ArticlePublisher preview available

Historical Disturbances Determine Current Taxonomic, Functional and Phylogenetic Diversity of Saproxylic Beetle Communities in Temperate Primary Forests

To read the full-text of this research, you can request a copy directly from the authors.

Abstract and Figures

The expected future intensification of forest disturbance as a consequence of ongoing anthropogenic climate change highlights the urgent need to more robustly quantify associated biotic responses. Saproxylic beetles are a diverse group of forest invertebrates representing a major component of biodiversity that is associated with the decomposition and cycling of wood nutrients and carbon in forest ecosystems. Disturbance-induced declines or shifts in their diversity indicate the loss of key ecological and/or morphological species traits that could change ecosystem functioning. Functional and phylogenetic diversity of biological communities is commonly used to link species communities to ecosystem functions. However, our knowledge on how disturbance intensity alters functional and phylogenetic diversity of saproxylic beetles is incomplete. Here, we analyzed the main drivers of saproxylic beetle abundance and diversity using a comprehensive dataset from montane primary forests in Europe. We investigated cascading relationships between 250 years of historical disturbance mechanisms, forest structural attributes and the taxonomic, phylogenetic and functional diversity of present-day beetle communities. Our analyses revealed that historical disturbances have significant effects on current beetle communities. Contrary to our expectations, different aspects of beetle communities, that is, abundance, taxonomic, phylogenetic and functional diversity, responded to different disturbance regime components. Past disturbance frequency was the most important component influencing saproxylic beetle communities and habitat via multiple temporal and spatial pathways. The quantity of deadwood and its diameter positively influenced saproxylic beetle abundance and functional diversity, whereas phylogenetic diversity was positively influenced by canopy openness. Analyzing historical disturbances, we observed that current beetle diversity is far from static, such that the importance of various drivers might change during further successional development. Only forest landscapes that are large enough to allow for the full range of temporal and spatial patterns of disturbances and post-disturbance development will enable long-term species coexistence and their associated ecosystem functions.
This content is subject to copyright. Terms and conditions apply.
Historical Disturbances Determine
Current Taxonomic, Functional
and Phylogenetic Diversity
of Saproxylic Beetle Communities
in Temperate Primary Forests
Daniel Koza
* Marek Svitok,
Michal Wiezik,
Martin Mikola
Simon Thorn,
Arne Buechling,
´k Hofmeister,
Radim Matula,
Volodymyr Trotsiuk,
Radek Bac
ˇimir Begovic
ˇch C
Martin Dus
Michal Frankovic
Jakub Hora
Pavel Janda,
Ondrej Kameniar,
Thomas A. Nagel,
Joseph L. Pettit,
Jessika M. Pettit,
Michal Synek,
Adela Wiezikova
and Miroslav Svoboda
Department of Forest Ecology, Faculty of Forestry and Wood Sciences, Czech University of Life Sciences Prague, Kamy
´cka 129, 165
21 Prague, Czech Republic;
Faculty of Ecology and Environmental Sciences, Technical University in Zvolen, T.G. Masaryka 24, 960
01 Zvolen, Slovakia;
Department of Ecosystem Biology, Faculty of Science, University of South Bohemia, Branis
´1760, 370 05
Ceske Budejovice, Czech Republic;
Field Station Fabrikschelichach, Biocenter, University of Wu¨ rzburg, Glashu¨ ttenstraße 5, 96181
Rauhenebrach, Germany;
Swiss Federal Institute for Forest, Snow and Landscape Research WSL, Zu¨ rcherstrasse 111, 8903 Bir-
mensdorf, Switzerland;
Department of Forest Protection and Entomology, Faculty of Forestry and Wood Sciences, Czech University
of Life Sciences Prague, Kamy
´cka 129, 165 21 Prague, Czech Republic;
Department of Forestry and Renewable Forest Resources,
Biotechnical Faculty, University of Ljubljana, 1000 Ljubljana, Slovenia
The expected future intensification of forest dis-
turbance as a consequence of ongoing anthro-
pogenic climate change highlights the urgent need
to more robustly quantify associated biotic re-
sponses. Saproxylic beetles are a diverse group of
forest invertebrates representing a major compo-
nent of biodiversity that is associated with the
decomposition and cycling of wood nutrients and
carbon in forest ecosystems. Disturbance-induced
declines or shifts in their diversity indicate the loss
of key ecological and/or morphological species
traits that could change ecosystem functioning.
