Primary forests are of high importance for their significant contribution to biodiversity, climate change mitigation and sustainable livelihoods. As part of the Food and Agriculture Organization of the United Nations (FAO) Global forest resources assessment, countries report on primary forest extent, defined by FAO as “naturally regenerated forest of native tree species, where there are no clearly visible indications of human activities and the ecological processes are not significantly disturbed”. However, past global assessments show that there is considerable variation in how countries understand the FAO definition of primary forest in their own circumstances. That raises questions about the comparability of the reported data among countries and their applicability for informing policy decisions. To address this, the FAO has initiated together with countries and partners a study to improve the guidance for reporting on the extent of primary forests by biome. The work started in the boreal biome with a joint workshop of seven countries (Canada, China, Finland, Norway, the Russian Federation, Sweden and the United States of America) and experts from FAO, Convention on Biological Diversity (CBD), United Nations Economic Commission for Europe (UNECE) and the Joint Research Centre (JRC). Definitions and methods used to measure and report on boreal primary forests in those countries were reviewed and a common framework to improve reporting on primary forest for the boreal biome was developed as a possible solution. The review of the status of the data reported on primary forest in those seven countries revealed major differences and similarities in the datasets and measurement approaches, and considerations which may be unique to the boreal biome. A novel decision tree framework is proposed to enhance the consistency, comparability, completeness and quality of estimates of the extent of primary forests for the boreal biome.

Unmanaged, old-growth boreal forests have a crucial role in protecting biodiversity and storing large amounts of carbon in the biomass, litter, and soil pools. Recent studies have suggested a continuous carbon sink of old-growth forests, questioning the hypothesis of a steady-state system. The carbon sink capacity of boreal old-growth forests is, however, insufficiently known due to a lack of knowledge regarding the spatiotemporal patterns of growth, mortality, and regeneration. Aiming to produce information for scenario modelling and to improve our knowledge concerning the role of old-growth forests in climate change mitigation, we explored the development of carbon balances in unmanaged forests that have been susceptible to various disturbance agents, such as wind, snow, and pests. The carbon stocks of living trees, snags, and logs were quantified based on a time-series dataset consisting of measurements taken from 1990 to 2019 from 27 Norway spruce (Picea abies) dominated Finnish forest stands. The dataset was also used to improve the process-based forest model PREBAS, enhancing its ability to simulate the impacts of climate change on old-growth forests. Here we present the observed carbon balance of the studied forest stands and discuss the role of stand structure, disturbances and climate conditions in explaining the patterns. Applying the updated PREBAS model to forested landscapes can importantly help in determining areas where biodiversity conservation and climate change mitigation could be optimized through carbon sequestration.

Boreal old-growth forests provide critical habitats and ecosystem services in the current context of climate change and biodiversity loss. The high importance of these ecosystems depends notably on their fine-scale diversity of structure and composition. Old-growth forest areas, however, continue to decline at a rapid rate due to anthropogenic disturbances. In particular, forest management targets mainly old-growth forests with the highest economic value or higher wood volume, implying loss of ecosystem services and particular habitats.

In this context, it is important to provide widely applicable forest survey tools capable not only of identifying boreal old-growth forests, but also of effectively discriminating their diversity of structure and composition at finer scale. We thus explored the potential of a combined use of aerial LiDAR (Light Detection and Ranging) and satellite data to address this issue in two boreal territories in eastern Canada, where old-growth forests are still abundant. One of these areas was dominated by balsam fir (Abies balsamea) and the other by black spruce (Picea mariana). Aerial LiDAR and satellite data were effective in discriminating old-growth forests characterized by specific structures and compositions resulting from different natural disturbance histories. In comparison, forest survey data obtained by traditional photo-interpretation of aerial photographs greatly underestimated stand complexity, and thus the presence of boreal old-growth forests.

The dissemination of increasingly accurate remote sensing data can therefore contribute to a more refined identification of the abundance and diversity of old-growth forests in boreal landscapes. They are indispensable tools for the implementation of forest management strategies that maintain the habitats and functions that characterize boreal primary forests.

