However, future research should be conducted in the field to verify the abilities of hybrid and European aspens and S. psammophila to remediate soil contaminated by hydrocarbons, Cd, or Zn, and such studies should also use different planting densities and soil amendments over longer periods.
Boreal peatlands harbour large stores of carbon as peat below their surfaces. Climate change is expected to cause drying in northern peatlands, which will in turn impact the carbon balance of these ecosystems that is maintained by high water tables and the hydrologically sensitive plants growing there. This study aims to quantify how vegetation will be structured (I) and photosynthesize (II, III) in a future climate as emulated by long-term water level drawdown (WLD). To do this, changes in the vegetation and its photosynthesis after WLD are linked, and the response of Sphagnum mosses to periodic drought is investigated.
Field measurements were done at a long-term WLD field experiment that contained a rich (mesotrophic) fen, a poor (oligotrophic) fen and a bog (ombrotrophic) site. Measurements included vegetation surveys from existing permanent sample plots and leaf-level carbon dioxide exchange measurements. For an experiment in controlled conditions peatland surface cores from this field experiment were transported to a greenhouse where the photosynthesis of lawn Sphagna during and after an experimental periodic drought was measured.
The field study revealed that the response of peatland vegetation to WLD depend on peatland type. The species composition in the rich fen was the most impacted by WLD, while the bog vegetation demonstrated stability. Similarly, large increases in photosynthesis occurred following WLD on the vascular plant-covered rich fen, while changes were negligible on the Sphagnum-carpeted bog. The vegetation on the two fens shifted from an open sedge-, or sedge and Sphagnum-dominated ecosystem, to a tree-dominated ecosystem. Canopy development following WLD further accelerated vegetation changes by shading and sheltering the understorey vegetation. Vascular plants were the most likely to increase productivity from WLD as they are best suited to utilize the nutrients made available by peat mineralization, while Sphagnum moss photosynthesis was impacted little. The greenhouse study revealed that lawn Sphagnum mosses exposed to long-term WLD were more vulnerable to drought compared to those from wet sites. Large capitula typical to fen Sphagnum species appeared to be beneficial for surviving periodic drought.
This work demonstrated that climate change as emulated by long-term WLD will have a large impact on the vegetation composition of northern peatlands and increase photosynthetic function of these ecosystems, fens in particular. To better predict climate feedbacks from these changes, carbon dynamics including peatland vegetation dynamics should be updated in global process models. Future research to better understand the tipping point of different peatland types after WLD in different climatic regions will help us to predict changes in these diverse and globally important systems.
Plant physiology concentrates on the study of plant internal processes, such as growth, nutrient uptake and photosynthesis. The quantification of photosynthesis regulation is significant in understanding how plants react to the changing climate. Spectral remote sensing methods, using both reflected light in the visible and near infrared wavelengths, as well as chlorophyll fluorescence, are used to gather information about plant physiological variables. These methods have developed rapidly, prompted by the advances in remote sensing platforms and sensors.
However, interpretation of remote sensing signals can be challenging. Due to canopy heterogeneity, the signal is affected by various elements, such as scattering, soil background and canopy structural effects. Additionally, open questions remain linked to the underlying mechanistic processes in the leaf modulating the optical signal, such as nutrient contents and leaf photochemistry, and how these processes and the optical signals diverge in response to temporal variation. Through multi-scale measurements, this thesis aims to advance the interpretation of optical remote sensing signals as they are affected by spatial and temporal variation, while promoting the use of novel methods and devices.
Results indicate that diurnal and long-term variation of solar induced fluorescence (SIF) is driven by photosynthetic and structural factors, causing possible misinterpretations in SIF data. Additionally, depending on the scale of observation, results show that the capacity of remote sensing to detect changes in foliar nutrients depends on the covariation of nutrients, pigments and canopy structure, underlining the need for both leaf and canopy level measurements. Finally, we advocate for the implementation of a novel miniaturized fluorometer, demonstrating the ability to track the seasonal regulation of photosynthesis using integrated measurements of chlorophyll fluorescence and gas exchange. The results from this thesis underline the need for simultaneous multi-scale measurements of leaf and canopy physiological factors to further our understanding of photosynthesis regulation.
In Finland, women comprise 41% of private forest owners. However, studies examining forest ownership from the gender perspective are scarce. Forestry and forest ownership is a field dominated by masculine and techno-economic values. For example, this is manifested in the ideal of ‘active forest owner’ in forest policy documents. Therefore, this dissertation studied the concept of ‘active forest ownership’ from the perspective of women forest owners. Different conceptual lenses were used, such as the gender theory and service-dominant logic. Specifically, the thesis focused on four questions: 1. Are women less active than men when a variety of forestry related activities are studied? (Article I); 2. How do women forest owners understand the concept of active forest owner, how does it differ from the one from Finnish forest policy and what kind of attributes impact women forest ownership? (Article II); 3. Do women forest owners have differing objective structure compared with men? (Article III); and 4. Is the relationship between objectives and activity different between women and men? (Article IV).
Both quantitative (Articles I, III and IV) and qualitative (Article II) methods were applied. Articles I and III employ exploratory factor analysis and Article IV confirmatory factor analysis. Two sets of data were used: a questionnaire of the Finnish Forest Owner 2020 research project (n=6558) and 22 semistructured interviews. In this thesis, women were found to be less active than men when a selection of forestry related activities were studied (Article I). Women forest owners also had more diverse objective structure compared with men (Article III). In addition, the relationship between forest owner objectives and activity differed between genders (Article IV). Women also defined the concept of ‘active forest owner’ as a much wider concept than Finnish policies. (Article II).
These findings suggest that forest ownership is a gendered performance and that there is a lack of service-dominant logic, that is, value cocreation corresponding to the objectives of women. More specifically, the results indicate that women owners need support, especially when forest ownership is something new. Furthermore, gendering and the prevailing forest values impact the whole forest owner population, their behaviour and forest owner research. Understanding this can enable the design of more equal and inclusive forest policies and services.
The impact of urbanization, industrialization, agriculture, mining, and stormwater runoff on ecosystems has resulted in significant water pollution concerns worldwide. Significant attention has been paid to the removal of potentially toxic elements (PTE) and metalloids (e.g., arsenic (As), selenium (Se) and lead (Pb)) by various plant species. However, little research has been published on the simultaneous accumulation of cadmium (Cd), chromium (Cr), and nutrient removal, by floating treatment wetlands (FTW), from stormwater runoff, and the accumulation and recovery of rare earth elements (REE) through energy biomass cultivation. This research bridges knowledge gaps in the remediation of REE using short-rotation willow (Salix spp.) and simulated stormwater remediation of Cd and Cr with Phragmites australis and Iris pseudacorus. In this context, three different microcosm experiments were conducted with perennial plants (P. australis and I. pseudacorus) in FTW. Stem growth, dry biomass, root length, chlorophyll content index (CCI), anatomical plant tissue changes, Cd accumulation and N and P removal from simulated stormwater were investigated over a 50-days period under different Cd doses (0, 1, 2 and 4 mg L−1). In addition, the effects of Cr dose (0, 500, 1000 and 2000 μg L−1) on the growth and anatomy of P. australis and I. pseudacorus, as well as on the accumulation of Cr in plant biomass and N and P removal were studied in FTW over a 50-day period. In addition, the effects of REE doses on stem growth, dry biomass, root length and their accumulation in biomass were investigated in two Salix species (S. myrsinifolia and S. schwerinii) and two cultivars (Klara and Karin) in FTW over a 28-day period. The REE treatments contained a single-dose of lanthanum (La: 50 mg L−1), multi-solute of six-REE (La: 11.50 mg L−1 + yttrium (Y: 11 mg L−1) + neodymium (Nd: 10.50 mg L−1) + dysprosium (Dy: 10) + cerium (Ce: 12 mg L−1) + terbium (Tb: 11.50 mg L−1)) and control (without REE). Moreover, REE recovery from biomass ash after combustion was investigated. In this study, P. australis and I. pseudacorus growth parameters were not hampered by Cd stress, their roots accumulated more Cd than the shoots and were capable of lowering N and P concentrations. The impact of Cr was more evident on plant growth under the low- and medium doses (500 and 1000 μg Cr L−1). However, anatomical changes were observed under the high dose (2000 μg Cr L−1, respectively). Both species were able to remove a substantial (98−99%) concentration of N and P within a 10-day period of increased Cr loading. The greatest amount of Cr was retained in P. australis and I. pseudacorus roots. Salix species and cultivars did not show REE toxicity symptoms and displayed a strong growth response compared to the control. All Salix accumulated REE in their biomass, although the greatest amounts of accumulated REE were found in the roots of the Klara and Karin cultivars. The substantial deposition of Cd and Cr in the roots of P. australis and I. pseudacorus, and REE in the Salix roots show their phytostabilization potential. Approximately 80% of the REE was retained in the Salix ash following combustion of the biomass at 1000 °C. The findings in this research reveal that these perennial plants could be suitable candidates to control the runoff from Cd, Cr and REE affected waterbodies into freshwater resources through immobilization aligned with efficient biomass production.
Boreal peatland forests are an important source of timber. Recently, timber harvesting has been extended to warmer months, resulting in machinery traffic over unfrozen soils, and leading to higher levels of soil disturbance, such as deeper ruts. Despite this, our knowledge of the impact of soil disturbance on peat physical properties and soil biochemistry is still limited. To address this gap, I conducted a study to examine the effects of soil disturbance caused by harvesting machinery during thinning operations on the soil physical, chemical, and biological properties and vegetation of drained boreal peatland forests. To assess the rate of recovery, I sampled six sites that formed a chronosequence covering 15 years since thinning. The results showed that soil disturbance caused an increase in the bulk density and field capacity of peat, along with a decrease in total porosity. In the vegetation, moss biomass and root production were reduced, but sedge cover increased. Furthermore, recently disturbed areas exhibited greater soil CO2 production potential, as well as higher soil CO2 and CH4 concentrations compared to control areas. However, CO2 and CH4 emissions, microbial communities, and cellulose decomposition rate were not impacted. Although the rate of recovery varied, all studied properties impacted by disturbance were fully recovered within 15 years. As the water retention characteristic (WRC) describes soil structure and its alterations, it a useful for disturbance assessment. Thus, I propose how WRC can be predicted using artificial neural networks. Overall, the study demonstrated that while drained boreal peatlands are sensitive to disturbance, they are also resilient to mechanical soil disturbance caused by thinnings.
Forested peatlands are globally significant carbon pools, important forest resources and areas for other bioproduction. Management of drained peatland forests has partly contradictory targets, such as economic profit, climate change mitigation and adaptation, and water protection. Balancing between these targets by comparing different management options requires a thorough understanding of the ecosystem processes, as well as modelling tools that are able to represent their complexity. This thesis presents three such tools, which are based on process-based models, and their applications to concrete water table management scenarios in drained peatlands.
All three works are built upon a common peat hydrological model. Two of the studies analyze the effect of canal-blocking restoration practices on the water table and carbon dioxide emissions in tropical peatlands. The first work shows that using optimization algorithms to choose the location of a fixed number of canal blocks can lead to sizeable improvements on the amount of peat they rewet. The second work systematically analyzes the impact of canal blocks on tropical peatland water tables, and provides insights about their performance for different weather conditions and peat types. The third study presents a peatland ecosystem model focused on the effect of drainage on nutrient dynamics and forest growth in boreal peatlands. By connecting the relevant hydrological and biogeochemical processes, this ecosystem model enables the study of interconnected phenomena such as the identification of the stand growth limiting factor, and the impact of typical ditch network management operations on the nutrient balance and forest productivity.
This thesis examines service trends in the operating environment of the forest-based sector on the level of companies and the evolving industrial production systems. The analytical framework is based on sociotechnical transitions research and service research knowledge bases on services and ongoing organizational changes in production and the markets. Three empirical studies have been conducted to detect service trends by investigating: 1) role of services in the European RDI roadmaps of the forest-based sector and parallel industries, 2) distribution of value and business model changes in the supply networks of industrial wood construction, and 3) market offerings and service innovation in sustainable housing construction projects in Finland. The empirical studies demonstrate evolving product service systems (PSS) in the further downstream customers of the forest-based sector, exemplified here by the construction sector. A game changing question for the forest-based sector is whether its industries and organizations focus on serving the PSS of today or whether they will seek to contribute to the next generation of PSS solutions, exemplified here by the potential for system change in construction regime. None of today’s PSS models alone capture the future PSS, but alternative scenarios are needed and assessment of their implications for the forest-based sector and future bioeconomy.
The global crises – climate change and biodiversity loss – have created a need for precise and wide-scale information of forests. Airborne laser scanning (ALS) provides a means for collecting such information, as it enables mapping large areas efficiently with a resolution sufficient for object-level information extraction. Deadwood is an important component of the forest environment, as it stores carbon and provides a habitat for a wide variety of species. Mapping deadwood provides information about the valuable areas regarding biodiversity, which can be used in, e.g., conservation and restoration planning. The aim of this thesis was to develop automated methodology for detecting individual fallen and standing dead trees from ALS data.
Studies I and II presented a line detection based method for detecting fallen trees and evaluated its performance on a moderate-density ALS dataset (point density approx. 15 points/m2) and a high point density unmanned aerial vehicle borne laser scanning (ULS) dataset (point density approx. 285 points/m2). In addition, the studies inspected the dataset, methodology, and forest structure related factors affecting the performance of the method. The studies found that the length and diameter of fallen trees significantly impact their detection probability, and that the majority of large fallen trees can be identified from ALS data automatically. Furthermore, study I found that the amount and type of undergrowth and ground vegetation, as well as the size of surrounding living trees determine how accurately fallen trees can be mapped from ALS data. Moreover, study II found that increasing the point density of the laser scanning dataset does not automatically improve the performance of fallen tree detection, unless the methodology is adjusted to consider the increase in noise and detail in the point cloud.
Study III inspected the feasibility of high-density discrete return ULS data for mapping individual standing dead trees. The individual tree detection method developed in the study was based on a three-step process consisting of individual tree segmentation, feature extraction, and machine learning based classification. The study found that, while some of the large standing dead trees could be identified from the ULS dataset, basing detection on discrete return data and the geometrical properties of trees did not suffice for acquiring applicable deadwood information. Thus, spectral information acquired with multispectral laser scanners or aerial imaging, or full-waveform laser scanning is necessary for detecting individual standing dead trees with a sufficient accuracy.
The findings of this thesis contribute to the existing deadwood detection methodology and improve the understanding of factors to take into account when utilizing ALS for detecting dead trees at a single-tree-level. Although remotely sensed deadwood mapping is still far from a resolved topic, these contributions are a step towards operationalizing remotely sensed biodiversity monitoring.
Water quality is significantly affected by the forest logging activities that are carried out in drained peatlands, which causes a notable enhancement in sediment loading and nutrient export to water bodies. Furthermore, the seasonal fluctuations in nutrient concentrations in the runoff further underscore the need for efficient water protection tools in peatland forestry.
To address these issues, biochar-based adsorption methods can potentially offer an effective alternative for water protection in peatland forestry. The current thesis investigates the potential for adsorption-based nutrient recovery from clear-cut peatland runoff water using Norway spruce and Silver birch biochars. In particular, the aim is to i) study the adsorption characteristics in relation to biochar properties and nutrient compounds in runoff waters in a small-scale laboratory experiment (Paper I); ii) investigate the adsorption characteristics of nitrogen (N) compounds from runoff water in a meso-scale laboratory experiment that utilises biochar reactors (Paper II); and iii) investigate the dynamics of biochar adsorption and desorption under fluctuating total nitrogen (TN) concentrations in runoff water (Paper III).
Biochar made from birch and spruce were shown to efficiently adsorb N compounds from the water. Across all experiments, the TN content declined significantly, irrespective of the scale, or whether the runoff volume ranged from litres (I and III) to hundreds of litres (II). Furthermore, the TN content at the beginning of the experiment declined at the fastest rate. The results indicate that cases of relatively low adsorption capacity were attributed to the low initial TN concentrations in the water. In addition, TN adsorption occurs above a threshold concentration in natural runoff water. The spruce did not adsorb TN when the concentrations in the runoff water fell below 0.4 mg L-1. In this thesis, biochar emerges as a compelling water protection solution, particularly in regions where clear-cut peatlands release substantial quantities of nutrients.
Numerous phenomena, such as sustainability challenges and the increasing importance of knowledge and digitalisation, have tremendous impacts on the global socio-economic system. These phenomena affect the dynamic and complex business environment where different actors from various sectors interact with each other. Responding to the phenomena and changes in the business environment calls for a systemic change in the ways that value-creating activities are performed. One suggested systemic change is a transition to a sustainable circular bioeconomy. Changes in the business environment pressure established business sectors, such as the forest sector, to reconfigure their networks and value creation logic, i.e., the ways in which actors co-create value.
In this dissertation I investigated how the value creation logic of the forest sector changes when entering the sustainable circular forest-based bioeconomy. The research design followed a qualitative theory-guided interdisciplinary case study strategy. I analysed scientific and non-scientific documents to determine the past and currently occurring adaptations within the forest industry’s value creation logic. I conducted interviews to identify the possible future value creation logic of forestry service providers and the readiness of forest owners to respond to the occurring changes.
According to the findings, the forest sector’s value creation logic is incrementally changing towards holistically sustainable, collaborative and cross-sectoral value co-creation logic. The sector has been able to reconfigure its networks and value creation logic in the past and it seems that the sector’s actors have understood the importance of cross-sectoral collaboration and intangible resources in the sustainable value-creating activities. They have acknowledged that their attitudes and actions will affect the future value creation within the sector. To reach holistic sustainability, actors need to consider the whole forest ecosystem as a capital and a resource base from where value and benefits for the common good are co-created in a forest-based sector.
As the need for genuine sustainability transformation crystallises, data’s digitalisation-enabled use creates opportunities to refine how businesses and societies operate. With the power of diverse data sources, available in increasing quantity, actors can set feasible environmental targets, identify improvement opportunities, implement actions, and follow development. The dissertation explores data’s role and value for corporate environmental sustainability and specifically for circular economy from four perspectives: the customer-perceived value of data for environmental sustainability (considered via studying a tissue-paper supplier), how data’ use influences sustainability pathways toward circular economy (specifically of textiles), paradoxical tensions that arise in utilising data to drive circular economy (in the textiles context), and how the literature characterises data’s role and value in circular business models. A company case study, disaggregative Delphi and literature review were used as research methods.
The work pinpointed availability of detailed, reliable product-specific data as crucial for supporting environmental sustainability and transparency of products’ value chains. Also, capturing data’s value here demands collaboration with customers and suppliers but also wider business networks, central to which are conditions for solid data-sharing. Consumers demand environmental sustainability, circularity, and accrue benefit from data-related decisions on individual purchases. The strategic and operative decisions/activities across business functions and throughout value chains further guide environmentally better-informed decisions. While use of data can be crucial to developing sustainable business models (for circularity specifically), the role varies less between models than with the activity supported.
The results clearly implies that neither environment-related data nor initiatives utilising data automatically benefit the environment; the interactions are more complex. Still, the data are a critical business enabler, and anticipating future data needs should dovetail with systematically developing environment-related data-management capabilities. These findings provide rich insight as to the elements, mechanisms, and critical issues of data driving environmental sustainability and circular economy.
Lignocellulosic energy crops can produce substantial amounts of biomass for energy purposes, but their introduction implies land-use changes as they are mainly cultivated in agriculturally dominated landscapes. This thesis presents a land-use analysis of lignocellulosic energy crops in the agricultural landscape in Sweden, specifically aiming to i) assess different energy crops’ regarding production, location and climatic profiles, ii) characterise and define the surrounding agricultural landscape, and iii) study the overall land-use changes derived from the establishment of energy crops in the country. The analysis is based on empirical data from commercial fast-growing tree plantations (willow, poplar, and hybrid aspen) and energy grasses (reed canary grass) at multiple spatial scales from field to landscape level, during the period 1986-2018. At field level, there is a trend for smaller and more regular fields dedicated to energy crops, with cultivation patterns moving towards more productive lands, reflecting an intensification in the land-use management. Willow was initially established mainly on fallow lands, but many plantations were subsequently replaced by cereals due to changes in global cereal prices. In the case of grasses, this pattern was similar, although changes appeared later and not so markedly. At landscape level, energy crops significantly diversify the agricultural landscape, as fast-growing tree plantations are largely introduced in cereal areas and grasses in forest-dominated landscapes. The methods and analysis of this thesis contribute to a better understanding of land-use changes associated to energy crops, and help define their contribution to diversifying the agricultural landscape.
To address the issue of climate change, the EU’s climate and energy framework has set targets to improve energy efficiency. Reducing greenhouse gas (GHG) emissions requires higher energy efficiency in the wood supply of forest industries. The aim of the study was to clarify the energy-efficiency baseline for wood-harvesting operations, define useful measures and follow up the total fuel consumption and resulting emissions.
The results indicated that wood-harvesting entrepreneurs have a positive attitude towards energy efficiency. The fuel consumption of wood-harvesting machines was the lowest for the final fellings, while in first thinnings, the consumption was highest per cubic metre harvested. The average cubic metre-based fuel consumption and GHG emissions in respect of wood harvesting were more than double in the first thinning compared to the final felling. Better allocation of harvesting machines could reduce fuel consumption and GHG emissions while improving work efficiency. Hour-based fuel consumption is most affected by machines’ engine power and wood-harvesting conditions of forest stands. Fuel consumption per cut cubic metre is affected by wood-harvesting conditions and machine units.
The calculated energy efficiency was highest in final fellings. A more significant factor than fuel consumption (input) is the amount of harvested wood (output) in the energy-efficiency equation. Energy efficiency can also be improved by operator education. Trucks which are used for harvesting-machine relocation have a significant impact on wood-harvesting operations' total fuel consumption and emissions. It is therefore essential to minimise the number of relocations and operational and resource planning should be developed. In the future, the examination of fuel consumption and GHG emissions should be extended to the entire wood-harvesting chain, including long-distance transportation and timber trade, and for example the effect of operator should be investigated in more detail.
Stable carbon isotope composition (δ13C) recorded in trees responds sensitively to the changing environmental conditions and thus provides a powerful tool for paleoenvironmental reconstructions. The retrospective interpretation of tree δ13C signal depends on comprehensive understanding of how environmental and physiological signals are recorded in δ13C during photosynthesis and how the δ13C signal is modified after photosynthesis.
This thesis aims to improve the understanding of photosynthetic and post-photosynthetic isotope fractionation processes, and to examine the suitability of tree ring δ13C for intra-seasonal reconstructions of intrinsic water use efficiency (iWUE). The former goal was studied by combining compound-specific isotope analysis of organic matter with isotope discrimination models and online δ13C measurements of leaf CO2 fluxes for field-grown mature Scots pine (Pinus sylvestris L.). The latter was achieved via comparing 18-year-long intra-seasonal iWUE chronologies estimated from laser ablation derived tree ring δ13C, gas exchange and eddy covariance data.
Mesophyll conductance and time-integral effect of leaf assimilates had a clear impact on the intra-seasonal dynamics of leaf sugar δ13C. No significant use of reserves was observed for biomass growth of needles, stem or roots of Scots pine. Unlike sucrose, leaf bulk matters had a significant δ13C offset from new assimilates, leading to a distorted environmental signal documented in their δ13C. The reliability of tree ring δ13C data for intra-seasonal iWUE reconstructions was supported by an agreement of intra-seasonal patterns across the iWUE estimation methods.
These results broaden our knowledge of the less well-known photosynthetic and post-photosynthetic isotopic fractionation processes, demonstrate the benefits of analysing sucrose δ13C for understanding plant physiological responses, and show that the tree ring δ13C based iWUE reconstructions can be extended to intra-seasonal scale. This information not only helps to better unravel δ13C signal in trees, but also improves reliable reconstructions of environmental and physiological signals from tree ring δ13C.
Sustainable forest management practices are crucial for minimizing environmental impacts, and to keep forests and the underlying soils healthy to maintain productivity, and to improve adaptability to climate change and mitigate it in the long-term. There, carbon and nitrogen cycling play crucial roles in proper functioning of forest ecosystems.
The overall aim of this thesis was to explore the effects of logging residues on the early-stage dynamics of the main nitrogen and carbon cycling processes in upland forest soils after final felling. A specific aim was to compare the effects of logging residue piles consisting of different tree species, i.e., Scots pine (Pinus sylvestris L.), Norway spruce (Picea abies (L.) Karst.), and silver birch (Betula pendula Roth). A special attention was given to the response of soil to different amounts of residues.
The effect of logging residues on soil chemical properties and processes was stronger in the organic layer than in the mineral soil layer. Logging residue piles stimulated carbon and nitrogen cycling, especially net nitrification within the first year after the residue treatment. Subsequently, nitrogen was lost via leaching as nitrate and gaseous emission as nitrous oxide. Nitrous oxide fluxes were generally low, although higher in the plots containing logging residues. Spruce residues tended to stimulate nitrous oxide emissions for longer than the residues of the other tree species. Depending on the tree species, nitrous oxide production originated from both autotrophic nitrification and denitrification. Nitrogen concentrations in the soil percolate water already accelerated one year after the establishment of the residue piles. Logging residues increased nitrate and ammonium concentrations, which were highest under birch residues. The effect of logging residue piles on soil was stronger when compared to milder tree species effects. Biological nitrogen fixation activity tended to be higher in branches than in needles or leaves, and higher in coniferous residues.
The results of this study raise the importance of more even distribution of logging residues on the forest floor instead of piling them to avoid harmful environmental effects and to maintain soil nutrient balance. The ability of soils to retain nitrogen needs additional attention in forest management practices, especially in boreal areas where nitrogen limits the growth of forests.
Boreal forest soils are globally one of the most extensive carbon storages, whereas soil respiration (CO2 efflux) forms the largest carbon flux from the ecosystem to the atmosphere. Current changes in the world climate may have unpredictable effects on belowground carbon processes, and thereby, on the carbon balance of boreal forests.
To better understand the various processes in soil and to quantify the potential changes in the carbon cycle, forest-floor respiration (RFF) was partitioned into five different components, and tree-root respiration (RR) was estimated, using four different methods in a mature boreal Scots pine (Pinus sylvestris L.) stand in southern Finland. Non-structural carbohydrate (NSC) concentrations in tree roots were determined, and carbon allocation to belowground by trees was estimated with the whole-tree carbon model ‘CASSIA’. In addition, RR and heterotrophic soil respiration (RH) were separated using root exclusion in seven coniferous forests along a latitudinal gradient in Northern and Central Europe.
The RR comprised almost half of the RFF, the RH almost a third, and ground vegetation and respiration of mycorrhizal hyphae the remaining fifth in the boreal Scots pine stand. While the annual RR decreased throughout the first three study years, the RH increased when the mycorrhizal roots were excluded from the treatments. The RR and most of the NSC concentrations were higher in the warmer years and lower in the cooler, as estimated with most of the methods. Three methods resulted in rather similar RR estimations, while the RR estimated with root incubation was significantly lower. The RR was over 50% of the annual photosynthesis in the northernmost forest stand, whereas in the southernmost stand it was only up to 15%. Carbon allocation to the belowground, as modelled with CASSIA was a third of the annual photosynthesis on average and almost 5% for the symbiotic mycorrhizae.
This study aims to 1) quantify the spatial and temporal variation in diffusive and ebullitive methane fluxes, and to 2) assess the quantity and quality of BVOC emissions and how they are controlled by vegetation composition and environmental factors in boreal peatlands.
Methane fluxes were measured with static chambers and bubble traps from a boreal ombrotrophic bog and compared to eddy covariance measurements on the ecosystem level. BVOC emissions were measured with dynamic chambers from the same boreal bog and a nearby boreal fen. Vegetation removal treatments were applied to differentiate BVOC emissions from intact vegetation, mosses, and peat.
Both methane and BVOC emissions showed strong seasonality linked to temperature and vegetation phenology. While diffusive methane fluxes did not differ between three years or different plant community types, methane ebullition was highest during the wettest of the three years studied and varied spatially being greater from open water pools than from wet bare peat surfaces. Decrease in water table led to higher ebullition, but so did also increase in air pressure. In total, ebullition contributed only 2 % – 8 % to the methane emission on the ecosystem level, which supports the general paradigm that diffusion through peat and aerenchymatous plants are the main pathways for methane from peat to the atmosphere.
