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.
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.
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).
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.
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 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.
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 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.