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Planted monocultures of even-aged coniferous tree species are abundant worldwide but increasingly damaged by biotic and abiotic stressors and disturbances. In Central Europe, a fundamental goal of ecologically oriented forest management is thus the conversion of pure and often even-aged coniferous stands into structurally more diverse and mixed broad-leaved forests. This conversion is often achieved by single-tree selection resulting in small canopy openings that promote artificial or natural regeneration. Consequently, forest conversion aims at altering stand structure and tree communities. In order to describe the status quo of forest conversion and derive implications for forest management, we investigated changes of tree composition and forest structure in the Bavarian Spessart mountains in southwest Germany. We conducted a resurvey of 108 semi-permanent plots in four different coniferous stand types of Norway spruce, Scots pine, Douglas fir, and European larch about 30 years after the initial survey. We found significant differences in the stratification and cover of respective forest layers between the two sampling periods that indicated an increase in stand structural heterogeneity. While species richness of the overstorey remained constant, species richness and diversity of the shrub and lower canopy layer increased significantly. Regenerating "winner" species included late-successional broad-leaved (e.g., European beech, sessile oak), pioneer broad-leaved (e.g., silver birch, rowan) and shade-tolerant coniferous (e.g., silver fir, Douglas fir) species. Although Norway spruce was significantly reduced in the overstorey, it regenerated in parts extensively in the understorey. We conclude that the forest conversion in the Spessart mountains was overall successful in terms of diversifying forest structure and tree species. Its effects are, though, still emerging and the stands are in a transitional phase. Besides the preferred natural regeneration of target tree species, forest management may consider active measures to guide the facilitated diverse tree community of previously pure and even-aged coniferous stands towards stand maturity. [ABSTRACT FROM AUTHOR]

Summary: Forests harbour large spatiotemporal heterogeneity in canopy structure. This variation drives the microclimate and light availability at the forest floor. So far, we do not know how light availability and sub‐canopy temperature interactively mediate the impact of macroclimate warming on understorey communities.We therefore assessed the functional response of understorey plant communities to warming and light addition in a full factorial experiment installed in temperate deciduous forests across Europe along natural microclimate, light and macroclimate gradients. Furthermore, we related these functional responses to the species' life‐history syndromes and thermal niches.We found no significant community responses to the warming treatment. The light treatment, however, had a stronger impact on communities, mainly due to responses by fast‐colonizing generalists and not by slow‐colonizing forest specialists. The forest structure strongly mediated the response to light addition and also had a clear impact on functional traits and total plant cover.The effects of short‐term experimental warming were small and suggest a time‐lag in the response of understorey species to climate change. Canopy disturbance, for instance due to drought, pests or logging, has a strong and immediate impact and particularly favours generalists in the understorey in structurally complex forests. [ABSTRACT FROM AUTHOR]

Old-growth forests are essential to preserve biodiversity and play an important role in sequestering carbon and mitigating climate change. However, their existence across Europe is vulnerable due to the scarcity of their distribution, logging, and environmental threats. Therefore, providing the current status of old-growth forests across Europe is essential to aiding informed conservation efforts and sustainable forest management. Remote sensing techniques have proven effective for mapping and monitoring forests over large areas. However, relying solely on remote sensing spectral or structural information cannot capture comprehensive horizontal and vertical structure complexity profiles associated with old-growth forest characteristics. To overcome this issue, we combined spectral information from Sentinel-2A multispectral imagery with 3D structural information from high-density point clouds of airborne laser scanning (ALS) imagery to map old-growth forests over an extended area. Four features from the ALS data and fifteen from Sentinel-2A comprising raw band (spectral reflectance), vegetation indices (VIs), and texture were selected to create three datasets used in the classification process using the random forest algorithm. The results demonstrated that combining ALS and Sentinel-2A features improved the classification performance and yielded the highest accuracy for old-growth class, with an F1-score of 92% and producer's and user's accuracies of 93% and 90%, respectively. The findings suggest that features from ALS and Sentinel-2A data sensitive to forest structure are essential for identifying old-growth forests. Integrating open-access satellite imageries, such as Sentinel-2A and ALS data, can benefit forest managers, stakeholders, and conservationists in monitoring old-growth forest preservation across a broader spatial extent., (© 2024. The Author(s).)