Isoprene was the most emitted BVOC from both peatlands. Isoprene emission was strongly linked to sedges, and thus isoprene and total BVOC emission rates were higher in the sedge-dominated fen than the shrub-dominated bog. Moreover, total BVOC and isoprene emissions were highest from intact vegetation. However, organic halide emissions had stronger link with water level as they were absent during exceptional drought in the summer 2018. Therefore, warming climate and associated drougths and shrubification are likely to alter the quality and quantity of BVOCs emitted from boreal peatlands.
In Finland, peatland forests are significant for wood supply, although simultaneously, they are also important for biodiversity, carbon sequestration, water conservation, and recreation. In the 1960s and 1970s, peatland forests in Finland were extensively drained to increase tree growth and fulfil the needs of the forest sector. However, this extensive drainage has negatively impacted on the biodiversity of peatland ecosystems, and substantially increased nutrient and sediment emissions to lakes and rivers resulting in eutrophication, turbidity, and brownification of these water bodies.
This dissertation presents a number of approaches to move peatland forest management in a more environmentally sound direction, which may increase the general acceptability of peatland forestry. Airborne LiDAR (Light detection and ranging, i.e., laser scanning) derived 3D point cloud provides useful data, for example, to estimate forest biomass, to identify low-productive peatland forests, to model overland water flows, and to identify wet areas. The strength of airborne LiDAR is the ability of laser pulses to pass through tree canopies and obtain accurate observations from the ground level. The information derived from airborne LiDAR can enhance the planning of peatland forest management, as much of the planning can be done remotely, and supplementary field work can be implemented in areas of strategic need.
This study presented the novel idea of applying local binary patterns for the prediction of terrain trafficability, which should be considered in further studies and practice. The moisture index derived from the local neighborhood can reveal the small-scale variations in terrain moisture. This study also presented the novel idea to create spatial models to identify suitable locations for water protection structures, which may help forest managers to plan water protection of ditch network maintenance or peatland restoration operations. Overall, the utilization of airborne LiDAR-derived information for the development of peatland forestry practices shows great potential.
Boreal forests assimilate a substantial fraction of global atmospheric CO2 and thus play a key role in the global carbon cycle. However, due to the prevalence of evergreen species, monitoring photosynthetic dynamics of boreal forests is challenging when using conventional greenness- or vegetation-indices. Fortunately, an increasing body of evidence suggests that chlorophyll-a fluorescence (ChlF) – a weak red-to-far-red radiation emitted by the chlorophyll a molecules nanoseconds after light absorption – can enhance our capacity to assess photosynthetic dynamics in evergreen-dominated ecosystems. However, before extracting complete information embedded in the ChlF, comprehensive understanding and quantitative characterization of the mechanisms that connect the measured ChlF to photosynthesis across various scales are essential.
In this thesis, I discuss several challenges that we currently need to face to leverage the full potential of ChlF. I present a roadmap through these challenges, towards a more comprehensive interpretation of ChlF. The main focus is laid on the challenges concerning ChlF measured at a leaf-level in methodological and mechanistic contexts. In other words, this thesis contributes to the interpretation of ChlF by contextualizing the influence that methodological and mechanistic factors have on leaf-level spectral ChlF.
An impact of methodological factors, measuring geometry and sample arrangements, on spectral ChlF was analysed. Results indicate that ChlF shape is less dependent on measuring geometry as compared to ChlF magnitude and that if needle-mats are used, measuring geometry does not lower the comparability between studies using different setups. Mechanical factors were investigated in terms of their effect on spatial and temporal variation in spectral ChlF. The diversity of species and light environments within an ecosystem was shown to generate a temporarily-invariant, baseline variation in leaf spectral ChlF, as well as contrasting seasonal photosynthetic acclimation patterns. Consequently, I suggest the need for considering both the methodological and mechanistic contexts in the interpretation of ChlF.
Forests are dynamic ecosystems that are constantly changing. The most common natural reasons for change in forests are the growth and death of trees, as well as the damage occurring to them. Tree growth appears as an increment of its structural dimensions, such as stem diameter, height, and crown volume, which all affect the structure of a tree. Repeated measurements of tree characteristics enable observations of the respective increments indicating tree growth. According to current knowledge, the tree growth process follows the priority theory, where trees aim to achieve sufficient lightning conditions for the tree crown through primary growth, whereas increment in diameter results from the secondary growth. Tree growth is known to have an effect on the carbon sequestration potential of trees as well as on the quality of timber. To improve the understanding of the underlying cause–effect relations driving tree growth, methods to quantify structural changes in trees and forests are needed.
The use of terrestrial laser scanning (TLS) has emerged during the recent decade as an effective tool to determine attributes of individual trees. However, the capacity of TLS point cloud-based methods to measure tree growth remains unexplored. This thesis aimed at developing new methods to measure tree growth in boreal forest conditions by utilizing two-date TLS point clouds. The point clouds were also used to investigate how trees allocate their growth and how the stem form of trees develops, to deepen the understanding of tree growth processes under different conditions and over the life cycle of a tree. The capability of the developed methods was examined during a five- to nine-year monitoring period with two separate datasets consisting of 1315 trees in total.
Study I demonstrated the feasibility of TLS point clouds for measuring tree growth in boreal forests. In studies II and III, an automated point cloud-based method was further developed and tested for measuring tree growth. The used method could detect trees from two-date point clouds, with the detected trees representing 84.5% of total basal area. In general, statistically significant changes in the examined attributes, such as diameter at breast height, tree height, stem volume, and logwood volume, were detected during the monitoring periods. Tree growth and stem volume allocation seemed to be more similar for trees growing in similar structural conditions.
The findings obtained in this thesis demonstrate the capabilities of repeatedly acquired TLS point clouds to be used for measuring the growth of trees and for characterizing the structural changes in forests. This thesis showed that TLS point cloud-based methods can be used for enhancing the knowledge of how trees allocate their growth, and thus help discover the underlying reasons for processes driving changes in forests, which could generate benefits for ecological or silvicultural applications where information on tree growth and forest structural changes is needed.
The era of airborne laser scanning (ALS) and the development of new forest inventory methods has reduced the need for field visits and overall inventory costs over the last two decades. Although the development of inventory methods has been considerable, some systematic field visits are usually always required. For example, the most common ALS inventory method, the area-based approach (ABA), leans on field sample plot measurements. Likewise in the ALS inventory, the ABA method can also be used in drone-based inventories with image point cloud (IPC) data. Due to the small areal coverage of the drones, local sample plot measurements in drone image point cloud (DIPC) inventories are not usually profitable. The objective of this thesis was to examine the performance of ALS-based forest attribute models in ALS- and DIPC-based ABA inventories without new in-situ field measurements.
In this study, nationwide ALS models for three forest attributes (stem volume, above ground biomass and dominant height) were fitted for the whole of Finland, and regional-level error rates of the nationwide model predictions were assessed. As the nationwide models tended to exhibit systematic region-wise under- and over-predictions, different calibration methods were examined. First, calibration of nationwide models with a small number of new field measurements from the target area was simulated. Second, the nationwide stem volume model or its regional predictions was calibrated without new in-situ field measurements by three test scenarios: a) using additional calibration variables in the models to account for geographical and environmental conditions throughout the country, b) refitting of the models by using existing sample plots from nearby regions, and c) matching the regional-level predictions with national forest inventory data. The DICP-based forest inventory without new in-situ field measurements was evaluated by replacing the ALS metrics from the ALS-based models with DIPC metrics when the models were applied. In the DIPC inventory, the metrics used in the ALS models were selected carefully so that they would be similar to the corresponding DIPC metrics.
The results showed that forest attributes can be predicted without new in-situ field measurements using nationwide ALS-based models with moderate error rates. The systematic errors associated with the nationwide models decreased when the models were fitted with additional calibration variables, such as degree days, precipitation, and tree species proportions. However, the measurement of a carefully selected set of sample plots (e.g., 20 plots) from the target area for the calibration of the nationwide model is recommended, in instances where it is economically feasible. Prediction of forest attributes using ALS-based models with DIPC metrics is possible provided the predictor variables describe the upper canopy layer. The lowest error rates in DIPC-based inventories were obtained when the ALS-based model was fitted in a nearby region and the inventory units were disaggregated to coniferous and deciduous dominated areas before the prediction.
In Finland, there is a desire to extend the planting season from spring and early summer to autumn, and to use the closed cardboard box storage method for both dormant and non-dormant seedlings. This thesis examined the effects of planting practices and the growing environment on the early performance of boreal container seedlings, and specifically: i) What are safe durations for the field storage of non-dormant Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) seedlings in closed cardboard boxes and open tray storage for different planting seasons (I); ii) How planting success differs in one-year-old spring, summer, and autumn plantings of Norway spruce and Scots pine in practical forestry (II); iii) How the planting depth and/or planting season affect the early field performance of small-sized silver birch (Betula pendula Roth) and Scots pine container seedlings (III) and iv) How warmer growing conditions affect the growth and emissions of biogenic volatile organic compounds in boreal seedlings in a controlled field experiment (IV). Non-dormant conifer seedlings can be stored in closed boxes for three days in August and a week in May, September, and October, whereas for open-stored seedlings the duration is a couple of days longer (I). Norway spruce plantings can be successful from spring to autumn if seedling storage, duration, and planting instructions are followed carefully. In Scots pine, it is still recommended to plant seedlings only in spring and early summer due to the higher failure risk (II). Deeper planting (60-80 % of shoot underground) may also enhance the early field performance of small-sized seedlings (III). Silver birch might benefit more from climate warming compared to conifer seedlings (IV). To ensure forest regeneration success with boreal tree species, recommendations for seedling materials, storage, and planting practices in different planting seasons should be carefully followed.
Information on timber assortment recovery and wood quality is crucial for wood procurement planning, as the various tree species and wood dimensions and qualities may be utilized and refined in separate mills. The aim of this thesis is to improve our understanding of the timber trade in digital environments in order to support the planning of harvesting operations.
The work for the thesis was carried out in three areas, two of which (discussed in Papers I and II) were located in Eastern Finland and one (Paper III) in Southern Finland. The field data comprised tree characteristics obtained from 79, 99 and 665 sample plots (Papers I, II and III, respectively), 249 harvested stands (Paper III) and a stem quality database (Papers I and III), whereas the remote sensing material consisted of aerial imagery (Papers I and III) and airborne laser scanning (ALS) data (Papers I, II and III) covering all the sites.
With the stated overarching aim, we set out in Papers I and III to estimate timber assortment volumes, economic values and wood paying capabilities (WPC) for plots (Paper I) or stands (Paper III) with different bucking scenarios, and used the resulting timber assortment estimates to assess logging recoveries. The alternative bucking scenarios investigated were (1) bucking-to-value using maximum sawlog and pulpwood volumes but excluding quality (theoretical maximum), and (2) bucking-to-value using sawlog lengths at 30 cm intervals for Scots pine (Pinus sylvestris L., Papers I and III) and Norway spruce (Picea abies (L.) H.Karst, Paper III) and veneer logs of lengths 4.7 m, 5.0 m, 6.0 m and 6.7 m for birch (Betula spp., Paper III), either excluding or including wood quality indicators. The first approach resembled the state-of-the-art in Nordic forestry business circles and the second approach went beyond that. The commercial value of timber stands is substantially affected by the quantity of understorey trees, and pre-harvest clearing is typically needed when forest stands have an understorey vegetation that hinders harvesting operations. We therefore proposed a method in Paper II for estimating this need for the pre-harvest clearing of small trees (diameters at breast height < 7 cm).
The results showed that use of the methods developed in this thesis could support wood procurement practices by (1) locating valuable stands with the desired timber assortment distributions (Papers I and III), (2) identifying understorey vegetation that needs to be removed before harvesting (Paper II), and (3) reducing costs, as the number of field visits needed before harvesting will diminish (Papers I, II and III).
In conclusion, the present findings may make timber markets more competent, since the methods developed here provide detailed pre-harvest information that can be used as a decision support tool by either buyers or sellers of timber in traditional and digital marketplaces.
For the past 25 years, the Finnish state has supported the diffusion of wooden multistory construction into the construction sector. Given the socio-cultural and economic value of Finland’s forest sector, there is precedent to do so. Nonetheless, wooden multistory construction remains a niche construction practice in its formative phase. This dissertation researches the diffusion of wooden multistory construction by analyzing perceptions from municipal civil servants tasked with overseeing land use planning in Finland. Despite being gatekeepers of local construction activities, their perceptions towards wooden multistory construction are understudied. To access these perceptions, this research applies the theory of planned behavior. At the root of this theory lies the notion that beliefs underpin human action. Specifically, this dissertation research identifies (Article I) and operationalizes (Article II-III) the attitudes and beliefs that municipal civil servants hold towards wooden multistory construction. The results are distilled into three empirical accounts. Why not wood? (Article I) reframes elicited beliefs as barriers and benefits to wooden multistory construction. Benefits include a variety of holistic topics ranging from improving the lifestyles of citizens and supporting local wood-based businesses, to facilitating aspects of building construction. On the other hand, multiple barriers coalesce to form a risky and costly environment that results in project aversion. Wood versus concrete (Article II) analyzes how outcomes of implementing wooden multistory buildings are relativized against concrete multistory buildings. In large part, wooden multistory buildings are believed to possess several superior qualities (e.g., environmental performance, economic development outcomes). Nevertheless, apprehensions persist (e.g., they are more expensive to build and maintain, they are more susceptible to fire). Background experiences, especially occupational profession, play a key role in shaping several beliefs. Planning for wood (Article III) studies the relationship between how beliefs (i.e., environmental performance, economic development, cost-related attributes, technical qualities) form attitudes towards wooden multistory buildings. The prioritizations of beliefs vary according to occupational profession. Planning practitioners form attitudes holistically, based on the building’s environmental performance, technical qualities, and economic development outcomes. Other administrators form attitudes primarily based on the project’s economic development outcomes and technical qualities. Ultimately, municipal civil servants appear receptive towards implementing wooden multistory buildings in their municipalities, but this receptiveness hinges on project outcomes and the “societal goods” prioritized by the individual respondent. Even if wooden multistory buildings are perceived to possess superior qualities (e.g., environmental performance), these qualities may not strongly impact an individual’s attitude towards favoring the project. Different prioritizations among municipal civil servants might lead to planning tensions within the municipal administration, but it remains to be seen how these tensions enable (or hinder) wooden multistory construction diffusion.
The utilization of forest side-streams is associated with the applied bioenergy technology that must be impellent to support the increasing demand for biofuels and resources while lowering greenhouse gas (GHG) emission from the transport sector. This study aimed to estimate potential biofuel production from eutrophic (EL) and mesotrophic (ML) lake bottom biomass and the manufacturing side-streams from the pulp and paper mill (PI – PVIII). Theoretical biogas and bioethanol productions were modeled by Aspen Plus® simulation through 1) saccharification and fermentation, 2) gasification and mixed alcohol synthesis, 3) gasification-syngas fermentation, and (4) anaerobic digestion processes. In addition, the different process stages of the pulp and paper side-streams was studied by ABE fermentation using Clostridium acetobutylicum DSM 1731.
The bioethanol produced from EL and ML biomass from indirect gasification and mixed alcohol synthesis were 244.5 L/t and 57.1 L/t, whereas the yields from saccharification and fermentation were 137 L/t and 40 L/t, respectively. The EL biomass produced the most profitable bioethanol production from the latter process. The ML and EL biomass produced biogas of 38.9 mL/g volatile solid and 136.6 mL/g volatile solid, respectively. The ash from the EL and ML biomass and the dried samples of PI and PIII could be used as fertilizer because the harmful elements for Finnish fertilizer products were below the detectable limit. The primary sludge (PII) sample had found high N and P concentrations and cadmium (Cd) concentration (3 mg/kg), which exceeded the Cd limit for Finnish fertilizer products (1.5 mg/kg). However, wet primary sludge (PII) forming 300,000 tonnes/year (72600 dry tonnes) produced anhydrous ethanol about 3011 kg/h (24,090 tonnes/year) when PII was used for the gasification-syngas fermentation process in the bioethanol plant model.
Three pulp and paper side-streams (PI, PII and PIII) with unwashing and water washing were pretreated with dilute acid (0.2% H2SO4 at 180 °C for 10 min), followed by saccharification and ABE fermentation. The results suggested that water washing did not affect the PII and PIII prehydrolysate sugar recovery, as well as enzyme hydrolysis of the rejects from kraft pulping (PI) did not require prewashing before dilute acid pretreatment. In addition, the unwashed PI side-stream yielded the highest ABE concentration of 12.8 g/L, compared to the unwashed PII and PIII side-streams, 5.2 g/L, and 6.3 g/L, respectively. The side-streams from different process stages in pulp and paper mill were concluded to be high potential feedstocks for biofuels production due to their chemical compositions. The unwashed PI was suitable feedstock for butanol production, while PII could be fully utilized in the integrated gasification-syngas fermentation process. Primary sludge (PII) was found to be a promising feedstock for bioethanol and an internal rate of return (IRR) of 15 % can be obtained by two implementations. One was a cost-competitive ethanol selling price (ESP) of €0.61–0.71/L with an ethanol subsidy of €150/t at different tax rates, and the other was an ESP of €0.60–0.70/L with the imposition of a €20/t gate fee. In the future, the addition of an integrated biofuel production operations unit, installed close to a pulp and paper mill, could utilize the different pulp side-streams and create further revenues to the mill owners.
The forest biomass supply represents an important part of the value chain for different wood-based products, and its environmental impacts are also frequently crucial. The performance of biomass supply chains (BSCs) can be assessed for various purposes and using a variety of methodological approaches, either including or excluding spatial properties. The purpose of this thesis was to investigate what kind of spatial data are required and available for case-specific BSC analyses in Finland, and what would be suitable levels of spatial precision for the various approaches. This thesis consists of five papers, one of which reviews case studies carried out in various geographical BSC environments around the world, while the remaining four are spatial case studies of BSC systems in Finland, three of them focusing on bioenergy production and one assessing the performance of a novel pulpwood transportation concept. A geographical information system (GIS) was used as the principal tool in one study, while in the other three the role of GIS was to produce spatially analysed data for life-cycle assessment and agent-based simulation. The main conclusion is that a spatial precision of between 1 km and 10 km, where each point of origin represents roughly an area of 1–100 km2, is sufficient for forest biomass data in Finnish BSC systems. The final precision should be determined collectively by the setup of the case study, factors leading to complexity in the supply chain system and the geographical extent of the area concerned. Relative to many other parts of the world, Finland has a readily available high quality source of spatial data for BSC research. It is recommended that GIS-based research could be improved by adding dynamic properties and stochasticity to the models, because temporal variations in feedstock supply and demand will probably increase in the future.
Decision making for sustainable development calls for scientific support in anticipating the possible consequences of decision alternatives and identifying the trade-offs between these alternatives. At the EU level, there has been a consistent movement toward the utilization of Sustainability Impact Assessments (SIA). First, the EU Strategy for Sustainable Development voiced the need to look at how EU policies contribute to sustainable development. Next, the European Commission committed to perform impact assessments of all proposed major initiatives. SIA can be used to study how factors such as policy, management, or technology development affect the sustainability of a sector or value chain and helps to inform decision makers about consequences of decision alternatives.
The Tool for Sustainability Impact Assessment (ToSIA) was developed to achieve a holistic assessment method for structuring sustainability questions as value chains of interlinked processes that enable evaluating the impacts of changes in these chains. To evaluate these changes, indicators of ecological, economic and social sustainability are utilised to describe different sustainability dimensions. Selecting the preferred alternative within these calculated differences in sustainability indicators may imply trade-offs and is enabled for example by the multi criteria analysis appended on top of ToSIA. The use of ToSIA is demonstrated through its application in numerous case studies conducted by various organizations and scholars.
This thesis presents the developed ToSIA from a methodological point of view, describing how the method is used. ToSIA is the first software implementation of a method that combines material flow based value chain analysis with indicators of different sustainability dimensions and harmonized system boundaries. ToSIA is a valid tool for evaluating consequences of the difficult decisions ahead that need to be made as we strive to enact a transition both to a 1.5 degree warming future, as well as a more sustainable humankind.
Below-ground carbon (C) allocation studies in boreal forests are scarce and have high levels of uncertainty in ecological and modelling studies. The uncertainty of fine root turnover and the heterogeneity of fine root distribution are the main barriers to quantifying the below-ground C allocation. Unravelling the below-ground C litter inputs of boreal forests, including fine roots and ectomycorrhizal (EcM) mycelia, could provide fundamental information for quantifying biogeochemical cycles. This thesis evaluated the below- and above-ground litter C inputs along a site type gradient of Scots pine (Pinus sylvestris) sites in southern Finland, and a distinct silver birch (Betula pendula) site in northern Finland. Furthermore, the Scots pine pioneer/fibrous root growth phenology was observed and compared with the modelled growth of the above-ground organs (predicted by the dynamic CASSIA model) in southern Finland in 2018, when there was an unusual summer drought. Fine root turnover was observed by minirhizotrons (MR) and the root growth phenology was observed by flat-bed scanners, both of which direct methods are known to provide reliable results in root research.
Based on the daily root growth monitoring experiments, we found that the timing of intensive root growth lagged behind the growth of above-ground organs (shoots, secondary xylem, buds, and needles). Interestingly, we found a clear root growth increase while the needle growth decreased, which may have been caused by a shift of non-structural carbohydrates (NSC) from above-ground to below-ground. The low temperature and summer droughts may have constrained the fibrous root growth, but not influenced the pioneer root growth, which indicates that pioneer roots could be more tolerant to severe climate variations.
Increasing nutrient availability could clearly increase the above-ground C allocation but not the below-ground allocation. Our study sites CT, VT, MT were named after Cajander’s Finnish site type theory in the order of increasing nutrient availability. Our study found that the nutrient-poor site CT tends to have significantly higher fine root longevity and biomass than the relatively nutrient-rich sites VT and MT. Fine roots could allocate more biomass below the ground and survive longer in nutrient-poor conditions. The distal tips of tree roots reflect the forest foraging ability, as shown by the fact that EcM root tips per basal area and fine root biomass per basal area both increased gradually from nutrient-rich to nutrient-poor sites and from low to high latitudes. Overall, we found that below-ground litter accounts for 21-58% of total litter inputs in boreal forests. This finding indicates that the C allocation pattern could be a specific effect of species and latitudes. The Scots pine in the southern sites allocated up to one third of total litter inputs below the ground but the northern silver birch allocated over half of total litter inputs below the ground.
In conclusion, we suggest that the growth phenology and litter inputs of below- and above-ground organs should always be observed and quantified together. Understory species contributed significantly to litter C inputs which should not be neglected in boreal forests.
Moreover, future studies should be focused on the shifting of below- and above-ground C allocation response to extreme climate and also on the need to include EcM mycelia and root exudates in the accounting of below-ground litter pools.
Forests and forest-related sectors could play a major role in the transition of the global economy from dependence on fossil fuels and non-renewable raw materials to sustainable production and consumption. Forest resources in Russia account for over 20 % of global stocks and can play a significant role in the development of the new forest-based bioeconomy. However, Russian forestry remains very much orientated towards traditional, long-standing foundations that were designed in the middle of the last century. Many of the foundations are out of date and require development. Several attempts have been made to innovate Russian forestry, and recently these have been closely linked to learning and understanding the Nordic experience in forestry, particularly from Finland and Sweden. Interest in Nordic forestry was stimulated by the greater productivity and profitability, achieved under very similar environmental conditions to Russia. Investment in soil preparation, active silvicultural systems, and road construction, as well as the utilisation of wood-based energy, are among the factors that affect the outcomes of forestry in Nordic countries. As such, it is believed that Nordic forest practices could bring several innovative and proven-over-time solutions to the development of forestry in Russia. However, due to the unique institutional and operational frameworks that currently exist in the country, Nordic forest solutions cannot be readily adapted for the local conditions. Transfer and implementation of the solutions require an understanding of the Russian operational environment.
Thus, the general aim of this thesis was to systematically analyse the opportunities and challenges of reforming the forestry sector in Russia through the adoption of possible innovations from Finland and Sweden. The study focused on the Nordic forest solutions in intensive forest management (NIFMS), road construction (NFRS) and forest energy utilisation (NFES). In addition, the general principles of strategic planning and thinking used by the Russian forestry companies were studied. The empirical part of the study was based on an analysis of the situation in the Republic of Karelia, one of the main forest regions in Russia, whose territorial and resourcing indicators are commensurate with Finland and Sweden. The key findings and conclusions are of relevance for other forest regions in Russia.
According to the results, Nordic forest solutions look promising for the Russian forestry sector, although transferring and implementing the solutions in Russia might be limited due to political and legislative factors in the local operational environment. Specifically, the prospects of NFRS are accompanied by an unprepared regulatory climate regarding the prolongation of forest leasing contracts, while NFES is stymied by a lack of sufficient economic and legislative drivers to support the development of biofuels in Russia. A sufficiently dense road network and the utilisation of energy wood are important components of NIFMS, where the latter is cited as the centrepiece of the solutions. Therefore, the solutions need to be addressed in an integrated manner, as a single packaged issue. The planning and application of the solutions should follow the principles of sustainable development, otherwise, the solutions might fail in the long-term. These principles are not yet embedded in the Russian operational environment and this should be carefully considered in future forestry development in the country.
Forest fires are an ambivalent issue in Fennoscandia. Although most long-term fire-history studies show a decrease in burned areas, the recent large fires have set challenges for the future given the increasing demand to develop more effective fire management methods. On the other hand, the low impact of fire has raised concerns regarding how to safeguard fire-induced biodiversity. Related to these subjects, in my thesis I have studied fire scar formation, the flammability of the most common ground layer fuels and the state of prescribed burning in Finland.
The main findings of my thesis were:
These major findings of my thesis could be of use in enhancing forest fire prevention and prescribed burnings as well as in interpreting past fire regimes.
The performance of a forest inventory is typically evaluated using error indices, such as root mean square error (RMSE) and the difference between means of observed and predicted attributes (MD). However, error indices or errors as such, do not fully reveal the practical usefulness of forest inventory data. Using erroneous inventory data as a basis for management planning may have harmful effects on forestry decision-making. Errors in inventory data can lead to the selection of management prescriptions that differ from the optimal prescriptions based on error-free data. Eventually, differences in the selected prescriptions result in losses in regard to the objectives set for the management. The main aim of this thesis was to assess the effects of inventory errors on forest management where the objective is to maximize the net present value (NPV) of timber production and carbon payments. The studies considered different combinations and levels of errors in forest stand attributes and evaluated the effect of errors on the optimality of management prescriptions based on the expected economic losses, which were measured in NPV. The results showed that expected losses depend on the error rate of those forest stand attributes, which are used to describe the present state of the forest in the planning system. In particular, the results indicated that errors in mean diameter can be more harmful than errors in the basal area. Increasing the sample size in a remote sensing-based forest inventory increased the accuracy of predicted stand attributes and decreased the expected losses. The inclusion of carbon payments in the maximization of NPV showed that the effect of errors on expected losses decreases when the carbon price increases. The findings of this thesis indicate that it is very important that the effects of inventory errors are considered in forest management planning.
Frost hardiness (FH) is one of the limiting factors for the successful growth of woody plants in the boreal zone. To cultivate the plants in cold conditions, they need to be tested before they are launched to the farmers and forest owners. Appropriate preconditioning for the different progenies of the plus tree of forest seedlings within the same species, and different horticultural woody species and cultivars are not known well. To answer those questions, this study designed and implemented experiments for Scots pine (Pinus sylvestris L.) progenies, for three horticultural species, i.e., apple (Malus domestica Borkh.), blueberry (Vaccinium corymbosum L.), blackcurrant (Ribes nigrum L.), and for pear cultivars (Pyrus communis L.). The study is composed of three parts with the following aims: i) to determine whether the pollination site affects the FH of the Scots pine progenies, ii) to determine the proper late-autumn preconditioning before running the frost hardiness tests of different apple, blueberry, and blackcurrant cultivars, and iii) to determine the effects of a short warm spell in mid-winter on the FH of pear cultivars. One of the important aims of the thesis was to assess and compare the different FH testing methods with the help of the experiments executed here.
