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The results of detection (segmentation) of forest disturbances (logged and windthrow areas) based on Sentinel-2 satellite images with convolutional neural networks of U-net architecture in different regions of the European territory of Russia and the Urals are presented. The volume of the training sample was over 17 thousand objects. Overall, both logged and windthrow areas are detected with satisfactory accuracy (the average F-measure is over 0.5). At the same time, substantial differences in detection accuracy were found depending on the characteristics of both disturbances themselves and the affected forest cover. Thus, the maximum accuracy was achieved for tornado-induced windthrow areas, due to their geometric features. The dependence of windthrow detection accuracy on the species composition of damaged forests is not obvious and requires clarification; at the same time, the average area of damaged forest sites has a substantial effect on it. The maximum F-measure calculated for logged areas detected on test pairs of Sentinel-2 images reaches 0.80, which is substantially higher than in previously published studies with the U-net model. The maximum accuracy is typical for large clear-cuts in mixed and dark coniferous forests, while selective logged areas in deciduous forests are characterized by lowest one. The accuracy for wintertime and summertime pairs of images is substantially higher than for multiseasonal pairs. Also, the accuracy strongly varies for different types of logged areas. Thus, forest roads on summertime images are detected with the lowest producer's accuracy, while logged areas on wintertime images are detected with highest one. [ABSTRACT FROM AUTHOR]

This study aimed to examine the dynamics of soil functional indicators under the influence of deadwood in old mixed beech forests in northern Iran. In January and February 2006, several strong wind events occurred in the forest of Khanikan, which led to severe windthrow. All the fallen trees remained in the protected parcel and were not removed. Immediately after tree felling in the studied areas, five common tree species [Fagus orientalis (Fagus), Acer velutinum (Acer), Carpinus betulus (Carpinus), Alnus subcordata (Alnus), and Tilia begonifolia (Tilia)] with the highest abundance of deadwood (with 14 individual trees) were marked as permanent plots for monitoring their effect on soil functions. Wood samples were collected from the trunks and soil samples (0–10 cm depth) from the lower part of deadwood in August 2011, 2016, and 2021. In addition, soil samples were taken from areas that did not have deadwood as control areas. For the study of soil biological parameters, soil samples were collected in August and November (2011, 2016, and 2021). However, for monitoring soil N transformation, soil samples were taken in August, September, November, and December (2011, 2016, and 2021). We found that Alnus and Carpinus deadwood had higher N, K, P, and Ca contents than deadwood of other species. Higher values of C and Mg were observed in Fagus deadwood in the final stages of sampling (2021). Anlus deadwood enhanced the stability of soil aggregates, soil nutrient contents, as well as soil enzyme and microbial activities, and soil fauna and microflora populations during the decay process. Based on our findings, the intensity of soil functions increased in the order control < Fagus < Tilia < Acer < Carpinus < Alnus, which corresponds to the increasing quality of the deadwood of the tree species. Our data emphasize that retaining deadwood is highly effective in boosting carbon and nutrient cycling in forest ecosystems, which may have implications for forest management strategies to improve soil ecological functions and forest sustainability. Although our observations were obtained in an old mixed beech forest, the importance of deadwood on soil functional characteristics can also be assumed in a broader range of forest environments, but this requires further investigation to determine the mechanisms that explain these phenomena. [ABSTRACT FROM AUTHOR]

The usual practice following a windthrow event is salvage logging of all damaged trees. This study was carried out in a pine stand affected by storms with varying disturbance severities in which no salvage logging was performed. Epigeic carabids (Coleoptera) were the test taxon. How does windthrow severity and disturbance legacies affect the abundance, richness and life traits of carabid assemblages? Two hypotheses were formulated: (1) the more severe the disturbance, the higher the abundance and species richness, and the lower the proportion of late-successional fauna in carabid assemblages, and (2) pine tree crowns lying on the ground support a higher proportion of late-successional carabid species, the effect of which should be more pronounced in more severely disturbed stands but will decrease as needles fall off over the next 3 years. To test the first hypothesis, 3 degrees of stand disturbance were distinguished. Both hypotheses were partially supported. Simultaneously, it was demonstrated that the importance of the leaf area index for carabids decreased over the 3 years, while the significance of the soil respiration rate and soil humidity increased. During the 3 years, the percentage of carabid forest species living under the fallen tree crowns remained at the same level. The findings indicate that there is a rationale for leaving fallen trees in place together with their crowns, while in tree stands where salvage logging is performed, whole crowns should be left cut-off from trunks to provide shelter for forest species. [ABSTRACT FROM AUTHOR]

