Forest Management Activities Research Articles

Forest Disturbances Threatening Cypripedium calceolus Populations Can Improve Its Habitat Conditions

Inappropriate forest management activities, above all clear-cutting, are recognized as the major threats to an iconic orchid species—the lady’s slipper orchid (Cypripedium calceolus), the flagship species of nature protection in Europe. Although clear-cutting in protected species’ localities is strongly regulated in many European countries, salvage logging is allowed in some circumstances (e.g., following windstorms, and insect outbreaks) and can threaten C. calceolus populations. In this paper, we review a database of recently registered populations of this species in the Czech Republic and study historical maps, to better understand the history of local habitat conditions and assess threats to C. calceolus populations by bark beetle outbreaks. We found that about one-third of the C. calceolus populations have suffered in coniferous or mixed tree plantations with a high proportion of spruce trees, which are forests with a high risk of bark beetle infestation. We review bark beetle management measures and distinguish management efforts in areas with known C. calceolus populations that result in no damage to the population and, at times, improve habitat conditions for the species. Thus, the bark beetle—usually understood as the enemy—can be transformed into a savior if smart management measures will replace the panic salvage logging.

Trade-offs between greenhouse gas mitigation and economic objectives with drained peatlands in Finnish landscapes

In Finland, the widespread drainage of boreal peatlands has led to increased forest productivity. The cost is a dramatic increase in soil greenhouse gas emissions. Empirical research of drained peatlands has found a correlation between greenhouse gas emissions and the ground water table. This suggests an opportunity to mitigate greenhouse gas emissions through forest management. We explore this opportunity at the landscape level through a simulation and optimization framework. We explore how forest management actions can impact the ground water table and the related greenhouse gas emissions. There are various economic and societal constraints for a set of forested peatland landscapes in Finland. First, we link forest simulations with hydrological and statistical models to predict CO2, CH4, and N2O emissions from the drained peatlands. We then present the range of landscape level solutions that prioritize between minimizing the net ecosystem greenhouse gas emissions, the economic timber value, and the even flow of timber income over time. Our results highlight the impact that integrating peatland soil greenhouse gas emissions will have on the planning process. This promotes the use of management options that benefit both biomass growth and reduced peatland soil greenhouse gas emissions.

While Experiencing a Forest Trail, Variation in Landscape Is Just as Important as Content: A Virtual Reality Experiment of Cross-Country Skiing in Estonia

It has long been understood that diversity is a key aspect of what makes a landscape attractive but to what degree of diversity and how is it experienced? Many forest landscapes are generally monotonous in character or are broken up by forest management activities such as clear cutting, which may negatively impact their potential for recreation and psychological well-being benefits. We conducted a virtual reality experiment where people were taken on a trip along a simulated cross country skiing track in an Estonian forest. Participants followed a route at simulated speeds typical of cross-country skiing. The route was long enough to experience several minutes passing through one type of forest landscape with a series of small variations in character followed by several minutes passing through a notably different forest landscape. The restorative experience obtained by the visit was measured periodically in each version of the landscape. Univariate general linear modelling analysis was statistically significant (r2 = 0.651, F(198, 965) = 9.108, p < 0.001) and showed that while respondents preferred less-dense forest in general (B = 0.189, p = 0.001)—an expected result—a comparable amount of positive restorative response could also be attributed to prominent changes in forest character, regardless of the type of forest (B = 0.401, p < 0.001). We hypothesise that respondents were reacting favourably to sudden changes in forest appearance after prolonged exposure to one forest type—that diversity is important in maintaining interest, reducing boredom, and in providing a restorative experience. The implications are, firstly, that a virtual experience can detect restorative effects and, secondly, that recreational trails should be designed to pass through varied landscapes offering continually changing diverse experiences—the impact of which can be tested in the virtual setting because there is control of all variables.

