Search Results (867)

Understanding how endangered carnivores partition spatiotemporal distribution in human-dominated landscapes is pivotal for mitigating biodiversity loss in climate-sensitive boreal ecosystems. Here, we used kernel density data derived from a 16-month camera-trap survey (140 UVL7 cameras), cold single-season (November–April) occupancy models, and MaxEnt 3.4.4 to identify the effects of biotic interactions, anthropogenic disturbance, and environmental factors on the spatiotemporal distribution of the wolverine (Gulo gulo) in Beijicun National Nature Reserve, Heilongjiang Province, China. We found that wolverines exhibited crepuscular activity patterns using night-time relative abundance index (NRAI) = 50.29% with bimodal peaks (05:00–07:00, 13:00–15:00), with dawn activity predominant during the warm season (05:00–06:00) and a bimodal activity pattern in the cold season (08:00–09:00, 14:00–15:00). Temporal overlap with prey (overlap coefficient Δ = 0.84) and competitors (Δ = 0.70) was high, but overlap with human-dominated temporal patterns was low (Δ = 0.58). Wolverines avoided human settlements and major roads, preferred moving along forest trails and gentle slopes, and avoided high-altitude deciduous forests. Populations were mainly concentrated in southern Hedong and Qianshao Forest Farms, which are characterized by high habitat integrity, high prey densities, and minimal anthropogenic disturbance. These findings suggest that wolverines may influence boreal trophic networks, especially in areas with intact prey communities, competitors, and spatial refugia from human disturbances. We recommend that habitat protection and management within the natural reserve be prioritized and that sustainable management practices for prey species be implemented to ensure the long-term survival of wolverines. Full article

Anthropogenic disturbances interact with wildfire, altering successional dynamics across North America’s boreal forest. Linear disturbances, including seismic lines used for oil and gas exploration, dissect forests, while wildfire is a fundamental agent of forest succession. However, little is known about early succession dynamics after both seismic line creation and wildfire, especially across transitions from uplands to peatlands. To address this, we characterized and compared regeneration and recruitment after individual and successive disturbances in peatland, transitional, and mesic upland forests across the oil sands region of Alberta, Canada. We used non-metric multidimensional scaling to compare composition and mixed-effects generalized linear models to compare densities of trees and tall shrubs 10 to 24 years after disturbance. Compositionally, regeneration was similar within forest types and between transitional and peatland forests, while patterns in recruitment were more influenced by past disturbances. Overall, we found evidence of dominant, additive, and interactive effects on early successional patterns within linear disturbances in boreal forests. In transitional and peatland forests, disturbances influenced tree and tall shrub regeneration and recruitment in complex ways. Early successional dynamics after disturbance influence forest structure and composition and are vital to understanding recovery in boreal forests, especially across boreal forest transitions. Full article

The cumulative impact of decades of oil and gas exploration has left Alberta’s boreal forests densely fragmented by seismic lines, which are expected to naturally regenerate; however, recovery is often highly variable and generally poor in peatlands due to increased wetness and reduced microtopography. In this study, we evaluated seismic lines in lowland ecosites with some degree of successful natural regeneration to gain a better understanding of the natural recovery process in these areas. We compared stand characteristics between the seismic line (23 to 48 years post-disturbance) and the adjacent undisturbed forest. We found that soil properties were similar, but seedling (height < 1.3 m) density was significantly higher on the seismic line, with 252% more tamarack and 65% more black spruce than in the adjacent forest. Relative to the adjacent forest, there were significantly fewer trees (height > 1.3 m) on the seismic line, with an 84% and 50% reduction in black spruce and tamarack, respectively. By analyzing tree ring data from seismic lines, we found that the length of time before tree establishment was 10 years for black spruce and 8 years for tamarack. On average, it took 12 years for tree density to reach 2000 stems per hectare (sph). We modeled growth rates for black spruce and tamarack and found that they were growing faster than their adjacent forest counterparts, reaching 3 m after an average of 38 and 33 years, respectively. Stands on seismic lines were projected to a final stand age of 61 years using the Mixedwood Growth Model (MGM) to evaluate future stand characteristics. Full article

