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Spatial and temporal extents of natural disturbances differentiate deadwood-inhabiting fungal communities in spruce primary forest ecosystems
Abstract
Understanding the processes shaping the composition of assemblages at multiple spatial scales in response to disturbance events is crucial for preventing ongoing biodiversity loss and for improving current forest management policies aimed at mitigating climate change and enhancing forest resilience. Deadwood-inhabiting fungi represent an essential component of forest ecosystems through their association with deadwood decomposition and the cycling of nutrients and carbon. Although we have sufficient evidence for the fundamental role of deadwood availability and variability of decay stages for fungal species diversity, the influence of long-term natural disturbance regimes as the main driver of deadwood quantity and quality has not been sufficiently documented. We used a dendroecological approach to analyse the effect of 250-years of historical natural disturbance and structural habitat elements on local (plot-level) and regional (stand-level) species richness of deadwood-inhabiting fungi. We used data collected from 51 study plots within nine best-preserved primary spruce forest stands distributed across the Western Carpathian Mountains. Historical disturbances shaped the contemporary local and regional species richness of fungi, with contrasting impacts of disturbance regime components at different spatial scales. While local diversity of red-listed species has increased due to higher disturbance frequency, regional diversity of all species has decreased due to higher severity historical disturbances. The volume of deadwood positively influenced the species richness of deadwood-inhabiting fungi while canopy openness had a negative impact. The high number of observed rare species highlights the important role of primary forests for biodiversity conservation. From a landscape perspective, we can conclude that the distribution of species from the regional species pool is-at least to some extent-driven by past spatiotemporal patterns of disturbance events. Natural disturbances occurring at higher frequencies that create a mosaic forest structure are necessary for fungal species-especially for rare and endangered taxa. Thus, both the protection of intact forest landscapes and forest management practises that emulate natural disturbance processes are recommended to support habitats of diverse fungal communities and their associated ecosystem functions.
... However, there is emerging evidence that medium-to high-severity and scale disturbances were also historically a part of BDPF disturbance regimes, although to a much lower extent than in SDPF (Frankovič et al. 2021). The diversity of disturbance regimes has differing effects on forest structure, which thereby has divergent effects on habitat availability for different taxonomic groups of species, thereby altering biological assemblages (Kozák et al. 2020;Langbehn et al. 2021;Ferenčík et al. 2022). Therefore, disentangling the impacts of disturbances across different forest types is crucial in these times of rapid biodiversity decline. ...
... However, in a study relating disturbance histories with the data on occurrence of one species, Capercaillie (Tetrao urogallus), a significant relationship was found (Mikoláš et al. 2017). The relationships between disturbance history variables and organism assemblages were found in other taxonomic groups such as fungi (Ferenčík et al. 2022), lichens (Langbehn et al. 2021) and saproxylic beetles (Kozák et al. 2020). In our case this relationship was probably distorted by the high mobility of birds and by the impact of recent disturbances which occurred in approximately the last 20 years, which are not detectable by our methods. ...
Mountain spruce- and beech-dominated forests (SDPF and BDPF) are of major importance in temperate Europe. However, information on the differences between their historical disturbance regimes, structures, and biodiversity is still incomplete. To address this knowledge gap, we established 118 circular research plots across 18 primary forest stands. We analysed the disturbance history of the last 250 years by dendrochronological methods and calculated disturbance frequency, severity, and timing. We also measured forest structure (DBH, tree density, volume of deadwood, and other parameters). Breeding bird populations were examined by point count method during the spring seasons 2017–2018 (SDPF) and 2019–2020 (BDPF). Using direct ordination analysis, we compared the disturbance history, structure and bird assemblage in both forest types. While no differences were found regarding disturbance regimes between forest types, forest structure and bird assemblages were significantly different. SDPF had a significantly higher density of cavities and higher canopy openness, while higher tree species richness and more intense regeneration was found in BDPF. Bird assemblage showed higher species richness in BDPF, but lower total abundance. Most bird species which occurred in both forest types were more numerous in spruce-dominated forests, but more species occurred exclusively in BDPF. Further, some SDPF- preferring species were found in naturally disturbed patches in BDPF. We conclude that although natural disturbances are important drivers of primary forest structures, differences in the bird assemblages in the explored primary forest types were largely independent of disturbance regimes.
... Differing from the strong biome effect with a much stronger correlation of boreal compared to temperate forests reported in a previous meta-analysis from Lassauce et al. (2011), we found no influence of bioclimate with no significant difference between correlations of total dead wood volume and biodiversity in boreal and temperate forests. Recent studies included in the present meta-analysis reported very strong positive correlations in temperate forests (for e.g., Atrena Cours et al., 2021;Ferenčík et al., 2022;Gallo et al., 2021;Kropik et al., 2021). Such effect changes with advances in research supports the argument for regularly updating meta-analysis in ecology and evolutionary biology to synthesize knowledge incorporating more recent information (Koricheva et al., 2013b). ...