Spatial Application of Southern U.S. Pine Water Yield for Prioritizing Forest Management Activities

Forest management depends on forest condition data and the ability to quantify the impacts of management activities to make informed decisions. Spatially quantifying water yield (WY) from forests across large landscapes enables managers to consider potential WY changes when designing forest management plans. Current forest water yield datasets are either spatially coarse or too restricted to specific sites with in situ monitoring to support some project-level forest management decisions. In this study, we spatially apply a stand-level southern pine WY model over a forested landscape in the Florida panhandle. We informed the WY model with pine leaf area index inputs created from lidar remote sensing and field data, a spatial and temporal aridity index from PRISM and MODIS data, and a custom depth to groundwater dataset. Baseline WY conditions for the study area were created using the Esri and Python tools we developed to automate the WY workflow. Several timber thinning scenarios were then used to quantify water yield increases from forest management activities. The results of this methodology are detailed (10 m spatial resolution) forest WY raster datasets that are currently being integrated with other spatial datasets to inform forest management decisions.

Network analysis of a northern long-eared bat (Myotis septentrionalis) maternity colony in a suburban forest patch

Abstract Many bat species are highly social, forming groups of conspecifics, particularly during the maternity season. In temperate North America, these social groups are typically comprised of closely related individuals or individuals that share some common trait (i.e. reproductive state or shared hibernacula from the previous winter). In the summer, when bats use forests for day-roosts, these social groups often demonstrate nonrandom patterns of periodically associating in common roosts and disassociating using different roosts as a ‘fission–fusion society’. As cave hibernating bat species in North America continue to decline due to the impacts of White-nose Syndrome, opportunities to describe these dynamics are becoming rare. Unfortunately, these patterns often are still poorly documented, yet understanding these behaviors is critical for species-specific habitat conservation and management. In our study, we tracked female northern long-eared bats (Myotis septentrionalis) to their day-roosts in a small, suburban forest fragment in coastal New York, USA, in the summers of 2018 and 2019. We confirmed that the bats shared roost sites and, using network analyses, analyzed social dynamics and space use. In contrast to previous research on this imperiled species in large, unfragmented core forests, we found a more dense, connected roost network that concentrated around forest patch edges. Unusual for this species, primary roosts were anthropogenic structures. Our findings suggest that northern long-eared bats can utilize small forest patches and that incorporation of specific types of anthropogenic roosts might be an effective strategy for long-term conservation in more urbanized landscapes where forest management actions to enhance day-roosting conditions are impractical and the risk of stochastic loss of roosts is high.

An iterative site-scale approach to calibrate and corroborate successional processes within a forest landscape model

Forest landscape simulation models (FLM) have been extensively used for projecting ecosystem dynamics and carbon fluxes. However, more guidance and methods for formal calibration and corroboration of FLMs are needed to ensure higher fidelity results from these models. We developed a novel systematic methodology for calibrating and corroborating a FLM at the grid-cell scale using empirical estimates from the national forest inventory in the United States (US) which uses an equal probability sample design.We illustrate our approach by using the Forest Inventory and Analysis (FIA) data from the US Department of Agriculture Forest Service across the state of Wisconsin to represent initial site conditions and calibrate parameters for the Density Succession extension of the LANDIS-II model, formally coupled with an iterative model corroboration stage focused on the growth and internal competition component of the model at a site-scale using plot remeasurement data that span 20 years. We used a formal equivalence testing approach to compare model predictions to empirical estimates for permanent sample plots.We found that the model performed well, with 21 out of 30 species demonstrating equivalence in the estimator used to characterize basal area following initial parameterization. Upon calibration of the estimator, the nine species not initially equivalent all showed reduced bias, with five of the species ultimately passing the equivalence test. The species that did not achieve equivalence through calibration were generally the least abundant ones.These results have increased our confidence that the Density Succession algorithms were well implemented within the model and provides a useful additional succession option within the LANDIS-II framework. We believe this methodology can capture a wider range of local scale variability compared to previous methods conducted at a landscape level using summary statistics. The iterative nature of the method also gives an opportunity for learning about the model components and the reference plot data. Our approach will help researchers using landscape simulation models to follow a replicable framework for corroborating their results and prioritize forest management activities and land use planning, which can help reduce external pressures on forests and help mitigate climate change effects.