The first part of the study consisted of the progenies of Scots pine plus-tree seed orchards in Finland and Ukraine, in addition to the progenies from natural stands in Finland, with three seed lots from each site. FH was examined twice during cold acclimation in controlled conditions. The second part concerned the effects of different preconditioning temperatures (+3, −3, −7, and −10 °C) and their durations (one or three weeks) on the FH of two apple cultivars, three blueberry cultivars, and three blackcurrant cultivars. The third part concerned the effects of short term warm spells in mid-winter on the FH of three pear cultivars that were preconditioned in natural conditions, then dehardened in a growth chamber at +5 °C for either 3-4 days or 16 days, and then rehardened at −7 °C for 5-7 days.
It was found that the freezing test temperature had a strong effect on the physiology and growth of different organs of the plus-tree progenies of Scots pine, but no consistent differences were found in FH among the progenies. The proper preconditioning temperature for the development of the maximum frost hardiness of the aboveground parts in late autumn is three weeks at −3 °C for apple and blueberry, though a shorter time for blackcurrant would be enough. The frost hardiness of the pear cultivars responded to temperature changes in mid-winter, but less than expected, and the responses were similar in all cultivars. In addition, the FH estimates of the stem by electrical impedance spectroscopy (EIS) and relative electrolyte leakage (REL) were quite similar, but these methods overestimated FH when compared to the FH by visual damage scoring. DTA results had a small variation compared to other methods but the use of DTA is limited due to the low occurrence rate of the low temperature exotherm (LTE) in several species (e.g., blackcurrant).
This study creates new methods for assessing unpaved forest road quality using airborne laser scanning (ALS) data. The low and high pulse density ALS data were first processed and digital elevation models (DEMs) created at several resolutions from 0.2 m to 1 m. Different interpolation methods such as IDW, NN, Spline, and Kriging were compared in the first phase, and IDW was chosen for further calculations. The work focuses on road quality properties such as surface flatness, surface wear quality, road structure, ditch quality, road drying properties, and water accumulation, and also the vegetation cover on and beside the road.
The roads were divided into three categories using the Metsäteho forest road quality assessment system. Active/deactivated road status was assessed on Vancouver Island, Canada. Linear discriminant analysis was used to find the best predictors of the road quality classes, the result being validated using confusion matrices, by k-fold cross-validation, and/or by calculating kappa values. A combination of surface indices, the topographic wetness index and soil information provided high precision (81.6–89.8%) information about unpaved forest road quality. Simultaneously, the indices individually showed promising results when applied to high pulse density data. The classification based on vegetation growth was up to 73% correct, while the presence of a ditch system and its status as mapped using the high resolution LiDAR data was up to 92% correct.
The findings indicate that the use of LiDAR data can help forest managers gain more information about the quality and status of forest roads in remote areas without spending extra resources (time, transportation costs, personnel) on checking the road network manually. Although the use of ALS data for road quality assessment cannot yet replace field visits, it opens up possibilities for further research and offers the option of combining these novel approaches with other road assessments.
This dissertation examines current collaborative practices in wooden multistorey construction (WMC) projects through a business ecosystem approach to detect effective and ineffective practices when working with novel wooden materials and gaining knowledge of them. Furthermore, it deepens our understanding of citizen perceptions and homeowner experiences towards WMC, to ensure that professionals are able to construct buildings that are not only profitable, but also appreciated by end-users and functional in daily use. Qualitative means are used to provide an in-depth view of the matters.
The findings reveal that while construction projects are essentially collaborative efforts, the novelty of WMC materials and methods requires increased communication and learning between the business ecosystem participants. The keystone of a business ecosystem has a fundamental role in enabling deeper, long-term commitment between participants through procurement practices and meetings. These allow participants to work towards a common goal and to accumulate knowledge of wooden construction also between projects. Feedback processes should be improved between the participants, but homeowner experiences should also be utilized more efficiently. The results imply that while the business ecosystem approach provides a usable lens to study collaboration in WMC projects, it should not be seen as a static system concentrating on the design and construction phases, but one that evolves throughout a building’s life cycle, incorporating end-users as the ecosystem keystones when moving to the use phase of the building.
Furthermore, the results support previous literature in that end-users appreciate soft aspects of wood material, such as aesthetics and ambiance, while durability and maintenance needs create concerns. However, the qualitative approach used in this study reveals that some aspects are multifaceted, carrying both positive and negative meanings for the end-users. Homeowner experiences indicate the importance of the everyday usability of home materials. Furthermore, the ‘liveliness’ of the wooden material seemed to surprise some of the homeowners, indicating that they are more familiar with other urban construction materials. Communication with end-users should therefore be improved to decrease concerns, but also to inform about the material’s practical benefits such as pleasant soundscapes.
To better understand the underlying processes of many natural phenomena, accurate observations and measurements must be carried out in space and time. Considering forest ecosystems, monitoring the development and dynamics of tree characteristics is essential in this regard. An era of three-dimensional (3D) sensing techniques and point clouds has revolutionized individual tree observations, enabling measurements at an unprecedented level of detail. The feasibility of using point clouds to characterize trees and tree communities in space and their development in time was investigated in this thesis. The objective was to develop point cloud–based methods for distinguishing and characterizing trees and downed dead wood and to test the feasibility of the developed methods in boreal forest conditions.
Point cloud–based methods for detecting and characterizing forest structure were developed in studies I–III. Downed dead wood trunks could be distinguished from the undergrowth vegetation and near-ground objects by means of their regular, cylindrical geometry. Smooth, cylindrical surfaces and vertical continuity, on the other hand, were the key characteristics of point cloud structures to separate woody structures of standing trees from foliage and a tree stem from branches. The methods were tested in diverse boreal forest structures to validate these methodological principles.
The feasibility of the developed methods for characterizing trees and tree communities in space and time was tested in studies II–V. The structural complexity of a tree community was noted as the most important factor affecting tree-detection accuracy. High performance of the point cloud–based method was achieved on managed forest stands with a low degree of variation in tree size distribution. In controlled thinning experiments, thinning intensity was found to be a more significant factor affecting the performance than thinning type (i.e. thinning from below, thinning from above, and systematic thinning). The hemispherical measurement geometry of terrestrial point clouds was successfully complemented with aerial point clouds acquired from above the canopy to improve the vertical characterization of trees and tree communities. Finally, the capacity of bitemporal terrestrial point clouds to characterize changes in the structure of trees and tree communities was demonstrated. If there was an increase or decrease in the attributes of trees within a tree community detected with conventional forest mensuration techniques, a similar outcome was achieved with the point clouds.
The findings of this thesis improve the current knowledge of the feasibility of using point cloud–based methods in observing tree characteristics. Detailed 3D reconstruction of forests expands the spectrum of tree observations, as the dynamics of trees and tree communities can be monitored in more detail. This increases the understanding of processes shaping ecosystems and provides new approaches to improve ecological knowledge.
This research focuses on stand dynamics and ecological recovery in miombo woodlands, Morogoro, Tanzania. The study uses the Kitulangalo Permanent Sample Plots (PSPs) to analyse tree species’ site-specific growth, regeneration dynamics, and stand development using empirical and modeling approaches. The high number of tree species in miombo necessitated the formulation of three species groups involving 1) trees that grow relatively rapidly to be dominants in top canopy layers 2) trees that stay mainly in the lower and middle canopy levels and 3) trees that grow slowly but persistently and may eventually rise to dominant and codominant canopy positions applied in studies I and III. Study III also applies three harvesting alternatives, which align with the recommended harvesting practices for these woodlands.
Diameter increment varied with the change in basal area growth across species groups, reaching a maximum of 3.2 cm (group 1) during 2008-2016. Density-dependent mortality and ingrowth also varied with species group as higher mortality rates dominated the lower and middle canopy layers due to asymmetrical competitions. Fencing the plots prompted thick grass cover. The drop in the total number of regeneration stems and the simultaneous increase in the number of main stems in fenced areas and dense plots indicated a self-thinning process induced by competition. This is linked to multi-stem regeneration undergoing a morphological transformation into single-stem saplings (main stems) and eventually becoming small trees. Harvesting intensity, density-dependent mortality, and ingrowth regulated stand basal area and therefore stand growth and development during the simulation. Stand structural development was dominated by species groups 1 and 2, indicating sustainability in species composition and structures. Stand development was affected by the addition of new stems of each species in each simulation year.
Miombo stands have demonstrated the potential to attain a steady-state condition over the medium-term under-regulated stand conditions and silvicultural treatments. The developed models, treatments, and harvesting alternatives may be limited in application to Kitulangalo and similar lowland miombo woodlands in Tanzania. Future studies concerning stand conditions, silvicultural treatments, and harvesting alternatives are vital for a better understanding of stand dynamics in miombo woodlands in Tanzania.
This dissertation studies the stand-level economics of continuous cover and rotation forestry. The main method of this dissertation is economic-ecological optimization, where statistical-empirical size-structured ecological models are coupled with economic optimization models including fully flexible optimization between continuous cover and rotation forestry. The dissertation consists of a summary section and three original research articles. The first article compares the favourability of continuous cover forestry between pure Norway spruce (Picea abies (L.) Karst.) and Scots pine (Pinus sylvestris L.) stands and studies the effects of ecological models on economically optimal solutions. The second article studies the economics of mixed-species stands with up to four tree species. The third article studies the economics of arctic forestry in the homeland region of the Sámi people using a model that simultaneously includes timber production, carbon storage, and negative externalities of forestry on reindeer husbandry.
According to the results, the differences in continuous cover forestry favourability between tree species are largely dependent on both species-specific differences in natural regeneration and natural regeneration differences between ecological models. Under realistic economic parameters, our model specification yields the result that continuous cover forestry is optimal for Norway spruce in both single- and mixed-species stands. In contrast, Scots pine favours rotation forestry in both single- and mixed-species stands. Physical overyielding of a species mixture does not reveal the economic preferability of that species mixture. In addition, we demonstrate that economically optimal continuous cover forestry avoids “high grading”, i.e. selective harvesting that leads to a completely different and economically inferior outcome. Including the negative externalities of forestry on reindeer husbandry into the economic model favours continuous cover forestry in arctic Scots pine stands. A carbon price between €14–€20 tCO2-1 is enough to imply that saving old-growth forests as carbon storages and reindeer pastures becomes optimal.
Establishing protected areas and maintaining biodiversity in managed forests are the main methods to conserve forest habitats and their biodiversity. The habitat characteristics that affect forest biodiversity in both protected and managed forests occur on different spatial scales, with the smallest scale consisting of structures at the level of single trees and smaller. Under the influence of dynamic processes (ecological succession, natural and anthropogenic disturbances) small-scale structures may be strongly affected, altering their contribution to local biodiversity.
In this thesis, I studied two small-scale structures in northern boreal forests: deciduous trees (mainly European aspen (Populus tremula)) in conifer-dominated forests and woodpecker-made breeding cavities. These structures provide resources for multiple species. However, their abundance could be affected by dynamic processes, also in protected areas. I examined the temporal dynamics of these structures through long-term (16–30 years) monitoring. Specifically, I studied the recruitment of deciduous trees in managed forests, aspen demography in old-growth forests, the effect of tree- and stand-level factors on cavity persistence, and the potential to detect aspen for conservation purposes via remote sensing.
My main findings were:
1) Recruitment of deciduous trees is enhanced by prescribed burning. Mammalian herbivory impacts recruitment significantly, although its effect depends on forest age.
2) Living aspens declined by 37% in protected old-growth forests over an 18-year period and recruitment rate was low despite an abundance of saplings. Recruitment primarily occurred on forest edges.
3) Tree species, size, and condition affect the persistence of woodpecker-made cavities, with cavities lasting longer in coniferous, healthy, and larger trees. For aspen, cavities in small trees also persisted a long time.
4) Multispectral drone images can be used to detect scattered mature aspen trees in old-growth forests, most ideally in late spring.
My results emphasize that dynamic processes in forests can alter forest characteristics that are important for biodiversity quickly. Small-scale structures, that are essential to maintain local biodiversity, underwent strong changes in just a few decades. My thesis highlights the importance of continuous monitoring of biodiversity-rich habitat structures to uncover major changes in the ability of protected areas to sustain biodiversity. Remote sensing is potentially a valuable monitoring tool, also for tree-level small-scale forest structures.
Ozone (O3) and nitrogen oxides (NOx: nitrogen monoxide NO and nitrogen dioxide NO2) are reactive gases with an important role in atmospheric chemistry. Terpenes are a reactive subgroup of BVOCs (biogenic volatile organic compounds) emitted by plants. Needle or leaf surfaces are the first point of contact between the atmosphere and a plant. Boreal forests represent a significant portion of the global land area available for atmosphere-biosphere interactions.
The aim was to develop methods for observing the exchange of NOx in field conditions and to explore the roles of terpenes on needle surfaces and nitrate fertilization on the fate of O3 and NOx in plant-soil-atmosphere interfaces. The methods included whole-canopy measurements, shoot-scale chamber measurements, needle sampling and laboratory analyses, utilizing both continuous observations and experimental setups.
In the studied low- NOx environment, the shoot-level NOx fluxes were too small to be monitored accurately in field conditions with an automated dynamic chamber. In addition to interference, the signal to noise ratio was low, and a significant proportion of the observed fluxes were to/from chamber walls. No clear NOx fluxes from Scots pine foliage were detected, and there was no effect of nitrogen fertilization on the observed fluxes. It seems unlikely that a fertilization treatment could cause significant NOx emission from boreal pine forests. The fluxes reported in our earlier studies included compounds other than NOx.
Shoot terpene emissions and needle wax extracts were both dominated by monoterpenes. There was variation in the terpene spectra of both emissions and wax extracts. The proportion of sesquiterpenes was higher in the epicuticular waxes than emissions, and the observed sesquiterpene compounds were for the most part different in the emissions and wax extracts. The role of direct transport through the cuticle from sites of terpene synthesis may be more important than has been assumed.
This study analyzes the political legitimacy of forest and forest-related nature conservation policies in Finland. Legitimacy is defined here that the forest and nature conservation regimes and related political institutions are perceived as rightful among the people.
The major contribution of this study is the comprehensive conceptual framework of legitimacy based on several theories, mainly from political science. The framework analyzes the objects of support, patterns of legitimacy, performance evaluations, and how these relate to one another. In this study, the objects of support refer to forest-related political institutions; these include regulations and public incentives, as well as decision-making processes, political programs, and administrative procedures. The framework is intended to be especially useful in the empirical analyses of pluralistic public political discussion and uses a methodology developed for this purpose. The study also analyses the social values of organized political actors.
The empirical part of this study explores a data set from Finnish print media discourse, based on letters to editors in three newspapers and in one journal, along with comments given during the preparation of Finland's National Forest Programme 2010. Another empirical data set consists of qualitative semi-structured interviews and the writings of the organized interest groups.
Many different groups of citizens were found to participate in public discussion on forests. Quite a large number of individuals shared the overall publicity, despite the fact that there were some very active writers. Nature conservation organizations, researchers, and politicians were well represented. However, the participation of governmental officials from both the forest and environmental sectors can be characterized as insufficient, considering their importance in the implementation of policies.
The study of letters to editors found that groups of common social values served as patterns of legitimacy in the performance evaluations of forest policies. These include welfare and wellbeing derived from forests; values related to nature conservation; democratic values; distributive justice; good governance; core regime principles; and fair markets. Of all performance evaluations, 52% were negative while 26% were positive and 22 % were mixed.
The welfare of citizens and the nation, export incomes and employment were the most common justifications used in the legitimacy evaluations while economic growth was a topic that divided opinions. Principles related to values of nature and sustainable development were almost as common in the data. A common argument related to the wellbeing of future generations combined the ideas of benefits and nature values with the idea of distributive justice.
Democratic values, especially the public participation of the involved groups of people and public deliberation were common sources of legitimacy. Most political actors supported the ideal of conciliatory decision-making, while smaller group preferred strictness and non-compromising political action.
Private property rights and the so-called everyman's right were found to be strong supporting arguments. In addition to the recognition of private ownership of forests, they were on the other hand perceived as national heritage. The perceived fairness of the distribution of benefits and burdens was mostly based on comparisons between people or groups of people; these include countryside vs. cities, Finland vs. foreign countries, forestry vs. other forest user groups, and present vs. future generations.
Both forest and nature conservation-related public administration faced positive and negative feedback. Public officials were expected to obey domestic and international legislation and to oversee the implementation of laws in an impartial and consistent manner. On the contrary, perceived arbitrariness, paternalism, and disrespectful behavior by officials were perceived as illegitimate.
Concerning the markets, the rules of fair competition were often mentioned as a source of legitimacy, while monopolies and cartels were mentioned as sources of illegitimacy.
In the interviews of organized actors, the forestry actors maintained that the central sources of legitimacy are the benefits for the national economy, employment and export incomes, as well as property rights and the value of nature in terms of its benefit for humans while the nature conservation-oriented actors had an understanding that nature has an intrinsic value independent of its benefits to people. Lack of trust was characteristic of the polarized policy field. However, traditional rights of ownership, everyman's right, and citizens’ rights to influence forest policy comprised a common ground between the actors.
Domestic, EU-level, and international legality were commonly perceived as sources of the legitimacy of policies. Finland's good international standing and its role as a moral and economic forerunner were very common principles in the evaluations in both the forest and nature conservation policies, in all parts of data. The same idea was also found central in the national forest programs and strategies. The shared goal of the Finns seems to be that the nation would be best in the world both in forest and nature conservation policies.
Despite some disagreements concerning the performance of institutions, most of the social values that serve as a basis of legitimacy seem to be quite commonly supported in Finland, where support of major governmental institutions and general trust among people are at a relatively high level. The value discussion related to forests is part of a larger discussion on social values that seems to continue far into the future.
The aim of this thesis was to test the possibility of using the residues and side-streams from Finnish wood and coffee industries as active ingredients in wood preservative formulations, as well as to compare their acute ecotoxicity. Pyrolysis distillates of bark from Norway spruce (Picea abies (L.) H. Karst.), silver birch (Betula pendula Roth) and European aspen (Populus tremula L.), the organic acids identified in these distillates, spent coffee extract, coffee silverskin extract, caffeine and the commercial Colatan GT10 tannin-rich extract were tested. Celcure C4 industrial copper preservative (for above ground use) and pine oil were used as industrial references. Antifungal tests against wood-decaying fungi and wood decay—mini block—tests were performed in vitro, and leaching tests of the potential preservatives from wood were performed. An acute ecotoxicity test with Aliivibrio fischeri photoluminescent bacteria was performed in order to compare the ecotoxicity of the potential bio-based preservatives with that of the industrial reference.
All potential bio-based preservatives showed some activity against the fungi in the antifungal tests. The minimum inhibitory concentration of the extracts from coffee industry residues needed to inhibit completely all the wood-decaying fungi was over 1%. The pyrolysis distillates were able to inhibit most fungi at concentrations close to 1%. The organic acids and caffeine were able to inhibit wood-decaying fungi in the malt agar media at concentrations below 1%, showing that these constituents play a significant role in the antifungal activity of the tested distillates and extracts. However, when the potential bio-based preservatives and their constituents were tested in the wood decay tests, none of them performed efficiently as wood preservatives.
The acute ecotoxicity test showed that most of the potential bio-based preservatives had low ecotoxicity, but one of the distillates exhibited IC20 of 0.02 mg/L and IC50 of 0.2 mg/L, a much higher ecotoxicity than Celcure C4, which had IC20 and IC50 values of 12 mg/L and 19 mg/L respectively. This shows that we must test the ecotoxicity of all potential antifungals before proposing them as possible wood preservatives, to ensure that new solutions are not as harmful to the environment as the present ones. It can be concluded that some of the constituents of the potential bio-based preservatives act as antifungals against wood-decaying fungi and could be included in wood preservative formulations, but their performance alone is insufficient to function as wood preservatives.
Airborne laser scanning (ALS) is widely used to predict the total volume of trees in a forest stand. However, in operational forestry, it is usually not sufficient to consider the total volume only, because the various tree species and timber assortments are priced differently. As tree quality strongly affects how harvested logs are assigned to different timber assortments, tree quality information prior to harvesting, for example, would improve the planning of harvesting operations. The main aim of this thesis was to test different methods to predict tree quality, especially sawlog volume, by means of ALS.
The three sub-studies of this thesis were implemented using datasets from eastern Finland (3 datasets) and south-eastern Norway (1 dataset). All the study forests were dominated by Scots pine (Pinus sylvestris L.) or Norway spruce (Picea abies (L.) Karst.). The first study focused on the effects of transferring tree-level models between inventory areas. In the second study, various methods to predict plot-level (30 m × 30 m) sawlog volume were tested. The third study focused on the field-calibrations of stand-level merchantable and sawlog volumes by using basal area measurements. All the ALS-based predictions were made with either linear mixed-effects models or k-nearest neighbor imputations at the tree or plot-levels (15 m × 15 m).
The results showed that there is only weak correlation between the ALS metrics and tree quality. Nevertheless, sawlog volume predictions with relative root mean squared error values between 20–30 % were obtained after aggregations to the 30 m × 30 m and stand-levels. Moreover, the study-specific results showed that a notable decrease in accuracy can be expected when tree-level models are transferred between inventory areas, and that basal area information is not generally useful to increase the accuracy of sawlog volume predictions in Norway spruce dominated stands.
Accurate forest structural type (FST) assessment provides a valuable support tool to distinguish the different structures in forest stands, achieve sustainable forest management and formulate effective decisions. Data from four research sites within three biogeographical regions – Boreal, Mediterranean and Atlantic – were used in this study, and reliable methodologies were developed for FST assessment. First, the Gini coefficient (GC) of tree size inequality was used for the structural characterisation, and the effects of plot size, stand density and point density of airborne laser scanning (ALS) on the ALS-assisted GC estimations were evaluated for the Boreal region. Second, four forest structural attributes – quadratic mean diameter (QMD), GC , basal area larger than the mean (BALM) and stand density (N) – from the three biogeographical regions were used to develop region-independent methods for FST assessment. Lastly, a threshold value to represent maximum entropy was determined and was used to classify the various FST directly from ALS data using L-coefficient of variation and L-skewness of ALS echo heights. Aboveground biomass (AGB) was predicted for each FST and was compared with the AGB predictions without pre-stratification. The results showed that (a) plot size had a greater effect on the ALS-assisted estimation compared to stand size and point density, and that 250–450 m2 plot size (radius 9–12 m for circular plots) is the optimal plot size for reliable ALS-assisted GC estimations, (b) GC and BALM are the most reliable bivariate descriptors for FST assessment, and single storey, multi-storey and reversed-J type forest structures can be separated by lower, medium and upper GC and BALM values, respectively, while QMD and N are relevant for the separation of young/mature and sparse/dense subtypes, and (c) based on the mathematical proofs, the threshold values calculated from ALS echo heights and tree basal areas to represent maximum entropy should be 0.33 and 0.5, respectively. Moderate improvements were observed in the AGB predictions from FST classified directly from ALS data compared to the full dataset but critical differences were identified in the selection of ALS metrics by the prediction models. For example, higher percentiles were more relevant in uneven-sized structures and open canopy areas, while cover metrics and average percentiles were important in the even-sized structures and closed canopy areas. Thus, these results are very useful in improving our understanding of the relationships that underpin the choice of ALS predictors in structurally complex forests.
The growing conditions in northern boreal forests have remained similar for millennia. However, amplified climate change may cause higher mean annual temperatures and precipitation sums, longer growing seasons, along with increased occurrence of extreme weather events (drought, heavy rain, or summertime frost) in the region. The relationship that forest vegetation has with soil nutrients and the exchange of carbon dioxide (CO2) between the forest and atmosphere may change. This dissertation focuses on quantifying the baseline status of northern boreal forests from these aspects, to be able to predict the upcoming changes more precisely. Soil total phosphorus (P) and nitrogen (N) contents were important factors in explaining the community composition of understory vegetation in the study site. The site was located in a region near a phosphate ore, where soil nutrient contents are highly variable. The number of herb, grass, and sedge species increased with N and P contents in the humus, especially with P. The increasing P content, on the other hand, positively correlated with downy birch (Betula pubescens Ehrh.), which was the dominant tree species of the research plot.
The understory vegetation had an important role in the CO2 exchange rates of a northern boreal Scots pine (Pinus sylvestris L.) forest site. The annual CO2 dynamics varied between the canopy and understory, so that when the canopy began photosynthesizing in the spring, the understory was still under snow cover. The cumulative temperature sum had a higher positive correlation with photosynthesis than the total ecosystem respiration (TER) rate of the pine site. Overall, the pine site was a weak carbon sink during the growing season, although it temporarily turned into a carbon source during a cold and rainy summer.
Extreme weather events, and their effects on the CO2 dynamics of forests, were studied on a Scots pine site and a Norway spruce (Picea abies (L.) Karst.) site. Both sites had experienced extreme summers during the studied times, but the CO2 flux rates in the Norway spruce site responded more clearly to them. The TER rates of the Norway spruce forest declined when it was warm and dry. This likely happened because of decreased decomposition of organic matter. The decline was, however, only temporary, and TER returned to normal when the temperature and precipitation returned to their average levels. Thus, the studied forest sites seemed to, so far, be rather resilient towards extreme weather events.
Several studies have found that N availability will increase because of warmer temperatures, which speeds up decomposition and nutrient mineralization. However, decomposition may potentially slow down in some spruce forests due to heat. Local variation may thus be high when it comes to the availability of nutrients or to the CO2 dynamics of forests. While modeling studies are important for predicting the responses of northern forests to climate change on the large scale, our research reminds that local-scale studies are also inevitable for gaining a more precise picture.
This dissertation examines how carbon storage in forests may be increased by changing forest management at the stand level. To extend the economics of forest carbon storage beyond single-species even-aged stands, this dissertation develops a bioeconomic model framework that incorporates the internal structure of the stand, and the optimal choice between continuous cover forestry and forestry based on clearcuts. The studies apply empirically estimated growth models for boreal conifer and broadleaf tree species.
The first article presents an analytically solvable economic model for timber production and carbon storage. Continuous-time optimal control theory is utilized to solve the thinning path and the potentially infinite rotation age: if no optimal finite rotation age exists, thinnings are performed indefinitely while maintaining continuous forest cover. The second article extends this model by applying a size-structured growth model for Norway spruce, a detailed description of revenues and costs, and several carbon pools. The timing and intensity of thinnings, the rotation age, and the management regime are optimized numerically. In the third article, the optimization approach of the second article is extended to mixed-species size-structured stands. Species mixtures include the commercially valuable Norway spruce and birch, and other broadleaves (e.g. Eurasian aspen and maple) that have no market value.
Optimal rotation age is shown to either increase or decrease with carbon price depending on interest rate and the speed of carbon release from harvested wood products. Given empirically realistic assumptions, carbon pricing increases the rotation period and eventually causes a regime shift from rotation management to continuous cover management. Hence, carbon pricing heightens the importance of determining the management regime through optimization.
Optimal thinnings are targeted to the largest size classes of each tree species. Carbon pricing postpones thinnings and increases the average size of harvested and standing trees. Without carbon pricing, commercially non-valuable other broadleaves are felled during each harvesting operation. When carbon storage is valued, some of the other broadleaves are retained standing until they are large, thus increasing tree species diversity and deadwood quantity.
The results suggest that moderate carbon price levels increase timber yields, especially of sawlog. Increasing carbon storage through changes in forest management is shown to be relatively inexpensive, and the marginal abatement cost is the lower, the higher the number of tree species in the stand.
Process-based soil carbon models can simulate small short-term changes in soil organic carbon (SOC) by reconstructing the response of soil CO2 and CH4 emissions to simultaneously changing environmental factors. However, the models still lack a unifying theory on the effects of soil temperature, moisture, and nutrient status on the boreal landscape. Thus, even a small systematic error in modelled instantaneous soil CO2 emissions and CH4 emissions may increase bias in the predicted long-term SOC stock.
We studied the environmental factors that control CO2 and CH4 emissions in Finland in sites along a continuum of ecosystems (forest-mire ecotone) with increasing moisture and SOC (I and II); soil CO2 emissions and SOC in four forest sites in Finland (III); and SOC sequestration at the national scale using 2020 forest sites from the Swedish national forest soil inventory (IV). The environmental controls of CO2 and CH4 emissions, and SOC were evaluated using non-linear regression and correlation analysis with empirical data and by soil C models (Yasso07, Q and CENTURY).