Bark beetle outbreaks have intensified in many forests around the globe in recent years. Yet, the legacy of these disturbances for future forest development remains unclear. Bark beetle disturbances are expected to increase further because of climate change. Consequently, feedbacks within the disturbance regime are of growing interest, for example, whether bark beetle outbreaks are amplifying future bark beetle activity (through the initiation of an even‐aged cohort of trees) or dampening it (through increased structural and compositional diversity).We studied bark beetle–vegetation–climate interactions in the Bavarian Forest National Park (Germany), an area characterised by unprecedented bark beetle activity in the recent past. We simulated the effect of future bark beetle outbreaks on forest structure and composition and analysed how disturbance‐mediated forest dynamics influence future bark beetle activity under different scenarios of climate change. We used process‐based simulation modelling in combination with machine learning to disentangle the long‐term interactions between vegetation, climate and bark beetles at the landscape scale.Disturbances by the European spruce bark beetle were strongly amplified by climate change, increasing between 59% and 221% compared to reference climate. Bark beetle outbreaks reduced the dominance of Norway spruce (Picea abies (L.) Karst.) on the landscape, increasing compositional diversity. Disturbances decreased structural diversity within stands (α diversity) and increased structural diversity between stands (β diversity). Overall, disturbance‐mediated changes in forest structure and composition dampened future disturbance activity (a reduction of up to −67%), but were not able to fully compensate for the amplifying effect of climate change.Synthesis. Our findings indicate that the recent disturbance episode at the Bavarian Forest National Park was caused by a convergence of highly susceptible forest structures with climatic conditions favourable for bark beetle outbreaks. While future climate is increasingly conducive to massive outbreaks, the emerging landscape structure is less and less likely to support them. This study improves our understanding of the long‐term legacies of ongoing bark beetle disturbances in Central Europe. It indicates that increased diversity provides an important dampening feedback, and suggests that preventing disturbances or homogenizing post‐disturbance forests could elevate the future susceptibility to large‐scale bark beetle outbreaks. [ABSTRACT FROM AUTHOR]

Context: Structural diversity strongly influences habitat quality and the functioning of forest ecosystems. An important driver of the variation in forest structures are disturbances. As disturbances are increasing in many forest ecosystems around the globe, it is important to understand how structural diversity responds to (changing) disturbances. Objectives: Our aim was to quantify the relationship between forest disturbances and structural diversity with a focus on diversity in canopy height. Methods: We assessed diversity in canopy height for two strictly protected Central European forest landscapes using lidar data. We used a multi-scale framework to quantify within-patch (α), between-patch (β), and overall (γ) diversity. We then analysed the variation in canopy height diversity over an extensive gradient of disturbance rates. Results: Diversity in canopy height was strongly driven by disturbance rate, with highest overall diversity between 0.5 and 1.5% of the forest area disturbed per year. The unimodal responses of overall diversity to disturbance emerged from contrasting within- and between-patch responses, i.e., a decrease in within-patch diversity and an increase in between-patch diversity with increasing disturbance. This relationship was consistent across study landscapes, spatial scales, and diversity indicators. Conclusion: The recent wave of natural disturbances in Central Europe has likely fostered the structural diversity of forest landscapes. However, a further increase in disturbance could result in the crossing of a tipping point (at ~ 1.5% of forest area disturbed per year), leading to substantial structural homogenization. [ABSTRACT FROM AUTHOR]

Plant diversity is an important driver of diversity at other trophic levels, suggesting that cascading extinctions could reduce overall biodiversity. Most evidence for positive effects of plant diversity comes from grasslands. Despite the fact that forests are hotspots of biodiversity, the importance of tree diversity, in particular its relative importance compared to other management related factors, in affecting forest‐associated taxa is not well known. To address this, we used data from 183 plots, located in different forest types, from Mediterranean to Boreal, and established along a climatic gradient across six European countries (FunDivEUROPE project). We tested the influence of tree diversity, tree functional composition (i.e. functional trait values), forest structure, climate and soil on the diversity and abundance/activity of nine taxa (bats, birds, spiders, microorganisms, earthworms, ungulates, foliar fungal pathogens, defoliating insects and understorey plants) and on their overall diversity and abundance/activity (multidiversity, multiabundance/activity). Tree diversity was a key driver of taxon‐level and overall forest‐associated biodiversity, along with tree functional composition, forest structure, climate and soil. Both tree species richness and functional diversity (variation in functional trait values) were important. The effects of tree diversity on the abundance/activity of forest‐associated taxa were less consistent. Nonetheless, spiders, ungulates and foliar fungal pathogens were all more abundant/active in diverse forests. Tree functional composition and structure were also important drivers of abundance/activity: conifer stands had lower overall multidiversity (although the effect was driven by defoliating insects), while stands with potentially tall trees had lower overall multiabundance/activity. We found more synergies than tradeoffs between diversity and abundance/activity of different taxa, suggesting that forest management can promote high diversity across taxa. Our results clearly show the high value of mixed forest stands for multiple forest‐associated taxa and indicate that multiple dimensions of tree diversity (taxonomic and functional) are important. [ABSTRACT FROM AUTHOR]