Effects of compound disturbance on Canada lynx and snowshoe hare: Wildfire and forest management influence timing and intensity of use

Wildfires are increasing in scale and impact on the landscape, altering large amounts of wildlife habitat and forest ecosystems. The reduction of fuels through forest management is considered a primary way to reduce the extent and severity of wildfires before they occur but may lead to a decrease in tree density prohibitive of some species’ habitat. Alternatively, management actions undertaken after a fire may speed the trajectory of burned areas back into quality habitat but may also impede this development if the wrong type of treatment is undertaken. Thus, information on how different management actions, applied either pre- or post-fire, can influence the timing of a burned area’s return to suitable habitat will help managers conserve species on the landscape. Our study aims to understand how a rare carnivore, Canada lynx (Lynx canadensis), uses stands managed with different silviculture actions at different times relative to wildfire. We used GPS locations from 39 individual lynx collected from 2004 to 2015 to examine the response of lynx to wildfire compounded by active forest management, where time since fire at time of use ranged from 1 to 27 years. To understand the drivers behind lynx use of wildfires, we also focused on the primary prey of Canada lynx, snowshoe hares (Lepus americanus), using pellet counts across a similar range of post-fire treatment types in fires between 22 and 28 years old. We also assessed vegetation recovery and forest structure over time since wildfire using remotely sensed data and field measurements. We found that lynx intensity of use differed based on timing and type of management action, with the greatest lynx use ∼25 years after a wildfire managed with post-fire regeneration cuts (removal of the majority of the canopy). Lynx use was likely driven by hare abundance, which was also highest in post-fire regeneration cuts, characterized at time of use by dense lodgepole pine stands. We conclude that managing landscapes with a mosaic of active (pre- and post-fire treatments) and passive (hands-off) management will best conserve a desirable range of lynx habitat in an increasingly fire-impacted landscape.

New Structural Complexity Metrics for Forests from Single Terrestrial Lidar Scans

We developed new measures of structural complexity using single point terrestrial laser scanning (TLS) point clouds. These metrics are depth, openness, and isovist. Depth is a three-dimensional, radial measure of the visible distance in all directions from plot center. Openness is the percent of scan pulses in the near-omnidirectional view without a return. Isovists are a measurement of the area visible from the scan location, a quantified measurement of the viewshed within the forest canopy. 243 scans were acquired in 27 forested stands in the Pacific Northwest region of the United States, in different ecoregions representing a broad gradient in structural complexity. All stands were designated natural areas with little to no human perturbations. We created “structural signatures” from depth and openness metrics that can be used to qualitatively visualize differences in forest structures and quantitively distinguish the structural composition of a forest at differing height strata. In most cases, the structural signatures of stands were effective at providing statistically significant metrics differentiating forests from various ecoregions and growth patterns. Isovists were less effective at differentiating between forested stands across multiple ecoregions, but they still quantify the ecological important metric of occlusion. These new metrics appear to capture the structural complexity of forests with a high level of precision and low observer bias and have great potential for quantifying structural change to forest ecosystems, quantifying effects of forest management activities, and describing habitat for organisms. Our measures of structure can be used to ground truth data obtained from aerial lidar to develop models estimating forest structure.

Formalizing a Two-Step Decision-Making Process in Land Use: Evidence from Controlling Forest Clearcutting Using Spatial Information

In this paper, we examine a particular case of land use pattern: forest management activities facing an uncertainty related to spatial information signals received. We investigate the combination of two well-known theoretical approaches, the Blackwell theorem and entropy analysis, in providing a decision support framework for decision makers. We examine the uncertainty related to the information signals received within a decision support context and compute the optimal actions. Drawing on satellite imagery as an additional source of information provided by French spatial data infrastructure (SDI), we illustrate our approach through a clear-cutting control case study. The control of clear-cutting is a central issue in forest management. In order to perform an efficient control operation, uncertainty regarding the decisions to be taken needs to be minimized. Reducing uncertainty in a decision-making context related to forest management provides greater opportunities for improving productivity and for saving time and money. The results show that the information structure through the SDI signals has the most significant information power. Moreover, a maximum of two information structures can be compared when applying the Blackwell theorem. However, while using the entropy approach, a comparison of several information structures can be performed.