A study of the trunks of spruce and birch trees after a windblow on the territory of the Zvenigorod Biological Station of Moscow State University and the Sima Quarry Nature Reserve (Moscow oblast) was carried out. The diversity of epiphytic lichens depending on height of the trunk was studied. It is shown that the position on the tree trunk significantly affects the number of identified lichen species, which increases monotonously with height. Both spruce and birch trees are characterized by a high non-matching diversity of lichen biota in the lower and upper parts of the trunk (and especially in the crown). The complex of the dominant lichen species was changing throughout trunks examined. It is noted that the finds of Bryoria and Usnea spp. protected in the Moscow oblast are concentrated in the upper part of the trunks. [ABSTRACT FROM AUTHOR]

The anticipated increase in extreme disturbance events due to climate change is likely to expose Norway spruce (Picea abies (L.) Karst.) dominated forests in northern Europe to new conditions. Empirical data on the resilience of such natural (unmanaged) forests to disturbance and the long-term patterns of regeneration in its aftermath are currently scarce. We performed a quantitative assessment of natural forest stands in north–western Latvia to identify and characterise the patterns of stand structure 44 years after a stand-replacing disturbance and investigated the effects of legacies on regeneration. The spatial distribution of tree species and their dimensions were assessed in 71 circular sample plots (500 m2 each) in natural forest areas, where Norway spruce dominated prior to the windthrow and salvage logging was not carried out. Spatial indices (species mingling index, size differentiation index, and aggregation index) were used to characterise stand structure and diversity. The different initial states (age and coverage of surviving trees) of stands affected eventual tree species dominance, size differentiation, degree of mingling and aggregation. Our results demonstrate a close relationship between disturbance legacies and spatial indices. The pre-storm understory and canopy survivors decreased species mingling, whereas survivors increased size differentiation. The size differentiation increased also with a higher degree of species mingling. Leaving differential post-storm legacies untouched promotes a higher structural and species diversity and therefore supports the management approach of preserving canopy survivors. [ABSTRACT FROM AUTHOR]

In November 2004 a large windstorm affected forests dominated by Norway spruce (Picea abies (L.) H. Karst, 1881) in the High Tatras National Park, Slovakia, and was followed by a wildfire (2005) and bark beetle outbreak. In this study we investigate temporal changes of breeding bird community (their species richness, density and diversity) as well as different nest-position guilds, in relation to disturbance type. Bird species composition was surveyed in two periods (2006 and 2007, and 2017 and 2018) using the point count method on four plots differing by disturbance type – undisturbed forest, unlogged windthrow, salvage logged windthrow and burnt salvage logged windthrow. A total of three visits per point and breeding season were performed at forty point count sites. We also assessed the successional shift in habitat characteristics between the two monitored periods. In total, 55 bird species and 2059 individuals were recorded on the plots during the study. We observed no effect of disturbance type on mean species richness, abundance and Simpson's diversity per point; however, those characteristics did significantly increase over the study duration. While differently disturbed points had previously differed in their (nest-position) guild number and diversity, the differences between them disappeared over time. We found different trajectories of temporal change in the composition of the species communities and guild diversity in relation to disturbance type, but in a similar direction. During the first period, the greater the initial differences in the severity of disturbance among the disturbance types, the greater the differences were in the composition of bird communities; however, the differences gradually diminished as the forests regenerated. Alterations in habitat structure caused by natural and anthropogenic disturbance and by subsequent succession were the most probable reasons for the altered bird communities and observed patterns of recovery. [ABSTRACT FROM AUTHOR]

Ungulate herbivory can alter functional plant communities of early-successional forest ecosystems. The consequences of such vegetation changes on soil carbon cycling are still not fully understood. Here, we used an ungulate exclusion experiment to investigate how different levels of herbivory and associated changes in vegetation succession modulate soil CO2 efflux and its heterotrophic and autotrophic sources following windthrow in temperate mountain forests. Our results indicate that only high levels of ungulate herbivory and associated vegetation shifts from tree to rather grass dominated plant communities affect soil CO2 fluxes. We did not find evidence that a moderate herbivory level and accompanied smaller shifts in the functional plant community affect soil CO2 fluxes. A greater soil CO2 efflux under the influence of high herbivory pressure was primarily attributed to accelerated heterotrophic respiration, likely due to warmer soil conditions. Moreover, autotrophic respiration from grass roots and associated microbial communities is suggested to contribute to higher soil CO2 fluxes. We conclude that intense herbivory and accompanied successional changes in the functional plant community enhance soil carbon losses following forest windthrow. This might have negative consequences for the soil carbon stocks and for the climate system. [ABSTRACT FROM AUTHOR]