Boreal forest biodiversity is closely linked to habitats heterogeneity, while forest management causes habitat homogenization. Stand-level forest management approaches have been developed with an aim to restore within-stand habitat heterogeneity, but we do not know how their application at the landscape scale would promote biodiversity.

Objective. We introduce the concept of management diversity and investigate the potential benefit of diversifying management regimes to increase landscape-level heterogeneity (between stand), including its temporal dimensions.

Method. Building on the concept of spatio-temporal heterogeneity, we developed hypotheses on how management diversity can benefit biodiversity and tested them in a representative forest landscape of central Finland. Forest stands were simulated 100 year into the future (over 20 time-periods) under regular management, set-aside (no management) and 12 alternative management regimes. We created virtual landscapes to (i) compare the individual performance of management regimes, and (ii) test for the management diversification hypothesis at different levels of set-aside. For each virtual landscape, we evaluated habitat availability of six biodiversity indicator species, multispecies habitat availability, and their temporal variability.

Results. Each indicator species responded differently to management regimes, with no single regime being optimal for all species at the same time. Management diversification lead to a 30% gain in multispecies habitat availability, relative to current management practice. By selecting a subset of five alternative management regimes with high potential for biodiversity, gains can reach 50%. Analyses on temporal variability at stand and landscape levels are still in a preliminary stage.

Conclusions. Various alternative management regimes provide diverse habitats for different biodiversity indicator species. Management diversification can yield large gains in multi-species habitat availability with no or low economic cost, and thus can be considered a cost-effective biodiversity tool if the management regimes are thoughtfully selected. Management planning also need to account for temporal variability to avoid bottlenecks.

Boreal forests are being affected strongly by climate change. Given the rate of change, these impacts are anticipated to have global effects. In Canada, home to just under 30% of the boreal forest, the drivers of change vary regionally, as may the changes themselves. Much of the discussion about what these changes maybe and how to respond, are at a high level; however, at such a level, they fail to distinguish potential regional differences, characterize human activities as either harmful (such as harvesting) or beneficial (establishing protected areas), and simplify trade-offs between these opposing alternatives. We argue that this dichotomous view of human interaction does not fit well with the dynamic nature of the boreal (which is a disturbance-driven forest) nor does it provide much guidance as to how to adapt to these changes. We would argue that while we do need to pay attention to the science, it is equally important-if not more-to pay attention to the governance arrangements that will affect how we respond (and even view these risks). We argue what is required is a management system that is more responsive to the various values people place upon those goods and services and capacity in identifying and responding to risks to support appropriate management actions. We offer an example of such a system in Northern Saskatchewan, where Mistik Management has timber rights on public lands and manages for these various values and the Indigenous communities that are part owner of those rights. We discuss how Mistik has managed trade-offs, and is now addressing the risks climate change poses and how management-including harvesting-may mitigate those risks. There are key lessons, not only in how management is structured at the local level, but also in their approach and how this may be scaled.

Uneven-aged management is currently seen by many forest ecologists as an extensive management approach when compared to more traditional even-aged methods, offering interesting compromises between timber production and other important ecosystem services. But uncertainties remain concerning its impacts on longer time periods and broader spatial scales, where harvesting activities and forest roads construction extend over larger areas. Here, we explored the impacts of uneven-aged management on the composition and fragmentation of a 800 000ha landscape over a 150 years-planning horizon. To that end, we used the forest landscape model LANDIS-II, along with an extension that simulates the expansion of the forest road network. We compared 30 different management scenarios that varied the proportion of even- and uneven-aged management, the level of aggregation of the harvested areas, and the presence of pre-existing forest roads on a forested landscape of Mauricie (Québec, Canada).