FOREST INVENTION ASSESSMENT OF THE STATE OF PLANTS AFTER SELECTIVE FELLING IN THE VOLOGDA REGION

Our research was carried out in the summer of 2021. The laying of trial plots was carried out taking into account the requirements of OST 56-69-83 and using modern taxation tools and devices. Processing of field materials was carried out by methods generally accepted in forestry and taxation. Analyzing the data obtained, it can be noted that the through felling had a positive effect on increasing the size of the remaining trees for growing. Statistical processing of data confirms the differences in this indicator between trees in the experimental and control plots after forest management activities.

Sustaining Carbon Storage: Lessons from Hemiboreal Old-Growth Coniferous and Deciduous Forest Stands

AbstractFor the last three decades, the area of old-growth forest stands in Europe has continued to increase as has their importance in achieving forest-related policy goals. This has triggered an increase in research interest in old-growth forests, both from climate change mitigation and biodiversity protection perspectives. However, carbon stock in old-growth stands in European hemiboreal forests had not been systematically studied. Therefore, in this article, we characterize differences in carbon stock between mature and old-growth stands on fertile mineral soils in hemiboreal Latvia to contribute to the understanding of carbon storage changes under different management strategies for forest lands. Carbon stock varied significantly both between old-growth stands of different dominant tree species and between mature (1.9–2.3 times younger) and old-growth stages of the same dominant species in forest stands. The carbon stock of tree biomass and deadwood was larger in old-growth stands, but their mean annual carbon stock change was significantly lower than in mature stands (27% to 47% depending on dominant tree species). Old-growth stands can serve as carbon reservoirs in areas with limited natural disturbances; however, for maintenance of climate neutrality, it is essential to expand the area of managed stands with larger annual carbon stock increase.Study Implications: Forest ecosystems play a major role in regulation of global climate: They can store high quantities of carbon and also can gain or lose it rather quickly. For the last three decades, the area of old-growth forest stands in Europe has continued to increase as has their importance in achieving forest-related policy goals. Old-growth forests can represent the baseline carbon-carrying capacity in particular conditions. Therefore, we characterized differences in carbon stock between mature and old-growth stands on fertile mineral soils in hemiboreal Latvia to contribute to the understanding of carbon storage and for planning forest management activities.

Stand-Density Effects on Aboveground Carbon Dynamics in Secondary Pinus and Quercus Forests of Central USA

Abstract Temperate forests play an important role in the sequestration and storage of carbon. We evaluated the long-term effects of manipulating stand density on aboveground live tree carbon dynamics and volume production for separate pine (Pinus spp.) and oak (Quercus spp.) forests of central USA. For both species groups, stand-level carbon storage in standing live trees was greatest without management, with unthinned pine plateauing around 100 Mg/ha of carbon at approximately 50 years old and the oak stands increasing to around 100 Mg/ha of carbon by about 80 years old. In the pine stands, stand-level carbon sequestration was greatest in stands that were thinned but maintained fully stocked conditions. Consequently, the gross carbon that accumulated during the study period, which included standing carbon in live trees and carbon from trees that were harvested or otherwise died, was maximized when stand stocking was maintained at an average of around 80% stocking during the study period. These results were compatible with the production of sawtimber volume, which was greatest for stands that were maintained in fully stocked but not overstocked conditions. Our results demonstrate that thinning can be a forest management strategy to achieve multiple objectives, including those for carbon management and sawtimber production. Study Implications: Our results support stand-density management (i.e., thinning) as a forestry practice compatible with carbon objectives and more traditional objectives of timber production. Aboveground carbon stored in live trees was greatest without thinning, but gross production and sequestration rates were greatest when stand density was maintained in fully stocked but not overstocked conditions. Active forest management during stand development can provide managers with the flexibility to address multiple objectives and may be used with other carbon management practices such as extended rotations or continuous canopy cover, particularly in the central and northeastern United States where forests are generally aging uniformly throughout the region.