In the upland forest-mire ecotone, the instantaneous variation in soil CO2 emissions was mainly explained by soil temperature (rather than soil moisture), but the SOC stocks were correlated with long-term moisture. During extreme weather events, such as prolonged summer drought, soil CO2 emissions from the upland mineral soil sites and CH4 emissions from the mire sites were significantly reduced. The transition from upland forest to mire did not act as a hot spot for CO2 and CH4 emissions. The CO2 emissions were comparable between forest/mire types but the CH4 emissions changed from small sinks in forests to relatively large emissions in mires. However, the CH4 emissions in mires did not offset their CO2 sinks. In the Swedish data, upland forest SOC stocks clearly increased with higher moisture and nutrient status. The soil carbon models reconstructed SOC stocks well for mesotrophic soils but failed for soils of higher fertility and wetter soils with a peaty humus type. A comparison of measured and modelled SOC stocks and the seasonal CO2 emissions from the soil showed that the accuracy of the estimates varied greatly depending on the mathematical design of the model’s environmental modifiers of decomposition, and their calibration.
Inaccuracies in the modelling results indicated that soil moisture and nutrients are mathematically underrepresented (as drivers of long-term boreal forest soil C sequestration) in process-based models, resulting in a mismatch for both SOC stocks and seasonal CO2 emissions. Redesigning these controls in the models to more explicitly account for microbial and enzyme dynamics as catalysts of decomposition would improve the reliability of soil carbon models to predict the effects of climate change on soil C.
Tree vascular tissues connect resource availability to tree physiological processes and growth. The xylem transports water from the soil up to the canopy of even 100-metre tall trees, whereas phloem transport connects the photosynthesis in leaves and the tree metabolic processes, including growth and tree defences against insect and pathogen attacks. Water deficit results in the closing of leaf stomata and decreasing photosynthetic production, as water and carbon dioxide are exchanged through the stomata between the leaf and ambient air. Phloem transport is driven by turgor pressure gradients generated by the interplay of phloem osmotic concentration and xylem water potential. Trees have adapted to local environmental conditions and they adjust to fast environmental changes with physiological responses. This thesis investigates tree physiological responses in vascular tissues, such as osmolality, water potential and stomatal conductance, to environmental conditions in two conifers: Scots pine and Norway spruce.
Seasonality in soil temperature and soil water content affect soil-to-leaf hydraulic conductance, and stomatal conductance is connected to these seasonal patterns in water transport. Soil environment is thus mediated to tree functionality through tree water transport. This thesis also supports Münch’s theory that it is plausible to explain phloem transport in conifers in field conditions with osmotic gradients and gravity. Xylem water potential reflects to osmotic potential and turgor pressure of the inner bark by modifying tissue solute and water content. The turgor gradients hence seem to determine daily and seasonal carbon allocation patterns according to water availability. Pathogenic infections may introduce more rapid changes in tree hydraulic conductance through a decrease in xylem sap surface tension and xylem conductivity during massive invasions of bark beetles that vector blue-stain fungi such as Endoconidiophora polonica. These pest attacks weaken tree vitality and may also increase tree vulnerability to hydraulic failure in the xylem.
Species of the Heterobasidion annosum sensu lato (s. l.) complex are causing root and butt rot of conifers. Mycoviruses are usually cryptic, but some of them may cause hypovirulence (reduced virulence) or mutualistic effects on their fungal hosts. We explored new Heterobasidion viruses, and analyzed their taxonomy and effects on their hosts. The viruses were obtained from fungal culture collection of the Natural Resources Institute Finland (Luke) or from newly collected isolates.
This thesis addressed the taxonomy of Heterobasidion viruses as well as their transmission, effects on hosts’ phenotypes, and distribution. A new dsRNA virus from H. annosum s.s., Heterobasidion RNA virus 6 (HetRV6), was taxonomically distant from all previously known viruses of Heterobasidion spp., but related to the mutualistic Curvularia thermal tolerance virus. Populations of this species exhibited a considerable degree of geographical and host-related differentiation. Virus isolates HetRV6-ab6 and Heterobasidion partitivirus 3 (strain HetPV3-ec1) conferred different and condition-dependent effects on different host strains. Four new partitivirus species, HetPV12, HetPV13, HetPV14 and HetPV15, clustered in a clade within the genus Alphapartitivirus, that includes also HetPV3 and Helicobasidium mompa partitivirus V70. HetPV13 strains were found to have a high dispersal capacity. A high infection rate by four species of partitiviruses was observed in H. annosum in a heavily infected forest. Two of these species were previously unknown (HetPV16 and HetPV20). Three fungal isolates were co-infected by two different partitiviruses (HetPV13-an2 and HetPV7-an1 or HetPV16-an1 and HetPV20-an1), supporting the view that multiple infections are common.
Taken together, the global diversity and prevalence of Heterobasidion viruses is considerable, and their transmission may occur between somatically incompatible strains. They may co-infect single host strains, transmit over species borders and confer variable phenotypic effects on their hosts. Further studies are necessary to determine the biocontrol potential of these viruses.
The importance of forests and soil in carbon (C) sequestration and storage is continually increasing with climate change. Disturbances, such as storms and insect outbreaks, are the drivers of forest functioning, composition and structure, and many of them are predicted to become more common in the future. However, environmental factors that predispose forests to disturbance as well as the diverse effects of disturbances on forest C cycling are not fully known. In this dissertation, stand, site and soil characteristics predisposing forests to outbreaks of two common insect species that can cause tree damage and mortality—the common pine sawfly (Diprion pini L.) and the European spruce bark beetle (Ips typographus L.)—were examined, and the impacts of storm and I. typographus disturbance on soil respiration, tree and soil C stocks, and microbial community composition and associated C contents were investigated in forests located in eastern and southern Finland.
The level of tree damage by D. pini and I. typographus in managed Scots pine (Pinus sylvestris L.) and urban Norway spruce (Picea abies (L.) Karst.) forests, respectively, were associated with various site and soil characteristics. Defoliation of P. sylvestris by D. pini was more severe on sites with soil properties indicating greater fertility (e.g. lower soil C/N ratio and finer textured). Highest cumulative probabilities for severe I. typographus infestation of P. abies were associated with trees growing on sites having an east-facing aspect and the most fertile site types combined with either moderately steep slopes, shallow till soil or high soil C/N ratio.
The effects of storm and I. typographus (5–7 years and circa 1–4 years after tree mortality, respectively) disturbance on forest C were studied in P. abies dominated forests that had been left unmanaged after disturbance. Soil surface total and heterotrophic CO2 effluxes, and topsoil C stocks of storm and I. typographus disturbed and undisturbed sites differed little, despite the shift in tree C stocks from living to dead after both disturbances and greater litter detritus C stocks on the I. typographus disturbed sites. Soil surface autotrophic CO2 effluxes were mostly lower at the disturbed sites than at undisturbed ones. The most distinct differences in the humus layer microbiology were the lower abundances of tree-symbiotic ectomycorrhizal fungi, and consequently slightly lower microbial and fungal biomasses in the storm and I. typographus disturbed sites in comparison to the undisturbed sites. The remaining living trees on or in close proximity to the disturbed sites probably mitigated the belowground response to disturbance to some extent.
This dissertation shows that certain site and soil characteristics predispose trees and forests to insect outbreaks, which could help in identifying forest sites that are susceptible to insect disturbance. Furthermore, it provides new information about the short-term effects of natural disturbance on boreal forest C cycling and soil microbiology, which is important for improving understanding of the complexity of the possible impacts of climate change on forest C sequestration.
Climate change mitigation aims to reduce greenhouse gases in the atmosphere. Forest mitigates climate change by accumulating atmospheric carbon to biomass. This biomass can be used to various products which also act as a carbon sink. Carbon sequestration is the opposite of carbon emission, but not fully. Forest carbon storages are uncertain and temporal but the role of forests as temporary carbon storages still has value. However, climate policy must take this into account both in the implementation of policies and in the valuation of carbon sinks.
The thesis consists of four articles and a summary chapter. Articles represent different perspectives of the forest sector and the use of forests and wood products to mitigate climate change. They cover the use of forests from the growth of trees to the use of wood products.
In the first article we analyze with an age-class model how forest owners will change their forest management if there is a subsidy based on the forest carbon storage. The results show that enhancing investments for forest growth increases and that forest rotation will be longer. We also investigate how subsidies for silvicultural investment will affect carbon sequestration of the forest. The second article analyses wood consumption and HWP carbon stock in Finland until 2050. The main HWP carbon pool consists of products made of sawn wood. The HWP carbon pool in Finland seems to increase until 2050 even in the case of decreasing consumption of sawn wood. The third article deals with optimal forest management where the growth of the forest is described by a size-class model. The results show a feature on size-classified matrix models that significantly reduces the comparability of forest management results of these models. The optimal thinning intensity and rotation length of forest are highly dependent of the specification of the model. The fourth article analyzes the existing climate policy for forestry in the EU. Because the policy only applies to one period, we can use a simple two-period model to describe the impact of the policy. The results show that constraints on current climate policy design reduce the potential of using forests to mitigate climate change.
The framework in the summary of the articles complements the conclusions in the articles and builds a view towards a more comprehensive conclusion for governance of forest sector to mitigate climate change.
Thermal modification (TM) has been widely used to improve the dimensional stability and durability of wood. However, the performance of thermally modified wood (TMW) in condi-tions where it must endure continuous changes in ambient moisture content are not entirely clear. This thesis investigated the chemical components, cellular structure, and physical prop-erties of thermally modified Scots pine, Norway spruce, and European ash wood exposed to long-term water contact condition, different temperature and relative humidity condition and natural weather condition.
The results showed that increase in TM intensity reduced the equilibrium moisture content (EMC) and improved the dimensional stability of wood mostly in a tangential direction. TM did not affect Brinell hardness, while increase in EMC decreased wood hardness. Prolonged exposure to water mainly changed hemicelluloses and cellulose and increases the hygrosco-picity of both modified and unmodified wood. In addition, the initial higher acidity of TMW tends to promote the degradation of the cell-wall compounds, resulting in faster degradation in TMW than in unmodified wood during water contact exposure.
Degradation of lignin and leaching of the degradation products during the weathering ex-posure leaves wood with a grey hue and surface with higher relative cellulose and hemicellu-lose content. TMW presented less changes in lignin structure and color due to its condensed lignin structure and lower hygroscopicity compared to unmodified wood. The lower EMC and fiber saturation point (FSP) value of TMW compared to unmodified wood indicates that TM can limit water absorption during weathering. Therefore, TMW showed less cupping than unmodified wood in wet conditions. Brinell hardness was slightly decreased in all specimens due to cell wall degradation and increase in EMC. Additionally, increase in the TM intensity improved weathering performance of wood by reducing the surface chemical changes, water accessibility and cell wall porosity.
Modern remote sensing-based forest inventory methods utilize airborne light detection and ranging (LiDAR) and optical image data for the prediction of forest attributes by tree species. These methods assume that the three-dimensional information provided by LiDAR can be used to predict the total growing stock attributes, while the spectral reflectance of tree crowns, contained in optical image data, are beneficial for the discrimination of tree species. In Finland, airborne image data has been found suitable for the discrimination of the most common tree species: pine (Pinus sylvestris), spruce (Picea abies) and broadleaves (mainly Betula pendula and Betula pubescens). There are, however, numerous issues in the collection and use of two different types of datasets in the inventory process, such as incorrect co-registration of datasets and increased data acquisition and processing costs.
In the wake of advances in algorithms and hardware, two new data sources have been merged as single sensor solutions for tree species-specific forest inventories: stereo matching of aerial images and multispectral airborne LiDAR. Both data sources offer structural and optical information beneficial in tree species classification. However, due to differences in observational geometry, the interpretation, and, thus, the usefulness of the optical information may differ between these two data sources. It is, therefore, essential to examine whether the differences in data characteristics between stereo matching of aerial images and multispectral airborne LiDAR affect the performance of the inventory.
In this thesis, stereo matching data and multispectral airborne LiDAR data are evaluated as single sensor solutions for tree species-specific forest inventories. The results provide a unique insight as to how these data sources compare to the traditional use of single wavelength airborne LiDAR and aerial images. The findings can be used to support future species-specific forest inventories on the selection of remotely sensed data.
This dissertation develops a framework to examine socially optimal forest management when nutrient and sediment loads from forestry are considered as a negative externality. The Faustmann rotation model is extended to include the runoff function to describe the water quality impacts of nutrient and sediment loads from forestry.
This thesis consists of an introductory section and four articles that analyze the different forest management practices and associated water protection. Examined practices include final harvesting in both mineral soils and peatlands, stem-only harvesting and whole-tree harvesting in peatlands, and ditch network maintenance. The water protection measures included are buffer zones in mineral soil forestry and overland flow fields and sedimentation ponds in drained peatlands.
The main contribution of this thesis is the developed framework for analyzing socially optimal forest management when water quality is taken into account. The analysis shows that the nutrient and sediment load damages associated with forest management depends highly on management practices. The nitrogen load caused by final harvesting in mineral soils results in relatively low nitrogen load damages. In contrast, the sediment load damages due to ditch network maintenance in the sensitive headwater catchment are very high. Furthermore, the cost-effectiveness of water protection measures differs significantly. From society´s viewpoint, the buffer zones used in mineral soil forest management are not a cost-effective water protection measure but when biodiversity benefits are taken into account, in addition to water quality, they become socially desirable. Overland flow fields are very cost-effective water protection measures for peatland forestry. Finally, the water protection costs in forestry and agriculture are compared in a river basin model. A cost-effective solution requires the highest nutrient reductions in agriculture, though it also implements water protection measures, especially in drained peatland forestry.
Managed forests play crucial roles in ongoing climatic and environmental changes. Among other things, wood is capable of sinking and storing carbon in both standing timber and wood products. To promote these positive effects, more precise planning is required that will ensure sustainable forest management and maximal deposition of harvested wood for long-term applications. Information on wood properties plays a key role; i.e. the wood properties can impact the carbon stocks in forests and the suitability of wood for structural timber.
With respect to the theoretical background of wood formation, stem, crown, and branching constitute potential inputs (i.e. wood quality indicators) to allometric wood property, tree biomass, and wood quality models. Due to the complex nature of wood formation, measurements of wood quality indicators that could predict wood properties along the relevant directions of variation have previously been elusive in forest inventories. However, developments in laser scanning from aerial and terrestrial platforms support more complex mapping and modeling regimes based on dense three-dimensional point clouds.
The aim here was to determine how wood properties could be estimated in remote-sensing-aided forest inventories. For this purpose, methods for characterizing select wood quality indicators in standing timber, using airborne and terrestrial laser scanning (ALS and TLS, respectively) were developed and evaluated in managed boreal Scots pine (Pinus sylvestris L.) forests. Firstly, the accuracies of wood quality indicators resolved from TLS point clouds were assessed. Secondly, the results were compared with x-ray tomographic references from sawmills. Thirdly, the accuracies of tree-specific crown features delineated from the ALS data in predictive modeling of the wood quality indicators were evaluated.
The results showed that the quality and density of point clouds significantly impacted the accuracies of the extracted wood quality indicators. In the assessment of wood properties, TLS should be considered as a tool for retrieving as dense stem and branching data as possible from carefully selected sample trees. Accurately retrieved morphological data could be applied to allometric wood property models. The models should use tree traits predictable with aerial remote sensing (e.g. tree height, crown dimensions) to enable extrapolations.
As an outlook, terrestrial and aerial remote sensing can play an important role in filling in the knowledge gaps regarding the behavior of wood properties over different spatial and temporal extents. Further interdisciplinary cooperation will be needed to fully facilitate the use of remote sensing and spatially transferable wood property models that could become useful in tackling the challenges associated with changing climate, silviculture, and demand for wood.
Diameter distributions are usually characterized in forest management inventories using probability density functions (PDF). Depending on the inventory method, the PDF parameters are derived using either predicted or assessed forest attributes. The application of PDF is not essential for forest inventories that rely on remotely sensed data, because the diameter distributions can be predicted using empirical tree lists via the nearest neighbor (NN) approach. This thesis comprises three objectives. The general aim is to investigate NN-based prediction of diameter distributions in Finnish forest inventories. Firstly, the response configurations of the NN approach were examined in the prediction of species-specific diameter distributions. Secondly, different remote sensing datasets were utilized in the prediction of diameter distribution for logwood-sized trees. For example, bitemporal and multispectral airborne laser scanning (ALS) datasets were compared to the Finnish forest inventory standard in which unispectral ALS and aerial images are used. Thirdly, two approaches that fuse an area-based approach (ABA) and individual-tree detection (ITD) in the prediction of diameter distributions were proposed. The results showed that the standard response configuration used in NN imputation is suboptimal if diameter distributions are of interest. The findings also indicate that the multispectral ALS dataset performs poorly in the prediction of logwood volumes by tree species. Instead, the use of bitemporal ALS (leaf-off and leaf-on) data provide almost comparable error rates with the use of ALS data and aerial images in the prediction of logwood volumes by tree species. The ABA-ITD fusion of diameter distributions provided slight improvements in the mean error index values associated with the predicted diameter distributions. It should be noted, however, that ITD is more sensitive to errors than ABA, for example, in forests with a bimodal or descending diameter distribution. Structural analysis of forests using ALS data is a possible indicator for the selection of prediction approach. The pulse density of the national ALS data will be increased in the 2020s, which opens up the possibility to apply the ABA-ITD fusion approach in practical applications.
Nitrogen (N) and associated carbon (C) cycling were studied in an N-limited boreal Scots pine (Pinus sylvestris L.) forest in Hyytiälä, southern Finland and were compared to two N-rich temperate forests, the Speulderbos Douglas fir (Pseudotsuga menziesii (Mirb.) Franco) forest in the Netherlands and the Sorø European beech (Fagus sylvatica L.) forest in Denmark.
Nitrogen and carbon cycling in the Scots pine forest were modelled. These results were compared to continuous year-round observations to obtain an overall understanding of nutrient cycling in the forest. The N balance of the Scots pine forest was calculated based on direct measurements, measurement-based estimations and model results. Nitrogen uptake and resorption by trees were estimated based on continuous measurements. Litter fall dynamics of the Scots pine and Douglas fir forest were compared. Scots pine needle N dynamics were compared between the three forests.
Soil was the main N storage in the boreal Scots pine forest and most of this N was in recalcitrant form. Scots pine trees were very efficient at saving and recycling N. This together with atmospheric N deposition, potential N uptake by the canopy and organic N uptake mean that the importance of mineralization as the process driving N cycling may have been overestimated.
Most of the N was allocated simply to replace dead tissue in the Scots pine forest. This means that the additional N received via N deposition may significantly increase the N pool size that trees have for extending their biomass N (net growth). Because Scots pine trees were found to be dependent on efficient N use and recycling, this adversely also means that even slight snow and storm damages may cause foliar biomass to decrease due to reduced relocation on top of the direct effect of losing the foliage due to damage, affecting forest carbon sink strength.
Social, economic and environmental impacts vary in different wood utilization patterns, and national level strategies should consider possible trade-offs and regional needs. This thesis explored a variety of wood utilization scenarios in Finland and assessed their possible future benefits and trade-offs in environmental, economic and social sustainability, forming plausible pathways to actualize preferred outcomes reflecting different priorities in the goal setting. The research was conducted by using model-based sustainability assessment tools, material flow based Tool for Sustainability Impact Assessment (ToSIA) and Lifecycle Assessment (LCA), and explorative participatory scenario methods visualizing the targets quantitatively. The participatory methods utilized actor and researcher stakeholders from industry, policy, and multiple R&D fields. The results showed that cascading and shifting secondary wood flows e.g. industrial side streams and end-of-life wood-based products from energy uses to material uses, results in increased climate benefits and economic competitiveness. Energy use of wood had lower employment, value added, and substitution benefits as well as shorter carbon storing time compared with material uses of wood. Thus, modern wood-based construction, chemicals, textiles and composites need to increase their share in the product portfolios. National policy tools can support this development only to a limited extent, because the global markets set the market framework for wood uses. To change the global market environment, internationally renewed policies aiming at restricting fossil uses are needed to make wood-based material applications more competitive. European Union (EU) policies should also apply incentives to support factor integrates supporting renewable resource savings. Public financial support to develop new processing technologies and product design of wood-based modern applications are needed to boost cost-competitiveness. Industries and other private investors can contribute to sustainable development by focusing on improving existing processing technologies and making them more resource and energy efficient. However, international policy efforts are still needed to increase the mix of alternative clean energy forms in Finland
The use of marketed mushrooms is predicted to increase worldwide. Currently, the marketed mushroom yields in Finland remain largely unutilized, and forest management mainly aims at timber production. In this thesis, the availability and limitations of the raw material procurement and market supply of marketed mushrooms in Eastern Finland were studied. Empirical yield models were formulated for the most marketed species in spruce stands: cep (Boletus edulis), milk cap (Lactarius spp.) and all marketed mushrooms. Optimal stand management was defined for the joint production of timber and mushrooms. The socially acceptable limits for mushroom picking on private land were investigated through a forest owner survey, and the supply of marketed mushrooms was modeled to study which factors affect the marketed quantities of mushrooms in Eastern Finland.
The results suggest that the Eastern Finnish spruce stands produced their highest mushroom yields right before the first commercial thinning, and precipitation during the yield season promoted the yields. The production of timber and marketed mushrooms was largely in synergy, and if mushrooms are picked for sale, the total soil expectation value (SEV) in good mushroom stands can be remarkable. The forest owners in Eastern Finland expressed some restriction needs for organized commercial picking, but they were otherwise content with the everyman’s rights regarding mushroom picking. The supply of marketed mushrooms was affected by biological and economic factors; precipitation had a positive influence on cep and milk cap supplies and market price negatively impacted the supplies of ceps and chanterelles.
The results contribute to a more stable and sustainable raw material supply to the mushroom supply chains by providing novel information on the supply of marketed mushrooms and limits of socially acceptable mushroom picking and by developing concrete tools to integrate mushroom production into forest management planning and to plan for mushroom picking.
Soil erosion processes are common in Mediterranean areas due to its climatic conditions, abrupt topography, and its long history of human influence and intensive land management. Forests have a fundamental protective role in combatting soil erosion and land degradation. This research focused on i) assessing soil erosion on forest lands linked to forest variables, and ii) integrating erosion risk into forest management and planning. In more detail, the first goal focused on the relation between erosion occurrence and possible influencing factors such as forest structure and composition, site and land-use characteristics, and, based on this, integrating erosion protection as an objective into multi-functional forest management. The data source was the Spanish National Forest Inventory, which provided erosion records as well as traditional tree and plot measurements. The modelling methods used included classification trees and binary logistic regression analysis. Models were developed for the stand and landscape levels to predict the probability of erosion. Erosion risk was also studied spatially by producing maps based on the predictions of the models. Finally, the models were integrated into a simulation optimisation system in order to assess management alternatives.
The results show that, at the stand level, a higher probability of surface erosion occurrence was strongly related to the forest type and stand structure. For example, sparse stands on slopes in semiarid areas and dense stands with large trees in pure Abies alba and Facus sylvatica forest had higher erosion probability. At the landscape level, a low stand basal area, andisol and cambisol soil types, large size and steep slope of the drainage area, the presence of unpaved roads and increased urban land use resulted in a higher probability of gully erosion. Based on the developed models, erosion protection was used as the management objective in multi-functional forest planning at the stand level, together with timber production and structural diversity. The results demonstrated evident trade-offs between these ecosystem services, depending on the steepness of the slope. The results of this work can help to identify forest areas vulnerable to soil erosion. It provides tools to integrate erosion risk into forest planning, thus enhancing the use of forests in erosion protection in sensitive Mediterranean areas.
This dissertation examines forest owners’ views of forest-related decision support services and knowledge use in them in private forests in Finland. Decision support services provide information through forest management planning and advice. The decision-making about and implementation of forest management take place in a multi-actor network that produces, distributes, and utilises knowledge in technical and social knowledge systems. The thesis is based on two surveys, extensive focus group data and field notes from workshops. It adopts a mixed methods approach.
The results show that forest owners with timber production objectives considered the current decision support services most useful. Those who emphasised nature values or had multiple objectives were less satisfied. Forest management preferences are more versatile than what they appear based on overall ownership objectives. The majority of owners are interested in diversifying their forest management to increase other forest functions alongside timber production. Two knowledge systems, technical and social, influence knowledge use in forest management. Several points of discontinuity were identified in knowledge flows within and between forest-related actors and organisations. The codified, technical knowledge system dominates knowledge production and use. The importance of the social knowledge system has not been fully recognised. Independence from time and place, gratuitousness and ease-of-use make forest-related e-service more inviting. Lack of forest inventory data or its perceived low quality and discordance with forest owner objectives deter owners from using e-service.
Forest owners expect decision support services to acknowledge their diverse and multiple forest use objectives. Information services on the management of nature values and integration of various objectives are needed. Knowledge flows are weakened by the domination of codified, forest resource-related knowledge, social structures and practices that inhibit the diffusion of knowledge within an organisation, and emphasis on the economic targets. Organisations on the forest sector are in key positions for changing the prevailing decision support practices, but so far the development of new practices has been slow.
Northern Hemisphere permafrost soils store approximately 50% of the global soil carbon (C), a quarter of which could thaw by the end of the century. Thawing exposes previously frozen soil organic matter (SOM) to decomposition, resulting in release of greenhouse gases (GHG) from the soils. Vast areas of permafrost soils are covered by boreal forests currently acting as sinks of C. As global warming is strongest at northern latitudes, the occurrence of boreal forest fires may increase. Forest fires further advance permafrost thaw and forest soils may turn from sinks to sources.
This thesis examines how forest fires affect the quality of SOM and GHG emissions from permafrost soils in boreal forests by conducting chemical fractionation of SOM and soil incubations, as well as manual chamber measurements of GHGs.
Forest fires increased the active layer depth on top of permafrost, altered species composition of vegetation and affected the organic layer depth and the SOM pools. Fires decreased the quality of SOM, observed as reduction in the proportional amount of labile SOM fraction and increased SOM temperature sensitivity, as well as enrichment with heavier isotopes of 13C and 15N. GHG measurements showed that fire initially decreased carbon dioxide flux from the soil and it returned to its pre-fire status approximately 50 years after the fire. The effects of fires on methane and nitrous oxide fluxes were not significant.
Forest fires have significant effects on the release of GHGs from permafrost soils. In the future, the fate of permafrost stored SOM is dependent on its degradability, the frequency of fire events and the ability of forests to regenerate, allowing permafrost recovery, in the changing climate. There is a demand for further studies investigating the specifics of different permafrost ecosystems and building a complete picture to estimate total emissions from permafrost regions.
Stump harvesting for bioenergy production is an option for by which the forestry sector in Finland can accelerate the development of a green economy, which is also known as a bioeconomy. Furthermore, it contributes to the discussion on how stump harvesting affects pest management. This dissertation analysed and synthesised stump harvesting for bioenergy production in terms of sustainability, especially in terms of forest health and societal acceptance. This research consequently used an interdisciplinary approach. The effects of human intervention by stump harvesting on pine weevil (Hylobius abietis) breeding, feeding, and seedling damage was studied via field experiments. Stakeholder perception and acceptance of stump harvesting were studied via questionnaires and a literature review. Field experiments showed that stump harvesting is a secondary tool in the regulation of pine weevil breeding and feeding. The questionnaires indicated that respondents were divided on the topic of to stump harvesting for pine weevil reduction, site preparation, and bioenergy production. Furthermore, the social acceptance study found that there have been contradictory research findings in this regard over the past decades. Consequently, society remains confused about stump harvesting for bioenergy production. According to the questionnaires, high level administrators were especially critical of stump harvesting whereas farmers and foresters were in favour of this practice. As Finland aims to be a bioeconomy pioneer, it needs to consider updated knowledge on and social acceptance of stump harvesting for bioenergy production. In addition, technological investment and market acceptance of stump harvesting contribute to the bioeconomy. Future research therefore needs to focus on the policy implications of stump harvesting with updated technological guidelines that consider stakeholder perceptions.
Global environmental change alters the structure and dynamics of boreal old-growth forests. Changes in these forests greatly influence key ecosystem properties such as biodiversity and carbon cycle. Hence, understanding the development of the remaining natural boreal forests is particularly important.
We examined how forest structure varies in space and changes over time in three natural boreal forest landscapes in northern Fennoscandia and two landscapes in eastern North America. Canopy cover that was visually interpreted from stereopairs of aerial photographs taken between the years 1959 and 2011 was used as a surrogate measure of forest structure, and Bayesian inference was used to separate credible ecological phenomena from the noise caused by interpretation error.
