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 majority of global forest area is considered neither forest plantation nor formally protected. In these forests multiple-use prevails and forests have the potential to be managed sustainably while providing multiple ecosystem goods and services. However, in practice, management in these forest areas is usually intensive, often securing the provision of a single commodity: wood biomass. This management leads to forest simplification, disregarding forest multi-functionality, biodiversity conservation and ecosystem services provided by forest biodiversity.
In this thesis, I evaluate the effect of increasing forest functional heterogeneity on biodiversity and multiple ecosystem services in managed boreal forests. My research takes advantage from a large-scale, replicated ecological experiment initiated in Finland in 2000, where forest structure was manipulated following disturbance guided management, with several retention levels at harvesting in combination with prescribed fire in 24 study sites.
The results show that local scale heterogeneity mediated by fire and high retention improves lingonberry yield and performance in burnt harvested forests. Dead wood and post-fire soil structure from these forests are beneficial for bee abundance and diversity, through an increase in nesting resources. Early successional burned forests exhibit increased levels of parasitoid functional diversity driven by higher structural complexity of vegetation mediated by disturbance.
At a landscape scale, old-growth forests provide with abundant bilberry cover, spring flowering and berry yield, offering complementarity of flowering resources for pollinators nesting on post-harvest forests. Habitat diversity generated by old-growth forests, variable tree retention and fire intensity, promotes pollinator spatial and temporal turnover, especially in burned harvested forests, and large-scale parasitoid functional trait diversity.
In conclusion, emulation of forest disturbance at harvesting, together with the preservation of natural old-growth forests increase functional heterogeneity in managed boreal forests and hold promise for reconciling production forestry with sustainable forest management, provision of critical ecosystem services and biodiversity conservation.
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.
Export of dissolved organic carbon and nitrogen (DOC and DON) from terrestrial ecosystems to watercourses has increased in the boreal zone. However, the effects of decomposing material and soil food webs on the release rate and quality of DOC and DON are poorly known. The objective of this study was to quantify the release of carbon (C) and nitrogen (N) from mor and peat, which are the most common organic soil types in the boreal zone. The impact of soil fauna on the release processes was also estimated. Decomposition products were divided into intermediate products (DOC and DON) and mineralised end products, i.e. carbon dioxide (CO2-C) and ammonium (NH4+-N). The release of C and N into the soil solution, extractable pools, and CO2-C efflux were measured. DOC and DON were further divided into high molecular weight (HMW) and low molecular weight (LMW) fractions.
Carbon release was slightly different in each soil type. In absolute terms, the peat released less C and in relative terms more DOC than mor. Enchytraeids worms (Cognettia sphagnetorum) affected the quantity and composition of the decomposition products by enhancing mineralisation and the release of HMW-DOC.
In the slightly decomposed peat, the net release of N occurred in the form of DON, whereas the other soil types mainly released NH4+-N. The slightly decomposed peats are typically located close to water bodies, in the topmost soil layer, where the water discharge is the highest. Therefore, the slightly decomposed peats might have an important role in controlling the quality and quantity of N export.
The results were used to further develop the decomposition model ROMUL to account for DOC and DON processes and the division between intermediate and end products. The parameterisation and structure of the model was analysed by means of the GLUE (Generalised Likelihood Uncertainty Estimation) method, and several simultaneously measured variables, which is novel in this research field.
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.
The aim of research study was to use acid catalyzed pretreatment for efficient solubilization of hemicellulosic sugars from lignocellulosic materials and test the fermentability of the liquid prehydrolysate via acetone-butanol-ethanol (ABE) fermentation. Three different lignocellulosic materials were chosen: barley straw (Hordeum vulgare), a willow species (Salix schwerinii), and a spruce species (Picea abies). The aim of the pretreatment was to clarify the most optimal conditions to liberate hemicellulosic sugars into a fermentable monomeric form without serious degradation and leave the cellulose as intact as possible.
With the barley straw, xylan was completely extracted into the liquid prehydrolysate with the combined severity (CS) 1.27 (120°C, 1% H2SO4 and 60 min) and with willow, approximately 65% of xylan was extracted as monosaccharidic xylose with the CS 2.29 (0.1% H2SO4, 200C, 30 min). Microwave pretreatment was shown to be effective with Norway spruce, with almost complete extraction of mannan, galactan, and xylan to the liquid prehydrolysate. Additionally, low concentrations of degradation products including furfural, HMF, formic acid, and levulinic acid were produced during acid-catalyzed pretreatments.
On the other hand, results showed that the dilute acid catalyzed pretreatments tested gave incomplete enzymatic saccharification of the willow and Norway spruce pretreated solid materials. Results showed, however, that with the optimization of pretreatment conditions based on the lignocellulosic biomass used, hemicelluloses could be extracted more selectively to fermentable sugars and cellulose preserved for further biorefining.
The liquid prehydrolysate of willow without detoxification but supplemented with starch was successfully fermented to butanol using Clostridium acetobutylicum, with butanol and ABE yields of 0.22 g/g and 0.35 g/g monosaccharide, respectively. It was also found that starch from barley grain ensured the essential nutrients for ABE fermentation. For efficient utilization of hemicellulose for butanol production, combining starch-containing side-streams to the hemicellulosic side-streams would offer an option for industrial ABE production.
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.