Early аnd Late Wood оf Scots Pine under Conditions of Varying Degrees of Lighting

The condition of pine stands in Polissia is deteriorating due to an increase in the number of outbreaks of sharp-dentated bark beetle (Ips acuminatus) against the background of climate change, therefore, the relevance of this problem is beyond doubt. The purpose of the study is to identify the features of the dynamics of late and early Scots pine wood (Pinus Sylvestris L.) in areas with varying degrees of illumination after continuous cutting in the foci of the sharp-dentated bark beetle (Ips acuminatus) in Polissia. Standard dendrochronological, dendroclimatic, and statistical methods are used. It is established that after continuous logging in 2013 in the adjacent areas, on the one hand, there was an increase in the radial growth of pine trees, because the nutrition areas increased and the lighting conditions of trees improved, and on the other hand, trees growing next to the logging area are weakened and have fragile cores, which indicates a loss of wood quality. After cutting, during 2014-2020, the average values of late pine trees of illuminated time trial areas compared to the corresponding values in the control were 43-45%. For early wood, these values ranged from 38-42%. The growth change indices showed, that after the 2013 logging, violations occurred for trees in illuminated temporary trial areas as opposed to the control. The most sensitive to climatic factors were tree-ring chronologies of late wood in the most illuminated trial area. An increase in the sensitivity of the radial growth of pine trees was found depending on the increase in the degree of illumination. The weakening of plantings in the most illuminated area is indicated by the fact that the greatest number of significant relationships between growth and climate were found for the tree-ring chronology of early and late wood, while there was no critical decrease in trends in late and early wood layers. The findings can be used for planning forest management activities

Tall, heterogeneous forests improve prey capture, delivery to nestlings, and reproductive success for Spotted Owls in southern California

Abstract Predator–prey interactions can be profoundly influenced by vegetation conditions, particularly when predator and prey prefer different habitats. Although such interactions have proven challenging to study for small and cryptic predators, recent methodological advances substantially improve opportunities for understanding how vegetation influences prey acquisition and strengthen conservation planning for this group. The California Spotted Owl (Strix occidentalis occidentalis) is well known as an old-forest species of conservation concern, but whose primary prey in many regions—woodrats (Neotoma spp.)—occurs in a broad range of vegetation conditions. Here, we used high-resolution GPS tracking coupled with nest video monitoring to test the hypothesis that prey capture rates vary as a function of vegetation structure and heterogeneity, with emergent, reproductive consequences for Spotted Owls in Southern California. Foraging owls were more successful capturing prey, including woodrats, in taller multilayered forests, in areas with higher heterogeneity in vegetation types, and near forest-chapparal edges. Consistent with these findings, Spotted Owls delivered prey items more frequently to nests in territories with greater heterogeneity in vegetation types and delivered prey biomass at a higher rate in territories with more forest-chaparral edge. Spotted Owls had higher reproductive success in territories with higher mean canopy cover, taller trees, and more shrubby vegetation. Collectively, our results provide additional and compelling evidence that a mosaic of large tree forest with complex canopy and shrubby vegetation increases access to prey with potential reproductive benefits to Spotted Owls in landscapes where woodrats are a primary prey item. We suggest that forest management activities that enhance forest structure and vegetation heterogeneity could help curb declining Spotted Owl populations while promoting resilient ecosystems in some regions.