We identified credible changes in forest structure in each studied landscape, but also noted that the visual interpretation of canopy cover was prone to systematic and random error that depended on, e.g., aerial photo quality. The multi-scale change analysis revealed a synchronous and prevalent canopy cover increase at large spatial scales in the majority of the studied landscapes, and canopy cover decrease and increase in areas that were subjects to disturbances. Changes of variable direction and magnitude were detected at smaller spatial scales. Furthermore, forest structure varied at multiple spatial scales which showed similarities despite the differences in dominant tree species and disturbance regimes between the studied landscapes. The variability was connected with scale-dependent driving processes that also showed similarities among the landscapes.
Our observations indicate that the structure of natural boreal forests may vary at characteristic scales that are independent of, e.g., tree species composition and disturbance regime. However, contrary to the conventional view of boreal old-growth forest dynamics, the results suggest that the studied forests are currently undergoing large scale changes that increase their canopy cover and consequently biomass.
Russia has approximately 43 million hectares of forests under the Forest Stewardship Council (FSC) certification scheme. This thesis investigated the perceptions of certified and non-certified companies towards forest certification (FC), and to what degree the representatives of these companies agree with the benefits and barriers of the FC process. The Due Diligence System (DDS) employed by each company were analyzed to investigate their effectiveness in tracking and preventing illegal timber entering the timber supply chain of the company. Moreover, non-conformities (NCs) to FSC Principles during the period 2011–2015 were analyzed based on severity (minor and/or major) as per the FSC principles, geographical location, and size of leased forest area.
The results of these interconnected studies showed that both certified and non-certified companies perceive FC as an economic initiative and as an opportunity for new markets. FC is seen to provide access to new markets and, thus, enables additional sales but also ensures legality of the timber and improves the company’s image and competitiveness in foreign markets (Article I). The company’s own tracking system and DDS appeared functional, but require further improvements to meet EU Timber Regulation requirements (Article II). Analyzes of the NCs in Northwestern (NW) region and within the Russia showed that the number of minor NCs have increased since 2011; from 221 to 363 incidents by 2015, which also coincides with the increase in the number of issued FSC certificates i.e. increased area under certification. The highest number of recorded minor and major NCs in NW region and Russia were related to Principle 6. The results further indicated that the total number of identified NCs was highest for large-size leaseholders in the NW region. However, in the Russia as a whole the majority of minor and major NCs occurred with small-sized leaseholders (Article III and Article IV).
The main aim of this work was to study the magnitude of phenotypic variation in different growth, wood density (WD) and wood anatomy properties, and correlations between these, in 41-year-old clones and provenance hybrid clones of Norway spruce (Picea abies (L.) Karst.). Additionally, the development of height and autumn frost hardiness in their seed offspring, under different temperature and/or atmospheric CO2 concentration treatments, were studied under greenhouse conditions over one growing season.
Local Finnish clone V43, and two Finnish–German V449 and V381 provenance hybrid clones had higher stem volume than the average of the 25 genotypes included in the study (Paper I). They had also relatively high overall WD compared to the average of all the genotypes. The geographical transfer of father parent trees affected the overall WD. The averages for tracheid length, double cell-wall thickness (2CWT) in both earlywood (EW) and latewood (LW), and lumen diameter in LW, differed in five genotypes selected for detailed analyses of wood anatomy (Paper II). These parameters and the number of rays correlated with the widths and wood densities of EW and LW. The 2CWT of the tracheids closest to resin canals differed from that in the normal tracheids (Paper II). These differences may be partly affected by the origins of the genotypes.
Under greenhouse conditions, elevated temperatures increased the height growth in seedlings. It delayed the onset of autumn frost hardiness development and shortened its duration. Elevated CO2 did not affect the development of height and frost hardiness. None of the genotypes showed both superior growth and frost hardiness (Paper III).
A need for further studies on wood anatomy – for example, to consider genotype-specific variations in structural compounds – emerged based on this work. The obtained understanding of phenotypic variation in different genotypes may provide support for tree breeding in the future.
Trees have various mechanisms for avoiding and mitigating biotic and abiotic stresses. Resin is one such mechanism, and it is essential for conifer trees. Conifer resin is also a large pool of monoterpenes that – similarly to other biogenic volatile organic compounds (BVOCs) produced by plants, e.g. methanol, acetone and acetaldehyde – play important roles in tree signalling and atmospheric chemistry once emitted to ambient air. BVOC emissions from various tree parts and resin dynamics depend on environmental variables, with intrinsic effects on conifer defence.
This thesis aims to clarify the environmental and physiological drivers of resin dynamics and BVOC emissions from the shoots and stem of mature boreal Scots pines (Pinus sylvestris) in field conditions, with special attention given to the effect of tree water relations. Resin pressure dynamics were studied using pressure transducers and BVOC emissions using an online mass spectrometer and dynamic chamber system. Resin and monoterpene emission compositions were analysed based on gas chromatography measurements.
Temperature explained resin pressures and BVOC emissions from both the shoots and stems of Scots pine in the short term. Over a longer period, resin pressures and stem monoterpene emissions decreased with decreasing soil water availability and water potential in stem. In addition, the emission dynamics of water-soluble acetaldehyde, methanol, and acetone from the shoots and stem were connected to transpiration rate and soil water content, indicating an important effect of their transport in the xylem sap.
These results show that although often overlooked, tree stems are an important source of BVOCs and that even relatively small changes in water availability may alter BVOC and resin dynamics despite their strong short-term temperature control. This information may help to understand the potential susceptibility of conifer trees to biotic stresses in various environmental conditions and improve BVOC emission modelling by accounting for stem emission dynamics
The involvement of local people in the governance process, reliable and transparent engagement of disadvantaged people in decision-making and justice in benefit sharing have been the emerging strategies for the acceptance of REDD+ (Reducing Emissions from Deforestation and Forest Degradation, forest conservation, sustainable management of forests and enhancement of carbon stocks). However, closer scrutiny of the values of forest governance is needed in order to evaluate its effectiveness, contribute to its legitimacy and understand the interactions of governance attributes. At the same time, both at the international and national level, there is lack of clarity around the kinds of governance arrangements that can be implemented at the ground when striving for REDD+.
This PhD thesis assesses the practicability and priorities of community forestry governance to articulate climate change mitigation initiatives by forest users. The focus includes factors associated with benefit sharing process, patterns of engagement of disadvantaged groups in community forestry and the impact of REDD+ implementation on social inclusivity of community forest user groups in Nepal`s Terai region. The study is based on grounded theory of qualitative approaches that builds on case studies from three community forest user groups and REDD+ interventions. Through the lens of a theoretical framework of common resources governance, the study assesses the similarities and differences between policy goals and observations of forest governance values and their impacts. Second, the study explains the nature of factors affecting benefit sharing and their impacts under REDD+ and other benefit sharing process in community forestry. Third, the study explores how existing policies and practices engage Dalits in community forestry governance processes. Finally, the study investigates how social inclusivity under REDD+ enhances representation and deliberation of disadvantaged groups and requires responsiveness in community leaders within community forestry.
The study results are based on the focus group discussions, in-depth interviews and participant observation in three community forests of the Nepal´s Terai. Similarities and differences between the factors of forest governance are apparent within the specific conditions of each community. Qualitative differences in the implementation of governance initiatives have increased the level of dissatisfaction among the community forest users. Though poor users of community forest were highly dependent on forest resources, rich users benefit comparatively more due to their control over decision-making structures. The formal structures for engagement of disadvantaged groups in community forestry do not provide enough space for genuine participation. The benefits of REDD+ implementation have not trickled down as expected to ground level. However, the implementation of REDD+ has also positively supported governance in community forestry. Proportional representation of disadvantaged groups has been achieved but the criteria need revisiting to prioritize the inclusion of highly dependent users in community forestry.
Cultural Factors of Environmental Disputes in Lapland studies the cultural meanings of Lapland’s nature and its use. The focus is on the shared meanings and practices of local people and natural resource management. Social and cultural sustainability, as well as conflict management, are the basic concepts and themes permeating this academic dissertation, which is based on several case studies. The geographical focus of study is in the home district of the Saami people in Upper Lapland, but is not strictly limited to this area.
The thesis consists of seven separate articles published in domestic and foreign scientific publications. The theoretical framework for the articles is anchored in the management of natural resources and environmental disputes, as well as the theories of shared cultural meanings. The data was gathered through surveys and interviews – thus the materials and methods of analysis are quantitative and qualitative. The research belongs to the field of socio-scientific environmental research.
The main findings of the study stress that environmental disputes and their management in Lapland are characterised by the diversity of stakeholders that often do not share the same views. The roles and motivations of the stakeholders in environmental conflict situations are often unclear or problematic, and often no shared understanding of the nature, causes and possible consequences of the dispute can be reached. For governmental natural resource management, there has been a lack of institutional structures and processes which are culturally sensitive and socially sustainable. However, new and better practices have been introduced in recent years.
In Lapland, the importance and appreciation of traditional livelihoods such as reindeer herding and subsistence-use of natural resources are emphasised. However, the cultural meanings of these land-use patterns are not adequately recognised. This thesis argues that more cultural sensitive approaches are needed in resource and environmental conflict management. In Upper Lapland, which has undergone rapid cultural transformation, the past is strongly present and explains the valuations and meanings of local people’s use of nature. Nature conservation is, in particular, an important form of land use in upper Lapland. Successful and sustainable conservation should use transparent and culturally novel approaches to achieve the approval and support of the local population. In the future, nature conservation projects will be in favour of exploiting cultural information related to nature and its use, together with ecological knowledge, so that projects receive positive reception.
Non-industrial private forest (NIPF) owners are important forest ecosystem service providers and users. Along with the structural and general lifestyle changes of owners, their forest ownership objectives have become more diverse, strongly emphasizing intangible forest values alongside timber production. Therefore, NIPF owners and their versatile forest ownership objectives are a potential source of information for exploring the untapped future potential that could help the forest sector to retain its future viability on the road towards a bioeconomy.
This doctoral thesis aims to understand the drivers of demand for new forestry services and forest-based business opportunities from the perspective of NIPF owner objectives and forest meanings. Objectives and forest meanings are examined from methodological, socio-demographic and NIPF owner sustainable lifestyle perspectives, leading to more general examination of NIPF owner perceptions of future utilization prospects of forests and the forest sector. Thus, the objective of the thesis is to build a more in-depth understanding of NIPF owner objectives and to examine how this information could be used in the development and marketing of forestry services and other forest-related products and services.
The findings present a way to systematically analyse the objectives of forest ownership and also illustrate how certain segments of forest owners value aesthetics and biodiversity conservation over a traditional monetary value orientation. The results also indicate that the owners with the highest sustainable consumption orientation place a greater emphasis on multiple benefits of forests than owners who have a lower such orientation. The findings show that the future value creation of forests will be based on multiple aspects, and the widening of perspective beyond raw material dominance in the utilization of forests is important. Thus, recognizing customer pressure towards more diversified forestry services would be essential in meeting the versatile needs of forest owners but also from the perspective of developing new forest-based businesses.
The majority of forests in Finland have been subject to intensive clear-cutting and thinning, and peatlands have been extensively ditched and fertilized. Such changes have modified forest environments but the effects of these changes on macrofungi are still unclear. This thesis examines macrofungal communities in boreal forests and peatlands, with particular focus on the effects of wildfire, prescribed burning and tree retention (timber harvest intensity) on ectomycorrhizal (ECM) and saprotrophic (SM) macrofungi (Basidiomycota and Ascomycota). The thesis is based on empirical field data, which includes over 550 species and a monitoring period of up to 12 years.
Fertile forests had more diverse ECM and SM assemblages than the dry and semi-dry forests. Non-ditched pine bogs had less macrofungi than drained spruce mires, pine mires and pine bogs. Rare and Red-listed agarics and aphyllophoroid wood-associated macrofungal species were rare in managed forests.
In general, wildfire increased the richness and sporocarp production of several SM species and also modified assemblage composition. ECM diversity was greatest in the mild and intermediate fire sites where it was three-fold higher than the high-severity fire sites. The succession of fire-associated pyrophilous species in burned humus was rapid.
Prescribed burning and harvest intensity had a major influence on macrofungal populations. However, these effects were strongly dependent on the functional group. Clear-cut areas had an overall adverse effect on macrofungi; ECM species in particular disappeared after clear-cutting. Several SM species occurred exclusively on burned areas, and retention areas had a slight positive effect on macrofungi, including ECM species.
My results show that macrofungal assemblages are diverse and vary systematically in forest and peatland site types. Intensive forest management has mostly negative effects on macrofungi, including edible mushroom species. Prescribed fire in the forest landscape and a reduction in harvest intensity can be used to maintain fungal assemblage diversity in managed forests.
Climate change is amplifying forest disturbances, especially those by insect pests. Invasions by alien insects are also threatening forest health. Uncertainties related to insect pest infestations are increasing along the risk of high impacts. There is a demand of accurate and cost-efficient methods for forest health monitoring to prevent, control, and mitigate the negative impacts. Current needs for information for efficient forest health management are complex and extensive. The required quality cannot be met with traditional forest inventory methods. Forest information should be up-to-date and available across a range of spatial and temporal scales. Rapid development of remote sensing and spatial modeling could also support forest health monitoring and management; however, an extra challenge with increased uncertainties are encountered.
The dissertation aims towards improved forest health monitoring, particularly disturbances by defoliating insect pests. Insect-induced disturbances were evaluated in six sub-studies. Different remote sensing sensors and modeling approaches were employed for disturbance evaluation in Fennoscandia and North America. Pattern, frequency, scale, and intensity of insect infestations vary depending on pest and forested landscapes in question, affecting the applied methodology. Sensors, platforms, and modeling methods have to be chosen accordingly. Timing of data acquisition is crucial; early detection and timely management operations are often the only way to mitigate insect outbreaks. Importance of varying information is also affected by the scale and resolution of investigation.
Forest health monitoring should be included into forest monitoring systems, including accurate and timely disturbance detection, monitoring of infestations, and impact evaluation. Higher and lower spatial resolution remote sensing should be combined and spatial modeling techniques incorporated for flexible and cost-efficient monitoring over a gradient of different forest ecosystems, climatic conditions, and forest inventory and management practices. Open access remote sensing archives with high temporal resolution could facilitate continuous monitoring of wide forest areas. Developing satellite technology may respond to these needs. However, more research is needed before these systems can be adopted at the managing level.
The World’s forests are facing novel stress due to climate change. Pest insects and pathogens are shifting towards new latitudes and heat stress is resulting in increased tree mortality and more frequent forest fires globally. Uncertainty in estimating the magnitude of climate change induced forest and tree decline requires new methods for unbiased estimation of tree decline. The development of remote sensing methods to detect early tree decline has been a major challenge due to the subtle nature of the early changes caused by different stressors. Multispectral lidar technology has the potential of detecting early tree decline by providing accurate three-dimensional and spectral information of tree structure simultaneously.
The main objective of this thesis was to investigate the capabilities of multispectral terrestrial lidar in the detection and assessment of tree decline caused by different stressors. This was done by investigating the estimation of a remotely detectable indicator of tree decline, leaf water content (LWC). Specifically, new methods for measuring LWC using multispectral lidar intensity were developed from the leaf to the canopy scale in various environments and the relationship between LWC and tree decline induced by various stressors was investigated. Furthermore, the developed methods were tested in a forest environment to assess the applicability of multispectral lidar in the detection of bark beetle infestation in the field.
Studies I-III focused on investigating the relationship between LWC and lidar intensity at multiple wavelengths. First, a hyperspectral lidar instrument was used to detect significant changes between fresh and drought-treated Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies L.) trees (study I). Then, a leaf-scale study (II) with Scots pine, Norway spruce, Small-leaved lime (Tilia cordata L.), Norway maple (Acer platanoides L.) and Silver birch (Betula pendula L.) was conducted and a strong relationship (R2=0.93) between a normalized difference index (NDI) calculated from 1550 nm and 690 nm wavelengths and LWC was found. This was followed by a study (III) where LWC estimation and pathogen- and drought-induced variation in LWC was studied with Norway spruce seedlings. Blue-stain fungi (Endoconidiophora polonica) inoculated seedlings expressed a rapid decrease in LWC while drought-treated seedlings showed more stable LWC until a very severe drought. LWC of the seedlings was predicted with an R2 of 0.89 using an NDI with 1550 nm and 905 nm wavelengths.
In study IV, the developed method and the relationship between LWC and tree decline was investigated in the field with European spruce bark beetle (Ips typographus L.) infested trees. It was found that of the LWC metrics studied, gravimetric water content showed significant differences in the early stages of infestation and was more sensitive to bark beetle induced tree decline than equivalent water thickness (i.e. amount of water per leaf area). Linear discriminant models that were developed between infestation severity and lidar intensity metrics from 1550 nm and 905 nm wavelengths showed that green attack stage of the infestation could classified with an overall accuracy of 90%.
This dissertation contributes both to the development of an objective and automatable method for detecting and measuring tree decline in the field, and to the understanding of the relationship between LWC and tree decline with implications to remote sensing. The dissertation will be published and popularized as a music video here: http://bit.ly/idanproffa.
This thesis summarises the findings of four case studies focussing on the redesign of specific aspects of the forest chip supply chain, the use of alternative terminals for chip supply, the interdependencies of chipper and chip trucks and the performance of individual machines after machine alteration. The aim of the work was to analyse and improve the fuel economy and energy efficiency of the forest chip supply system by modifying the settings of CTL harvesters, investigating the performance of an innovative hybrid chipper, introducing alternative supply systems through the use of a feed-in terminal and an analysis of forest chip supply systems under selected operational and environmental conditions. The analysis of the case studies involved individual machines and the entire forest chip supply system. Two study methods were used: work study and discrete event simulation (DES). Work study carried out to investigate the performance of individual machines and their alteration; the DES method was used for investigating the organisational redesign of the forest fuel supply system. The study resulted in the following findings and conclusions: 1) extreme machine settings have a statistically significant impact on the fuel economy of CTL harvesting machines; 2) hybrid machine technology can improve the fuel consumption and energy efficiency of chipping operations in forest chip production; nevertheless the productivity of the analysed prototype was below that for compared traditional chippers; 3) as an alternative to the direct supply of forest chips, the effect of utilising terminal operations on the overall supply cost can be quantified; terminal use improves the annual use of the supply fleet and enhances fuel supply security to the plant thereby reducing the need for supplementary fuel and 4) applying different types of types of chipper and truck-trailer combinations, supply costs and efficiencies can be quantified and vehicles with increased carrying capacity can improve the cost competitiveness. In the study an integrated approach taking physical, technological, enterprise and industrial levels of energy efficiency into account is proposed. Thereby state-of-the-art forest technology and current biomass supply ideally can be upgraded to achieve new, improved levels of performance and energy efficiency.
Emissions of biogenic volatile organic compounds (BVOCs) cool down the global climate via their impacts on aerosol and cloud formation. Climate change will likely have a major impact on BVOC fluxes from the biosphere, including soils, due to temperature-driven plant biosynthesis of volatile organic compounds (VOCs), compound volatility and microbial activity. Soils are a poorly quantified source of VOCs, where the diversity of driving factors creates high spatial and temporal variability in soil VOC fluxes.
The aim of this study was to analyse the magnitude and variability of forest floor VOC fluxes, to determine the role of the boreal forest floor in the forest stand BVOC exchange and to estimate plant ecophysiological and microbiological processes, which drive forest floor VOC exchange. Forest floor VOC exchange was determined using a steady-state flow-through chamber technique coupled with mass spectrometry in the boreal and hemiboreal climates.
We revealed that the boreal forest floor contributes significantly to forest stand fluxes, but its importance varies between seasons. The forest floor accounted only a few per cent of the total forest stand fluxes of monoterpenes in summer, while in spring and autumn it could be up to 90%. The forest floor VOC exchange was stable between years, while fluxes had clear seasonal dynamic. Monoterpenes and oxygenated VOCs originated from fresh litter, microbial activity, and ground vegetation VOC biosynthesis. Air inside soil layers was found to contain diverse compounds. Forest floor VOC fluxes varied strongly depending on climate and tree species.
Atmospheric chemistry may be strongly affected by soils during periods when plant-related BVOC biosynthesis and fluxes are low. In the future, we need continuous and simultaneous VOC exchange measurements from forest floors and forest stands in various ecosystems and climate zones. The global budget for soil VOC emissions should also be defined based on existing studies.
Human land use affects the climate through various channels. This thesis focuses on the optimal (i.e. welfare-maximizing) regulation of land use sector climate impacts using market-based instruments, such as taxes and subsidies. The thesis consists of four articles and a summary chapter. Each article focuses on a separate aspect of land use sector climate policy.
The first article outlines a comprehensive tax policy for jointly regulating carbon storage in biomass, soils and products. Considerations regarding soil carbon storage are emphasized.
The second article concerns the regulation of CO2 emissions from the energy use of logging residues. The harmfulness of these emissions is compared with that of fossil emissions. A way to harmonize the carbon taxation of the both energy sources is presented.
The third article regards the application of the additionality principle to forest carbon subsidies. In the stand-level context it appears that the additionality principle can be implemented without distorting the optimal rotation, by reclaiming subsidies for baseline carbon storage by a site productivity tax on forests. However, at the market-level such a tax distorts the optimal rotation and the optimal land allocation. These distortions can be avoided, if the excess subsidies are eliminated by general land taxation (which also targets other land use).
The fourth article presents a new concept: the Social Cost of Forcing (SCF), which is the social cost of the marginal unit of radiative forcing at a given moment. It is a fundamental price that can be used to value different forcing agents. Forcing agents’ prices that are based on the SCF are consistent with the Social Cost of Carbon, and can therefore be consistently applied in cost-benefit analysis or utilized to harmonize the regulation of non-CO2 forcing agents.
Together the four articles contribute to our understanding of land use sector climate policy design.
Forests as a renewable energy resource offers opportunities to boost the bioeconomy, energy security and environmental benefits. This doctoral study aims to analyse the potential expansion of forest biomass based bioenergy production (methanol, Fischer Tropsch biodiesel, CHPs) in Finland. Therefore, a spatially explicit techno-economic Mixed Integer Linear Programming (MILP) model was applied to optimize the potential new bioenergy plant locations by minimizing the full costs of the supply chain with respect to forest resources supply, industrial competition, and energy demand. In addition to optimisation modelling, survey amongst 210 farmers in Poland was conducted to identify key societal parameters that helps to optimize the future production plant locations taking into account of economic, environmental and societal aspects of the bioenergy value chain.
The results of this study provide valuable information to investors and decision makers on geographical energy planning strategy to meet the Finland’s 2020 target of liquid biofuel share in traffic and forest chips consumption in energy generation. The model results include cost-optimal production plant locations, choice of technology, feedstock resource allocation with import options, minimized cost of supply chain, income from by-product sales and CO2 emission savings.. The model parameter sensitivity analysis shown that the investment costs, conversion efficiency and heat price variations were the most plant influential parameters followed by feedstock cost, electricity price, subsidies, and transport cost. These parameter variations under uncertain market conditions favoured by unstable policies would cause serious challenges to promote the use of forest biomass in the future biofuel and CHP industries. Survey analysis identified that farmer’s willingness to supply biomass would play a vital role for secured biomass availability to liquid biofuel and CHP industries. Therefore, formulation of socially inclusive policies are imperative for the future success of bioenergy industries with long-term market stability.
Information needs associated with forest monitoring have become increasingly complex. Data to support these information needs are required to be systematically generated, spatially exhaustive, spatially explicit, and to capture changes at a spatial and temporal resolution that is commensurate with both natural and anthropogenic impacts. Moreover, reporting obligations impose additional expectations of transparency, repeatability, and data provenance. The overall objective of this dissertation was to address these needs and improve capacity for large-area monitoring of forest disturbance and subsequent recovery. Landsat time series (LTS) enhance opportunities for forest monitoring, particularly for post-disturbance recovery assessments, while best-available pixel (BAP) compositing approaches allow LTS approaches to be applied over large forest extents. In substudies I and IV, forest monitoring information needs were identified and linked to image compositing criteria and data availability in Canada and Finland. In substudy II, methods were developed and demonstrated for generating large-area, gap-filled Landsat BAP image composites that preserve detected changes, generate continuous change metrics, and provide foundational, annual data to support forest monitoring. In substudy III a national monitoring framework was prototyped at scale over the 650 Mha of Canada’s forest ecosystems, providing a detailed analysis of areas disturbed by wildfire and harvest for a 25-year period (1985–2010), as well as characterizing short- and long-term recovery. New insights on spectral recovery metrics were provided by substudies V and VI. In substudy V, the utility of spectral measures of recovery were evaluated and confirmed against benchmarks of forest cover and height derived from airborne laser scanning data. In substudy VI the influence of field-measured structure and composition on spectral recovery were examined and quantified. By focusing on four key aspects of forest monitoring systems: information needs, data availability, methods development, and information outcomes, the component studies demonstrated that combining BAP compositing and LTS analysis approaches provides data with the requisite characteristics to support large-area forest monitoring, while also enabling a more comprehensive assessment of forest disturbance and recovery.
The fungal species complex Heterobasidion annosum sensu lato (s.l.) is considered one of the most devastating conifer pathogens in the boreal forest region. They affect European coniferous forests with root and butt rot, causing annual economic losses of €800 million. Despite several efforts in practical forestry to control the disease, the economic loss remains considerable. Therefore, it is still necessary to introduce alternate control measures for Heterobasidion infection.
Heterobasidion spp. are infected by a diverse community of mycoviruses, mostly partitiviruses. Here, these viruses were studied to find potential viruses for biocontrol purposes. We described six novel Heterobasidion partitivirus (HetPV) species phylogenetically related to Helicobasidium mompa partitivirus V70 that infect four pathogenic Heterobasidion species. Interestingly, our study revealed that HetPV13-an1 causes severe phenotypic debilitation in its native and exotic fungal host. The RNA sequencing of isogenic virus infected and cured fungal strains showed that HetPV13-an1 affected the transcription of 683 genes. The RT-qPCR analysis showed that the response toward HetPV13-an1 infection varied between H. annosum and H. parviporum. Moreover, the wood colonization efficacy of H. parviporum infected by HetPV13-an1 was restricted in living Norway spruce trees.
The ratio of polymerase and coat protein genome segments/transcripts of eight partitiviruses analysed was highly variable in mycelia. All the virus species had unique ratios of the genome segments, which were stable over different temperatures and hosts.
The co-infection with HetPV13-an1 and HetPV15-pa1 reduced host growth up to 95%. Regarding the transmission efficacy of mycoviruses, HetPV15-pa1 transmission to a pre-infected host was elevated from zero to 50% by the presence of HetPV13-an1, and a double infection of these viruses in the donor resulted in an overall transmission rate of 90%. Altogether, the study demonstrated that the interplay between co-infecting viruses and their host is highly complex and that partitiviruses show potential for biocontrol.
European energy and environmental policies have extensive effects on the Nordic forest products market. This thesis focuses on four main questions. First, the effects of global changes in the consumption, production, and trade of Finnish and Swedish forest products market. Second, investigate the effects of the policies on the substitution of fossil fuel (coal) by a solid form forest-based biofuel. Third, compares and evaluates Nordic countries’ research perception with the European Union’s other regions’, based on experts’ perceptions on attaining the European Union’s 2020 targets. Fourth, forecasts the interaction between the renewable energy and wood fuel energy production of Sweden, Finland, Denmark, and Norway. The first and fourth studies followed econometric analysis, the second study executes by developing a theoretical model, and third studies followed a questionnaire survey analysis.
The results show that during 1981–2012, structural break years are 1991 and 1992 for the Finnish model and 2004, 2005, and 2006 for the Swedish model. The fossil fuel replacement study showed that combining tax and subsidies increases the aggregate demand for biofuel and increase substitution by about 19% and 31%, respectively. A regional assessment showed that with the Nordic countries’ experts, an overwhelming majority (82–93%) from the European Union’s other regions suggested for stable and adequate incentives to meet renewable energy targets for biomass and perceive that 2020 targets will not be achieved. Finally, estimation between renewable energy and wood fuel show that due to shocks, renewable energy had positive and the wood fuel had an always negative reaction to their own and mutual positive shocks. The thesis concludes that tax and subsidies together have a strong effect on the replacement of fossil fuels by forest-based biofuels, any unexpected shocks may increase renewable energy production and decrease wood fuel production, and consistent policy tools are necessary to achieve European Union targets.