In recent years, devastating wildfires have occurred in less fire-prone areas, and an increase in boreal region wildfires is expected in the future. Using a qualitative comparative approach based on a literature review and policy document analysis, this study aims to examine the wildfire management systems and practices in Sweden and Finland, focusing on the remarkably different outcomes of the 2018 wildfire season. Despite experiencing similar climatic conditions, in Sweden a total of approximately 25,000 hectares of forest burned, compared to the 1200 hectares in Finland. The analysis examines thematic areas from general disaster management and wildfire-specific elements. The main differences in the organizational structures between the two countries are identified. Ecological aspects of boreal forests, fire suppression effectiveness, and response times are compared, and current and emerging technologies for fire detection and suppression, such as unmanned aerial vehicles, are presented. The role of volunteer fire brigades and their sustainability in rural areas, together with the effectiveness of host nation support arrangements and international cooperation mechanisms, are discussed. Based on this comparison of identified best practices and lessons learned, the authors provide recommendations for improving wildfire resilience both in Finland and Sweden, as well as in other boreal region countries. Full article

The increasing frequency of wildfires in larch forests across the discontinuous permafrost zone of Eastern Eurasia heightens the vulnerability of soil organic matter (SOM) under a warming climate. However, post-fire SOM thermal stability in this frequently burned forest region remain poorly understood. We assessed the long-term effects of wildfire on SOM structure and thermal stability in burned and unburned larch forests using complex analytical approaches: pyrolysis–gas chromatography/mass spectrometry (TMAH-py-GC/MS) and thermogravimetry/differential thermal analysis (TG/DTA). The focus was on the upper mineral soil horizon, where fire impacts may persist for decades. Sixteen years post-fire, total carbon content did not differ significantly between burned and control soils. Nonetheless, the molecular composition and thermal properties of SOM showed marked post-fire alterations. Burned soils exhibited higher proportions of lignin-derived compounds and reduced levels of short-chain fatty acid methyl esters. A lower degradation temperature (T50) and a higher thermal mass loss of labile fractions indicate a decrease in the thermal stability of SOM after fire. Our study shows that recurrent forest fires in larch forests of the Russian Far East decrease the thermal stability of soil organic matter, thereby increasing its vulnerability to subsequent fire degradation. Full article

Oil sands mining in northeastern Alberta, Canada, has disturbed large areas of the northern boreal forest which must be restored to pre-disturbance levels through reclamation. The oil sands tailings have high pH and elevated levels of Na⁺ which are harmful to plants. A novel non-segregating tailing (NST) was developed to accelerate consolidation of fine tailings, yet its effects on boreal plant species are not well characterized. In oil sands reclamation, a capping layer—either forest mineral soil mix (FMM), salvaged from upland boreal forest sites, or peat mineral mix (PMM), sourced from peatlands—is typically applied over overburden materials and coarse tailings sands prior to revegetation. Plants in oil sands revegetation sites frequently experience nutrient deficiencies, such as nitrogen and phosphorus, and impaired physiological processes due to the high pH and soil salinity. In this study, we examined the effects of nitrogen and phosphorus supplements in the NST-amended reclamation soils on growth and physiological parameters of trembling aspen (Populus tremuloides) and white spruce (Picea glauca) seedlings. We found that the growth and physiological responses of seedlings were superior in the mixture of NST and FMM compared with NST and PMM. Phytotoxicity of NST was associated with elevated boron levels. Trembling aspen exhibited greater sensitivity to NST but showed stronger growth improvements with increased nitrogen and phosphorus supplementation compared to white spruce. High levels of nitrogen and phosphorus supplementation alleviated the adverse effects on both species that were caused by mineral nutrient imbalance. Full article