UPRLIMET: UPstream Regional LiDAR Model for Extent of Trout in stream networks

Predicting the edges of species distributions is fundamental for species conservation, ecosystem services, and management decisions. In North America, the location of the upstream limit of fish in forested streams receives special attention, because fish-bearing portions of streams have more protections during forest management activities than fishless portions. We present a novel model development and evaluation framework, wherein we compare 26 models to predict upper distribution limits of trout in streams. The models used machine learning, logistic regression, and a sophisticated nested spatial cross-validation routine to evaluate predictive performance while accounting for spatial autocorrelation. The model resulting in the best predictive performance, termed UPstream Regional LiDAR Model for Extent of Trout (UPRLIMET), is a two-stage model that uses a logistic regression algorithm calibrated to observations of Coastal Cutthroat Trout (Oncorhynchus clarkii clarkii) occurrence and variables representing hydro-topographic characteristics of the landscape. We predict trout presence along reaches throughout a stream network, and include a stopping rule to identify a discrete upper limit point above which all stream reaches are classified as fishless. Although there is no simple explanation for the upper distribution limit identified in UPRLIMET, four factors, including upstream channel length above the point of uppermost fish, drainage area, slope, and elevation, had highest importance. Across our study region of western Oregon, we found that more of the fish-bearing network is on private lands than on state, US Bureau of Land Mangement (BLM), or USDA Forest Service (USFS) lands, highlighting the importance of using spatially consistent maps across a region and working across land ownerships. Our research underscores the value of using occurrence data to develop simple, but powerful, prediction tools to capture complex ecological processes that contribute to distribution limits of species.

Effects of forest management on the spatial distribution of the willow tit (Poecile montanus)

Modification, fragmentation and loss of boreal forest habitats have been intensive during the last century due to forestry practises and land use. This has been related to population declines of many forest species, yet the mechanisms affecting on the background are largely unknown. The willow tit, a primary cavity-nesting species that was once the 4th most common bird species in Finland is nowadays endangered. Earlier findings suggest that the willow tit population is affected by the reduction of nesting sites, decaying snags in forests and the loss of mature forests which contain the food storages during the winter. In this study we are searching for the mechanisms how the forest management methods could explain the decline of the willow tit population. We used long-term breeding data of the willow tit nesting sites from 1990 to 2020 collected in a study area in northern Finland to analyse if forest management affected nearest neighbour distances and natal dispersal and breeding dispersal distances. We used Geographic Information System (GIS) methods to combine the ecological breeding data to accurate spatial forest management and habitat quality data. The data was analysed with linear mixed models. We found that clear-cuttings affected the willow tit dispersal and neighbouring nest distances more than thinnings. Both clear-cuttings and thinnings increased the nearest neighbour distances. The natal and breeding dispersal distances were lengthened by increasing proportions of clear-cuttings. The habitat loss caused by clear-cuttings and the decrease in habitat quality caused by thinnings has had a major role in the decline of the willow tit population. The forest management actions were estimated to explain about 65 % of the willow tit breeding density decrease in the study area. The effects of forest management were witnessed in a cumulative 0–30-year period meaning that forest management causes long-term habitat degradation and loss. Availability of deciduous snags in the forests can compensate the habitat loss to some extent by providing better breeding opportunities. As the effects of clear-cutting were more severe to the willow tit than thinning, we recommend using other forest management methods than clear-cutting as the main management method.

Forest values and application of different management activities among small-scale forest owners in five EU countries

Forests are important for the transition to a bioeconomy. With 60% of Europe's forest area owned and managed by small-scale owners, these owners' management behaviour is key. Identifying commonalities and differences between owners in different EU countries promotes effective implementation of EU strategies for a sustainable transition to a wood-based bioeconomy. This study examines the value orientations and management behaviour of private small-scale forest owners in five EU countries. Based on a questionnaire survey in Austria, Finland, Germany, Slovenia, and Sweden (n = 2524), we analysed these owners' values, and how various management activities are perceived in relation to management strategies. Respondents rated the importance of economic, environmental, and social values regarding their forest holdings, and were divided into groups based on their value orientation. Overall, the largest value group was ‘All values very important’; more so in Austria, Finland, and Germany than in Slovenia and Sweden. In Finland and Sweden the proportion of respondents in the ‘Economic and environmental values’ value group was low. This suggets that small-scale forest owners in these countries rarely consider economics and the environment together. Forest management activities were applied to varying degrees in the five countries. However, respondents in all countries who considered all values to be very important were the most active in all management activities compared to those who considered all values to be somewhat important. Our analysis highlighted the importance of context, showing that the propensity to use a particular activity was explained to a lesser extent by owner characteristics and value orientation and, in the case of most activities, more strongly by country. The way objectives of policies and management strategies are communicated may need to be adapted to the specific conditions of each country.