Functional and phylogenetic diversity of biological
communities is commonly used to link species
communities to ecosystem functions. However, our
knowledge on how disturbance intensity alters
functional and phylogenetic diversity of saproxylic
beetles is incomplete. Here, we analyzed the main
drivers of saproxylic beetle abundance and diver-
sity using a comprehensive dataset from montane
primary forests in Europe. We investigated cas-
cading relationships between 250 years of historical
Received 12 November 2019; accepted 22 March 2020;
published online 20 April 2020
Electronic supplementary material: The online version of this article
( contains supplementary
material, which is available to authorized users.
Authors Contributions: DK, MM, MW, ST, MSvi, MSvo, JHor con-
ceived the ideas and designed study. DK, MW, MM, PJ, RB, VC
ˇ, VT, OK,
AW, MSy, MD and MF contributed to and organized data collection.
MSvi, ST, DK analyzed the data. DK, ST, AB, MM, TAN, JLP, JMP, JHof,
RM led the writing of the manuscript. All authors contributed critically to
the study and gave final approval for publication.
*Corresponding author; e-mail:
Ecosystems (2021) 24: 37–55
2020 Springer Science+Business Media, LLC, part of Springer Nature
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
... Furthermore, most studies focus on the taxonomical responses of biological communities to forest dieback (Cai et al. 2021, but see (Thorn et al. 2014Kozák et al. 2020;Sire et al. 2022). Nonetheless, phylogenetic and functional diversity are highly relevant indicators of ecosystem functioning (Devictor et al. 2010). ...
... Nonetheless, phylogenetic and functional diversity are highly relevant indicators of ecosystem functioning (Devictor et al. 2010). Phylogenetic diversity reflects the evolutionary history of a community through lineage relatedness while functional diversity reflects the diversity of the phenotypical traits selected by a particular environment, i.e. biotic and abiotic filters (Devictor et al. 2010;Kozák et al. 2020). Consequently, few studies have monitored taxonomic, functional, and phylogenetic responses of arthropods to forest disturbances at various spatial scales (Kozák et al. 2020). ...
... Phylogenetic diversity reflects the evolutionary history of a community through lineage relatedness while functional diversity reflects the diversity of the phenotypical traits selected by a particular environment, i.e. biotic and abiotic filters (Devictor et al. 2010;Kozák et al. 2020). Consequently, few studies have monitored taxonomic, functional, and phylogenetic responses of arthropods to forest disturbances at various spatial scales (Kozák et al. 2020). ...
Full-text available
Context Many forest ecosystems around the world are facing increasing drought-induced dieback, causing mortality patches across the landscape at multiple scales. This increases the supply of biological legacies and differentially affects forest insect communities. Objectives We analysed the relative effects of local- and landscape-level dieback on local saproxylic beetle assemblages. We assessed how classical concepts in spatial ecology (e.g., habitat-amount and habitat-patch hypotheses) are involved in relationships between multi-scale spatial patterns of available resources and local communities. Methods We sampled saproxylic beetle assemblages in commercial fir forests in the French highlands. Through automatic aerial mapping, we used percentage of dead tree crown pixels to assess dieback levels at several nested spatial scales. We analysed beetle taxonomic, phylogenetic and functional diversity related to differing levels of multi-scale dieback. Results We found that taxonomic, functional, and phylogenetic diversity of saproxylic beetle assemblages significantly benefitted from forest dieback, at both local and landscape scales. We detected significant effects in the multiplicative models combining local and landscape variables only for phylogenetic diversity. Increased landscape-scale dieback also caused a functional specialisation of beetle assemblages, favouring those related to large and well-decayed deadwood. Conclusions Increasing tree mortality under benign neglect provides conservation benefits by heterogenising the forest landscape and enhancing deadwood habitats. Legacy retention practices could take advantage of unharvested, declining forest stands to promote species richness and functional diversity within conventionally managed forest landscapes.
... The most important agents of natural disturbance on a global scale are windstorms, insect outbreaks, and wildfires (FAO, 2010). These natural disturbances create biological legacies (Burris and Haney, 2005) that are important for many taxa, including, for example, beetles (Kozák et al., 2020), birds (Kortmann et al., 2018;Repel et al., 2020), fungi (Veselá et al., 2019), and lichens . The various disturbance types affect forest structure differently (Swanson et al., 2011). ...