Due to climate effects and human influences, wildfire regimes in boreal forests are changing, leading to profound ecological consequences, including shortened fire return intervals and elevated tree mortality. However, a critical knowledge gap exists concerning the spatiotemporal dynamics of fire-induced tree mortality specifically within the vast North American boreal forest, as previous studies have predominantly focused on Mediterranean and tropical forests. Therefore, in this study, we used satellite observation data obtained by the Moderate Resolution Imaging Spectroradiometer (MODIS) Aqua and Terra MCD64A1 and related database data to study the spatial and temporal variability in burned area and forest mortality due to wildfires in North America (Alaska and Canada) over an 18-year period (2003 to 2020). By calculating the satellite reflectance data before and after the fire, fire-driven forest mortality is defined as the ratio of the area of forest loss in a given period relative to the total forest area in that period, i.e., the area of forest loss divided by the total forest area. Our findings have shown average values of burned area and forest mortality close to 8000 km²/yr and 40%, respectively. Burning and tree loss are mainly concentrated between May and September, with a corresponding temporal trend in the occurrence of forest fires and high mortality. In addition, large-scale forest fires were primarily concentrated in Central Canada, which, however, did not show the highest forest mortality (in contrast to the results recorded in Northern Canada). Critically, based on generalized linear models (GLMs), the results showed that fire size and duration, but not the burned area, had significant effects on post-fire forest mortality. Overall, this study shed light on the most sensitive forest areas and time periods to the detrimental effects of forest wildfire in boreal forests of North America, highlighting distinct spatial and temporal vulnerabilities within the boreal forest and demonstrating that fire regimes (size and duration) are primary drivers of ecological impact. These insights are crucial for refining models of boreal forest carbon dynamics, assessing ecosystem resilience under changing fire regimes, and informing targeted forest management and conservation strategies to mitigate wildfire impacts in this globally significant biome. Full article

While boreal forests constitute 30% of the Earth’s forested area and are responsible for 20% of the global carbon sink, there is considerable concern about their sustainability. This paper focuses on the role of elevated CO₂, examining whether wood volume in these forests has responded to increased CO₂ over the last 60 years. To accomplish this, we use a rich set of wood volume measurement data from the Province of Alberta, Canada, and deploy quasi-experimental techniques to determine the effect of elevated CO₂. While the few experimental studies that have examined boreal forests have found almost no effect of elevated CO₂, our results indicate that a 1.0% increase in lifetime exposure to CO₂ leads to a 1.1% increase in aboveground wood volume in these boreal forests. This study showcases the value of research designs that use natural settings to better account for the effects of prolonged exposure to elevated CO₂. Our results should enable improved delineation of the drivers of historical changes in wood volume and carbon storage in boreal forests. In addition, when combined with other studies, these results will likely aid policymakers in designing management or policy approaches that will enhance the sustainability of forests in boreal regions. Full article

The fraction of absorbed photosynthetically active radiation (FAPAR) stands as a pivotal parameter within the Earth system, quantifying the energy exchange between vegetation and solar radiation. Accordingly, there is an urgent need for comprehensive validation studies to accurately quantify uncertainties and improve the reliability of FAPAR-based applications. This study validated five global FAPAR products, MOD15A2H, MYD15A2H, VNP15A2H, GEOV2, and GEOV3, over four boreal forest sites in North America. Qualitative quality flags (QQFs) and quantitative quality indicators (QQIs) of each product were analyzed. Time series high-resolution reference FAPAR maps were developed using the Harmonized Landsat and Sentinel-2 dataset. The reference FAPAR maps revealed a strong agreement with the in situ FAPAR from AmeriFlux (correlation coefficient (R) = 0.91; root mean square error (RMSE) = 0.06). The results revealed that global FAPAR products show similar uncertainties (RMSE: 0.16 ± 0.04) and moderate agreement with the reference FAPAR (R = 0.75 ± 0.10). On average, 34.47 ± 6.91% of the FAPAR data met the goal requirements of the Global Climate Observing System (GCOS), while 54.41 ± 6.89% met the threshold requirements of the GCOS. Deciduous forests perform better than evergreen forests, and the products tend to underestimate the reference data, especially for the beginning and end of growing seasons in evergreen forests. There are no obvious quality differences at different QQFs, and the relative QQI can be used to filter high-quality values. To enhance the regional applicability of global FAPAR products, further algorithm improvements and expanded validation efforts are essential. Full article