Our results show that compared with even-aged management, uneven-aged management increased both the quantity of forest roads and their operational costs, the fragmentation per se of the older forests, and the quantity of forest with older tree cohorts. In addition, differences in landscape fragmentation between even-aged and uneven-aged management were reduced in the northern region of the landscape, in the boreal forest, where forest fires tended to fragment old forests irrespectively of the type of management approach employed. We conclude that the choice of uneven-aged over even-aged management should depend on the type of fragmentation and habitat considered, the patterns of fragmentation resulting from natural disturbances, and on the perceived effects of fragmentation per se in the landscape. We also conclude that aggregation of the harvested areas could help reduce the negative impacts of uneven-aged management, but that they are unlikely to compensate them entirely.

Wildfire is a dominant driver of forest characteristics, structure, and dynamics within the boreal region. Through interactions with vegetation structure, soil moisture, organic layer depth, fuels consumption, and post-fire regrowth, fire has the capacity to create lasting legacies of alternative forest types. Climate change, however, may alter these interactions and break these legacy effects. The University of Virginia Forest Model Enhanced (UVAFME) is an individual tree-based gap model that has been successfully updated and validated within the North American boreal zone. Results from UVAFME, informed by field data, provides the ability to simulate shifting climate and disturbance regimes at multiple scales and across whole regions. Such simulations improve our understanding of the degree of interaction between climate, vegetation, and disturbances within the boreal zone and can help inform regional management strategies and identify locations that are particularly vulnerable or resilient. We have updated UVAFME to include management treatments such as clear-cutting, shearblading, thinning, and prescribed burns. These updates are used to create a portable, easy-to-use application that allows users to apply the model at set pre-parameterized and tested locations. Users can modify which sets of sites to run, which climate change, fire, or management scenarios to use, and can modify a select number of scenario-related parameters. These scenarios can be conducted at specified sites or across a specified region. This modeling tool will facilitate easier use of UVAFME and will allow forest managers and other stakeholders to test climate change and potential mitigation strategies in key areas.

Forestry in European boreal forests have left forest landscapes transformed and dominated by young and middle aged managed forests with only few and small remnants of natural forests left. However, in the westernmost part of northern Sweden, a belt of forests with limited harvesting still exists – the Scandinavian Mountain Green Belt (SMGB). This belt extends 1000 km, including more than 2.2 Mha forestland with a significant share of old-growth and natural forests with high biodiversity values, unique in a European perspective.

The debate around the future of the SMGB is intense. Although a significant share of the area is already protected, a recent government review has suggested to set aside additionally 500 000 ha as a contribution from Sweden to fulfil the goals and targets of international agreements. Beyond the conservation benefits, this will have implications for rural development in the region. It would support the economy for the tourism sector, support amenity migration, secure land for reindeer husbandry and provide opportunities for value chains related to non-wood resources such as fishing, hunting, berry- and mushroom harvest and carbon sequestration. On the other hand, forestry actors sees the initiative as a threat to their resource base.

We have analyzed the spatial distribution of different forests types and presence of forests with high natural values across the SMGB and how these are distributed across public, forest company and non-industrial private forest owners. Wood-based economic value chains are often in conflict with value chains based on socio-cultural and ecological benefits and hence calls for discussion on multiple-use strategies involving all landowner categories and other stakeholders. There is an urgent need to identify methods for comparing biomass-based value chains and value chains that take into account both direct and indirect benefits linked to immaterial forest values, as well as bequest values.

The target of the European Union (EU) biodiversity strategy is to protect at least 30% of EU’s forest area in 2030. This can have potentially a large effect on the competitiveness of the EU forest sector. In this study, we investigate the EU protected area target and its impact on the EU forest sector by using a spatially-explicit forest sector model (GLOBIOM-forest). The model is solved in 5 arc min resolution based on the recent land-use data from Copernicus Global Land Cover (CGLC), Word Database on Protected Areas (WDPA) and Nature Map Explorer (NME). Our results indicate that the EU protected area target has only a negligible effect on the competitiveness of the EU forest sector if the target is applied in the EU level and divided 10% for set-side and 20% for Natura2000 management requirements. The reason is that the EU is already protecting 24 % of its forest area (5% for set-aside and 19% for biodiversity) and the decreasing demand for some forest sector products such as graphical papers in the future. However, if the target is applied in the country level or the share of set-side protection is increased to 30% of the EU forest area, then the effect on the competitiveness of the EU forest sector become significant. On the other hand, if the target is applied in the EU level, but extended to 50% (10% for set-side and 40% for Natura2000 management requirements) in 2050, then the target has a small effect on the competitiveness of the EU forest sector.