Although natural disturbances are likely to occur more frequently and be more severe in future as a result of climate change, we have little evidence concerning the effect of disturbance size and severity on species diversity. We aimed to compare effects of varying size and severity of natural disturbances on bird species composition in the non-intervention area of Š umava National Park, Czech Republic. For this purpose, we surveyed bird communities in 1) small-and 2) large-scale disturbance, 3) enclaves of live trees in large-scale disturbance areas, and 4) non-disturbed forests. Furthermore, we used habitat characteristics to identify structural factors affecting species composition of bird communities. Birds were sampled by the point count method during the 2021 breeding season and analysed using linear models. Additionally, we use principal component analysis (PCA) to characterize four defined disturbance classes using habitat characteristics. The most important habitat characteristics for bird communities are structural complexity, live tree density, and understorey cover. Small-scale disturbances increased structural complexity of a forest and had a generally positive effect on birds. Both small-and large-scale disturbances supported species nesting on the ground and shrub layer. In contrast, large-scale disturbances negatively affected canopy nesting and specialist species. This likely was due to a reduction of small-scale habitat heterogeneity with increasing disturbance severity. High-severity disturbance changes structurally rich forests to rather uniform, open-canopy habitats that are temporally unsuitable for closed-canopy birds. On the other hand, low-severity disturbance enhances large-scale habitat heterogeneity and maintains suitable habitat for species of closed-canopy forest, including some specialist species.
... In previous multi-taxon studies, the number of traps per plot varied from one to four, but mostly only one trap was used. Traps were checked every 2 weeks or monthly (Bouget et al., 2013;Franc & Götmark, 2008;Janssen et al., 2016;Kozák et al., 2020;Kraut et al., 2016;Sabatini et al., 2016;Vandekerkhove et al., 2016). ...
... To preserve natural montane spruce-forest communities in their full complexity, nature protection should be focused on large forest areas that encompasses all disturbance regimes (Kozák et al. 2021). Such "disturbance diversity" is essential for sustainable forest development, including its overall plant diversity, and it plays an important role in forest adaptation to climate change. ...
Development of primary spruce forests is driven by a series of disturbances, which also have an important influence on the understorey vegetation and its diversity. Early post-disturbance processes have been intensively studied, however, very little is known about the long-term effects of disturbances on the understorey. We quantified disturbance history using dendrochronological methods to investigate its impact on vascular plant diversity and understorey species composition. We sampled 141 plots randomly assigned throughout primary stands located in the zone of natural montane acidophilous forests dominated by Picea abies (L.) Karst. in the Western Carpathians. Dendrochronological, dendrometric, and environmental parameters were related to understorey properties using ordination methods and a Bayesian approach using multilevel linear models (GLMM). Time since the last disturbance (23–260 years ago; mostly windstorms and bark beetle outbreaks) had a significant effect on understorey species composition of the current communities, and it also interacted with disturbance severity to influence species diversity. The effect of disturbances on the understorey was largely mediated by the alteration of stand structure (age, DBH, canopy openness), Vaccinium myrtillus L. cover, and topsoil chemical properties. A period of severe disturbances between 1860 and 1890 resulted in a legacy of our current, relatively homogeneous spruce stands with less diverse sciophilous understorey dominated by V. myrtillus, which is in contrast to heterogeneous stands (in terms of age and spatial structure) driven by small-scale, lower-severity disturbances, which led to an understorey enriched by species with higher demands on light and topsoil quality (higher K concentration and lower C/N ratio). All developmental pathways following disturbances create a unique complex of spatiotemporal understorey variability in the montane spruce forests. Therefore, to preserve their full diversity, disturbances of all severities and sizes should be accepted as natural drivers, both in the field of nature conservation and close-to-nature forestry efforts.
... Forest biodiversity suffers in particular under management intensification across major parts of Central Europe (Seibold et al. 2015), turning light and heterogeneous deciduous forests into comparatively dark and uniform monocultures of coniferous trees (Naumov et al. 2018). However, most forest species rely on light forests and heterogeneous vegetation structures consisting of various (deciduous) trees species, shrubs, and herbs, and the co-existence of various successional stages (Kozák et al. 2021). A prominent example is the scarce fritillary butterfly Euphydryas maturna. ...