Aim: Forest understorey microclimates are often buffered against extreme heat or cold, with important implications for the organisms living in these environments. We quantified seasonal effects of understorey microclimate predictors describing canopy structure, canopy composition and topography (i.e., local factors) and the forest patch size and distance to the coast (i.e., landscape factors). Location: Temperate forests in Europe. Time period: 2017–2018. Major taxa studied: Woody plants. Methods: We combined data from a microclimate sensor network with weather‐station records to calculate the difference, or offset, between temperatures measured inside and outside forests. We used regression analysis to study the effects of local and landscape factors on the seasonal offset of minimum, mean and maximum temperatures. Results: The maximum temperature during the summer was on average cooler by 2.1 °C inside than outside forests, and the minimum temperatures during the winter and spring were 0.4 and 0.9 °C warmer. The local canopy cover was a strong nonlinear driver of the maximum temperature offset during summer, and we found increased cooling beneath tree species that cast the deepest shade. Seasonal offsets of minimum temperature were mainly regulated by landscape and topographic features, such as the distance to the coast and topographic position. Main conclusions: Forest organisms experience less severe temperature extremes than suggested by currently available macroclimate data; therefore, climate–species relationships and the responses of species to anthropogenic global warming cannot be modelled accurately in forests using macroclimate data alone. Changes in canopy cover and composition will strongly modulate the warming of maximum temperatures in forest understories, with important implications for understanding the responses of forest biodiversity and functioning to the combined threats of land‐use change and climate change. Our predictive models are generally applicable across lowland temperate deciduous forests, providing ecologically important microclimate data for forest understories. [ABSTRACT FROM AUTHOR]

The north-western Caucasus is exceptional in Europe because of its 1.3 million hectares of unmanaged 'virgin' forest. The Caucasus State Nature Reserve protects some 200,000 hectares, but contiguous areas are exposed to forest loss, fragmentation and degradation. Such an extensive region of virgin forest provides a unique opportunity to document diversity along key ecological gradients for an undisturbed system in Europe. Focusing on lichen epiphytes, we surveyed local diversity hot-spots along a 1200 m altitudinal gradient. Our main results are that: (a) species richness is enormously high in 1-hectare plots (between 233 and 358) representing a new baseline for Europe, (b) species composition differs substantially among plots with turnover increasing for difference in altitude. Cumulative species richness along the gradient was 597. More than a half of detected species had an affinity for, or were restricted to either the lower or the uppermost parts of the altitudinal gradient. However, this was related to differences in forest structure, rather than altitude per se. Species richness in plots increased significantly with the proportion of sparse/open forest. Length of an ecotone line, number of available tree and shrub species and number of dominant tree species also tend to increase species richness. These four variables had higher values at the lower and upper parts of the gradient, than at mid-altitudes, explaining a bimodal relationship of species richness with altitude. We conclude that loss of forest habitat at the lower and upper margins of the altitudinal gradient will cause the most significant decline in epiphytic lichen diversity. [ABSTRACT FROM AUTHOR]