Global climatic changes are of serious concern to the world community and require urgent steps to mitigate their negative consequences, which will affect most components of natural ecosystems and lead to the transformation of many natural processes, including hydrological cycles. In this regard, predictive estimates of changes in the river runoff of rivers that form the water yield in the permafrost zone of Central Siberia are of particular relevance.

We aimed to predict the probable changes in river runoff in Central Siberia under various scenarios of climate change and forest cover of catchments.

Air temperatures and precipitation chronology analysis in Central Siberia indicates high rates of global warming in the region. Mean annual air temperatures increasing by 0.26-0.36 °С per decade. Unlike temperature trends, which demonstrate positive dynamics, trends in atmospheric precipitation in the area do not show consistency and differ not only in absolute values, but also varying from positive to negative values, e.g. +21.1 to -9.5 mm per decade.

Using conjugate analysis of the annual river runoff with changes in the forest cover of catchments and climatic indicators, a regional hydroclimatic model was obtained. Numerical experiments with the model showed that forest cover increase in the river basin in the northern latitudes contributes to an increase in the annual river runoff. In contrast, in southern regions increasing of forest cover in the river basin contributes to the annual river runoff decrease. At the same time, with an increase in global air temperatures by 1.5–3.0 °С, the annual river runoff in the forest-tundra will decrease by 18-30 mm, and in the northern and middle taiga by 47-73 mm.

Thus, the model can serve as the basis for sustainable forest management in order to obtain the desired hydrological effect, taking into account the natural conditions of the regions.

The intensification of forest management practices namely the removal of harvest residues for bioenergy raises sustainability questions with respect to biodiversity, soil fertility and carbon storage. Here we report changes in woody debris and soil carbon storage 5 years post-harvest in whole-tree harvesting (WTH) and stem-only harvesting (SOH) treatments from 11 sites (encompassing 52 individual plots per treatment) across the province of Québec, Canada. Microbial communities were also assessed using DNA metabarcoding in one site having two additional treatments: an extreme residue removal treatment and an unharvested control. WTH reduced the amount of woody debris by 36% on average relative to SOH. After 5 years, no differences in the decomposition dynamics of these debris were observed between harvesting treatments. WTH and SOH both increased soil organic carbon (SOC) by 26% after 5 years, especially in the mineral soil, suggesting a C transfer/incorporation from the newly accumulated deadwood pool to the mineral soil horizons. No differences in SOC were observed between harvesting treatments. The microbial communities’ assessment showed that the intensity of harvesting treatment had an overall limited impact on alpha and beta diversity of bacteria and fungi. However, the relative abundance of ectomycorrhizal and saprotrophic fungi was respectively lower and higher in all harvesting treatments relative to the unharvested control. Examination of environmental variables suggests that forest composition is a key factor influencing C dynamics in these systems and should therefore be taken into consideration when establishing regulatory policies for biomass harvesting.

Forests are subject to a wide range of natural disturbances over their lifetime. Natural disturbances have been responsible for large economic losses during the last 150 years in Europe and storms alone accounted for half of this damage. Long-term adaptive strategies to reduce windstorm damage to the forest are needed and one way of achieving them is to include spatial considerations in the planning process. In this study, we present and evaluate a model that is optimizing the spatiotemporal arrangement of final fellings to reduce the risk of wind damage over time in a forest property. The model accounts for the amount of borders at Norway spruce (Picea abies) stands that are affected from edge effects from adjoining stands. This is done by minimizing the overall edge length with large height differences between stands with common boundaries. To evaluate the model and to analyze the trade-off between net present value (NPV) and vulnerable borders, the optimization problem was solved with increasing demands on the NPV and with even-flow harvest constraints for a case study area in southern Sweden. The model successfully minimized the vulnerable border length by aggregating final fellings in space and time. This resulted in an increase of clustered forest stands in terms of heights for the whole property implying a large reduction of the forest exposure over time. The results indicated that reductions of 1% and 2% of the maximum NPV produced large vulnerable border decreases by 41% and 51% respectively. The harvested volume from both, final fellings and thinnings, varied up to 32% over the periods for a demand of, at least, 97% of the maximum NPV. Conversely, the amount of volume and forest area over the minimum final felling age increased moderately with escalating NPV reductions.