A Survey of Computer Vision Techniques for Forest Characterization and Carbon Monitoring Tasks

Estimation of terrestrial carbon balance is one of the key tasks in the understanding and prognosis of climate change impacts and the development of tools and policies according to carbon mitigation and adaptation strategies. Forest ecosystems are one of the major pools of carbon stocks affected by controversial processes influencing carbon stability. Therefore, monitoring forest ecosystems is a key to proper inventory management of resources and planning their sustainable use. In this survey, we discuss which computer vision techniques are applicable to the most important aspects of forest management actions, considering the wide availability of remote sensing (RS) data of different resolutions based both on satellite and unmanned aerial vehicle (UAV) observations. Our analysis applies to the most occurring tasks such as estimation of forest areas, tree species classification, and estimation of forest resources. Through the survey, we also provide a necessary technical background with a description of suitable data sources, algorithms’ descriptions, and corresponding metrics for their evaluation. The implementation of the provided techniques into routine workflows is a significant step toward the development of systems of continuous actualization of forest data, including real-time monitoring. It is crucial for diverse purposes on both local and global scales. Among the most important are the implementation of improved forest management strategies and actions, carbon offset projects, and enhancement of the prediction accuracy of system changes under different land-use and climate scenarios.

Forest expansion in abandoned agricultural lands has limited effect to offset carbon emissions from Central-North Spain

We assessed the process of carbon (C) accumulation as a consequence of forest expansion in abandoned agricultural lands over the period 1977–2017 in a vast (9.4 million ha) area of Mediterranean continental environment in Central-North Spain. We achieved this objective, through obtaining AGC and BGC estimations based on direct field measurements taken in 30 plots (25 m × 25 m), and extrapolating to the landscape using Synthetic Aperture Radar (SAR) satellite data from 2018. Using aerial photographs and forest maps, we found that 145,193 ha of agricultural land in 1957 (1.54% of the study regions’ total area) has since then regenerated naturally to forests and woodlands. Although mean AGC and BGC densities were modest (i.e. 18.04 and 6.78 Mg C ha−1), they reached relatively large maximum values (i.e. 60 and 21 Mg C ha−1). The BGC stock was also very large, representing 37.3% of the total C stock (10 Tg) accumulated. However, we detected a mean annual C sink of 0.25 Tg C·year−1 which barely offset 1.22% of the total regional CO2 emissions. Our findings point to a smaller sequestration potential under Mediterranean continental than under temperate-cold conditions. Nonetheless, the area affected by this process could be larger than detected and many of the recovering lands might have not still reached their C uptake peak. If such lands are to be used to store C, we strongly advocate for the application of active forest management measures to increase their CO2 sequestration potential.

Forecasting wildfire-induced declines in potential forest harvest levels across Québec

Wildfires are increasing in importance in many regions of the Canadian boreal forest and are an ongoing risk for forest management activities. We simulated the effects of fires on long-term harvest levels on the 59 forest management units of the province of Québec, Canada, for the 2020–2100 period. Different climate change pathways (stable, RCP 4.5 or 8.5) and salvage logging rates (20% or 70% of mature burned stands) were simulated. Changes in forest flammability due to climate change, species migration, and forest management were also considered. Under stable climatic conditions, the decline in potential harvest levels due to fire, based on 50 simulations per scenario, ranged between 3% and 33% (mean = 11%) when high salvage logging rates were simulated, compared to 6%–45% (mean = 20%) for low salvage rates. Climate change caused increases in burn rates between −3% and 39% for RCP 4.5 and between 33% and 69% for RCP 8.5 at the end of the 21st century, depending on fire zones. However, the effects of these modified burn rates on harvest levels did not differ substantially from those of baseline burn rates, probably because the projected burn rates were highest during the later part of the simulations (2070–2100), when their impacts on harvest level calculations were limited. This study indicates that potential harvest levels calculated without considering wildfires are likely to be non-sustainable.