The tree diameter distribution was used to characterize the impact of forest disturbances and the ecosystem dynamics during the process of regeneration in the absence of any management 44 years after the event. In addition, the impact of salvage logging after windthrow remains unknown, especially on long-term responses. In this study, comparisons were made between the "unsalvaged" and "salvaged" post-storm management scenarios. The study was conducted in Slitere Natural Park in the Northwest part of Latvia, where large-scale windthrow occurred on November 2, 1969. The three-parameter Weibull function was used to describe the diameter distribution of Norway spruce (Picea abies (L.) Karst.) stands formed after large-scale wind storm in two site types (on fertile mineral soils: with normal moisture regime (fresh)—Oxalidosa—and with periodic excess water (wet)—Myrtilloso-sphagnosa) and where salvage logging was or was not carried out (management scenarios). The naturally regenerated stands remained Norway spruce dominated and were independent of the post-storm management scenarios; still, they were significantly affected by a forest type. The three-parameter Weibull distribution function suited well to actual diameter distributions of the sample plots. Diameter distributions significantly differed between the forest types: In Myrtilloso-sphagnosa (wet) forest stands, it was a negative exponential and in Oxalidosa (fresh) stands unimodal and positively skewed. We did not detect distribution differences caused by salvage after a large-scale disturbance, indicating that other factors (like ecological importance of deadwood, a risk of insect outbreaks to neighboring areas, etc.) need to be considered, when deciding on the post-storm management. [ABSTRACT FROM AUTHOR]

Climate change is likely to affect windthrow risks at northern latitudes by potentially changing high wind probabilities and soil frost duration. Here, we evaluated the effect of climate change on windthrow risk in eastern Canada's balsam fir ( Abies balsamea [L.] Mill.) forests using a methodology that accounted for changes in both wind speed and soil frost duration. We used wind speed and soil temperature projections at the regional scale from the CRCM5 regional climate model (RCM) driven by the CanESM2 global climate model (GCM) under two representative concentration pathways (RCP4.5, RCP8.5), for a baseline (1976-2005) and two future periods (2041-2070, 2071-2100). A hybrid mechanistic model (ForestGALES) that considers species resistance to uprooting and wind speed distribution was used to calculate windthrow risk. An increased risk of windthrow (3 to 30%) was predicted for the future mainly due to an increased duration of unfrozen soil conditions (by up to 2 to 3 months by the end of the twenty-first century under RCP8.5). In contrast, wind speed did not vary markedly with a changing climate. Strong regional variations in wind speeds translated into regional differences in windthrow risk, with the easternmost region (Atlantic provinces) having the strongest winds and the highest windthrow risk. Because of the inherent uncertainties associated with climate change projections, especially regarding wind climate, further research is required to assess windthrow risk from the optimum combination of RCM/GCM ensemble simulations. [ABSTRACT FROM AUTHOR]

Environmental conditions developing at the boundary of windfall- and fire-damaged forest biocenoses at different stages of progressive succession have a positive effect on the total abundance of rodents, but the role of ecotone in forming the structure of their microhabitats is ambiguous. The complex of biotic and abiotic conditions in the ecotone has a positive influence on the size of shrub coverage area and the abundance of saplings, whereas the influence of the edge effect on other microhabitat parameters (namely, herbaceous and moss coverage) is negative or neutral. [ABSTRACT FROM AUTHOR]

The distance that ground-hugging pyroclastic density currents travel is limited partly by when they reverse buoyancy and liftoff into the atmosphere. It is not clear, however, what deposits are left behind by lofting flows. One current that was seen to liftoff was the surge erupted from Mount St. Helens on the morning of 18 May 1980. Before lofting, it had leveled a large area of thick forest (the blowdown zone). The outer edge of the devastated area-where trees were scorched but left standing (the scorched zone)-is where the surge is thought to have lifted off. Deposits in the outer parts of the blowdown and in the scorched zone were examined at 32 sites. The important finding is that the laterally moving surge traveled through the scorched zone, and hence, the change in tree damage does not mark the runout distance of the surge. Buoyancy reversal and liftoff are thus not preserved in the deposits where the surge lofted upwards. We propose, based on interpretation of eyewitness accounts and the impacts of the surge on trees and vehicles, that the surge consisted of a faster, dilute 'overcurrent' and a slower 'undercurrent,' where most of the mass (and heat) was retained. Reasonable estimates for flow density and velocity show that dynamic pressure of the surge (i.e., its ability to topple trees) peaked near the base of the overcurrent. We propose that where the overcurrent began to liftoff, the height of peak dynamic pressure rose above the trees and stopped toppling them. The slower undercurrent continued forward, however, scorching trees, but lacked the dynamic pressure needed to topple them. Grain-size variations argue that it slowed from ∼30 m s when it entered the scorched zone to ∼3 m s at the far end. [ABSTRACT FROM AUTHOR]

The article discusses a study which examines the impact of windfall disturbances on the structure and dynamics of ground beetles in the Central Forest Nature Reserve. Findings show that the windfall caused a decline to the diversity of ground beetle population, particularly Carabus glabratus, Pterostichus oblongopunctatus, and Calathus micropterus. It also indicates some species that are tolerant to windfall disturbances including Epaphius secalis, Leistus terminates, and Pterostichus niger.