Full-text available
Context Intensification of land-use caused a reduction of ecosystem heterogeneity and diversity, and subsequently led to dramatic decrease of biodiversity. Species depending on dynamic ecosystems are particularly affected from this trend of land-use intensification, landscape homogenization, and the optimization of land-use. Forest species suffer under the intensification of forest management, in the worst case transforming light and heterogeneous deciduous forests into species-poor intensively used deciduous forests optimized for wood production. This lead to the destruction of a mosaic consisting of various successional stages in parallel. Objective In this study we analyse the relevance of forest heterogeneity, forest disturbance and microhabitat preferences of egg oviposition and larval development for a highly endangered butterfly species, Euphydryas maturna . This butterfly species mainly occurs in light and moist deciduous forests, such as riparian forests along mountain streams in northern Austria. Methods We combine detailed field observations with high resolution aerial pictures taken with an Unmanned Aerial Vehicle (UAV) to build ensemble habitat suitability models from GAM, GBM, GLM, and Maxent models. Results We found that egg ovipositions take place exclusively on the tree species Fraxinus excelsior , preferably exposed to the south, partly shaded, and at medium height (3 m). Our habitat suitability models based on high resolution aerial pictures indicate that egg ovipositions are clustered and accumulate along forest edges and at sites with high forest heterogeneity. Conclusion Our study underlines the high relevance and importance of light deciduous forest structures with environmental dynamics creating the preconditions of specific microhabitat structures for endangered species, such as E. maturna . Our study shows that UAV-captured high precision aerial imagery are well suited to optimally connect two spatial scales, the ecosystem and microhabitat scale.
... The study was conducted in landscapes dominated by deciduous-evergreen mixed forest in the North Patagonia, southern Chile (40.3 • S-72.0 • W; Fig. 1) characterized by a rainy and temperate climate (Veblen et al., 1996). Study sites included stands of undegraded old-growth forest located in conservation areas in order to reduce the effects of historical disturbances on beetle communities (Kozák et al., 2021). The forest is composed by two southern beech species (Nothofagus pumilio and N. dombeyi) growing in association with other broadleaf evergreen tree species like Eucryphia cordifolia, Aextoxicon punctatum, and Laurelia philippiana (Muñoz Schick, 1980). ...
Full-text available
Although wood-inhabiting beetle species are known to contribute to the progressive degradation of wood by building larval galleries and dispersing fungal propagules, the relationship between decaying wood and beetle communities is difficult to be assessed. The ecological properties of trees, such as their mortality status and species, could modify the relationships between beetle communities and decaying wood. We used recently developed techniques of sonic tomography for the first time to address how the trophic structure of beetle communities varies with the internal wood decay. We developed a paired design where sonic tomograms taken in the trunk sections of live and dead trees of the Patagonian forest were related with beetles sampled with emergence traps. Beetles captured in the trunks of live trees responded weakly to the internal wood decay. Indeed, the diversity of predators in live trees was likely influenced by bark microhabitats. Conversely, most of the guild assemblages in the trunks of dead trees were impoverished as wood decay was more advanced, possibly due to decreasing microhabitat quality. Our preliminary study suggests sonic tomography offers the opportunity to distinguish how beetles modulate decaying wood, but also provides insights about the assessment of live trees with tomograms.
... This group of organisms (hereafter referred to as saproxylic) (Siitonen 2001) has been neglected for many years in forest ecosystems. Their role in ecological processes in forests was finally noticed, leading to an increasing number of scientific studies focusing on various aspects of their biology, evolution, diversity and ecology (Kozák et al. 2021). Saproxylic organisms are crucial in natural forest ecosystems as they play many roles in different trophic levels (sapro-, xylo-, cambio-or mycetophages and predators) and are thus fundamental for forest functioning (Hjältén et al. 2012). ...