Site preparation for oil and gas extraction often requires the complete removal of vegetation and surface soil on the well pad. Although subsequent reclamation then attempts to restore vegetation and soil properties on the well pad, given the magnitude of the extraction disturbance, the potential to shift its future successional trajectory is high. To address a lack of understanding of long-term successional trajectories of reclaimed oil and natural gas well sites in forested lands, we sampled plant community composition and soil attributes on 30 reclaimed and adjacent reference sites in Alberta’s boreal forest ranging from 7-48 years post-disturbance. We measured ecological properties to determine if certified reclaimed wellsites were on a positive successional trajectory for recovery. Multi-response permutation procedures and non-metric multidimensional scaling illustrated separation between reclaimed and reference sites plant community compositions. When accounting for forest type, seral stage, and time since last disturbance, there was further separation of sites, with only two sites (7%) resembling community structure of reference sites, and 18 sites (60%) resembling treeless grasslands, two of which were >35 years post disturbance, indicating an arrested recovery trajectory. The remaining 33% of sites are likely on a positive trajectory towards recovery. We used a joint generalized estimating equation (JGEE) to determine if reclamation had a significant effect on ecological properties. Using perMANOVA and Gower dissimilarity index to measure multi-trait functional dissimilarity, we found an overall directional change in plant functional composition with time since reclamation towards that observed in reference sites, but reclaimed sites remained significantly different from reference sites. Overall, our data indicate the anthropogenic disturbance impacts of well pads can be long lasting and may remain for half a century or more post reclamation, potentially flat lining the plant community and functional recovery trajectory of these reclaimed sites.

Evaluation of changes in disturbance regimes in boreal forests is essential for developing sustainable forest management strategies. Russia accounts for over 22% of the world’s forested area which is predominantly found in Siberia and the Far East (78%). Forests of the Angara region located in the southern taiga of Central Siberia have experienced significant disturbances during past decades due to wildfires and human activities (logging, mining, and construction of a hydropower station), making the region one of the largest hot spots of land cover change in Siberia. Here we estimated fire and logging disturbances using MODIS and Landsat data for the period 2002–2020. We found that annual disturbed area significantly increased during the last two decades leading to rapid forest degradation in the region. Mean annual disturbance rate almost doubled between 2002 and 2020 (1 to 2% of the region’s area, respectively). In total, over 4.1 million hectares (38% of the region) and 0.6 million hectares (6% of the region) were disturbed by fires and logging, respectively. Spatial analysis showed that more than 70% of fires were ignited within 15 km from anthropogenic features such as settlements, roads and logged sites. Roughly 5% of the Angara region was burned more than once during the 19 years of observations. Vast Siberian boreal forests can have a substantial impact on the global carbon cycle, climate change, and availability of forest products. Continued and repeated disturbances will significantly alter ecosystem dynamics, forest regeneration, wildlife populations through increasing forest degradation and fragmentation, and, ultimately, negatively impact a suite of valuable ecosystem services. The research was partially funded by the RFBR/KRFC Grant #20-44-242004.