Fossil fuel subsidy reform would not only decrease consumption, but also lower the world market price of traded fossil energy carriers, in particular oil. As a consequence, oil importers would lower their import bills by more than US$ 30 bn per year. Recycling at least a part of these savings to support low-carbon energy technologies in countries that reduce their subsidies could provide a mechanism to jointly incentivize transformation of the energy system and alter the political economy of subsidy reform. [ABSTRACT FROM AUTHOR]

Coniferous forests cover extensive areas of the boreal and temperate zones. Owing to their primary production and C storage, they have an important role in the global carbon balance. Forest disturbances such as forest fires, windthrows or insect pest outbreaks have a substantial effect on the functioning of these ecosystems. Recent decades have seen an increase in the areas affected by disturbances in both North America and Europe, with indications that this increase is due to both local human activity and global climate change. Here we examine the structural and functional response of the litter and soil microbial community in a Picea abies forest to tree dieback following an invasion of the bark beetle Ips typographus, with a specific focus on the fungal community. The insect-induced disturbance rapidly and profoundly changed vegetation and nutrient availability by killing spruce trees so that the readily available root exudates were replaced by more recalcitrant, polymeric plant biomass components. Owing to the dramatic decrease in photosynthesis, the rate of decomposition processes in the ecosystem decreased as soon as the one-time litter input had been processed. The fungal community showed profound changes, including a decrease in biomass (2.5-fold in the litter and 12-fold in the soil) together with the disappearance of fungi symbiotic with tree roots and a relative increase in saprotrophic taxa. Within the latter group, successive changes reflected the changing availability of needle litter and woody debris. Bacterial biomass appeared to be either unaffected or increased after the disturbance, resulting in a substantial increase in the bacterial/fungal biomass ratio. [ABSTRACT FROM AUTHOR]

Treefall pits and mounds, formed when trees are uprooted by wind, influence an exceptionally broad range of phenomena in forests, having impacts on vegetation composition, soil formation, erosion, and soil respiration, among other processes. For example, treefall pits and mounds are known to have plant species composition with more pioneer species than nearby undisturbed soil; these microsites also are wetter (pits) or drier (mounds) than undisturbed soil; and have lower rates of soil respiration. Therefore, knowledge of the extent or coverage of these microsites will improve estimates of several processes as well as vegetation composition at the stand and landscape scale. Such information would be timely, given predictions of climate-change driven increases in severe weather that is the primary agent of pit and mound formation. However, to date, there have been no attempts to define a robust relationship to predict the sizes of these microsites across multiple forest types in eastern North America. Here, we summarize field measurement of the relationship between tree size and treefall pit and mound sizes, across ten catastrophic windthrow study sites. We find that for all ten sites pooled, simple ln-ln regression explains almost 54% of the variation in sizes of treefall pits ( n = 1,039) and treefall mounds ( n = 962) on the basis of tree diameter. This relationship spans numerous soil types, 31 tree species, and tree sizes ranging from 5 cm to greater than 105 cm diameter. Such a relationship may be coupled with information on the severity of disturbance (for example, proportion of stems uprooted) and pre-disturbance tree size structure, to provide a basis for predicting the area covered by pit and mound microsites at the landscape scale, and thereby a basis to frame expected impacts on soil formation, carbon cycling, vegetation establishment, and other ecological, edaphic, and biogeochemical processes. [ABSTRACT FROM AUTHOR]

Windthrow, i.e. the felling of trees by wind, occurs continually in forest ecosystems. The uprooting of old trees creates multiple microsites (e.g. pit and mound landscape) that are the main source of soil heterogeneity. To determine the impact of pit and mound landscapes on soil features, a beech forest of the Langa district (Mazandaran province, Northern Iran) was studied. An area of 25 ha was considered for this study wherein three microsites were distinguished, including pit bottom (pit), mount top (mound) and level areas (closed canopy). In this area, 22 uprooted trees were also found. Soil samples were collected at different depths (i.e. 0-15, 15-30 and 30-45 cm) from all microsites and analysed. Our study shows that windthrow events should be considered as an important factor in influencing forest ecosystem, as they affect physical (i.e. density, texture and water content), chemical (i.e. pH, organic C, total N, cation exchange capacity and available nutrients) and biological (i.e. soil microbial respiration and earthworm density/biomass) characteristics of soil, thus resulting in pit and mound microsites that may strongly differ with respect to the closed canopy. [ABSTRACT FROM AUTHOR]