• Most of research has been conducted in Europe and North America. • Animal ecology and dead wood were most often studied topics. • Fusion of ALS and optical images was advantageous for tree species assessment. • Central tendency and dispersion were the most important ALS metrics. The role of forests in biodiversity assessment and planning is substantial as these ecosystems support approximately 80% of the world's terrestrial biodiversity. Forests provide food, shelter, and nesting environments for numerous species, and deliver multiple ecosystem services. It has been widely recognised that forest vegetation structure and its complexity influence local variations in biodiversity. As forests are facing threats globally caused by human activities, there is a need to map the biodiversity of these ecosystems. The main objective of this review was to summarise the use of airborne laser scanning (ALS) data in biodiversity-related assessment of forests. We draw attention to topics related to animal ecology, structural diversity, dead wood, fragmentation and forest habitat classification. After conducting a thorough literature search, we categorised scientific articles based on their topics, which served as the basis for the section division in this paper. The majority of the research was found to be conducted in Europe and North America, only a small fraction of the study areas was located elsewhere. Topics that have received the most attention were related to animal ecology (namely richness and diversity of forest fauna), assessment of dead trees and tree species diversity measures. Not all studies used ALS data only, as it were often fused with other remote sensing data – especially with aerial or satellite images. The fusion of spectral information from optical images and the structural information provided by ALS was highly advantageous in studies where tree species were considered. Relevant ALS variables were found to be case-specific, so variables varied widely between forest biodiversity studies. We found that there was a lack of research in geographical areas and forest types other than temperate and boreal forests. Also, topics that considered functional diversity, community composition and the effect of spatial resolution at which ALS data and field information are linked, were covered to much lesser extent. [ABSTRACT FROM AUTHOR]

• Throughout the year, urban forest edges are warmer and drier compared to forest interiors. • Warm and dry microclimates are present up to large edge distances in urban forests. • A denser forest structure buffers the microclimate irrespective of edge distance. • Maintaining dense canopies in wide edge zones can enhance microclimate buffering. The urban heat island (UHI) causes strong warming of cities and their urban forests worldwide. Especially urban forest edges are strongly exposed to the UHI effect, which could impact urban forest biodiversity and functioning. However, it is not known to what extent the UHI effect alters edge-to-interior microclimatic gradients within urban forests and whether this depends on the forests' structure. Here we quantified gradients of air temperature, relative air humidity and vapour pressure deficits (VPD) along urban forest edge-to-interior transects with contrasting stand structures in six major cities across Europe. We performed continuous hourly microclimate measurements for two consecutive years and analysed the magnitude and depth of edge effects, as well as forest structural drivers of microclimatic variation. Compared to edge studies in rural temperate forests, we found that edge effects reached deeper into urban forests, at least up to 50 m. Throughout the year, urban forest edges were warmer and drier compared to forest interiors, with the largest differences occurring during summer and daytime. Not only maximum, but also mean and minimum temperatures were higher at the urban forest edge up to large edge distances (at least 85 m). Denser forests with a higher plant area index buffered high air temperatures and VPDs from spring to autumn. We conclude that urban forest edges are unique ecotones with specific microclimates shaped by the UHI effect. Both forest edges and interiors showed increased buffering capacities with higher forest canopy density. We advocate for the conservation and expansion of urban forests which can buffer increasingly frequent and intense climate extremes. To this end, urban forest managers are encouraged to aim for multi-layered dense forest canopies and consider edge buffer zones of at least 50 m wide. [Display omitted] [ABSTRACT FROM AUTHOR]

• Literature review on correlations between forest structural attributes and species richness. • 85 studies and 410 correlations were analyzed. • Structures related to old-growth successional stage most important for many species groups. The effects of forest management on species richness and diversity have become important research interests. The need to maintain biodiversity for forest ecosystem functioning has led to the question of how strongly and in what ways forest management modifies the diversity and abundance of different species groups. It is well known that many forest species rely on specific structures that may be modified by forest management. Assessing the impact of forest management on species richness may therefore require identification of structural properties. For this literature review we identified a large set of structural attributes that can serve as potential drivers of the richness of different species groups. Most studies included here focused on only one or a few structural attributes as explanatory variables and a limited number of species groups as dependent variables; we therefore analyzed the available publications across species and structural properties. We gathered 410 relationships of structure and species richness out of 85 studies from the temperate region in Europe. Positive, negative, and neutral (non-existent) correlations between species richness and the presence of specific structural properties in European temperate forests were then compiled. Canopy gaps and structural attributes related to old-growth successional stage such as stand age and the share of large old trees were mostly positively correlated with species richness of the different taxa. Especially old-growth structures were ranked high in the reviewed literature. The structural attributes that were mainly positively correlated with species richness or the richness of groups of species may be used for further development of biodiversity monitoring concepts and forest management. [ABSTRACT FROM AUTHOR]