The sawmill industry’s current business strategies are based on traditional, production-oriented business logic. However, the ruling sources of competitiveness (lower prices and higher production volumes) are no longer sufficient to maintain the industry’s profitability. A shift from manufacturing to service economy includes vast potential to improve customer value and, hence, business performance. The service view suggests that instead of being created by production, customer value derives from processes in which the provider supports the customer’s value creation. This view positions the customer at the core of the business and challenges prevailing business approaches within traditional industries.
The goal of this thesis is to explore the sawmill industry’s business transformation toward customer orientation and service-based business. As firms do not operate in isolation from their surrounding business environment, the entire wood products industry is considered. Service logic was used as the research frame to accentuate the value-based business approach. The novelty of this thesis is applying customer orientation to improve the forest industry’s innovation and competitiveness. Digitalization is a core of innovation and offers potential to take customer orientation to a new level. Therefore, two closely connected concepts with customer orientation, innovation and digitalization, were also studied. Both interviews and case studies were used, comprising a total of 36 semi-structured interviews.
This thesis suggests that by positioning customers at the core of the business and by applying service-based business practices, the sawmill industry is in better position to achieve long-term competitiveness. This idea, however, necessitates significant strategic changes, questioning existing practices and principles of the entire wood products industry. The first step in the change toward a customer-oriented business (i.e., service-based business) is to gain more understanding of customer orientation and embrace this approach as an organization-wide attitude, not only within the sawmill industry, but throughout wood value chains.
Forest growth information is important, and it is an issue of concern for various stakeholders. Forest growth has been traditionally assessed by way of modeling, however models fitted for a larger area tend to be biased when applied to local settings, and there is thus a crucial need for localization or other ways to improve the growth prediction of such models. There are various ways to achieve this improvement, one of which is by introducing new data elements. Consequently, this presented research used the known effect of topography on soil moisture content to achieve growth prediction improvements for local forest growth. A total of 9987 tally trees and 1118 sample trees distributed in 197 plots were used to examine the suitability of using terrain attributes derived from digital terrain model (DTM), airborne γ-ray and leaf area index (LAI) data, in improving pre-existing diameter at breast height (dbh) model for a five-year period in southeastern Finland. Statistical examinations of the mixed effect modeling (linear and non-linear) and multilayer perceptron modeling were used in the analysis. The results varied between sample trees and species. The best root mean square error (RMSE) improvements of the national model were obtained for broadleaved trees, followed by pine and spruce. All of the γ-ray windows were shown to be significant in eliminating the local bias. The effect of the DTM source showed that a higher resolution with a lower focal neighborhood is the best combination for quantifying terrain attributes, notably the Topographic Wetness Index (TWI). The growth prediction improvement tended to be more accurate in less fertile site types. LAI demonstrated improvement when combined with terrain attributes, especially intensity-based LAI. The presented study concludes that the newly introduced elements are suitable for improving local forest growth prediction with RMSE improvement between 6-18%.
This thesis explores the effects of controlled burning and logging intensity on wood-decaying polypore fungi 10 years after the treatments. Intensive forest management, where most of the wood is removed from harvested sites, has resulted in many dead-wood-dependent species becoming Red-listed. The role that managed forests and novel, more biodiversity-oriented silviculture could play in safeguarding fungal diversity has remained largely unclear.
This thesis is based on data sets collected from five years: 2000, 2003, 2005, 2008 and 2011 from the same study areas. A large-scale, replicated experiment was established on 24 forest sites that were exposed to logging and burning treatments. The data comprised 98,136 observations of dead wood pieces and 22,150 observations from a total of 122 polypore species.
The main findings in this thesis were;
1) Retention tree levels need to be high in order to maintain polypore diversity. I observed more polypore species on sites with 50 m3 ha-1 of retention trees than sites with 10 m3 ha-1. The burning of retention harvested sites accelerates the death and fall of retention trees and diversifies the dead wood quality at a managed site. Red-listed species were found chiefly on the burned sites with the higher retention level.
2) Harvested sites comprise widely different types of dead wood substrates: old natural dead wood, stumps, slash and retention trees, and all these contribute to polypore diversity in managed forests. The response of polypore species to management can typically be seen only after a longer period of time. After a disturbance, such as logging or fire, these four different dead wood substrates are available for polypores over different periods of time.
3) Burning harvested and unharvested sites increases the number of polypore species and diversifies the polypore assemblages. Of the four dead wood types, burning specifically leads to an increase in the number of polypores on stumps.
These results demonstrate new possibilities for the conservation of dead-wood-dependent species outside protected areas. Leaving retention trees, abstaining from the extraction of logging residuals and maintaining old naturally formed dead wood are beneficial for polypore species. Prescribed fire can be utilized as an effective method to modify dead wood dynamics and for the creation of more variable dead wood substrates on managed forest sites.
The aim of this work was to improve the protocol of somatic embryogenesis (SE) and propagation efficiency in Norway spruce (Picea abies (L.) Karst.), which would enable the integration of SE into Finnish breeding programme and the nursery practices applied to seedlings. The studies specifically investigated the following three areas: i) how maturation, cold storage, germination and growing conditions (laboratory–nursery interface) affect the survival and height growth of emblings (Papers I and II); ii) how to improve the efficiency of embling production from genotypes from wide genetic backgrounds (Papers I and II); and iii) how to increase propagation efficiency by rooting cuttings from emblings, and produce field testing material by combining SE and the rooting of cuttings (Papers II and III). To evaluate the possibility of improving the efficiency of SE in the laboratory–nursery interface, a series of experiments were conducted. The cost structure of SE, and the effects of improvements on costs, was estimated.
As a result, the protocol improvements doubled the yield of cotyledonary embryos, nearly doubled embling survival, and increased the height growth of emblings in the nursery by so much that sufficient planting height was reached one year less than before. Emblings were also obtained from 356 genotypes (50% thawed), and embling cuttings rooted well in conditions similar to those used for seedling cuttings. The protocol improvements also reduced embling production costs by 75%. Based on this work, emblings may be grown in nurseries after one week of in vitro germination, without any measures that differ from seedlings after transplanting. Propagation efficiency may be further increased by rooting embling cuttings. Furthermore, large-scale clone testing can be initiated with 5–12 emblings acting as cutting donors.
This study employed scenario analyses to evaluate the effects of forest management and different CMIP5 climate projections on timber production and carbon stocks of upland boreal forests in Finland. The forest ecosystem model simulations were conducted over a 90-year period from the stand to regional level by using both model stand data (Paper I) and national forest inventory data (Papers II-III). In simulations, it was employed data from the current climate and several CMIP5 projections (multi-model means and selected climate model runs of 28 global climate models) under the RCP4.5 and RCP8.5 forcing scenarios. More specifically, it was studied the impacts of different climate projections and thinning regimes (Papers I and III), tree species preferences in forest regeneration (Paper II) and forest conservation scenarios (Paper III) on volume growth, carbon stocks and timber production (Papers I-III), economic profitability (Paper I), and the amount of deadwood of forests (Paper III).
The effects of different climate projections on volume growth, carbon stocks, timber production and its economic profitability and the amount of deadwood varied largely, depending on geographical region, tree species, and severity of climate change. The degree of differences in the responses of tree species and boreal regions increased with the severity of climate change. Regardless of the tree species, the positive impacts of climate change were larger in the north. In the south, Silver birch benefitted most from the climate change projections and the most under severe climate change. This was unlike Norway spruce and also partially, Scots pine. An increase in forest conservation area increased volume growth, carbon stock, and the amount of deadwood in forests, unlike timber production. Depending on boreal region, tree species, and severity of climate change, different adaptive forest management measures would be needed to utilize the positive impacts of climate change and to minimize harmful ones.
Tropical peatlands of South East Asia are major hotspots of biodiversity and great carbon stores. The main peat forming ecosystem is tropical peat swamp forest (TPSF) growing on top of meters deep peat. Forest degradation by vast scale land conversions and consequent pernicious impacts on the environment have raised an urgent need for conservation and restoration. This dissertation concentrates firstly on the peat soil properties, ground surface microtopograhy and vegetation patterns of the natural TPSF, and secondly on the vegetation restoration, i.e. reforestation of degraded tropical peatland.
In the studied natural TPSF type, the forest floor can be characterized as an irregular continuum of less common hummocks and more abundant flat low-lying surface where most of the peat surface is not inundated for most of the year. Unlike in the boreal and temperate peatlands, the ground surface microtopography had no regular patterning. The surface peat structure and chemistry had differences in relation to the surface microtopography. Higher surfaces had higher nutrient concentrations and saplings and trees were concentrated on higher surfaces whereas seedlings emerge in all ground surface elevations.
In the open degraded former TPSF area we tested 21 native tree species for their potential for reforestation in a planting experiment. We increased the knowledge on the species’ early stages flood and drought tolerances, species’ suitability for different conditions in reforestation areas and suitable species-specific seedling height for planting. For five species with known potential for reforestation purposes we tested the impact of three site preparation treatments, weeding, fertilizing and mounding, on the seedling performance. We analyzed also the effects of wildfires which caught the study area two years after planting.
With increased knowledge on both natural TPSF ecology and the seedling experiments on degraded areas, we could specify environmental condition requirements for several tree species for reforestation.
The artificial regeneration of Norway spruce (Picea abies (L.) Karst.) in the Nordic countries relies on planting containerized seedlings originating from seeds collected from either seed orchards or forest stands. The aim of this thesis is to investigate the effect of seed quality attributes on seedling production and to study whether it is possible to enhance germinability and seedling health through seed soaking treatments. The variation in seed quality among individual trees and clones and the components of seed weight variance are also studied.
Commercial seed lots were screened for microbes and the effect of soaking treatment on microbial abundance was analyzed. The three seed lots contained some pathogenic fungi, but most fungi found were saprophytic. The seed lots differed in their likelihood to suffer from damping-off when germinated in water agar medium but not in peat. With current production methods seed-borne fungi do not have a great impact for seedling health, but altering for example the growing media may increase their importance.
Seedling quality declined with increasing emergence time in an experiment on 1-year-old seedlings in the nursery, thus emphasizing the importance of fast germination. Seed soak-sorting hastened the emergence and increased seedling size more in 1.5-year-old containerized seedlings compared to the 1-year-old seedling crop in addition of decreasing the proportion of cull seedlings.
The proportion of full seeds varied between individual trees and clones in cones collected from a forest stand and from a seed orchard. The average seed weights differed between trees or clones, but intracone variation was the greatest source of seed weight variance. This indicates that weight-based seed sorting may have a smaller impact on the genetic diversity of seed lots than previously thought.
Seed and seedling producers as well as society have different preferences for seed quality attributes and different tools for quality management.
Human-induced disturbances may change vegetation and carbon (C) and nitrogen (N) processes in the forest floor and the soil beneath it. The aim of this dissertation was to study the effects of physical and chemical disturbance on boreal forest soil and vegetation. The specific aims were to evaluate the rate and direction of the forest ecosystem recovery from the disturbance and to assess how C and N processes are affected by different disturbances regimes. Two contrasting soil-affecting treatments – stump harvesting and sprinkling infiltration – were studied as case studies representing a disturbance. Sprinkling infiltration alters the chemical composition of forest soil, whereas stump harvesting results in changes especially in the physical structure of the forest soil. Furthermore, in contrast to stump harvesting where C and nutrients are removed from the soil with the removed biomass, sprinkling infiltration adds large quantities of C and nutrient-rich surface water into the forest soil. As stump harvesting and sprinkling infiltration are relatively newly introduced land use practices, very little is known of their long-term effects on boreal forest soil and vegetation.
The effects of stump harvesting on forest soil surface disturbance, C and N pools and mineralization rates, understory vegetation, seedling growth and coarse woody debris (CWD) were studied in Norway spruce (Picea abies (L.) Karst.) stands located in Central and Southern Finland. The results of this study indicate that stump harvesting causes soil mixing and relocation of organic matter in the soil profile, which in turn is reflected to the soil C and N dynamics as soil C and N pools tended to be lower following stump harvesting. Stump harvesting combined with site preparation tends to cause more extensive soil surface disturbance than site preparation alone, and the mixing effect of stump harvesting persists on soil surface after a decade since harvest. Furthermore, this study underlines that stumps, coarse roots and fine coarse roots represent a significant portion of the CWD, belowground biomass and nutrients in a forested stand, and thus their extraction results in substantial and direct removal of biomass, C and nutrients from the stand.
The effects of sprinkling infiltration on forest soil, tree growth and understory vegetation and their respective recovery were studied in an experimental stand that had been infiltrated with surface water in order to produce artificial groundwater. The study revealed that the previously observed changes soil chemistry had persisted in the experimental stand; soil pH and base cation concentration as well as the rate of net N mineralization were still significantly higher at the infiltrated plots after a 12–15-year recovery period. These results lead to the conclusion that sprinkling infiltration results in the long-term neutralization of the forest soil. In contrast to tree growth, theunderstory vegetation had not benefited from the added nutrients and organic matter, instead the large amounts of added water had created conditions unfavorable to certain plant species. In conclusion, sprinkling infiltration is an environment altering treatment which, based on the findings of this study, can have short-term effects on tree growth and long-term effects on soil processes and understory vegetation and ultimately, ecosystem recovery.
The results of this study demonstrate that disturbances affect the function and structure of forest soil and these changes can persist for at least a decade on the surface of the soil in the organic layer and deeper in the mineral soil. Furthermore, this dissertation highlights the need for long-term perspectives in ecosystem management and planning.
Passive recovery or active restoration approaches may be used in the repair of degraded ecosystems. The effects of such measures on ecosystem patterns and processes, including boreal forest soils and vegetation, are poorly understood. This thesis examines the impacts of both active and passive restoration approaches on soil organic matter (SOM) and vegetation in the boreal forests of eastern Finland.
The study sites were located in managed and protected boreal forests in the same region in Finnish North Karelia. In the study sites, I measured soil and vegetation patterns, and the environmental controls on SOM decomposition in relation to the proximity of decaying logs.
In actively restored sites, the burned, partly harvested site had lower humus SOM stocks and displayed vegetation biomass and cover patterns that suggested stronger disturbance than the other sites. Burning decreased and homogenized vegetation diversity through spatially-uniform extinctions and limited colonization 10 years after fire. Green tree retention partially alleviated the impacts of disturbance on vegetation biodiversity. Proximity of dead wood (but only of non-charred logs) enhanced conditions for SOM decomposition. Charred logs did not exhibit this effect, which suggests a previously unknown linking of forest fires to soil processes via charred wood.
In the passive recovery sites, legacies of slash-and-burn regimes have persisted in the forests for more than a century. The disturbed forests had a higher volume of large birch trees and lower SOM stocks. In boreal conditions, passive restoration may take more than a century before ecosystem properties return to their pre-disturbance state. Soil properties may be more challenging to restore than above-ground tree structures.
My results indicate that active and passive restoration approaches may produce quite different pathways and outcomes. In general, the active restoration approach with low severity fires that is currently applied appeared to not harm forest soils; in particular it left the deeper mineral layers intact, and may provide a more rapid way to restore ecosystem properties. However, there is an urgent need to cover a longer successional time series to reveal the exact differences between active and passive restoration trajectories. The inherent differences between the focus of the passive restoration approach (to recover ecosystem naturalness in a more holistic sense) and the active restoration approach (targeting specific species, habitats, structures and processes in the ecosystem) should be duly acknowledged.
Natural disturbances can rapidly change the structure and species composition of forests. Their effects can also compromise the provision of services and products from forest ecosystems. Therefore, it is very relevant that the risk of natural disturbances is considered when planning forest management prescriptions. This study presents a general framework for integrating risk into long-term forest management, via two main steps: 1) risk assessment (damage characterisation and modelling); and 2) risk management (simulation and optimisation). This research characterises the primary natural disturbances in Norway, and presents occurrence and damage models for the most relevant of these. The results show that the main natural disturbances in Norway are snow, wind and browsing from ungulates. The models identify which stand and site variables are more influential when predicting a forest’s vulnerability to damage. The browsing occurrence models show that the most relevant variables to explain stand vulnerability are stand age, size and density. The model predicting snow and wind damage occurrence highlights the importance of the stand density, structure, mean diameter and height, but also site-related variables, such as latitude or altitude. The models predicting the damage rate for snow and wind damage, use covariates, such as stand basal area, height, diameter and slenderness. Snow and wind damage models are used in a stand dynamic simulation to optimise management prescriptions for considering risk. The optimal management schedules for a spruce dominated stand leave lower volumes towards the end of the rotation and shorten the rotation length. This thesis provides relevant information that can be use by managers in considering the risk of natural disturbances in forest management and planning.
The use of airborne laser scanning (ALS) has enhanced forest inventory during the last decades due to the increasing capability of lasers to describe the three-dimensional structure of forests. This research focuses on the integration of ALS-based forest inventory into forest planning when the aim is to create dynamic treatment units (DTUs). In this approach, the management units are not fixed and predefined. They are temporary and formed by aggregating fine-grained inventory units. Management objectives and forest dynamics are the drivers of that aggregation process.
The research was conducted in two pine forests in Castilla y León (Spain) in which ground and ALS data were collected. This PhD thesis reviews four manuscripts concerning the implementation DTU (studies I and III), the implications of using alternative forest inventory units (FIU) in two types of problem formulations (studies I, III and IV), and the impact of plot positioning errors on the whole planning process starting from the sampling stage and ending with decision-making (study II). In all studies, growing stock attributes were estimated with ALS statistics, while diameter distributions and stand dynamics models developed in permanent plots were used to predict growing stock attributes. The alternative management schedules developed during the simulation phase aimed at maximizing a utility function composed of non-spatial (study III) and spatial objective variables (all studies).
The findings of this work highlight the good performance of irregular types of FIU and the benefit of using segmentation techniques when the aim is to generate compact DTUs. The use of spatial optimization improved the spatial layout of forest plans at a minor cost compared to non-spatial formulations. The use of spatial goals and spatially explicit harvest cost functions enhance the aggregation of FIUs. Heuristic-based optimization methods were effective when solving spatial combinatorial problems.
This PhD shows how the combination of ALS-based methods, widely used in forestry practice and spatial optimization contribute to the development of forest management planning methods.
The aim of the studies in this thesis was to apply and further develop methods in multi-source forest inventory tasks in boreal and tropical forests. The applications presented in this dissertation are based on optical remote sensing data and k-nearest neighbours techniques, both of which are common components in multi-source forest inventory.
The use of variograms as a texture information source in standwise volume estimation was tested using image data from a digitized aerial photograph taken in Hyytiälä, Finland. According to the leave one out cross-validation, the accuracy of volume estimation at stand level improved when empirical values of semivariance were included in the set of feature variables.
Landsat 5 Thematic Mapper (TM) satellite data was utilized in forest cover and volume mapping in Terai, Nepal. A corresponding multi-source forest inventory-oriented processing chain was also tested and demonstrated in forest volume mapping in the region of Kon Tum province in Vietnam. In these two studies, coarse scale MODIS reflectance products were used as a reference in a local correction approach conducted for the relative calibration of Landsat TM images.
Multi-source forest inventory techniques for obtaining biomass maps have facilitated the development of a spatially explicit methodology to estimate the bioenergy potentials of forest chips. The technical bioenergy potential of forest chips was calculated in a case study in Central Finland, based on the logging residues and stumps from final fellings.
An adaptation of the abovementioned methods and techniques in studies with target areas of forests in sub-tropical and tropical zones in Nepal and Vietnam was carried out using open source software tools. These studies serve the purpose of capacity building in utilizing remote sensing data in forest inventory activities related to the REDD+ mechanism, and estimating bioenergy potentials provides quantitative decision making support in the field of forest bioenergy production
This study aimed to investigate the climate impacts of carbon sequestration in forests, and the substitution of fossil energy (e.g., coal, oil) and fossil-based materials (e.g., concrete, steel, plastic) with harvested energy biomass and timber (pulpwood, sawlogs) under Finnish boreal conditions. The study employed forest ecosystem model simulations and a life cycle assessment tool to calculate the net CO2 exchange for the forest-based biosystem. The effects of stocking in thinning, nitrogen fertilization, and the use of varying rotation lengths and harvest intensities in final felling (timber, logging residues with and without coarse roots and stumps) on the climate impacts and economic profitability of biomass production were studied. Current Finnish forest management recommendations for thinning, aimed at timber production, were used as a baseline. In addition, the sensitivity of climate impacts to displacement factors and timber use efficiency was studied. This work was conducted at the stand level, with a mature stand as a starting point (Paper I), at the landscape level, under alternative initial forest age structures (Paper II), and at the regional level, using national forest inventory data in southern Finland.
This study revealed that the best option for increasing the climate impacts of biomass production and utilization was through maintaining up to 20% higher stocking, nitrogen fertilization, and using 80–100-year rotations, since they increased carbon sequestration and timber and energy biomass yields. However, there was a tradeoff between the greatest climate impact and the economic profitability of biomass production.Sawn wood products were the best option for long-term substitution and increasing carbon stocks of wood products. It was also found that the effects of substitution and timber use efficiency on climate impacts were higher than those of the thinning regimes. Consequently, the greatest climate impacts were found when intensified biomass harvesting was performed, and the prominent regions for increasing climate impacts over the next 40-year period were the southern and eastern sub-regions of Finland. Furthermore, the climate impacts were found to be sensitive to the initial conditions set for the analyses, which affected the timing of the climate impacts and the preference of forest management in climate change mitigation. This indicates that management measures, together with the initial conditions of the forests, should be considered when evaluating efficient options for increasing climate impacts by forests and substitution.
This dissertation explores the governance, local impacts and costs of community-owned renewable energy (CRE). The objective is to understand if and in what context collective local ownership models represent a feasible and effective means to operationalising a more ‘sustainable development’ in the renewable energy sector and beyond. The articles draw on a range of fields, from energy governance and project economics to impact evaluation. Specific methodologies used are systematic literature review, discourse analysis, historical institutional analysis and risk-extended net present valuation. Unique contributions of this work are a meta-level understanding of the community energy sector in the UK and an understanding of its emergence in context of technological and institutional change. In addition, it provides an explicit assessment of Quality of Evidence problems in this subfield of energy and social science research, placing it firmly in the context of current literature and methods in project economics and impact evaluation. Findings show that ownership patterns in the energy sector are precarious and subject to changing narratives that emerge in response to domestic socio-economic and political dilemma’s, exogenous shocks, and emerging economic schools of thought. CRE projects have the potential to generate a variety of positive local impacts that vary depending on the motivation and management of projects and project revenues. Under certain conditions CRE can empower community organisations to address systemic socio-economic problems in the public domain. Finally, in a competitive market setting and where CRE is implemented by newly-established grassroots organisations, projects face a range of risks that commercial projects do not, and that erode their financial viability. As such, the development and expansion of community renewable energy as a substantial proportion of the energy sector requires policy makers to assign it special status and provide policy support on the basis of its local social, economic and environmental benefits. Policy support for community renewable energy requires a willingness to integrate energy and social policy domains.
Plants synthesise thousands of biogenic volatile organic compounds (BVOCs) as part of their secondary metabolism. Scots pine (Pinus sylvestris) particularly produces mono- and sesquiterpenes, which are mainly stored in oleoresin in resin ducts. In this study, the monoterpene emission rate from stems was found to increase as a function of increasing resin pressure, which was positively correlated with the air temperature and foliage transpiration rate.
Monoterpene synthase activity describes the maximum monoterpene production potential. The seasonal cycle and needle age were observed to explain the majority of the variation in needle monoterpene synthase activities, monoterpene storage pools and monoterpene emissions from shoots. Variation in the monoterpene concentration between seasons, different needle age classes and different trees was observed to be minor. Monoterpene synthase activity was higher in <1-year-old needles compared to older ones. Within a single tree, the compound-specific composition of monoterpene synthase activities and monoterpene storages was not reflected in the composition of emissions. For example, the share of δ-3-carene was substantially higher in the emissions than in the storage pools and synthase activities.
An automated enclosure measurement system including a proton transfer reaction mass spectrometer was utilized to follow the VOC emissions from the woody compartments of trees over several years. This was the first study to quantify such emissions for an extended period. Scots pine stems were observed to emit monoterpenes and methanol into the ambient air. The fluxes displayed a seasonal cycle: methanol emissions were highest in the midst of the growing season, whereas monoterpene emissions peaked not only on the hottest summer days, but also in the spring when the photosynthetic capacity of trees recovered. The emissions of some monoterpenes exhibited distinct diurnal patterns in their enantiomeric compositions. The above-canopy air terpene concentrations reflected the emission rates from trees, the atmospheric reactivities of the compounds, the tree species composition of the measurement site and the abundances of different tree chemotypes.
Boreal peatlands are highly important sinks for carbon (C). This function is enabled largely by one peat-forming plant, the Sphagnum moss. In addition to slowing the decomposition by gradually creating ombrotrophic conditions, it gives a shelter for the organisms mitigating the emissions of methane (CH4) – an effective greenhouse gas formed in submerged, anoxic peat layers. These organisms, methane oxidizing bacteria (methanotrophs, MOB), inhabit the dead, water-filled hyaline cells of the Sphagnum and provide the plant carbon dioxide (CO2) derived from the CH4 oxidation. While several studies have confirmed the presence of Sphagnum-associated methanotrophs (SAM), it is still unclear how dependent they are on the mosses and how environmental conditions affect their community composition and activity.
This thesis evaluated SAM dynamics in the different stages of peatland development on both pristine and disturbed areas. Studies were based mainly on molecular methods, targeting the MOB-specific pmoA gene, and laboratory incubations, including stable isotope probing.
In the first study, the connection between the SAM and the mosses was assessed by testing whether the SAM will disperse through the water phase. This trait, considered to represent a facultative symbiosis, was demonstrated in two experiments. In the field, mosses inactive in CH4 oxidation were transplanted next to active ones. Within a month, SAM communities of the neighboring mosses become more similar. The water-based colonization was further confirmed by bathing inactive mosses in flark pore water that showed high CH4 oxidation activity. Within just 11 h, activity was induced and the SAM abundance significantly increased in the treated mosses.
The other two studies revealed similar SAM community composition patterns on a pristine chronosequence and on a gradient of re-vegetating cutover peatlands. Instead of the Sphagnum species, the general environmental conditions seemed to control the SAM community composition. Different types of SAM seemed to have their preferred environmental niches, with the type Ia MOB present and active especially in the young succession stages and the type II MOB in the older, hydrologically more stable stages. Despite the community differences, the potential CH4 oxidation did not differ along the gradients, suggesting functional redundancy. Only some drier bog samples did not show any detectable CH4 oxidation, demonstrating the regulatory role of the water table level on the SAM activity. The peat layers of the cutover gradient showed similar MOB community patterns but the potential CH4 oxidation increased with succession.
The ability to disperse through the water provides a recovery mechanism from disturbances such as droughts, which are predicted to increase with climate warming. In addition, the diversity and functional redundancy of the SAM communities enhance the resilience of this important CH4 biofilter formed by the living Sphagnum mosses. The potential SAM activity in the mosses of the youngest cutover site promotes the Sphagnum transplantation practice as a tool to not only enhance the re-vegetation process, but also to mitigate the CH4 emissions formed in the rewetting and restoration of disturbed peatlands.
The aim of this thesis was to investigate the use of portable bearing capacity measurement devices and alternative fly ash structures to improve forest road quality and rehabilitation practices. So far, few tools have proved suitable for practical evaluation of forest road trafficability. Bearing capacity is the main component of trafficability and bearing capacity measurements are rarely conducted on forest roads. Replacing subjective criteria with objective measurement methods is the first step towards avoiding rutting damages as well as improving rehabilitation decisions.