Full-text available
Sustainable management of forest ecosystems requires the use of reliable and easy to implement biodiversity and naturalness indicators. Tree-related microhabitats (TreMs) can fulfill these roles as they harbor specialized species that directly or indirectly depend on them, and are generally more abundant and diverse in natural forests or forests unmanaged for several decades. The TreM concept is however still recent, implying the existence of many knowledge gaps that can challenge its robustness and applicability. To evaluate the current state of knowledge on TreMs, we conducted a systematic review followed by a bibliometric analysis of the literature identified. A total of 101 articles constituted the final corpus. Most of the articles (60.3%) were published in 2017 or after. TreM research presented a marked lack of geographical representativity, as the vast majority (68.3%) of the articles studied French, German or Italian forests. The main themes addressed by the literature were the value of TreMs as biodiversity indicators, the impact of forest management on TreMs and the factors at the tree- and stand-scales favoring TreMs occurrence. Old-growth and unmanaged forests played a key role as a “natural” forest reference for these previous themes, as TreMs were often much more abundant and diverse compared to managed forests. Arthropods were the main phylum studied for the theme of TreMs as biodiversity indicators. Other more diverse themes were identified, such as restoration, remote sensing, climate change and economy and there was a lack of research related to the social sciences. Overall, current research on TreMs has focused on assessing its robustness as an indicator of biodiversity and naturalness at the stand scale. The important geographical gap identified underscores the importance of expanding the use of the TreMs in other forest ecosystems of the world. The notable efforts made in recent years to standardize TreM studies are an important step in this direction. The novelty of the TreM concept can partially explain the thematic knowledge gaps. Our results nevertheless stress the high potential of TreMs for multidisciplinary research, and we discuss the benefits of expanding the use of TreMs on a larger spatial scale.
Full-text available
Old-growth forests of different ages provide specific structures, habitats and ecosystem services. Methods to distinguish this internal diversity are still rare, especially in boreal forests. This research therefore aims to determine the ability of Airborne Laser Scanning (ALS) technology to identify age-related structural diversity in old-growth boreal forests. The study area was located in primary boreal forests in Quebec (Canada) dominated by black spruce (Picea mariana). This area contained 71.8 km² of early old-growth forests (burned 110 years ago), 17.1 km² of late old-growth forests (protected areas; unburned for at least 250 years) and 370 km² of old-growth forests of unknown age (> 125-years-old). We divided the study area into 1 ha tiles, where we extracted seven ALS indices representing vertical and horizontal forest structure. We trained random forest models using an iterative approach to discriminate between early and late old-growth forests based on ALS indices. Model predictions were applied to the old-growth tiles of unknown age, and to 86 field plots (28 from provincial forest surveys and 58 from a dedicated survey of old-growth forests) to evaluate the predictive capacity of the models. The models very accurately distinguished early and late old-growth forests (error-rate = 4.9%). Old-growth survey plots confirmed model ability to discriminate early and late old-growth forests, but not provincial survey plots, possibly because of a lower reliability of these data when forest age exceeds 150 years. Model predictions for tiles of unknown age highlighted the presence of very large tracts of late old-growth forests within a matrix of old-growth forests of intermediate age (≈150–200 years). Overall, ALS-data can contribute to a finer structural age distinction and mapping of boreal old-growth forests. This enhanced knowledge of old-growth landscapes will greatly help to improve their protection, restoration and management. The scarcity of reliable field data for model evaluation is, however, a limitation to be addressed.
Understanding the processes that structure biological communities along environmental gradients remains one of the main aims of ecological research. A leading question is how differences in species composition between sites, that is, β‐diversity, change in habitats ordered along environmental gradients and how such changes vary with species relative abundances. The existing literature remains descriptive, mostly comparing communities from different parts of a gradient, but not tracking sequential changes of β‐diversity along the entire gradient. Temperate deciduous forests in Central Europe. Saproxylic beetles. We applied a generalized concept of Hill numbers to data on the distribution of saproxylic beetles to test (i) whether community dissimilarities correlate with dissimilarities in major environmental variables (canopy openness, tree diameter and tree genus) and (ii) which mechanisms explain sequential changes of β‐diversity along these environmental gradients. Furthermore, we illustrate changes in the mean (α‐diversity) and total (γ‐diversity) number of species along the gradients. Dissimilarities in saproxylic beetle communities were positively correlated with dissimilarities in all studied environmental variables. Changes in β‐diversity along the gradients differed for different weighting of rare, common and dominant species, with rare and dominant species always showing opposite trends. β‐diversity increased simultaneously with increasing γ‐diversity when weight was given to dominant species. On the other hand, β‐diversity decreased when weight was given to rare species. The different response of rare and dominant species indicates a similar importance of stochastic and deterministic processes in determining β‐diversity. Although the changes in β‐diversity detected along the environmental gradients were relatively slight, major community dissimilarities were found when comparing communities in different locations of the environmental gradients.