Downed and standing deadwood (DW) is a key resource for maintaining forest biodiversity. Although extreme events such as windthrow and fires produce large quantities of DW, this substrate is often drastically reduced by logging activities. To elucidate the respecting consequences of salvage-logging, we assessed both quantity and quality of storm-derived DW (storms Vivian 1990 and Lothar 1999) in Swiss forests using a sample of 90 windthrow sites with ≥3 ha complete windthrow and at elevations ranging from 350 to 1,800 m a.s.l. The majority had been salvage-logged (SL) a few years after the windthrow. On each site, we recorded DW amount and quality on six circular sample plots 20 or 50 m in size. DW volume on SL sites was surprisingly high, with 76.4 m ha on average 20 years after Vivian and 73.8 m ha 10 years after Lothar. In comparison, DW volumes on unsalvaged sites, that is, with no post-windthrow intervention (NI), amounted to 270 m ha. A wide variety of wood decay stages and diameter classes (10 to ≥70 cm) was found on both NI and SL sites, suggesting considerable habitat diversity for DW-associated species irrespective of the treatment. The considerable amounts of DW left after salvage-logging distinctly exceed the minimum DW volumes in forest stands proposed by Müller and Bütler (Eur J For Res 129: 981-992, ) in a conservation context, which demonstrates the importance of wind disturbance for biodiversity. Further studies should quantify DW of individual tree species, since habitat requirements are species-specific. [ABSTRACT FROM AUTHOR]

The transformation of microenvironmental conditions in habitats of small mammals and related changes in their spatial structure, manifested in changing levels of interspecific contacts, have been studied in microhabitats of plots affected by anemogenic (windfall) and pyrogenic influence in a protected area of the Middle Urals. The association of the dominant species (the bank vole) and other species of the community (grey red-backed vole, northern red-backed vole, and common shrew) increases in environments disturbed by disastrous natural factors. Association of species is less pronounced in the pyrogenic area, compared to the anemogenic area. The type of association between species differs between stages of progressive succession depending on conditions in particular microhabitats and specific features of functional organization in populations of small mammal species. [ABSTRACT FROM AUTHOR]

Large woody debris (LWD) provides structural complexity to small streams. Riparian buffers are intended to provide long-term vegetation cover and supplies of LWD, but post-harvest windthrow often occurs. To evaluate the impacts of windthrow in riparian buffers and identify the components for a small stream LWD recruitment model, we sampled 26 streams in immature and older stands in wind-exposed areas of southwestern and northern Vancouver Island. These treed buffer strips had been exposed following clearcut harvest of adjacent timber on both sides 1-20 years previously. For stream sections 100 m long in each buffer, all logs greater than 7.5 cm diameter that spanned at least part of stream channel were measured. A total of 658 logs were recorded. Windthrown trees were comparable in characteristics to the trees that made up the buffer. The majority of logs derived from windthrown trees were oriented perpendicular to the stream channel and were suspended above the stream channel. Even 20 years after harvesting, two-thirds of the logs were still suspended above the stream. Logs in older buffers were more decayed, and the decay rate depended on tree species and initial diameter. Log height above stream was negatively correlated with log decay class and time since logging. Log length declined with time since harvest exposure and decay class. Sediment was exposed on upturned roots and within mineral soil pits. The volume of soil retained on upturned rootwads declined over time, but some soil remained even after 20 years. Very little of this exposed sediment was close enough to the creek to result in sediment delivery. [ABSTRACT FROM AUTHOR]

Wind damage in Japan is mainly caused by typhoons (i.e., tropical cyclones), which are characterized by intensive heavy rainfall and strong winds. In this study, we conducted tree-pulling experiments on two sites to find out whether rapidly supplied water on the soil would affect stability of root anchorage of hinoki (Chamaecyparis obtuse (Sieb. Et Zucc.) Endl.), as expected. For the experiments, we first supplied several quantities of water around the target trees, and then they were pulled down using a wire winch. On study site 1 (Kamiatago experimental forest), we applied general tree-pulling experiments (no water supply) in 2008 and six different irrigation treatments around the target trees in 2009. On study site 2 (Chiyoda experimental forest), we applied one irrigation treatment in 2009. As a result, five trees were uprooted and two were broken in 2008, and all nine trees were uprooted in 2009 on study site 1, regardless of irrigation treatment. On study site 2, two trees pulled down after 4 h of water supply were ruptured at the stem base, opposite to two trees pulled down immediately after supplying water. The water content below the root plate significantly affected root anchorage and more specifically, the maximum turning moment, stem angle at the maximum force, and stiffness index. Moreover, water inside the root plate increased root anchorage at the beginning of a tree failure process. However, it also reduced the root plate area of the hinge side. Conversely, high water content below the root plate decreased root anchorage. [ABSTRACT FROM AUTHOR]