• We quantified evaporation and soil and air temperature offsets in forest edges across Europe. • Roughly 10% of European broadleaved forests are affected by altered temperature regimes. • Macroclimate and management affected edge-to-interior temperature offset gradients. • Forest structure and the forest-floor biomass are important drivers of temperature offsets. • Dense forest edges can help mitigate edge influences and protect forest interior microclimates. Global forest cover is heavily fragmented. Due to high edge-to-surface ratios in small forest patches, a large proportion of forests is affected by edge influences involving steep microclimatic gradients. Although forest edges are important ecotones and account for 20% of the global forested area, it remains unclear how biotic and abiotic drivers affect forest edge microclimates at the continental scale. Here we report soil and air temperatures measured in 225 deciduous forest plots across Europe for two years. Forest stands were situated along a latitudinal gradient and subject to a varying vegetation structure as quantified by terrestrial laser scanning. In summer, the average offset of air and soil temperatures in forest edges compared to temperatures outside the forest amounted to -2.8 °C and -2.3 °C, respectively. Edge-to-interior summer temperature gradients were affected by the macroclimate and edge structure. From the edge onwards, larger offsets were observed in dense forest edges and in warmer, southern regions. In open forests and northern Europe, altered microclimatic conditions extended deeper into the forest and gradients were steeper. Canopy closure and plant area index were important drivers of summer offsets in edges, whereas in winter also the forest-floor biomass played a key role. Using high-resolution maps, we estimated that approximately 10% of the European broadleaved forests would be affected by altered temperature regimes. Gradual transition zones between forest and adjacent lands are valuable habitat types for edge species. However, if cool and moist forest interiors are desired, then (i) dense and complex forest edges, (ii) an undisturbed forested buffer zone of at least 12.5 m deep and (iii) trees with a high shade casting ability could all contribute to an increased offset. These findings provide important guidelines to mitigate edge influences, to protect typical forest microclimates and to adapt forest management to climate change. [ABSTRACT FROM AUTHOR]

• Assessment of tree species composition effects on communities of 13 species groups. • Oak, pine or spruce admixtures to beech affect diversity and community composition. • Effects often depend on tree species identity and on the proportion of admixture. • Admixture increases gamma diversity through heterogeneity and associated species. • Forest managers can assess ecological effects of altering tree species composition. Central Europe's temperate forests are heavily shaped by centuries of human activity. Their natural vegetation, mainly consisting of beech-dominated (Fagus sylvatica) deciduous forests, has been widely replaced by more profitable species grown outside of their natural ranges. This has strongly influenced forest-dwelling communities. Necessary adaptations to changing climatic conditions and the increasing demand for forest ecosystem multifunctionality are reversing these shifts in tree species composition. Integrative approaches that seek to balance production and conservation goals promote mixed forests of beech with spruce (Picea abies), pine (Pinus sylvestris), or oak (Quercus spp.). These mixed forests more closely resemble the natural vegetation and have reduced vulnerability to disturbances compared to coniferous monocultures, but higher commercial value compared to pure beech forests. However, our understanding of how different levels of admixture of commercially relevant tree species to beech forests affect multi-trophic diversity and community composition remains limited. We investigated herbaceous plants, fungi, oribatid mites, springtails, true bugs, beetles, birds and bats in 41 mature forest stands differing in tree species composition. We assessed the effects of admixtures on abundances and alpha and gamma diversity, i.e. the total number of species per forest type, and a measure of multidiversity by comparing reference beech stands with stands containing varying proportions of admixed species. At the plot level, the proportion of admixtures was especially important regarding oak and pine. Increasing shares of oak positively affected birds, true bugs and herbivorous beetles. Increasing shares of pine benefitted herbivorous true bugs and understory plants but negatively affected other true bugs, bats, and litter-decomposing fungi. Spruce admixture resulted in higher saproxylic beetle and bird diversity. At the landscape level, admixture significantly increased gamma diversity in plants, mycorrhizal and litter decomposing fungi and herbivorous and saproxylic beetles. Only springtail gamma diversity decreased in the presence of admixture. Admixture also significantly altered community composition for six out of 13 taxa. Indicator species were found for all forest types, and seven species groups included species significantly associated with pure beech stands. Our results indicate that forestry decisions determine forest biodiversity across trophic levels via tree species composition, combining habitat heterogeneity effects and tree species-specific associations. Even low shares of admixed species affect local abundances and diversity. By displacing some species while benefitting others, admixing also alters community composition. This study provides a basis for estimating how altering tree species composition in Central European forests changes the diversity and composition of forest communities. [ABSTRACT FROM AUTHOR]