Forests play a critical role in addressing some of the biggest world challenges such as mitigating climate change, conserving biodiversity, and providing a variety of ecosystems services, including nutrient cycling, air and water purification, carbon sequestration and storage, and wildlife habitats. Forests also have social and spiritual benefits and are key to cultural activities. Anthropogenic disturbances such as harvesting, and natural disturbances such as wildfire, are common in the boreal biome. They can have cascading effects on the capacity of forests to sustain provision of ecosystem services. Because it can mitigate these effects, successful regeneration is one of the keystones of sustainable forest management; it ensures that ecosystems submitted to stand-replacing disturbances go back to a forested state. Plantation forestry, including tree breeding and novel tools such as genomic selection, can support sustainable management of boreal forests in the face of climate change. Plantations can provide high yields and offer the opportunity to select for species, genotypes, stand density, and spatial arrangements. They play a significant role in augmenting, maintaining or restoring forest productivity in boreal landscapes, adapting forests to future conditions with trait selection and assisted gene flow, restoring and maintaining natural species, closed-forest landscapes and ecosystem functions, and sequestering carbon and supporting the bioeconomy. Plantation forestry, however, raises issues related to the scale, localization, and spatial arrangement of plantations, key attributes and resilience of natural forests, social acceptability and economic profitability, particularly in the context of ecosystem-based management. These risks are increasing as biotic and abiotic hazards are growing due to global change, while economic and social pressures are in constant evolution. Adaptive approaches, such as establishing multi-species plantations, maintaining biological legacies, keeping patches of natural forests, or restoring the highest possible degree of naturalness in the forest matrix can be used to address these complex issues.

At the northernmost limit of Canada’s boreal forest lies the sparsely populated North Yukon Region. This region is in the winter range of the Porcupine barren-ground caribou herd and includes an undeveloped oil and gas basin. A key recommendation of a plan for this region was to ensure that the cumulative effects of human activities are kept below levels that could excessively impact the caribou. More specifically, the plan recommended that two cumulative effects indicators, “surface disturbance” and “linear disturbance”, be quantified and tracked. The Plan went on to say that “recovered” disturbances were to no longer “count” as disturbances.

This pilot study, limited to a portion of the region with a history of oil and gas exploration, started by revisiting the Plan’s definitions of disturbance and recovery, then evaluated how disturbances could be best mapped using remote sensing. High-resolution imagery was purchased, and disturbances and their vegetative status were interpreted from it. These interpretations were supported by previous research plots and numerous oblique aerial photographs. This exercise detected disturbance levels approaching the management thresholds set in the plan – much more than anticipated. However, when recovery was considered using the interpreted vegetation status, effective disturbance levels were determined to be much lower.

This pilot study showed that the plan’s innovative cumulative effects framework can be implemented and recommended that it could be applied in other areas of the region and beyond.

Boreal forests provide a variety of ecosystem services for climate change mitigation, biodiversity conservation and sustainable livelihoods. Remote sensing data of forest extent and its changes over time have revolutionized forest monitoring globally and are widely used for conservation planning and decision-making. However, existing products are often limited to representing changes in tree canopy cover or tracking forested areas affected by human land use and related impacts. There is an increasing recognition that these efforts must include forest quality assessment reflecting the ecological value of different stands. To meet this need, we present a novel framework to assess forest ecosystem stability based on ecological theory and time series analysis of Moderate Resolution Imaging Spectroradiometer (MODIS) data at 500 m spatial resolution, which is indicative of ecosystem condition in relation to natural processes and disturbance regimes. We integrated several ecophysiologically-based metrics that provide insights into the productivity and stability of forest ecosystems based on the fraction of photosynthetically active radiation intercepted by vegetation canopy (fPAR) and the shortwave infrared water stress index (SIWSI) over the period 2003–2018. Using these metrics, we evaluated ecosystem stability levels, ranging from intact to highly disturbed or degraded ecosystems, in the southern taiga ecoregion of Siberia (Russia), as this region has experienced intensive logging and increasing fire incidence over the study period. The final forest stability map was validated against (i) the MODIS land cover type product MCD12Q1, (ii) 30-m digitized annual logged and burned areas upscaled to MODIS resolution, and (iii) Global Forest Change Data. We also analyzed how natural vs. anthropogenic disturbances affected forest condition regionally. By identifying stable forests, our framework represents a robust approach to provide timely and reliable information for ecosystem science, primary forest identification and conservation, and evolving national and international policies regarding land use.