Full-text available
Deadwood and microhabitats play a fundamental role in many forest ecosystem processes. Deadwood provides the substrate for a multitude of wood-dependent organisms, as well as a variety of microhabitats. Deadwood is a key factor in maintaining the ecosystem functionality and increasing the overall forest biodiversity. In Mediterranean forests, the relationship between stand-structure attributes and species-diversity indicators is still poorly investigated. In this study, we hypothesized that the abundance of saproxylic species was influenced by (i) the composition and amount of deadwood, and (ii) the heterogeneity in types and density of microhabitats. The investigation was carried out in a broadleaved mixed forest located in Central Apennine (Italy), in which silvicultural interventions were interrupted for several decades. The experimental area extends on approximately 240 ha; structural traits, deadwood and microhabitats were sampled on 50 plots of 530 m 2. Saproxylic beetles were collected using window flight traps and emergence traps on decaying deadwood. We applied joint species distribution models (JSDM) to quantify the relationship between forest attributes and the abundance of sa-proxylic species, explicitly including their functional traits (e.g., trophic level). Results demonstrated that mi-crohabitats, living biomass, basal area and coarse woody debris had a significant effect of saproxylic beetles belonging to different trophic categories. Considering the conservation status, only the stand basal area significantly affected the abundance of Near Threatened (NT) saproxylic beetles. This study highlighted the importance of integrating multiple biodiversity indicators to find sustainable solutions for conservation purposes, unlike many studies on conservation-oriented management strategies, more frequently focused on independent forest biodiversity indicators.
Full-text available
1.The successional dynamics of forests – from canopy openings to regeneration, maturation and decay – influence the amount and heterogeneity of resources available for forest‐dwelling organisms. Conservation has largely focused only on selected stages of forest succession (e.g. late‐seral stages). However, to develop comprehensive conservation strategies and to understand the impact of forest management on biodiversity, a quantitative understanding of how different trophic groups vary over the course of succession is needed. 2.We classified mixed mountain forests in Central Europe into nine successional stages using airborne LiDAR. We analysed α‐ and β‐diversity of six trophic groups encompassing approximately 3,000 species from three kingdoms. We quantified the effect of successional stage on the number of species with and without controlling for species abundances and tested whether the data fit the more‐individuals hypothesis or the habitat heterogeneity hypothesis. Furthermore, we analysed the similarity of assemblages along successional development. 3.The abundance of producers, first‐order consumers and saprotrophic species showed a U‐shaped response to forest succession. The number of species of producer and consumer groups generally followed this U‐shaped pattern. In contrast to our expectation, the number of saprotrophic species did not change along succession. When we controlled for the effect of abundance, the number of producer and saproxylic beetle species increased linearly with forest succession, whereas the U‐shaped response of the number of consumer species persisted. The analysis of assemblages indicated a large contribution of succession‐mediated β‐diversity to regional γ‐diversity. 4. Synthesis and applications. Depending on the species group, our data supported both the more‐individuals hypothesis and the habitat heterogeneity hypothesis. Our results highlight the strong influence of forest succession on biodiversity and underline the importance of controlling for successional dynamics when assessing biodiversity change in response to external drivers such as climate change. The successional stages with highest diversity (early and late successional stages) are currently strongly underrepresented in the forests of Central Europe. We thus recommend that conservation strategies aim at a more balanced representation of all successional stages. This article is protected by copyright. All rights reserved.
Full-text available
Wood-inhabiting fungi and saproxylic beetles are threatened by habitat degradation. Our understanding of the importance of macroclimate and local factors determining their taxonomic diversity has increased, but determinants of functional and phylogenetic diversity are poorly understood. We investigated assemblages of wood-inhabiting fungi and saproxylic beetles along a 1000 m elevational gradient of a temperate low mountain range. We (i) tested the relative importance of macroclimate (i.e. elevation) and local variables (microclimate, i.e. canopy closure, amount and diversity of dead wood) in determining observed and rarefied diversities and (ii) explored whether determinants of observed functional and phylogenetic diversities match those of taxonomic diversity. For both taxa, the determinants of observed phylogenetic and functional diversities largely matched those of taxonomic diversity. The diversity of wood-inhabiting fungi was predominantly determined by local variables, whereas that of saproxylic beetles was determined by both local variables and elevation. Taxonomic and phylogenetic diversities of saproxylic beetles decreased with increasing elevation, but standardized functional richness and entropy of both groups increased with increasing elevation. Diversities of wood-inhabiting fungi increased with canopy closure, while diversities of saproxylic beetles decreased with increasing canopy closure. Microclimate and dead-wood amount and diversity affected the observed and rarefied diversity of both saproxylic taxa, which justifies conservation actions that focus on attributes of dead wood and canopy cover. The contrasting responses of fungi and beetles highlight the need for amounts of diverse dead wood in the various microclimates to preserve functional and phylogenetic diversities of saproxylic organisms.