Abies nephrolepis and Picea jezoensis are native Pinaceae trees distributed in high mountainous regions of Northeast Asia (typically above ~1000 m a.s.l. on the Korean peninsula, northeastern China, Sakhalin, and the Russian Far East) and southern boreal forests, vulnerable to climate change and human disturbances, necessitating accurate habitat identification for effective conservation. While protected areas (PAs) are essential, merely expanding existing ones often fail to protect populations under human pressure and climate change. Using species distribution models with current and projected climate data, we mapped potential habitats across Northeast Asia. Spatial clustering analyses integrated with PA and land cover data helped identify optimal sites and priorities for new conservation areas. Ensemble species distribution models indicated extensive suitable habitats, especially in southern Sikhote-Alin, influenced by maritime-continental climates. Specific climate variables strongly affected habitat suitability for both species. The Kamchatka peninsula consistently emerged as an optimal habitat under future climate scenarios. Our study highlights essential environmental characteristics shaping the habitats of these species, reinforcing the importance of strategically enhancing existing PAs, and establishing new ones. These insights inform proactive conservation strategies for current and future challenges, by focusing on climate refugia and future habitat stability. Full article

Megafires are transforming western boreal forests, and many burned forests are salvage logged, removing more structure from landscapes and delaying forest regeneration. We studied forest-dwelling owls in a post-fire and salvage-logged landscape in central British Columbia, Canada, in 2018–2019 after the 2010 Meldrum Creek Fire and the 2017 Hanceville Fire. We examined owl habitat selection via call surveys compared to the habitats available in this landscape. Owl pellets were dissected to determine owl diets. We detected six owl species, of which Northern Saw-whet Owls (Aegolius acadicus) were the most common. Owls had weak and variable habitat selection within an 800 m radius of detections; all species used some burned area. Great Gray Owls (Strix nebulosa) and Great Horned Owls (Bubo virginanus) obtained more prey from mature forests (e.g., red-backed voles, Myodes gapperi, snowshoe hares, Lepus americanus) than other owls did, whereas other owls primarily consumed small mammals that were common in burned or salvaged areas. These results indicate a diverse community of owls can use landscapes within a decade after wildfire, potentially with some prey switching to take advantage of prey that use disturbed habitats. Despite that, owl numbers were low and some owls consumed prey that were not available in salvage-logged areas, suggesting that impacts on owls were more severe from the combination of fire and salvage logging than from fire alone. Full article

A comprehensive paleoecological study of a forested bog located in the middle taiga subzone of northeastern European Russia was carried out. According to the ¹⁴C radiocarbon dating and botanical composition analysis, the bog began forming 8200 calibrated years ago, evolving in three stages from grassy wetlands to its current state as a pine-Sphagnum peatland. Analysis revealed substantial carbon storage (81.4 kg m⁻²) within the peat deposit. Macrocharcoal particles were consistently present throughout the peat deposits, demonstrating continuous fire activity across the bog’s developing. High charcoal particle accumulation rates occurred not only during warm periods like the Holocene thermal maximum but also during colder and wetter periods. These periods include recent centuries, when high charcoal accumulation rates are likely due to increased human activity. Statistical analysis showed significant relationships between macrocharcoal content and several peat characteristics: higher charcoal levels correlated with increased soil carbon (r = 0.6), greater aromatic compounds (r = 0.8), and elevated polycyclic aromatic hydrocarbons (r = 0.7), all with p < 0.05. These findings highlight how fire has consistently shaped this ecosystem’s development and carbon storage capacity over millennia, with apparent intensification during recent centuries potentially linked to anthropogenic influences on fire regimes in the boreal zone. Full article