Three bearing capacity measuring devices were tested for predicting forest road rutting in the context of bearing capacity improvements with fly ash structures. Modulus of elasticity (E-modulus) was used as the measurement unit. E-modulus was used to quantify road stiffness as measured by two portable measurement devices and one trailer-mounted device. A light falling weight deflectometer (LFWD) and a dynamic cone penetrometer (DCP) were used to challenge the conventional falling weight deflectometer (FWD). Test sections were located on forest roads with both mineral and peat subgrades. The comparison showed logical correlations between the measured E-modulus values, and reliable regression models are presented for the differences between measuring devices. In most cases DCP and LFWD can be utilized on forest roads instead of the expensive FWD. The measurement results for the portable devices and the FWD were compared to rutting, as represented by the increases in rut depth per passing truck (mm/pass) measured by mobile laser scanning (MLS). The devices were used to quantify the relationships between the E-modulus and rutting. Rutting threshold values were then based on these relations. A rough rutting susceptibility table was outlined to aid forestry professionals to estimate the rutting damage risk per timber truck on forest roads during periods of thaw-weakening.
Growing bioenergy production and consumption has resulted in an increase in the amount of fly ash produced by the forestry sector. At the same time the cost for ash deposition at land-fills has increased considerably. Utilizing fly ash in forest roads is therefore seen as a potentially cost-efficient alternative for improving bearing capacity. The fly ash part of the study investigated therefore road rehabilitation work from both technical and economical perspectives. Four different rehabilitation methods were tested using wood- and peat-based fly ash. The four rehabilitation methods involved two structures mixed with aggregate and two structures with uniform fly ash. The resulting bearing capacity of the rehabilitated road sections was improved compared to the reference sections, especially for the mixed structures. The improvements were verified by statistical comparisons. The study also defined the various work phases of rehabilitation and estimated construction costs based on phase-specific machine productivities. Cost calculation equations were established for earthwork and the transportation of construction materials. The lowest construction costs were calculated for a 250-mm thick uniform layer of fly ash structure, however, a 500-mm thick uniform layer of fly ash provided the lowest total costs when taking into consideration the alternative cost for landfill deposition.
The overall aim of the thesis was to design efficient supply chain setups in the selected supply environments. Discrete event simulation was selected as a study method. To enhance the performance of the forest chip supply chain from roadside storage locations to end-use facilities, the following results and conclusions were obtained: 1) Rearrangements in the set-up of fuel reception stations and the logistics of fuel truck reception at the power plant as well as adaptive shift scheduling of trucks resulted in a notable decrease in the waiting times of fuel trucks at the power plant’s fuel reception. 2) Forest chip supply from roadside storage locations highly encourages the use of storage area location and quality information for smart material allocation to achieve a higher energy output with lower supply costs. 3) By introducing a feed-in terminal for forest chip supply, cost compensation for additional terminal-driven costs can be gained through a higher annual capacity utilisation of a fuel supply fleet and more secured fuel supply to power plants by decreasing the need for supplemental fuel, which can be more expensive at times when fuel demand is at its highest. 4) Inland waterway areas with existing waterway infrastructure and close connections to biomass resources and end-use facilities can offer a cost-competitive and supplemental method for the long distance transport of forest chips.
The reindeer (Rangifer tarandus L.) is a key species in Fennoscandia, where nearly 40% of the land area is used as reindeer pasture. Reindeer herding is an important source of income for local people and an intrinsic part of the Sami culture. In this thesis, the reindeer herding system is studied using a detailed interdisciplinary dynamic model. An age- and sex-structured reindeer-lichen model is developed using findings from previous research and novel data. The model also takes other winter resources, including supplementary food, into account in addition to ground lichens. This ecological model is combined with economic optimization and a description of the herding system with empirically estimated prices, costs, and governmental subsidies. The model is validated and calibrated to describe the reindeer herding system in the northern part of Finnish Lapland.
The results for population dynamics without harvesting show that the reindeer-lichen system described by the model is unstable in the absence of predators. However, high availability of arboreal lichens stabilizes the system. In economically optimal solutions increasing the interest rate increases the steady-state reindeer population level, opposite to classical understanding in resource economics. Natural mortality is close to zero in optimal steady-state solutions and harvesting is concentrated on calves. The number of adult males is kept as low as possible without decreasing the reproduction rate of the population. This leads to much higher shadow values for males compared to females.
The results show that in order to study sustainable and economically viable reindeer management, both ecological and economic factors must be taken into account, as they strongly affect the solutions and management recommendations. One of the main findings is that the economically optimal steady-state lichen biomass can be surprisingly low. High interest rate, lack of pasture rotation, low growth rate of ground lichen, high availability of arboreal lichens, and government subsidies all decrease the steady-state lichen biomass. Using intensive supplementary feeding to support larger reindeer herds, which leads to the depletation of lichens, can additionally become optimal in certain cases. When recovering from overgrazed lichen pastures, use of supplementary feeding and the amount of arboreal lichens have an important role in the optimal adaptation process.
The wintertime wastages estimated in this study are close to earlier suggestions, but summertime wastage is higher than expected. Seasonal pasture rotation could thus considerably help reduce the summertime trampling of winter pastures. The model validation solutions show that the model is able to describe changes in lichen biomass with good accuracy. Using the validated model and calibrated wastage values we found that reindeer numbers in northernmost Finland in the present situation are in most cases higher than in the management solutions given by the model.
Photosynthesis requires a balance between its light-dependent and light-independent reactions so that the energy input through photochemistry matches its consumption. Biochemical and physiological processes help to achieve this balance, as certain processes regulate the activity of light-dependent photochemical reactions, whilst others regulate the activity of temperature-dependent biochemical processes. Biochemical and physiological processes also modulate the absorbed energy available for photosynthesis by diverting a fraction into non-photochemical pathways that dissipate energy as heat and fluorescence. Interestingly, certain biochemical and physiological processes behind the dynamics of photosynthesis correlate with leaf optical properties (LOPs), which represent and approach to characterising the dynamics of photosynthesis. Yet, how solid is our knowledge concerning the biochemical and physiological processes influencing LOPs, and how accurately do LOPs and the biochemical and physiological processes behind the photosynthetic dynamics correlate when investigated across various spatio-temporal scales? This thesis investigated whether reflectance-based and fluorescence-based LOPs adequately correlate with the biochemical and physiological processes behind photosynthetic dynamics, and whether their correlations hold true at various spatio-temporal scales.
This thesis demonstrates the validity of reflectance-based and fluorescence-based LOPs as optical proxies for investigating the dynamics of photosynthesis. However, it also identifies sources of variability that cause the correlations between photosynthesis and LOPs to break down. This thesis classifies the sources of variability in terms of methodological (i.e. over-simplification and technical/instrumental constraints) and spatio-temporal limitations. The over-simplification of processes behind the dynamics of photosynthesis and LOPs was addressed by studying the absorption of photosynthetically active radiation (PAR) by conifer needles. PAR absorption is generally considered to be chlorophyll concentration-dependent, yet this thesis shows it to be additionally modulated by the effect that waxes have on needle PAR reflectance. Due to difficulties of directly measuring needle PAR absorption, PAR reflectance was used as a proxy of PAR absorption. To solve this technical/instrumental constraint, this thesis presents a new methodology that facilitates the direct estimation of PAR absorption. This thesis also demonstrates that certain LOPs appear to be insensitive to detecting the dynamics of certain biochemical and physiological processes over time. This was true for the photochemical reflectance index (PRI), which failed to detect zeaxanthin-independent processes behind the thermal dissipation of the absorbed PAR. Lastly, this thesis shows that LOPs can also be influenced by leaf morphology, which could affect the optically-based monitoring of larger-than-leaf scales. Despite the caveats highlighted in this thesis, the potential to monitor the dynamics of photosynthetic activity by optical means is unquestionable, and the results presented here can contribute to reducing uncertainty in the characterisation of photosynthesis by optical means at varying spatio-temporal scales.
This dissertation aims to develop the economics of even-aged Scots pine (Pinus sylvestris L.) management. In our economic-ecological model, a detailed process-based forest growth model is connected to an economic description of stand management. The process-based growth model is able to describe forest growth in management regimes and climate conditions previously not experienced, because it applies causal relationships and feedbacks instead of statistical correlations. Optimization is carried out with an effective general pattern search algorithm. The optimized variables include rotation length, initial stand density, and the timing, type, intensity, and number of thinnings. Essential model details include the quality pricing of timber and detailed harvesting cost functions. Integration of carbon subsidy systems into the model enables the determination of the economically optimal carbon storage with various carbon price levels. Finally, the growth model is extended to include a direct link between climate change and tree growth, to optimize stand management in a changing climate.
The dissertation thesis is composed of a summary section and three articles, which produce a coherent and comprehensive picture on the optimal stand management of Scots pine in the relevant growth conditions of Fennoscandia. The results demonstrate the necessity to simultaneously optimize all stand management variables, and the advantages of having a detailed model. Optimal stand management is shown to be sensitive to growth conditions, interest rate, and management objective, along with the design of the carbon subsidy system and the subsidy level. The stand-level analysis is additionally extended to the national level, and adapting forest management was found to potentially be a cost-efficient method for carbon abatement in Finland. Furthermore, the optimal adaptation of stand management in a changing climate remarkably improves the economic surplus from forestry.
This dissertation examines the economics of continuous cover forestry. The analysis is based on an economic description of continuous cover forestry using empirically estimated growth functions, with both size-structured and individual tree models. The optimization problem is solved in its general dynamic form using gradient-based interior point methods. Sensitivity analyzes are conducted for both the ecological and economical parameters.
The thesis consists of a summary section and four separate studies, in which we solve economically optimal continuous cover forestry in single and mixed species stands. We present results for optimal harvests and stand structure, with and without biodiversity consideration, transition toward the optimal steady state, the effect of interest rate and harvesting cost on stand structure, density and optimal harvest timing, and how the optimal results compare to the limitations found in Finnish and Swedish forest legislation. It is found that harvests typically target the largest trees in the stand. In mixed species stands at more productive sites, species diversity increases with the interest rate, with an optimal steady state being a mixed species forest. Taking biodiversity into account in forest management increases species diversity. The harvest timing and intensity are dependent on both the interest rate and the fixed harvesting cost, and if the initial stand is far from the optimal steady state, the legal limitations are violated at least during the transition period.
The degradation and disappearance of natural ecosystems and habitats – including forests – is one of the most important factors behind the current global decline in biological diversity. Since most of terrestrial biodiversity is found in forests, restoration of these ecosystems or their natural characteristics has been proposed as one of the main strategies to counteract global species loss.
In this thesis, I examined the ecological effects of forest restoration in disturbance- driven boreal conditions. The applied restoration methods (prescribed burning; creation of canopy gaps; dead wood restoration) used natural forest disturbances as the reference point. Specifically, I focused on the effects that restoration has on tree species composition, age- class structure, and the amount and diversity of dead wood in forest ecosystems. In addition to examining the changes in these structural attributes, I investigated dead-wood-associated fungal communities in the restored substrates, and assessed whether dead wood restoration could be used to conserve rare and threatened fungal species.
Of the examined restoration treatments, the combination of prescribed burning and the creation of canopy gaps was found to be the most promising measure for the restoration of age-class structure and tree species composition in pine-dominated forests. Dead wood restoration – by artificially creating standing and fallen large-diameter dead trees – clearly enhanced the amount of dead wood in both pine and spruce dominated forests. Although dead wood restoration increased the abundance of fungal species in the examined forests, all aspects of the qualitative variation in dead wood was found to be difficult to restore in the short-term, since the restored dead wood was mainly in the initial stage of decomposition. The use of various restoration treatments (e.g. the creation of both standing and fallen dead wood) can compensate for some of the missing variation in fungal communities in the restored substrates.
Based on my results, disturbance-based restoration produces promising results by the rapid re-introduction of some of the most important structural attributes that have been lost from forests previously managed for timber production. Although the findings in this thesis show the clear positive effects that restoration has on the re-creation of naturally occurring forest characteristics, it appears difficult to restore all the inherent variability of natural forests. A particular challenge originates from the extended time scale of the natural processes, which have created and maintained the full array of ecological structures in forests, including the generally slow processes of stand succession and wood decomposition. To build a more comprehensive understanding of the potential of forest restoration for the conservation of endangered forest-associated species, a substantially longer monitoring period of restored forests would be useful in future studies.
National forest inventory (NFI) data are commonly used in national and regional scenario analyses on forest production and utilization possibilities. There is an increased demand for similar analyses at the sub-regional level, and further, to incorporate spatially explicit data into the analyses. However, the fairly sparse network of NFI sample plots allows analyses only for large areas. The present dissertation explored whether satellite imagery, NFI sample plot data and the k nearest neighbour estimation method can be employed in generating spatial forest data for scenario analyses at the local level. The method was first applied in the area of two villages in Eastern Finland to quantify the effects of administrative land use and technical land-form constraints on timber production. Secondly, the impacts of three alternative regional felling strategies on suitable habitat for the Siberian flying squirrel (Pteromys volans) were assessed.
As a scenario analysis tool, the Finnish forestry dynamics model MELA was used. Management units for simulations of forest development and management activities were delineated by means of image segmentation and digital maps on restriction areas, and new weights for NFI sample plots, that is, the representativeness in these units, were estimated by means of satellite image data. The performance of different segmentation methods and different spectral features in the estimation were examined. Image segments corresponding to forest stands enabled the use of patch- and landscape-level models in the prediction of suitable habitat.
Satellite image-based estimation of new NFI sample plot weights was found to be a feasible method for generating forest data for scenario analyses in areas smaller than is possible with the plot data only, for example, for municipalities. Satellite imagery with large geographic coverage and continuous NFI field measurements provide cost-efficient data sources for versatile impact and scenario analyses at the local level.
Scenic beauty of forest stands and impact of management
The aim of this study was to find out what kind of forest is considered beautiful, and how forest management affects the scenic beauty. Differences between interest groups and the impact of season on scenic landscape were also examined. The research was a psycho-physical preference study, where the scenic quality of the landscape at the tree stand level was explained by descriptive variables of the forest, treatment and season. The study examined the landscape preferences of ordinary people rather than experts.
Photographs taken from the forest were used to evaluate scenic value in all sub-studies. The photographs represented typical tree species compositions, forest treatments and stages of stand development in Finnish commercial forests. The objects of the study were commercial forests, urban forests, and tourist areas. Local Finns and foreign tourists who arrived in Lapland evaluated the photographs.
The survey found that most people value large stems and relatively open forests. Reforestation always decreases the scenic value of the landscape. However, deterioration of scenic value after reforestation was short-lived if it is related to the entire rotation length. Natural regeneration is scenically clearly better than planting or seeding. The scenic value of the forest can also be increased by forest treatments, especially in dense untreated stands. Excessive stand density is particularly offending for Finnish. In other respects, the forest landscape preferences of Finns and foreign tourists seem to be very similar.
The mental images on the landscape effects of forest treatments were essentially very similar with the perceptions based on photographs - all the treatments, which evaluators thought to increase the beauty of the forests, increased it also on the basis of the image evaluation also in practice.
Predicting landscape value is not easy, because there are clear differences between different groups of people and, in particular, individuals in scenic valuations. For example, forest owners and forestry professionals feel the landscape effects of forest treatments more positive than other groups do. The study supports the view that the attitude towards forest management actions reflected in the perception of the landscape effects of treatments.
The study showed how unique and time bound the experience of the landscape is. The same stand of trees may be experienced in a very different way in summer and winter outfit. On average, commercial forests appear to be suitable for recreation and tourism clearly better in winter than in summer. The difference is particularly evident in reforestation areas.
This study aims to quantify how the spatially varying vegetation modifies the carbon sink of a boreal bog. Photosynthesis, respiration, biomass composition, biomass production and net ecosystem exchange were studied on three levels: plant species, community and ecosystem.
There was a clear plant species turnover and a strong decrease in standing biomassfrom dry to wet plant communities. Biomass production was even along the water table gradient due to higher biomass turnover rate of wet habitat species than hummock species. Both respiration and gross photosynthesis were the highest in dry plant communities, but their symmetrical water table responses resulted in no differences in net ecosystem exchange among plant communities. However, this evenness did not hold in the absence of Sphagna; sparsely vegetated bare peat surfaces were mostly carbon sources. The small difference in water table between Sphagnum-covered hollows and bare peat surfaces suggests that even a small change in water table could induce shifts between them.
The observed spatially-even carbon sink contradicts earlier studies. However, the components behind that spatial evenness showed high variability and responded to environmental conditions as previously observed. The site-specific relative abundances of functionally varied species appeared to have a larger effect on the overall carbon sink than anticipated.
Different plant species and communities had the highest photosynthesis and carbon sink at distinct times of the growing season, decreasing the ecosystem-level seasonal variation. Over the three studied years, the roles of plant communities in the ecosystem-level carbon sink changed. This indicates that the presence of species with different seasonal growth patterns and responses to environmental conditions could increase ecosystem resiliency in changing conditions. To verify this, the responses of functionally different components to environment, either based on natural variation or experimentally defined, should be included in processmodels predicting the fate of bog carbon sink in changing climate.
The demand for mechanized tree planting is expected to increase in the future. This dissertation assessed mechanized tree planting in Finland and suggests ways to improve its current productivity. The work on which this thesis is based was described in five peer-reviewed articles (I–V) addressing four specific research questions (SQs) that focus on productivity and cost-competitiveness, automation, capacity utilization, and the quality of planting work.
While productivity of mechanized planting is higher than manual methods, it is not yet cost-competitive. However, increasing efficiency by skilled operators and worksite selection make it possible for mechanized planting costs to remain lower than those of excavator spot mounding followed by manual planting. Increasing productivity and reducing operating costs are possible with an effective automatic seedling feeding system, although the Risutec APC is not yet sufficiently developed to reach that goal. Planting machine capacity is underutilized and could be utilized more effective to enhance productivity and cost-efficiency. Technical availability of planting machines in Finland is good, and the quality of mechanized planting work is high. Optimization and integration of the entire mechanized planting chain from the nursery to outplanting is important to minimize total cost.
In summary, for mechanized planting to be effective the following criteria must be satisfied: machine reliability; highly-skilled machine operator; suitable worksite; seedling quality, availability, and supply to worksite. In the future, it is important to continue developing new and existing machines to enhance productivity, e.g., by continuously working planting machines.
The peatlands in Southeast Asia have been impacted and turned to vast carbon dioxide sources (CO2) by land management often involving drainage and deforestation. The amount of released CO2 in decomposition is related to management intensity likely resulting from altered conditions for decomposition. However, the link between decomposition processes and land-use change are poorly understood.
To provide insight to the effects of land-use change intensities to decomposition processes in Central Kalimantan, Indonesia, we examined physical (dry bulk density, total pore space, particle size) and chemical properties (pH, loss-on-ignition; total concentrations of N, P, K, C, Ca, Mg, Mn, Zn, Al, Fe, S, Si, DOC and DON; organic matter quality characterized by infrared spectroscopy and on compound level), which together were used to determine the decomposition stage and decomposability (i.e., substrate quality) of peat. The peat biological properties (microbial biomass and enzyme activity) were used to provide insight to the decomposition activity at various land-use types and as a response to known peat properties. The study sites were: near-pristine swamp (i) and drained (ii) forest, deforested and drained degraded (iii), agricultural (iv) and reforested (v) sites.
At the most intensively altered deforested sites the peat was denser, finer and enriched with recalcitrant compounds. The highest enzyme activity and microbial biomass were in the surface peat of swamp forest, where the amount of labile carbohydrates was highest. The six years ago reforested site did not yet show signs of recovery in peat properties, which was likely due the limited litter production capacity of the young plantation and microbial activity limited by chemical weeding. The main conclusion is that the litter input, or rather the lack of it after land-use change, and intensive management practices forms the main factors affecting to decomposition processes and leading to poorer substrate quality and reduced biological activity.
The aim of this work was to analyze the responses of temporal and spatial variation in soil respiration to biotic and abiotic factors in a desert shrubland in Ningxia, northwest China. For this purpose, Rs together with abiotic (soil temperature (Ts), soil water content (SWC), precipitation (PPT) and biotic (root biomass, litter fall, leaf area index, soil nitrogen) factors were measured, and plant phenophases were recorded over a typical sand dune in 2012-2014. The specific aims of this study were to: (1) quantify the diurnal and seasonal variation of Rs and its controlling factors, and to understand the influences of SWC on the temperature sensitivity of Rs (Paper I); (2) explore the mechanisms controlling the spatial heterogeneity in Rs and the plant effects on spatial variation of Rs in different phenophases (Paper II); (3) examine the seasonal variation of diel hysteresis in Rs-Ts relationship and its controlling factors (SWC and photosynthesis) (Papers I and III); and (4) explore the influences of biological soil crusts on Rs and its climatic (Ts, SWC, PPT) responses (Paper IV).
As a result, both diurnal and seasonal variation in Rs were controlled dominantly by Ts, but the diurnal and seasonal response of Rs to Ts was modified by SWC and biological soil crusts (Papers I, III and IV). At diel scale, Rs was strongly regulated by Ts at moderate and high SWC, but decoupled from Ts under low SWC, due to significant diel hysteresis between Rs and Ts (Papers I and III). This diel hysteresis varied seasonally with SWC, showing increasing lag time with decreasing SWC (Papers I and III). Variation in the diel hysteresis with changing SWC was regulated by photosynthesis of the dominant shrub species (Paper III). At seasonal scale, Rs significantly correlated with Ts at SWC > 0.08 m3 m‑3 (Paper I). In addition, the temperature sensitivity of Rs increased with increasing of SWC (Paper I). The Rs at both non-crusted (NCS) and lichen-crusted (LCS) soils increased with increasing Ts, opposite to that on moss-crusted soil (MCS), where Rs declined with increasing Ts as Ts > ~ 20 oC (Paper IV). Root biomass of shrubs and grasses, litter fall and soil nitrogen affected the topographic variation in Rs (Paper II). During the flowering-bearing phase of the dominant shrub, root biomass affected Rs the most, whereas during the leaf coloration-defoliation phase, soil nitrogen content affected Rs the most, explaining 72 and 56% of the total variation, respectively(Paper II).
To conclude, SWC, biological soil crusts and shrubs exert strong influences on the temporal and spatial responses of Rs to Ts in a desert shrubland. These results highlight the necessity to account their interactive effects in estimation of carbon balance for desert ecosystems and in modelling of global carbon cycle in order to increase the accuracy of model predictions.
Low apoplastic water potentials can affect trees by decreasing the hydraulic conductivity of xylem due to embolism and by causing dehydration stress in living cells. Low apoplastic water potentials regularly occur in trees during summer and winter. These can either be caused by loss of water due to transpiration or by freezing due to the chemical properties of ice.
In this thesis the effects of low apoplastic water potential on trees were studied by causing low water potentials with three different methods: desiccation, freezing and by adjusting the osmotic concentration of xylem sap. Tree responses in this thesis were measured with stem diameter changes, leaf gas exchange, tree temperature and xylem water potential.
Living parenchyma cells are thought to have negligible effect on xylem diameter changes but this thesis shows that the role of parenchyma can, in fact, be much more significant. Evidence for the major role of parenchyma cells in the diameter changes of frozen xylem also supported the theory of extracellular freezing. Furthermore, mesophyll cells were shown to react to freezing with a rapid depression of photosynthesis.
It was also studied how a pressure increase in the xylem conduits, resulting from low water potentials, affects tree water relations during embolism formation and ice propagation. A gas burst was detected emerging from the tree stem during freezing. A decrease in the amount of gases in the xylem conduit can benefit trees in avoiding winter embolism. It was also experimentally confirmed that the formation of embolism in trees can temporarily even help relieve water stress due to the so called ´capacitive effect´. Low apoplastic water potential affects both the xylem and living cells in trees, and the interconnectedness of these responses are also shown in this thesis.
Environmental factors have a dual effect on growth as they affect both the momentary growth rate and the rate of ontogenetic development. Photosynthesized carbon on the other hand is needed for growth, respiration and other purposes. According to opposite theories, growth rate is determined by: 1) the availability of carbon for growth (source limitation) or 2) limitation that environmental factors cause on tissue ability to grow (sink limitation). Understanding the responses of wood, needle and root growth to environmental and other factors allows us to predict changes in tree growth and carbon balance in changing climatic conditions.
The purpose of this study was to define the effects of temperature on Scots pine growth at different temporal scales and to estimate the relative importances of the source and sink effects on growth. For that, a dynamic growth model CASSIA (Carbon Allocation Sink Source InterAction) was constructed.
CASSIA was able to predict daily primary, secondary and needle growth rate variation with indirect and direct effects of temperature. In addition, warm previous late summer was observed to lead to enhanced length (in temperature accumulation units) of shoot growth period in the following year. Growth onset during spring was a continuous process determined by temperature accumulation instead of momentary temperatures.
Short-term growth variations in normal conditions were concluded to be sink limited because the within year growth was satisfyingly predicted with temperature and without direct effect of photosynthesis or stored carbon. On the other hand carbon source effect (GPP) was needed to produce the between year variation in growth.
The results suggest that growth is limited by a complex combination of sink and source effects. Furthermore, environmental factors affect growth at different time scales varying from instantaneous to delayed effects from previous year(s). More research is needed to determine carbon flows to different processes.
The Moose is a valuable game animal in Fennoscandia but also the most severe pest in forest plantations. In this thesis, I examined factors that affect the habitat selection of moose and moose damage at multiple scales.
At the plot level, browsing increased with an increasing number of artificially regenerated pines and deciduous trees taller than pines. The damage risk was the highest in plantations with heavy soil preparation.
Moose summer home ranges had more fertile sites than the overall study area. Within summer ranges moose, selected non-pine-dominated habitats and mature forests and avoided human settlements. Winter ranges contained more pine-dominated plantations and other young successional stages, more pine dominated peatland forests and less human settlements and agricultural fields. Within winter ranges, moose used more non-pine-dominated plantations and mature forests and less human-inhabited areas than expected. At the home range level, there were no significant differences between sexes, but within home ranges males and females used different habitats during both seasons.
The occurrence of damage in nearby landscape decreased the probability to find a landscape without damage and predicted an increase in the number of damaged plantations. Increased food-cover adjacencies of mature forests and plantations increased damage. An increasing proportion of inhabited areas and the length of connecting roads decreased the number of damage at the landscape sizes of 1 km2 and 5 km2.
Moose-damaged stands were concentrated in SW and eastern Lapland in Peräpohja Schist Belt and Lapland’s Greenstone Belt with nutrient-rich bedrock. There was less damage in landscapes with an abundant amount of pine-dominated thinning forests. Moose damage plantations were located more on fertile bedrock and soils than undamaged ones. Regenerating Scots pine on fine-grained soils derived from nutrient-rich rocks and naturally occupied by Norway spruce might increase damage risk.
In this study, the effects of restoration of forestry-drained peatlands on the nutrient and organic carbon exports and methane dynamics of the restored sites are explored. The study consists of four sub-studies. Two of the sub-studies are concerned with the effects on water quality and export of elements of restoration and were conducted on a catchment scale. One of the studies was conducted in the laboratory, and assessed the release of elements from peat samples under anaerobic inundation simulating the effects of a rising water table after restoration or logging. The fourth study was again a field study, in which the differences in methane emissions between undrained, drained and restored spruce swamp forests were assessed. In all, 24 different pristine, drained and restored sites are featured in the study, one site being present in two of the sub-studies.
The results indicate potentially large effects of restoration especially on the nutrient rich spruce-dominated sites, which had the highest restoration-induced increases in organic carbon and nutrient exports in the catchment studies, and which also exhibited high methane emissions after restoration, higher than in the undrained or drained state. The results should prompt research into the techniques applied in restoration of such sites and into the processes which lie behind these large effects.
Urban forests provide various ecosystem services. However, they also require fairly intensive management, which can be supported with up-to-date tree-level data. Until recently, the data have been collected using traditional field measurements. Laser scanning (LS) techniques provide efficient means for acquiring detailed three-dimensional (3D) data from the vegetation. The objective of this dissertation was to develop methods for mapping and monitoring urban forests at tree level.
In substudy I, a method (MS-STI) utilizing multiple data sources was developed for extracting tree-level attributes. The method combined airborne laser scanning (ALS), field measurements, and tree locations. The field sample was generalized using the non-parametric nearest neighbor (NN) approach. The relative root mean square error (RMSE) of diameter at breast height (DBH) varied between 18.8–33.8%.
The performance of MS-STI was assessed in substudy II by applying it to an existing tree register. 88.8% of the trees were successfully detected, and the relative RMSE of DBH for the most common diameter classes varied between 21.7–24.3%.
In substudy III, downed trees were mapped from a recreational forest area by detecting changes in the canopy. 97.7% of the downed trees were detected and the commission error was 10%. Species group, DBH, and volume were estimated for all downed trees using ALS metrics and existing allometric models. For the DBH, the relative RMSE was 20.8% and 34.1% for conifers and deciduous trees respectively.