Large trees are keystone structures for the functioning and maintenance of the biological diversity of wooded landscapes. Thus, we need a better understanding of large-tree–other-tree interactions and their effects on the diversity and spatial structure of the surrounding trees. We studied these interactions in the core of the Białowieża Primeval Forest—Europe's best-preserved temperate forest ecosystem, characterized by high abundance of ancient trees. We measured diameter and bark thickness of the monumental trees of Acer platanoides L., Carpinus betulus L., Picea abies L. H. Karst, Quercus robur L., and Tilia cordata Mill., as well as the diameter and distance to the monumental tree of five nearest neighbor trees. The effects of the monumental tree on arrangements of the surrounding trees were studied with the help of linear models. We revealed that the species identity of a large tree had, in the case of C. betulus and T. cordata, a significant impact on the diversity of adjacent tree groupings, their distance to the central tree, and frequency of the neighboring trees. The distance between the neighbor and the large trees increased with the increasing diameter of the central tree. Our findings reinforce the call for the protection of large old trees, regardless of their species and where they grow from the geographical or ecosystem point of view. [ABSTRACT FROM AUTHOR]

Including biodiversity assessments in forest management planning is becoming increasingly important due to the importance of biodiversity for forest ecosystem resilience provision and sustainable functioning. Here we investigated the potential to include biodiversity indicators into forest management planning in Europe. In particular, we aimed to (i) identify biodiversity indicators and data collection methods for biodiversity assessments at the stand and landscape levels, and (ii) evaluate the practicality of those indicators for forest management planning. We performed a literature review in which we screened 188 research studies published between 1990 and 2020. We selected 94 studies that fulfilled the inclusion criteria and examined in more detail. We considered three aspects of biodiversity: structure, composition, and function, and four forest management categories: unmanaged, managed, plantation, and silvopastoral. We used three criteria to evaluate the practicality of forest biodiversity indicators: cost-effectiveness, ease of application, and time-effectiveness. We identified differences in the practicality of biodiversity indicators for their incorporation into management plans. Stand-level indicators are more practical than landscape-level indicators. Moreover, structural biodiversity indicators (e.g., large trees, canopy openness, and old forest stands) are more useful in management plans than compositional indicators, as these are easily observable by non-professionals and can be obtained by forest inventories. Compositional indicators such are vascular plants, fungi, bryophyte, lichens, and invertebrate species are hard to identify by non-professionals and thus are impractical. Functional indicators (e.g., nutrient cycling) are not sufficiently addressed in the literature. Using recently updated existing databases (e.g., national forest inventories and bird atlases) is very time and cost-efficient. Remote sensing and other technology (e.g., smartphone applications) are promising for efficient data collection in the future. However, more research is needed to make these tools more accurate and applicable to a variety of ecological conditions and scales. Until then, forest stand structural variables derived from inventories can help improve management plans to prepare European forests towards an uncertain future. [ABSTRACT FROM AUTHOR]

In Central Europe, the predominant conservation strategy in forests is integrative management, seeking to balance economic interests with conservation goals. This is complemented by unmanaged strict forest reserves, most often small and with a history of forest management. Whether and how such reserves contribute to conservation when the surrounding forest is under progressive integrative management remains unclear. We compared forest structure and biodiversity of several taxa between formerly managed forest reserves and stands under progressive integrative management in beech and beech-oak forests. Alpha diversity was higher in reserves for birds and bats and higher in managed stands for plants and beetles, with no significant differences for fungi. Community composition differed between reserves and managed stands for plants, wood-decomposing fungi, beetles and birds. Reserves had 17 indicator species, including three red-listed species, and managed stands had 34, including one red-listed species. Diversity metrics differed between reserves and managed stands for both beech and beech-oak forests. Our results indicate that progressive integrative management and reserves, even when located in formerly managed stands, are complementary approaches benefitting different taxa and hosting partly different communities. Higher numbers of plants and beetles in managed stands were associated with higher light availability, as reserves in our study were undisturbed mature stands characterized by low light availability and low deadwood volumes. To benefit light and deadwood demanding species, new reserves should include early or late successional stands. If this is not feasible, restoration measures prior to designation or where possible under current protection status should be discussed. • Birds are more abundant and bats are more active in forest reserves compared to forest under integrative management. • Plants and beetles are more abundant and have higher species numbers in managed forests. • Community composition of plants, wood-decomposing fungi, beetles and birds differs between managed forests and reserves. • Biodiversity conservation in forests should combine set-aside and integrative forest management. • Forest reserves should include more stands in early and late successional stages with higher light availability. [ABSTRACT FROM AUTHOR]