Full-text available
Aim Primary forests have high conservation value but are rare in Europe due to historic land use. Yet many primary forest patches remain unmapped, and it is unclear to what extent they are effectively protected. Our aim was to (1) compile the most comprehensive European‐scale map of currently known primary forests, (2) analyse the spatial determinants characterizing their location and (3) locate areas where so far unmapped primary forests likely occur. Location Europe. Methods We aggregated data from a literature review, online questionnaires and 32 datasets of primary forests. We used boosted regression trees to explore which biophysical, socio‐economic and forest‐related variables explain the current distribution of primary forests. Finally, we predicted and mapped the relative likelihood of primary forest occurrence at a 1‐km resolution across Europe. Results Data on primary forests were frequently incomplete or inconsistent among countries. Known primary forests covered 1.4 Mha in 32 countries (0.7% of Europe’s forest area). Most of these forests were protected (89%), but only 46% of them strictly. Primary forests mostly occurred in mountain and boreal areas and were unevenly distributed across countries, biogeographical regions and forest types. Unmapped primary forests likely occur in the least accessible and populated areas, where forests cover a greater share of land, but wood demand historically has been low. Main conclusions Despite their outstanding conservation value, primary forests are rare and their current distribution is the result of centuries of land use and forest management. The conservation outlook for primary forests is uncertain as many are not strictly protected and most are small and fragmented, making them prone to extinction debt and human disturbance. Predicting where unmapped primary forests likely occur could guide conservation efforts, especially in Eastern Europe where large areas of primary forest still exist but are being lost at an alarming pace.
Full-text available
As the terrestrial human footprint continues to expand, the amount of native forest that is free from significant damaging human activities is in precipitous decline. There is emerging evidence that the remaining intact forest supports an exceptional confluence of globally significant environmental values relative to degraded forests, including imperilled biodiversity, carbon sequestration and storage, water provision, indigenous culture and the maintenance of human health. Here we argue that maintaining and, where possible, restoring the integrity of dwindling intact forests is an urgent priority for current global efforts to halt the ongoing biodiversity crisis, slow rapid climate change and achieve sustainability goals. Retaining the integrity of intact forest ecosystems should be a central component of proactive global and national environmental strategies, alongside current efforts aimed at halting deforestation and promoting reforestation.
Given the global intensification of forest management and climate change, protecting and studying forests that develop free of direct human intervention-also known as primary forests-are becoming increasingly important. Yet, most countries still lack data regarding primary forest distribution. Previous studies have tested remote sensing approaches as a promising tool for identifying primary forests. However, their precision is highly dependent on data quality and resolution, which vary considerably. This has led to underestimation of primary forest abundance and distribution in some regions, such as the temperate zone of Europe. Field-based inventories of primary forests and methodologies to conduct these assessments are inconsistent; incomplete or inaccurate mapping increases the vulnerability of primary forest systems to continued loss from clearing and land-use change. We developed a comprehensive methodological approach for identifying primary forests, and tested it within one of Europe's hotspots of primary forest abundance: the Carpathian Mountains. From 2009 to 2015, we conducted the first national-scale primary forest census covering the entire 49,036 km 2 area of the Slovak Republic. We analyzed primary forest distribution patterns and the representativeness of potential vegetation types within primary forest remnants. We further evaluated the conservation status and extent of primary forest loss. Remaining primary forests are small, fragmented, and often do not represent the potential natural vegetation. We identified 261 primary forest localities. However, they represent only 0.47% of the total forested area, which is 0.21% of the country's land area. The spatial pattern of primary forests was clustered. Primary forests have tended to escape anthropogenic disturbance on sites with higher elevations, steeper slopes, rugged terrain, and greater distances from roads and settlements. Primary forest stands of montane mixed and subalpine spruce forests are more abundant compared to broadleaved forests. Notably, several habitat types are completely missing within primary forests (e.g., floodplain forests). More than 30% of the remaining primary forests are not strictly protected, and harvesting occurred at 32 primary forest localities within the study period. Almost all logging of primary forests was conducted inside of protected areas, underscoring the critical status of primary forest distribution in this part of Europe. Effective conservation strategies are urgently needed to stop the rapid loss and fragmentation of the remaining primary forests. Our approach based on precise, field-based surveys is widely applicable and transferrable to other fragmented forest landscapes.