This study deals with the problem of including the risk of wind damage in long-term forestry management. A model based on Graph-Based Markov Decision Processes (GMDP) is suggested for development of silvicultural management policies. The model can both take stochastic wind events into account and be applied to forest estates containing a large number of stands. The model is demonstrated for a forest estate in southern Sweden. Treatment of the stands according to the management policy specified by the GMDP model increased the expected net present value (NPV) of the whole forest only slightly, less than 2%, under different wind-risk assumptions. Most of the stands were managed in the same manner as when the risk of wind damage was not considered. For the stands that were treated differently, however, the expected NPV increased by 3% to 8%. [ABSTRACT FROM AUTHOR]

This work studied the temporal and spatial variability of the risk of snow-induced forest damage in Finland under current and changing climatic conditions until the end of this century. The study was based on a snow accumulation model in which cumulative precipitation, air temperature and wind speed were used as input variables. The risk was analyzed in terms of the number of days per year when the accumulated amount of snow exceeded 20 kg m − 2. Based on the risk, the forest area and mean carbon stock of seedling, young thinning and advanced thinning stands at risk were calculated. Furthermore, the number of 5-day periods, when the accumulated amount of snow exceeded a risk limit, was calculated for the current and changing climatic conditions in order to study the frequency of damaging snowfalls. Compared to the baseline period 1961–1990, the risk of snow-induced forest damage and the amount of damaging snowfalls were predicted to decrease from the first 30-year period (1991–2020) onwards. Over the whole country, the mean annual number of risk days decreased by 11%, 23% and 56% in the first, second and third 30-year period, respectively, compared to the baseline period. In the most hazardous areas in north-western and north-eastern Finland, the number of risk days decreased from the baseline period of over 30 days to about 8 days per year at the end of the century. Correspondingly, the shares of the forest area at risk were 1.9%, 2.0% and 1.0% in the first, second and third 30-year period, respectively. The highest mean annual carbon stocks of young stands at risk were found in central, north-eastern and north-western Finland in the first and second 30-year period, varying between 0.6 and 1.2 Mg C ha − 1 year − 1, meaning at highest 3% of the mean carbon stock (Mg C stem wood ha − 1) of those areas. This study showed that although the risk of snow-induced forest damage was mainly affected by changes in critical weather events, the development of growing stock under the changing climatic conditions also had an effect on the risk assessment. However, timely management of forest stands in the areas with a high risk of snow-induced damage contributes to the trees’ increased resistance to the damage. [ABSTRACT FROM AUTHOR]

We estimated how the possible changes in wind climate and state of the forest due to climate change may affect the probability of exceeding critical wind speeds expected to cause wind damage within a forest management unit located in Southern Sweden. The topography of the management unit was relatively gentle and the forests were dominated by Norway spruce ( Picea abies (L.) Karst.). We incorporated a model relating the site index (SI) to the site productivity into the forest projection model FTM. Using estimated changes in the net primary production (NPP) due to climate change and assuming a relative change in NPP equal to a relative change in the site productivity, we simulated possible future states of the forest under gradual adjustment of SI in response to climate change. We estimated changes in NPP by combining the boreal-adapted BIOMASS model with four regional climate change scenarios calculated using the RCAO model for the period 2071–2100 and two control period scenarios for the period 1961–1990. The modified WINDA model was used to calculate the probability of wind damage for individual forest stands in simulated future states of the forest. The climate change scenarios used represent non-extreme projections on a 100-year time scale in terms of global mean warming. A 15–40% increase in NPP was estimated to result from climate change until the period 2071–2100. Increasing sensitivity of the forest to wind was indicated when the management rules of today were applied. A greater proportion of the calculated change in probability of wind damage was due to changes in wind climate than to changes in the sensitivity of the forest to wind. While regional climate scenarios based on the HadAM3H general circulation model (GCM) indicated no change (SRES A2 emission scenario) or a slightly reduced (SRES B2 emission scenario) probability of wind damage, scenarios based on the ECHAM4/OPYC3 GCM indicated increased probability of wind damage. The assessment should, however, be reviewed as the simulation of forest growth under climate change as well as climate change scenarios are refined. [ABSTRACT FROM AUTHOR]