Finally, in substudy IV, a method utilizing terrestrial laser scanning (TLS) and tree basic density was developed for estimating tree-level stem biomass for urban trees. The relative RMSE of the stem biomass estimates varied between 8.4–10.5%.
The dissertation demonstrates the applicability of LS data in assessing tree-level attributes for urban forests. The methods developed show potential in providing the planning and management of urban forests with cost-efficient and up-to-date tree-level data.
A mature tree stem generally consists of a column of wood that is composed of a series of annual incremental layers and enclosed in a covering of bark. The dynamic variations of the bark are complex due to its structure and function: the thick outer-bark acts as a protective barrier against the abiotic and biotic environment; while the phloem is where sugar transport occurs. Much of the bark variation is due to the transport of sugars and its related processes. The xylem pathway, which transports water in the opposite direction, is connected to the phloem in parallel along the entire length of the stem. The immediate connection between these two transport pathways suggests a functional linkage.
The purpose of this thesis is to study the dynamic processes that occur within the bark and its interaction with other internal tree processes and the external environment. These interactions have not been thoroughly quantified, especially on an intra-annual (e.g. daily) scale.
The thesis consists of four papers, of which one is a modelling paper and three are experimental studies. Growth is estimated with the model by separating the water-related influences from measured inner-bark, revealing a growth signal – proxy for cambial stem growth. Using this signal, a correlation study to microclimate variables is examined in one paper; and to assumed growth respiration in a second paper. The remaining two papers explore the seasonality of photosynthesis and respiration, and bark stem dynamics during the spring recovery period.
As a conclusion of this thesis, these papers show how inextricably linked individual tree processes and the environmental are to the changes within the bark. The culmination of this thesis opens new opportunities to further understand the dynamics of bark hydraulics and ecophysiological processes by implementing field measurements and state-of-the-art modelling.
Cycling of carbon (C) and nutrients plays pivotal role for functioning of every ecosystem. Biogeochemical cycles of carbon and nitrogen (N) are balanced by a network of inter-actions between plants, litter and soil chemistry, microbial communities, enzyme machinery and climate conditions. This thesis focuses on the role of terpenes in C and N transformations in boreal forest soils. Terpenes are abundant plant secondary compounds. The focus was on certain mono-, di-, and triterpenes.
Soil incubation experiments revealed that terpenes increased the mineralization of carbon but decreased net nitrogen mineralization and net nitrification. Additionally they increased the amounts of carbon and nitrogen in the microbial biomass through enhancement of bacterial growth; however, they inhibited fungal growth. This study suggests that terpenes can act as a C source for some microbial communities. Moreover, terpenes showed inhibitory potential against enzymes, which are involved in C, N, P, S cycling. The mechanism of inhibition seems to be based at least partially on ability of terpenes to bind enzymes.
The field experiment presented the effect of logging residues and wood ash on composition of terpenes and C and N cycling in soil five years after clear-cutting a Norway spruce stand. Logging residue treatment increased the concentrations of certain terpenes in the organic layer. Both, logging residue and wood ash treatments increased net N mineralization and net nitrification. Some changes in terpene concentrations correlated with C and N cycling processes, but the relationship between terpene concentration and C and N cycling processes remained still unclear in the field conditions.
In conclusion, terpenes can affect C and N transformations in boreal forest soil. It is probable that terpenes change N cycling retaining more N in organic forms and potentially decrease nitrogen losses from forest ecosystem.
Increasing rain in winter with climate change may expose boreal forests especially on drained peatlands to winter or spring waterlogging. Information about the response of main forest species on soil waterlogging is important for improving predictions of forest productivity and assessing the demand for ditch-network maintenance. In this study, the aim was to find out the physiological and growth responses of one-year-old Norway spruce (Picea abies (L.) Karst.), silver birch (Betula pendula Roth) and pubescent birch (Betula pubescens Ehrh.) seedlings subjected to one-month waterlogging in late dormancy, and to find out the morphology, physiology and growth of both birch species subjected to one-month waterlogging in the early growing season.
Dormancy waterlogging (DW) led to a reduction of root volume in spruce, but did not affect dark-acclimated chlorophyll fluorescence or biomass of needles, stems and roots. Root biomass and root hydraulic conductance of silver birch were reduced but aboveground organs were not affected by DW. In pubescent birch stomatal conductance and net photosynthesis (Amax) were reduced by DW, however, root morphology and leaf, stem and root biomass was not negatively affected. In conclusion, these tree species tolerated one-month winter waterlogging well.
Growth waterlogging (GW) led to the reduction of stomatal conductance and Amax as well as leaf area in both birch species. Leaf contents of potassium, calcium, magnesium, manganese and boron were reduced in silver birch, whereas only calcium and magnesium contents were reduced in pubescent birch by GW. In pubescent birch, fine cluster roots, the occurrence of leaf trichomes and stem lenticels were increased by GW. However, silver birch did not show such acclimation to waterlogging. In conclusion, GW caused more negative effects to both birch species than DW. The morphological rather than physiological differences may explain why pubescent birch grows better in wet soil than silver birch.
Airborne laser scanning (ALS)-based mapping campaigns are expanding in numbers throughout the world. Lands are scanned for the purposes of topography mapping and forestry. Yet, as much of wildlife lives in forests, the data hold accurate information about the structure of wildlife habitats. This is valuable information, because vegetation structure is a key component of habitat suitability.
In this thesis, ALS data were used to analyze habitat use and behavior of moose. The ALS data were integrated into locations of GPS-collared moose. As a consequence, patterns in their habitat use were seen from the ALS point clouds. The types of forests moose used during different seasons, different times of day, or when under thermal stress, were examined in detail. Lastly, ALS data were used to identify moose browsing damages.
The results revealed the usefulness of ALS in wildlife ecology research. It was shown that habitats used during different seasons are significantly different from one another in terms of forest structure, which links to the type of food used during each season and where it exists. Also, the effect of temperature on moose habitat use was revealed: high summer temperatures made moose utilize thermal shelters under high and dense canopies. Views were also gained about the role of forest structure for calving females, who gave birth in open areas (mires) but moved to forests with dense shrub layers shortly after calving: cover and food for the growing calf and the lactating female. Finally, it was shown that differences in forest structure caused by intense moose browsing can be detected from ALS data.
Information about vegetation structure is valuable additional data for wildlife research and can easily be integrated with the existing methods. This thesis gives good examples of how to do this. The approach is applicable to other species as well.
The aims of the study were to identify factors related to temporal and spatial variation in forest soil CO2 efflux(Fs), compare measurement chambers, and to test effects of a climate change experiment. The study was based on four-year measurements in upland Scots pine forests.
Momentary plot averages of Fs ranged from 0.04 to 1.12 gCO2m−2 h−1 and annual estimates for the forested area from1750 to 2050 gCO2 m−2. Soil temperature was a dominant predictor of the temporal variation in Fs (R2=76–82%). A temperature and degree days model predicted Fs of independent data within 15% on the average but underestimated it during the peak efflux period (July–August), possibly because of seasonal pattern in growth of roots and mycorrhiza. A comparison sub-study indicated that the reliability of the measurement chambers was not related to the principle i.e. non-steady-state through-flow, non-steady-state non-through-flow or steady-state through-flow.
Spatial variability of Fs within 400 m2 plots in four stands was large; coefficients of variation (CV) ranged from 0.10 to 0.80, with growing season averages of 0.22–0.36. A positive spatial autocorrelation was found at short distances (3–8 m). In data from several stands, thickness of the humus layer explained 28% of the variation in Fs, and with the distance to the closest trees it explained 40%. Fs also correlated with root mass of the humus layer. Between-plot differences in Fs were small.
In the climate change experiment, CO2 enrichment and air warming consistently, but not always significantly,increased Fs in whole-tree chambers. Their combined effect was additive, with no interaction; i.e. +23–37% (elevated CO2), +27–43% (elevated temperature), and +35–59% (combined treatment), depending on year. Air warming was a significant factor in the 4-year data according to ANOVA. Temperature sensitivity of Fs under the warming, however, decreased in the second year.
In this study, 1) a model to estimate soil carbon dioxide (CO2) balance for forestry-drained peatlands was tested on site and countrywide levels in Finland. 2) A dataset of annual soil–atmosphere fluxes of CO2, methane (CH4) and nitrous oxide (N2O) from 68 sites was collected, and models fitted for their upscaling to a countrywide level. 3) The current greenhouse gas impact of the 68 study sites, including soil CO2, CH4 and N2O balances and the CO2 sink function of tree biomass increment, was estimated.
The soil CO2 balance estimation, as the difference between litter input to soil and CO2 efflux from soil, was straightforward to apply, but considerable uncertainty was caused by the inadequate level of knowledge on belowground plant–soil carbon fluxes. Soil–atmosphere gas fluxes could be upscaled to a countrywide level utilizing readily available forest inventory results and weather statistics. Soils in nutrient-rich study sites were sources of greenhouse gases while those in nutrient-poor study sites were sinks, on average. The current greenhouse gas impact, when no forest fellings occurred, was nevertheless climate cooling for both the nutrient-rich and poor sites due to the considerable CO2 sink formed by increasing tree biomass.
The aim of the study was to investigate the effects of climate change on soil hydrology and carbon (C) fluxes in boreal peatland ecosystems, with implications for the feasibility of cultivating reed canary grass (Phalaris arundinacea, L; RCG) as a way to restore the C sink in cutaway peatlands under Finnish conditions. First, hydrological models were developed for pristine peatland ecosystems and the cutaway peatlands under RCG cultivation. Concurrently, the hydrological responses to varying climatic forcing and mire types were investigated for these ecosystems. Thereafter, process-based models for estimating the seasonal and annual C exchanges were developed for the pristine mires and cutaway peatlands. The C models incorporated the hydrological models for corresponding ecosystems. Model simulations based on the climate scenarios (ACCLIM, developed by the Finnish Meteorological Institute, FMI) were further carried out to study the impacts of climate change on the C exchanges in the peatland ecosystems during the 21st century.
The simulation showed that the water table (WT) in the pristine Finnish mires would draw down slightly during the 21st century. Such a change in WT would be related to a decrease in the CO2 sink but an increase in the CH4 source at the country scale, as driven mainly by the rising temperature (Ta) and increasing precipitation (P). These changes in CO2 / CH4 fluxes would decrease the total C-greenhouse gas (GHG) sink (CO2 equilibrium) by 68% at the country scale, and the changes would be more pronounced toward the end of the century. The majority of pristine fens in southern and western Finland and the pristine bogs near the coastal areas would become centurial CO2 sources under the changing climate. On the other hand, the major distribution of fens in northern Finland would act to increase the CH4 source at the country scale, whereas the CH4 emission would tend to decrease with WT in the southern and western areas of Finland. Peat extraction and RCG cultivation tends to limit the influence of WT on the root-zone moisture content in a peatland ecosystem, resulting in a high sensitivity of soil moisture content to the regularity of summer rainfall. However, the phenological cycle of RCG may represent an adaptive feature of photosynthesis to the stochasticity of summer precipitation. By the end of the 21st century, climate change will decrease the CO2 sequestration by 63% - 87% in a cutaway RCG peatland during a main rotation period of 12 years. Nevertheless, the site could sustain a net CO2 sink, which is comparable to the pristine peatlands in the same region.
The species specific growth patterns make plastic crown architecture respond in different manner to different environments modifying their influence to neighbours. The main aims of this thesis were to separate the effect of neighbour species identity from the abundance, size and proximity of the neighbours in between-tree competition and to link crown architecture with hydraulic architecture by identifying the associated within-tree variation of crown traits.
The empirical part of the work was based on digitising three-dimensional (3D) crown architecture and measuring xylem anatomy. Digitising allowed the development of crown architecture models for Betula pendula (Roth.) and Pinus sylvestris (L.). The models were further applied to simulate light transmission in mixed stands.
Crown architecture of the studied species responded to increased competition intensity primarily by reducing branch number and size. Proportional biomass distribution to foliage and main branches over the stem increased in young B. pendula with increasing competition intensity, whereas Pinus sylvestris used the opposite strategy. In addition to competition intensity, crown architecture of the studied species showed plastic responses to the species identity of neighbouring trees. Lower overall growth but added height growth indicating stronger competition was found in mixtures of B. pendula and Pinus sylvestris when a tree was surrounded by interspecific neighbours compared to trees surrounded by intraspecific neighbours. Both species-specific effects on resource gradients and non-resource signals remain plausible explanations for this result: B. pendula transmitted more light than Pinus sylvestris at simulated dense stands.
Hydraulic architecture was shown to be interlinked with crown architecture as the conduit diameter varied as a function of tree compartment, branching hierarchy, leaf area and distance from the apex. The results suggest that the use of detailed tree structure models and species-specific competition analysis is useful in predicting and understanding growth in mixed boreal stands.
Heterobasidion annosum s.l. is a serious forest pathogen that causes significant economic losses, especially in the Northern Hemisphere. In Finland, the H. annosum s.s. and H. parviporum within the Heterobasidion complex affect the growth and wood properties of Norway spruce (Picea abies (L.) Karst.) and its suitability for different industrial purposes. The main aim of this PhD thesis was to study the wood degradation (WD) caused by H. annosum s.l. and enzymatic hydrolysis under laboratory conditions in wood specimens representing different genotypes and crown types of Norway spruce, and at positions along the stem. Furthermore, the relationship between WD and different traits such as tree growth, physical properties and wood chemical composition, as well as the production of reducing sugars (RS), were also studied.
The WD differed between normal-crowned Norway spruce clones, but not between normal- and narrow-crowned trees. H. annosum s.s. caused a higher WD than H. parviporum. The WD was also affected by the position within the wood discs, along the stem and by the age of the sample trees. In older trees, samples taken near the pith were more degraded than those taken near the bark and vice versa. In younger trees, wood density correlated negatively with WD. Positive correlations were also observed between RS and WD, suggesting that genotypes susceptible to WD may represent desired raw material for some other industries in which the hydrolysis of the main wood components is essential (i.e., biorefining). To conclude, this thesis showed that the genotypic variation observed in breeding material may represent an advantage for forest tree breeding to control and avoid Heterobasidion attacks, especially when studied along with other important traits and considering silvicultural practices such as the thinning regime and rotation length that may affect WD risk by H. annosum.
The aim of this work was to analyse how the seasonal biomass growth and allocation in a boreal bioenergy crop (Phalaris arundinacea L., hereafter RCG) were affected by elevated temperature and CO2 under different levels of groundwater. For this purpose, plants in peat monoliths representing young and old cultivations were grown in auto-controlled environmental chambers over two growing seasons (April-September, 2009 and 2010) under elevated temperature (ambient + 3.5°C) and CO2 (700 μmol mol−1). Three levels of groundwater, ranging from high (0 cm below the soil surface), to normal (20 cm below the soil surface) and low (40 cm below the soil surface), were used.
Compared to growth under ambient conditions, elevated temperature (ET) enhanced leaf development and photosynthesis in the RCG plant. Consequently, ET enhanced biomass growth during early growing periods. It also reduced photosynthesis and caused earlier leaf senescence during later growing periods. ET therefore reduced total biomass growth across the entire growing season. Elevated CO2 (EC) significantly increased biomass growth throughout the growing period primarily because of increased leaf area and photosynthesis. Lower groundwater level (LW) decreased the growth of RCG, mainly because of lower leaf area and photosynthesis. Furthermore, LW accelerated the cessation of growth, thus making the growing season shorter compared with the effects of higher groundwater levels. The LW- induced reductions in biomass growth were exacerbated by ET and partially mitigated by EC. The combination of elevated temperature and CO2 (ETC) slightly increased plant growth. The age of cultivation did not affect the biomass growth among the three major organs (leaf, stem and root) and thus did not affect total biomass. Biomass allocation was clearly controlled by plant phenology.
Biomass growth was mainly allocated to leaves and stems in the early growing season, to stems in the middle of the growing season and to roots later in the growing season. Under EC, root growth contributed more to total biomass growth compared to the leaf and stem growth in biomass, regardless of groundwater levels. The opposite was observed under ET and ETC and well-watered conditions (which was opposite to what was observed under LW). Our results show that climatic treatments affected biomass growth and biomass allocation to each of the three plant organs, while the direction and extent of climate-related changes in biomass growth and allocation depended on the availability of groundwater. The influence of groundwater level appeared to be crucial for the carbon gain regarding the production of RCG biomass for energy purposes and the concurrent sequestration of carbon in soils under changing climates in the mire sites used to cultivate RCG.
Europe was declared malaria free in 1975. The disappearance of malaria has traditionally been attributed to numerous deliberate actions like vector control, the screening of houses, more efficient medication etc. Malaria, however, disappeared from many countries like Finland before any counter measures had even started. The aim of this thesis is to study the population ecology of P. vivax and its interaction with the human host and the vector. By finding the factors that attributed to the extinction of vivax malaria it might be possible to improve the modern strategy against P. vivax. The parasite was studied with data from Finland, which provides the longest time series (1749-2008) of malaria statistics in the world. The malaria vectors, Anopheles messeae and A. beklemishevi are still common species in the country. The eradication of vivax malaria is difficult because the parasite has a dormant stage that can cause a relapse long after a primary infection. It was now shown that P. vivax is able to detect the presence of a potential vector. A dormant stage is triggered even from a bite of an uninfected Anopheles mosquito.
This optimizes the chances for the Plasmodium to reach a mosquito vector for sexual reproduction. The longevity of the dormant stage could be shown to be at least nine years.
The parasite spends several years in its human host and the behaviour of the human carrier had a profound impact on the decline of the disease in Finland. Malaria spring epidemics could be explained by a previous warm summer. Neither annual nor summer mean temperature had any impact on the long term malaria trend. Malaria disappeared slowly from Finland without mosquito control. The sociological change from extended families to nuclear families led to decreased household size. The decreased household size correlated strongly with the decline of malaria. That led to an increased isolation of the subpopulations of P. vivax. Their habitat consisted of the bedrooms in which human carriers slept together with the overwintering vectors. The isolation of the parasite ultimately led to the extinction of vivax malaria. Metapopulation models adapted to local conditions should therefore be implemented as a tool for settlement planning and socio-economic development and become an integrated part of the fight against malaria.
An important challenge in forest industry is to get the appropriate raw material out from the forests to the wood processing industry. Growth and stem reconstruction simulators are therefore increasingly integrated in industrial conversion simulators, for linking the properties of wooden products to the three-dimensional structure of stems and their growing conditions. Static simulators predict the wood properties from stem dimensions at the end of a growth simulation period, whereas in dynamic approaches, the structural components, e.g. branches, are incremented along with the growth processes. The dynamic approach can be applied to stem reconstruction by predicting the three-dimensional stem structure from external tree variables (i.e. age, height) as a result of growth to the current state. In this study, a dynamic growth simulator, PipeQual, and a stem reconstruction simulator, RetroSTEM, are adapted to Norway spruce (Picea abies [L.] Karst.) to predict the three-dimensional structure of stems (tapers, branchiness, wood basic density) over time such that both simulators can be integrated in a sawing simulator.
The parameterisation of the PipeQual and RetroSTEM simulators for Norway spruce relied on the theoretically based description of tree structure developing in the growth process and following certain conservative structural regularities while allowing for plasticity in the crown development. The crown expressed both regularity and plasticity in its development, as the vertical foliage density peaked regularly at about 5 m from the stem apex, varying below that with tree age and dominance position (Study I). Conservative stem structure was characterized in terms of (1) the pipe ratios between foliage mass and branch and stem cross-sectional areas at crown base, (2) the allometric relationship between foliage mass and crown length, (3) mean branch length relative to crown length and (4) form coefficients in branches and stem (Study II). The pipe ratio between branch and stem cross-sectional area at crown base, and mean branch length relative to the crown length may differ in trees before and after canopy closure, but the variation should be further analysed in stands of different ages and densities with varying site fertilities and climates.
The predictions of the PipeQual and RetroSTEM simulators were evaluated by comparing the simulated values to measured ones (Study III, IV). Both simulators predicted stem taper and branch diameter at the individual tree level with a small bias. RetroSTEM predictions of wood density were accurate. For focusing on even more accurate predictions of stem diameters and branchiness along the stem, both simulators should be further improved by revising the following aspects in the simulators: the relationship between foliage and stem sapwood area in the upper stem, the error source in branch sizes, the crown base development and the height growth models in RetroSTEM. In Study V, the RetroSTEM simulator was integrated in the InnoSIM sawing simulator, and according to the pilot simulations, this turned out to be an efficient tool for readily producing stand scale information about stem sizes and structure when approximating the available assortments of wood products.
The objective of this study was to model the growth and development of the stem and wood properties of Scots pine (Pinus sylvestris L.) in order to investigate how silvicultural management affects the knots and other properties of wood. In the above context, an existing three-dimensional model for the structural growth, stem and wood properties (especially knots) of a Scots pine was further developed (Paper I) and used with a sawing simulator (Paper II) to study how management (initial spacing, thinning and artificial pruning of branches) affects the quantity and quality of the sawn timber (Paper III). In addition, empirical models were developed for the distribution of diameter growth along the stem (Paper IV) and prediction of early wood percentage, wood density and fibre length along the stem (Paper V). These empirical models were also integrated with a process-based growth and yield model simulations (Papers IV and V).
Based on simulations, it was found that in order to maximize the quality of sawn timber, trees should be grown at relatively narrow spacing (up to 5 000 stems ha-1) at the beginning of the rotation to reduce the growth of branches, whereas towards the end of rotation they should be grown at relatively sparse spacing (e.g. 500 stems ha-1) to accelerate the self-pruning of dead branches and occlusion of knots, and to increase the volume growth of the stem (Paper III). It was also found that the diameter growth and the properties of wood vary in individual trees significantly depending on the stand development phase, management and tree status in a stand and depending on which part of stem is considered (Papers IV and V). To conclude, the integrated models developed in this work provide possibilities to assess simultaneously the impacts of management on the growth and yield and the properties of wood.
The objectives of this study were to analyze the impact of structural stand characteristics on ignition potential, surface fuel moisture, and fire behavior in Pinus sylvestris L. and Picea abies (L.) Karst stands in Finland and to explain stand-specific fire danger using the Canadian Fire Weather Index System and the Finnish Fire Risk Index. Additionally, the study analyzes the relationship between observed fire activity and fire weather indices at different stages of growing season.
Field experiments were carried out in Pinus sylvestris or Picea abies dominated stands during fire seasons 2001 and 2002. Observations on ignition potential, fuel moisture, and fire behavior were analyzed in relation to stand structure and the outputs of the Finnish and Canadian fire weather indices. Seasonal patterns of fire activity were examined based on national fire statistics 1996–2003, effective temperature sum, and the fire weather indices. Point fire ignition potential was highest in Pinus clear-cuts and lowest in closed Picea stands. Moss-dominated surface fuels were driest in clear-cut and sapling stage stands and presented the highest moisture content under closed Picea canopy. Pinus sylvestris stands carried fire under a wide range of fire weather conditions under which Picea abies stands failed to sustain fire. In the national fire records, the daily number of reported ignitions presented its highest value during late fire season whereas the daily area burned peaked most substantially during early season. The fire weather indices correlated significantly with ignition potential and fuel moisture but were unable to explain fire behavior in the experimental fires. During the initial and final stages of the growing season, fire activity was disconnected from weather-based fire danger ratings. Information on stand structure and season stage would benefit the assessment of fire danger in Finnish forest landscape for fire suppression and controlled burning purposes.
In the near future, the wood from silver birch (Betula pendula Roth) plantations will broadly increase as a source of raw material of saw and veneer logs. Due to the differences in growth rate and silviculture, the raw material from plantations is likely to have characteristics different from those of the wood harvested from naturally regenerated forests. In the further processing of sawn birch timber, the drying of wood is one of the most difficult phases: discolouration, deformation, moisture content gradient, being typical defects for dried birch timber.
The objective of this thesis was to study the drying behaviour and related wood and timber properties of plantation-grown silver birch. The wood procurement season and storage of logs were studied as a source of variation of wood properties and drying behaviour. To study the variation in wood properties and drying behaviour caused by the drying method, the conventional kiln drying (heat and vent drying) and vacuum drying were used. On the subject of drying method, wood colour, shrinkage, weight density, final moisture content, Brinell hardness and equilibrium moisture content were studied. The role of proanthocyanidins and their polymerisation as a chemical background for the discolouration was studied.
The drying behaviour, the initial moisture content of the wood, basic density and proanthocyanidin content were found to change with the wood procurement season. These changes were consequences of the physiological alterations in birch trees with the seasons and they were found to have an influence on colour, density, equilibrium moisture content and Brinell hardness of wood. Regarding the conventionally dried wood, the discolouration was the most intensive for summer-felled wood while the vacuum-dried wood discoloured the most intensively when it was felled in winter. In summer-felled and winter-felled wood the storage of timber as logs increased the discolouration of the wood during drying.
In this thesis are studied the role of decomposing logging residues and developing ground vegetation in nutrient dynamics of a clear-cut area. The main aims were to study how much nutrients are released from logging residues during the first three years after clear-cutting and what is the role of ground vegetation in the retention of nutrients on site after clear-cutting. The study was conducted in eastern Finland in a Norway spruce dominated mixed forest, part of which was clear-cut and part left uncut. The decomposition of Norway spruce (Picea abies Karsten), Scots pine (Pinus sylvestris L.) and silver birch (Betula pendula Roth.) logging residues i.e. foliage, fine roots (diameter ≤ 2 mm) and branches (diameter ≤ 1 cm), were studied using the litterbag method. Above- and below-ground biomass of the ground vegetation was sampled on one uncut plot and two clear-cut plots one year before and five years after clear-cutting.
In total, 33 % of the dry mass and C, 49 % of P, 90 % of K and 8 % of Ca were released from logging residues in three years, but there was no net release of N because more N accumulated in the roots and branches than was released from the foliage. The loss of mass, C, P and K was greatest during the first year, whereas there was no net release of Ca until the third year. Most of the released nutrients originated from the foliage. Total ground vegetation biomass and nutrient pools decreased after clear-cutting to one half or even lower, but returned to pre-cutting levels within 4-5 years, and the pools of P and K became even larger. In the first year after clear-cutting more N and Ca accumulated in the logging residues than were stored in the ground vegetation.
The results indicate that logging residues are a potential source of the elevated dissolved C and P, K and Ca observed in surface waters soon after clear-cutting, but are not a net source of N during the first three years. The ground vegetation is capable of taking up only a small fraction of the nutrients that are released from logging residues during the first two years after clear-cutting and the decomposing dead ground vegetation is a potential source of leached nutrients. The results suggest that nutrients released from logging residues are initially retained on site primarily through soil processes and microbial immobilization. Solely microbial immobilization in logging residues can initially play a more important role in the retention of N and Ca than the ground vegetation. Ground vegetation, however, recovers rapidly from clear-cutting and it becomes thereafter a significant nutrient sink.
Fast-growing, high-yield tree plantations are an increasingly significant source of wood in the tropics. In these areas, improved wood productivity is an important economic goal. In Costa Rica and other countries in Central America, most of the tree plantations, especially those of advanced age, have not had the productivity expected of them. In the general context of a closer relationship between management practices and quality wood production, the general objective of this research was to develop a set of intensive management scenarios that could lead to alternative timber production practices with attainable and promising economic returns.
Data for the different studies were collected in different regions of Costa Rica, covering almost all climatic conditions where T. grandis plantations have been established and where the species has adapted well. The study consisted fundamentally of the measurement of growth and yield parameters at the stand level and of the analysis of wood properties at the individual tree level and the interrelationship between silvicultural management and site conditions.
High intensity, timely thinnings yielded both individual tree and stand volume, i.e. the objective of high individual tree growth was met without a severe reduction in stand yield. Pruning up to a reasonable height and on time caused no reduction in tree growth and stand yield. Moreover, pruning may improve stem form (higher form factor, lower stem taper) and heartwood content.
Important characteristics, such as heartwood content and wood density, were found to be related more to tree age than to silvicultural management practices, especially at early plantation stages.
Growth scenarios for 20 and 30 year rotations with the objectives of high individual tree growth and high stand growth were developed for high, medium, and low quality sites. Different site classes, production objectives, rotation periods, and discount rates resulted in marked differences in the financial profitability projections of the developed scenarios.