... Species richness or α-diversity increases with increasing dead wood amount (Gao et al., 2015;Lassauce et al., 2011;Seibold et al., 2015), but the relationship may not always be linear. Indeed positive but non-linear relationships are reported (for e.g., Ferenčík et al., 2022;Grove, 2002;Hottola et al., 2009;Kropik et al., 2021;Runnel and Lõhmus, 2017;Ylisirnio et al., 2012), shifting the relationships to a curved function after a certain threshold volume, i.e., a minimum required amount of dead wood to maintain biodiversity. Müller and Bütler (2010) reviewed observational studies from European forests revealing 36 critical values for different forest types with a broad dead wood threshold volume range of 10-150 m 3 ha − 1 . ...
Dead wood is crucial for forest biodiversity. Previous analyses support a positive relationship between dead wood volume and biodiversity, but the strength and direction of the correlation may differ across biomes, forests, dead wood traits, and among taxa and functional groups. Therefore, an up-to-date quantitative synthesis of general patterns and global trends of correlations between dead wood and the biodiversity of common and rare species is needed. Here we present the findings of a global meta-analysis that synthesized 213 correlations from 40 studies using random effects models.
The correlations between dead wood volume and all species and rare species were significantly positive and moderate, however, there were noticeable differences between taxa. The summary effects by bioclimatic regions, forest types, stands and management regimes were generally positive and moderate with no statistically significant differences, suggesting a consistent positive effect of dead wood volume on biodiversity. Dead wood types and decay stages have statistically significant differences in correlations regardless of species' rarity status, where the volume of logs and the intermediate decay stage have the strongest correlations with biodiversity. Our results support the idea that dead wood volume can largely be considered an indicator of forest biodiversity, however, dead wood quality attributes are critically important, and hence, should be given priority in forest management and biodiversity conservation interventions. More research is needed in the (sub-)tropics and concerning the relationships between dead wood and rare, threatened, and red-listed species.
... ÚVOD Významným faktorom, ktorý formuje prírodné lesné porasty v strednej Európe, sú prírodné disturbancie, ako napríklad vietor, premnoženie hmyzu alebo ľad (Nagel et al. 2016;Synek et al. 2020). Menia štruktúru lesného porastu a to tak, že zvyšujú jeho heterogenitu a okrem hospodárskych škôd vytvárajú rôzne biologicky významné prvky ako je napríklad nahromadené mŕtve drevo Ferenčík et al. 2022). Tvorí sa tak rôznorodá vertikálna aj horizontálna štruktúra lesného porastu (Meigs et al. 2017). ...
Natural disturbances such as windthrows and bark beetle outbreaks are essential in the formation of natural forest ecosystem structures in Central Europe. Therefore, evaluating disturbances’ spatial and temporal extent and synchronicity is critical for understanding of forest dynamics. This study aimed to evaluate the long-term natural disturbance history of primary mixed-beech forests and investigate the species composition-temporal synchronisation relationship. We collected a unique dataset of > 6,000 tree cores across 14 forest stands on 174 study plots, and using dendroecological methods we reconstructed 200-year-long plot-level disturbance histories and evaluated synchronicity within the stands. Subsequently, we used GLMs to evaluate the tree species diversity-synchronicity relationship. The results showed substantial temporal variability of natural disturbances and a prevalence of low and moderate severity disturbances. Disturbance synchronisation was higher in the Western than in the Eastern Carpathian forests, which have a lower proportion of admixture tree species. Moreover, the GLMs showed a strong positive dependence of synchronicity on tree species richness. The results contradict the general assumption that mixed-species forests have higher resilience to disturbances than monospecific forests. The reason behind these findings can be attributed to the substantial admixture of Norway spruce, and its vulnerability to disturbances such as windthrow and bark beetle outbreaks.
... Only a few bat species hunt in the understorey vegetation and use lying deadwood as a foraging source (e.g., M. myotis or M. blythii hunt beetles that live in the logs; Arlettaz, 1999;Dietz and Kiefer, 2016), thus it is plausible that with higher amounts of lying deadwood, there are more bat species that are specialised in foraging at lower strata feeding on it (Langridge et al., 2019). In addition, our results showed that the species detected in forests with large amount of log deadwood were generalists, and the community is mostly composed of non-tree-roosting species; typically, the presence of coarse lying deadwood in the forest is the result of small-scale disturbance events (e.g., windthrows, heavy snow damages, or human activity; Ferenčík et al., 2022), creating heterogeneity within forest stands and allowing generalist bat species, like Pipistrellus pipistrellus, and open-space bats to take advantage of gaps (Heim et al., 2017;Nicholls and Racey, 2006). ...