Abstract  The wind damage probability (P DAM) in the forests in the federal state of Baden-Wuerttemberg (Southwestern Germany) was calculated using weights of evidence (WofE) methodology and a logistic regression model (LRM) after the winter storm ‘Lothar’ in December 1999. A geographic information system (GIS) was used for the area-wide spatial prediction and mapping of P DAM. The combination of the six evidential themes forest type, soil type, geology, soil moisture, soil acidification, and the ‘Lothar’ maximum gust field predicted wind damage best and was used to map P DAM in a 50 × 50 m resolution grid. GIS software was utilised to produce probability maps, which allowed the identification of areas of low, moderate, and high P DAM across the study area. The highest P DAM values were calculated for coniferous forest growing on acidic, fresh to moist soils on bunter sandstone formations—provided that ‘Lothar’ maximum gust speed exceeded 35 m s−1 in the areas in question. One of the most significant benefits associated with the results of this study is that, for the first time, there is a GIS-based area-wide quantification of P DAM in the forests in Southwestern Germany. In combination with the experience and expert knowledge of local foresters, the probability maps produced can be used as an important tool for decision support with respect to future silvicultural activities aimed at reducing wind damage. One limitation of the P DAM-predictions is that they are based on only one major storm event. At the moment it is not possible to relate storm event intensity to the amount of wind damage in forests due to the lack of comprehensive long-term tree and stand damage data across the study area. [ABSTRACT FROM AUTHOR]

Advanced recruitment and neutral processes play important roles in determining tree species composition in tropical forest canopy gaps, with few gaps experiencing clear secondary successional processes. However, most studies are limited to the relatively limited spatial scales provided by forest inventory plots, and investigations over the entire range of gap size are needed to better understand how ecological processes vary with tree mortality events. This study employed a landscape approach to test the hypothesis that tree species composition and forest structural attributes differ between large blowdown gaps and relatively undisturbed primary forest. Spectral mixture analysis on hyperspectral satellite imagery was employed to direct field sampling to widely distributed sites, and blowdown plots were compared with undisturbed primary forest plots. Tree species composition and forest structural attributes differed markedly between gap and non-gap sites, providing evidence of niche partitioning in response to disturbance across the region. Large gaps were dominated by classic Neotropical pioneer genera such as Cecropia and Vismia, and average tree size was significantly smaller. Mean wood density of trees recovering in large gaps (0.55 g cm−3) was significantly lower than in primary forest plots (0.71 g cm−3), a difference similar to that found when comparing less dynamic (i.e., tree recruitment, growth, and mortality) Central Amazon forests with more dynamic Western Amazon forests. Based on results, we hypothesize that the importance of neutral processes weaken, and niche processes strengthen, in determining community assembly along a gradient in gap size and tree mortality intensity. Over evolutionary time scales, pervasive dispersal among colonizers could result in the loss of tree diversity in the pioneer guild through competitive exclusion. Results also underscore the importance of considering disturbance processes across the landscape when addressing forest carbon balance. [ABSTRACT FROM AUTHOR]

Through the systematic field survey and observations, the factor quantification as well as setting the criteria, the sand disaster-forming environment along the Tarim Desert Highway can be divided into four grades by the classification and regionalization based on fuzzy mathematics. The length of the regions with significant sand disaster accounted for 37.1% of the total highway length. Particularly, the area along the Tarim Desert Highway, based on the sand disaster-forming environment classification as well as the difference in the five basic landform units along the highway, combined with the difference of wind regime, can be divided into five regions, in which the length of the regions suffering severe sand damage occupied 64.3% of the total highway length. In addition, the index of disaster formation grade along the highway decreased from north to south, showing a repeated spatial pattern in small length scales. [ABSTRACT FROM AUTHOR]

Quantification of the downed woody materials that comprise forest fuels has gained importance in Caribbean forest ecosystems due to the increasing incidence and severity of wildfires on island ecosystems. Because large-scale assessments of forest fuels have rarely been conducted for these ecosystems, forest fuels were assessed at 121 US Department of Agriculture forest service inventory plots on Puerto Rico, Vieques, and the US Virgin Islands. Results indicated that fuel loadings averaged 24.05 Mg ha-1 in 2004-2006. Forest litter decreased from wetter to drier forest life zones. These island forests showed a paucity of coarse woody fuels (CWD) (2.91 Mg ha-1) and relatively greater quantities of smaller-sized fine woody fuels (FWD) (10.18 Mg ha-1 for FWD and 10.82 Mg ha-1 for duff/litter) when compared to continental tropical forests. Between 2001 and 2006, CWD fuel loads decreased, while fine fuels and litter increased, such that total fuel loads remained constant on a subset of plots on Puerto Rico. This trend indicates that continued decomposition of CWD deposited by the last severe hurricane is balanced by increasing inputs of FWD from recovering and maturing secondary forests. Forest disturbance cycles and successional development must be taken into account by agencies charged with fire protection and risk assessment. [ABSTRACT FROM AUTHOR]