We assessed the impacts of tree improvement programs on the associated gains in yield of white spruce (Picea glauca (Moench) Voss) and hybrid spruce (Picea engelmannii Parry ex Engelmann x Picea glauca (Moench) Voss) over long temporal and large spatial extents. The definition of gain varied in the tree improvement programs. We assessed the definition of gain using a sensitivity analysis, altering the evaluation age with the definitions of the baseline and top performers. We used meta-data from provenance trials extracted from the literature to model the yields of provenances relative to those of standard stocks. Using a previously developed meta-model and a chosen gain definition, a meta-dataset of the gain of plantation ages was developed. Using this gain meta-dataset, a gain trajectory model was fitted for white and hybrid spruce provenances across Canadian boreal and hemiboreal forests. The planting site, mean annual daily temperature, mean annual precipitation, and number of degree days > 5 °C had large impacts on gain. This model can be used to predict gain up to harvest age at any planting site in the boreal and hemiboreal forests of Canada. Further, these gain trajectories could be averaged over a region to indicate the yield potential of tree improvement programs. Full article

We examined three decades of changes in the mammal fauna of Estonia, Latvia, and Lithuania in the context of climate variability, land use transformation, and anthropogenic pressures. We compiled distributional, abundance, and status data from publications, atlases, official game statistics, and long-term monitoring programs, and we evaluated trends using compound annual growth rates or temporal indices. Our review identified losses such as regional extinctions of garden dormice and European mink, declines in small insectivores (e.g., pond bats and shrews) and herbivores (e.g., Microtus voles), and the contraction of boreal specialists (e.g., Siberian flying squirrels). However, we also identified gains, including increases in ungulate numbers (e.g., roe deer, red deer, fallow deer, moose, and wild boars before African swine fewer outbreak) and the recovery of large carnivores (e.g., wolves and lynxes). Invasions by non-native species (e.g., American mink, raccoon dog, and raccoon) and episodic disturbances, such as African swine fever and the “anthropause” caused by the SARS-CoV-2 pandemic, have further reshaped community composition. The drivers encompass climatic warming, post-socialist forest succession, intensified hunting management, and rewilding policies, with dispersal capacity mediating the responses of species. Our results underscore the dual legacy of historical land use and contemporary climate forcing in structuring the fauna dynamics of Baltic mammal communities in the face of declining specialists and invasive taxa. Full article

Extensive wildfires and logging have affected the Russian boreal forests in recent decades. Scots pine (Pinus sylvestris L.) forests are widespread in Russia and are one of the most disturbed tree species in Siberia. However, the effects of disturbance on soil CO₂ efflux in the vast Siberian forests are still poorly understood. We used the LI 8100A infrared gas analyzer to study changes in soil CO₂ efflux into the atmosphere in mature Scots pine forests in the Siberian central taiga five–six years following fires and logging. Measurements of soil CO₂ efflux rates were performed on sites where automatic weather stations have been continuously operational since 2022, which gives us temporal patterns of meteorological fluctuations across forests with different disturbance histories. We found significant differences in soil efflux rates depending on the site and disturbance characteristics. In the undisturbed dry lichen-dominated forest, CO₂ efflux was 4.8 ± 2.1 µmol m⁻² s⁻¹, while in the wet moss-dominated forest it was 2.3 ± 1.3 µmol m⁻² s⁻¹, with soil efflux in Sphagnum sp. being twofold of that in feather moss. Both fire and logging significantly reduced CO₂ efflux, with a smaller reduction in soil CO₂ efflux observed in the moss-dominated plots (5%–40%) compared to the lichen-dominated plots (36%–55%). The soil efflux rate increased exponentially with increasing topsoil temperatures in lichen-dominated Scots pine sites, with disturbed plots showing less dependence compared to undisturbed forest. In the wet moss-dominated Scots pine forest, we found no significant dependence of soil efflux on temperature for all disturbance types. We also found a positive moderate relationship between soil efflux and forest floor depth in both lichen- and moss-dominated Scots pine forests across all the plots studied. Our findings advance the understanding of the effects of fire and logging on the carbon cycle and highlight the importance of accounting for disturbance factors in Earth system models due to changing climate and anthropogenic patterns. Full article