There is concern in the scientific community and among forest managers about potential reductions in the provisioning of forest ecosystem services due to the loss of tree species diversity. Many studies have shown how species diversity influences forest functioning, especially productivity, but the influence of structural diversity, such as tree size heterogeneity, has received much less attention. This study focused on understanding the relationship between stand productivity and several structural characteristics of spruce-fir-beech mountain forest stands in Europe. We used a dataset of 89 long-term plots in spruce-fir-beech forests distributed along the European mountains where the three species, Norway spruce (Picea abies (L.) Karst.), silver fir (Abies alba Mill.) and European beech (Fagus sylvatica L.), represent at least 75% of the basal area. Site-dependent conditions were accounted for in a linear mixed-effect basic model, which related the stand productivity with the morphological, climatic and pedological characteristics. The influence of tree species diversity, tree size heterogeneity, species size dominance, and species overlapping in the size distribution on stand productivity was analysed by adding variables to the basic model one by one and evaluating the change in the Akaike's Information Criterion (AIC). The variables that resulted in significant reductions in the AIC, and that were not correlated with each other, were used to build a model to estimate stand productivity. The model showed that in spruce-fir-beech mixed mountain forests (i) when Norway spruce, silver fir and European beech are evenly present within the size distribution (high evenness) the productivity decreases, (ii) the stand productivity increases when the diameter distribution is skewed to the right (higher numbers of smaller individuals), (iii) the stand productivity increases as the proportion of basal area that is spruce increases, and (iv) stand productivity increases with the variability in diameter. We discuss the implications of our results for the management of spruce-fir-beech mountain forest in Europe and for preserving and increasing the stand productivity of these mixed forests. [ABSTRACT FROM AUTHOR]

Forests dominated by European beech (Fagus sylvatica L.) are among both the most widespread in Europe and the most intensely exploited globally. One of the largest remnants of unmanaged beech forests in Europe is the Uholka‐Shyrokyi Luh forest in Transcarpathia, Ukraine, covering 8,800 ha of primeval forest. In 2000, a permanent forest plot of 10 ha has been established in the Uholka massif. All living and dead trees with a diameter at breast height (DBH) ≥ 60 mm were identified to species, DBH measured, stems tagged and mapped. Since then, the plot has been remeasured in 2005, 2010, and 2015. In total, 4,820 individual trees were measured with 14,116 individual measurements throughout all four inventories. In spring 2018, an Airborne Laser Scan was carried out, covering the Uholka‐Shyrokyi Luh forest. This data set allows us to derive a high‐resolution digital elevation model (DEM) of the plot area. European beech covers a share of ≈ 95% of the basal area (BA) of all living stems. While BA was relatively stable throughout all inventories (≈ 38 m2/ha), the number of stems increased considerably between 2010 and 2015 from 290 to 430 stems/ha. Additionally, the proportion of beech stems decreased from 95% in 2010 to 86% in 2015. The continuity of the share of beech on BA and the decrease in number of stems can be traced back to disturbance events, which led to an increase of more light demanding species in the recruitment but did not alter the distribution of BA as these small trees contribute very little to BA. The data set allows for important insights into the development and the spatial and temporal dynamics of primeval beech forests. It can be used to quantify the demographic processes growth, mortality, and recruitment, and to study inter‐ and intraspecific effects on demographic rates, stand structure, and species composition. No copyright or proprietary restrictions are associated with the use of this data set other than citation of this Data Paper. [ABSTRACT FROM AUTHOR]