In natural forest, disturbance changes tree species composition which in turn affects soil properties. Two areas in the Central Forest State Biosphere Reserve, in the Russian Southern Taiga Zone, differed in the intensity of disturbance: Norway spruce was the dominant species at one site, while at the other spruce was mixed with broadleaves. The presence of broadleaves was due to large gaps in the canopy having been formed, which have triggered vegetation succession. At both sites, five plots were selected to evaluate how the presence of broadleaves influences the properties of the soils under spruce. Soil samples were taken close to spruce trees and the O, A and E horizons were analysed. A difference in the distribution of organic matter in the soil horizons was evident, with a higher concentration in the O and A horizons at the spruce dominated site, while a more homogeneous distribution was found under spruce at the site where broadleaves were abundant. The organic matter did not only differ in quantity, but also in quality as estimated by the C/N ratio, and therefore affected the CEC and element relative availability. No differences at the two sites were found for water-extractable and exchangeable elements, but the ratio between the exchangeable and the acid-extractable forms were different, suggesting a higher relative availability of the elements at the spruce dominated site, and thus potentially higher leaching. Both theoretical and empirical studies have suggested that podzolisation and accumulation of organic matter in the O horizon are related to stagnation of ecosystem processes and ecosystem decline. Our data suggest that the presence to windthrow sites and the inclusion of broadleaf species acts to slow or even reverse podzolisation even in spruce dominated sites. [ABSTRACT FROM AUTHOR]

We (1) estimated how the possible changes in wind climate due to climatic change may affect the probability of exceeding critical wind speeds (CWS) expected to cause significant wind damage within a forest management unit located in southern Sweden, (2) analysed how the probability of exceeding an approximate CWS as observed in the management unit would change in different regions in Sweden if expecting a similar kind of forested area to occur in different geographical locations. The topography of the management unit was relatively gentle and the forests were dominated by Norway spruce (Picea abies (L.) Karst.). Seven regions across Sweden were selected for comparison of possible future probability of damaging wind speed. The model-system WINDA was modified and used for calculations of the probability of wind damage together with regionally downscaled climate change scenario (CCS) data. In total, two climate scenarios downscaled using the RCAO model for the control period 1961-1990 and four for the period 2071-2100 were used. The CCSs represent fairly central projections on a 100-year time scale in terms of global mean warming. Although there is ambiguity between different CCSs, the results indicated that the present pattern of more windy conditions in southern than in northern Sweden will remain. For most sites the probability of exceeding the CWS from westerly to south-westerly directions was indicated to remain comparatively high and the probability of damaging wind from south-westerly to south-easterly directions was indicated to increase in many places. For southernmost Sweden increasing probability of exceeding the CWS from the north-westerly to south-easterly wind directions were indicated for all but one CCS. The results were discussed with respect to spatial planning in forestry under a changing wind climate. [ABSTRACT FROM AUTHOR]

Prediction of windthrow risk to individual or groups of retained trees in harvested stands requires an improved understanding of canopy airflow dynamics. Large-eddy simulations were used to simulate wind-tunnel experiments in two and three dimensions to compare with observations for model validation and to address parameter space considerations for the design of subsequent retention pattern experiments. The three-dimensional simulations were similar to the observed wind-tunnel data for the statistical profiles for $$u/u_\ast, \overline {u^{{\prime}}w^{{\prime}}}/u_\ast^2, \sigma_u/\overline u, \sigma_u/u_\ast, \sigma_v/u_\ast$$ but there were greater differences in skewness and kurtosis. These results were obtained using a common leaf-area drag formulation without either skin friction or speed dependent drag that enables scaling with U 0 (ambient wind speed) and h (height of the canopy). This scaling results in a single non-dimensional parameter h/ h c where h c ( x, y, z) is the momentum range resulting from the canopy drag. The validity of the model scaling was tested using two-dimensional simulations. The irrotational component of the flow (potential flow) was found to be important when defining vertical domain limitations and has significant implications for time dependent flow (i.e. turbulent conditions) when considering retention pattern design. The sudden onset of drag associated with the isolated stand presents some unexpected challenges. The horizontal scales of the shearing instabilities were simulated in two dimensions and found to range between 2 h for early times to 7 h for later times. The early-time horizontal scales are in the range of logical retention pattern scales and as such need to be taken into account as part of the parameter space, i.e. a range of retention pattern lengths need consideration. [ABSTRACT FROM AUTHOR]

Focuses on a study which aimed to determine how an increase in annual mean temperature might modify the duration of soil frost and increase the risk of windthrow in trees in Finland. Methods; Outlines of windthrow models; Results and discussion.

The article focuses on the timing of cessation of breeding in forest voles in Middle Urals, Russia. It states that the large forest area in the Middle Urals damaged by windfall, where censuses of rodents on permanent trap-line cuts were taken to determine the absolute and relative abundance. It says that the length of the breeding period depends on the cessation of breeding and onset. Moreover, climatic conditions can lead to delayed breeding in spring and its cessation in summer.