Tree-related microhabitats (TreMs) are important features for the conservation of biodiversity in forest ecosystems. Although other structural indicators of forest biodiversity have been extensively studied in recent decades, TreMs have often been overlooked, either due to the absence of a consensual definition or a lack of knowledge. Despite the increased number of TreM studies in the last decade, the role of drivers of TreM profile in primary forests and across different geographical regions is still unknown. To evaluate the main drivers of TreM density and diversity, we conducted the first large-scale study of TreMs across European primary forests. We established 146 plots in eight primary forests dominated by European beech (Fagus sylvatica L.) in the Carpathian and Dinaric mountain ranges. Generalized linear mixed effect models were used to test the effect of local plot characteristics and spatial variability on the density and diversity (alpha, beta, and gamma) of TreMs. Total TreM density and diversity were significantly positively related with tree species richness and the proportion of snags. Root mean square tree diameters were significantly related to alpha and gamma diversity of TreMs. Both regions reached similarly high values of total TreM densities and total TreM densities and diversity were not significantly different between the two regions; however, we observed between the two regions significant differences in the densities of two TreM groups, conks of fungi and epiphytes. The density and diversity of TreMs were very high in beech-dominated mountain primary forests, but their occurrence and diversity was highly variable within the landscapes over relatively short spatial gradients (plot and stand levels). Understanding these profile provides a benchmark for further comparisons, such as with young forest reserves, or for improving forest management practices that promote biodiversity.
Primary forests represent the ultimate intact habitat for saproxylic insects. However, their extent has been considerably reduced over the past centuries, and those remaining are very heterogeneously distributed. Primary forests are still locally abundant in tropical and boreal zones but are rare in temperate zones. Consequently, many saproxylic insects that were adapted to typical characteristics of primary forests, such as large amounts of dead wood or overmature and senescent trees, might have become extinct regionally due to habitat loss. The remaining primary forests therefore function as refuges for those saproxylic species that cannot survive in managed forests because of their high ecological requirements. Here we identify six characteristics of primary forests important for saproxylic insects that differentiate these forests greatly from managed forests, namely, absence of habitat fragmentation, continuity, natural disturbance regimes, dead-wood amount and quality, tree species composition and habitat trees. These six characteristics highlight the importance of primary forests for the conservation of saproxylic insects in all three main climatic domains (tropical, boreal and temperate). As primary forests are rare in northern temperate zones and are being dramatically lost in boreal and tropical zones, we propose that they should be strictly conserved independently of their climatic zone. Furthermore, we recommend that studies in primary forests intensify to provide reference data for integrating primary forest characteristics into managed forests to improve the conservation of saproxylic species.
Natural amounts of dead wood in a forest vary considerably, depending on living tree biomass, decomposition rates, and rates of dead-wood development. In natural forests, dead wood is created by the senescence of trees and natural disturbances. However, dead-wood amounts in many forest ecosystems worldwide nowadays are largely influenced by human activities, such as timber and fuel wood production and post-disturbance salvage logging. The biodiversity of saproxylic insects is usually positively correlated with the amount of dead wood, and dead-wood amount affects species composition and functional characteristics of saproxylic assemblages. Dead-wood amount is in turn correlated with dead-wood diversity, and several studies highlight the importance of dead-wood diversity for saproxylic biodiversity, which suggests that habitat heterogeneity is a major driver behind the positive relationship between dead-wood amount and biodiversity. The strength of this relationship is mediated by temperature. Effects of both temporal forest continuity and spatial connectivity are often linked to differences in dead-wood amount. Frequent interactions and correlations between dead-wood amount and other habitat factors indicate that future studies should aim more precisely at unraveling the importance of individual factors for saproxylic biodiversity, which will help to improve conservation strategies to counteract negative effects of anthropogenically altered dead-wood amount and diversity. Such conservation strategies, particularly in Europe and North America, include passive and active measures to retain dead wood in managed forests and to restore amounts and diversity of dead wood similar to levels in natural forests. More research is needed in the subtropics and tropics where conservation strategies rarely consider dead wood, although the few existing studies suggest that dead wood is an important factor for biodiversity in these regions.