The global decline of biodiversity has affected European forests, involving many tree species and forest-dwelling threatened animals. An integrated approach linking forest structure and multi-taxon diversity is increasingly needed to maintain the multifunctionality of forest ecosystems. We investigated the relationship between forest structure, deadwood elements, canopy attributes, and tree-related microhabitats on bat and bird communities in the northeastern Italian Alps. We collected forest attributes, bats, and bird data on 40 forest plots encompassing the diversity of forest types. To assess the different contributions of each forest attribute variables we performed a two-step statistical analysis using generalised and linear models, including bat and bird taxonomical and functional diversity indices as response variables. Our findings reveal that bats and birds respond differently to variation in forest structural characteristics. Specifically, bat species richness was higher in forests with both higher standing tree and lying deadwood volume. The Shannon diversity index for bird community was higher in forests with high volumes of coarse lying deadwood and stumps. Moreover, plots with mature trees, gaps, and heterogeneous diameter distribution fostered the presence of generalist species of bats and birds, while the abundance of tree-related microhabitats was not significant for these two taxa. This study demonstrates that the optimal habitat conditions for bats and birds in Alpine forests are multifaceted. Promoting distinctive elements within forest stands and a complex forest structure through adaptations in forest management interventions would enhance the conservation of multi-taxon forest biodiversity.
... Our results supported the long-understood finding regarding importance of habitat quantity (i.e., the volume of deadwood) for fungal species richness on both deadwood-object and plot level (e.g., Heilmann-Clausen & Christensen, 2005, Bässler et al., 2012, Ferenčík et al., 2022. Higher habitat quantity allows for the presence of more individuals of organisms and, consequently, more species. ...
An ongoing loss of Europe’s old-growth forests urgently calls for improving our understanding of native biodiversity response to habitat changes. Studies disentangling the effects of habitat quantity, quality, and continuity on species diversity are rare, however, understanding the differences between these effects is crucial for forest management and conservation efforts. Here, we investigated the influence of habitat quantity, quality, and continuity on the total and red-listed species richness of wood-inhabiting fungi in old-growth mountain Norway spruce (Picea abies Karst.) forest in Central Europe. The fruitbody-based mycological survey conducted on permanent plots was combined with the measurements of forest structural characteristics such as deadwood volumes (indicating habitat quantity), dimensions, and decay stages (indicating habitat quality). Additionally, precise dendrochronological measurements were used to estimate the mean age of five oldest trees and the number of >250 years-old-trees (i.e., those that survived a probable logging activity about 250 years ago) as indicators of habitat continuity. Our results showed the total species richness of wood-inhabiting fungi to be best correlated with habitat quantity (volume of low snags and lying deadwood), while the red-listed species richness was best explained by habitat continuity indicated by the number of >250 years-old-trees. Our study provides novel evidence regarding uninterrupted habitat continuity being crucial in supporting red-listed fungal species. Stands with preserved habitat continuity (e.g., the absence of clearcutting and deforestation) as well as old-growth stands with long habitat history should be prioritised for conservation. Greater degree of retention forestry practices should be required in production forests to preserve habitat continuity. Our study shows that such decisions are likely to lead to positive effects that can persist for centuries.
The growing demand for woody biomass to meet the environmental and climate objectives of the European Green Deal raises concerns about the capacity of forest ecosystems to sustain their diverse services and functions. Deadwood, an often-overlooked source of biomass, exemplifies this dilemma, yet the evidence needed to enhance its management is sparse. Here, we put the role of deadwood into perspective through a literature review and comparison of estimates in managed and unmanaged forests. We demonstrate that deadwood intersects many overlapping and sometimes conflicting policies, playing a multifaceted role in the bioeconomy, biodiversity conservation, soil health, fire mitigation, bioenergy, and carbon storage. Given the increasing pressure on deadwood and the ecosystem services it provides, we argue that coherent and mutually supportive policies are needed to develop multifunctional pathways that reconcile deadwood management with biodiversity, bioenergy, and climate objectives. Therefore, we suggest that harmonized data and monitoring are essential, along with transdisciplinary collaboration, to identify trade-offs between biomass uses and values and ensure the maintenance of functional forest ecosystems.
Addressing the scope of biodiversity loss is a societal issue. However, consensus regarding effective management practices to attenuate species extinction is lacking. An assessment of spatial variation in species assemblages (beta-diversity) provides a promising framework for informing forest landscape planning. Within the context of recent European Union biodiversity conservation goals, this research demonstrates an application of beta-diversity theory to understand spatial patterns in the distribution of a suite of environmentally-sensitive taxa within Europe’s remaining best-preserved primary forests. We sampled the local community composition (alpha-diversity) of four taxonomic groups (birds, epiphytic and epixylic lichens, saproxylic beetles, and deadwood-inhabiting fungi) to estimate corresponding levels of beta-diversity, as well as the underlying spatial components of nestedness and turnover. To identify particularly sensitive sites on the landscape that are potentially important for multiple species, we assessed beta-diversity congruence among the taxonomic groups. To elucidate critical abiotic factors and resource attributes underpinning biodiversity patterns, we regressed observed levels of local species richness against selected habitat variables. Results show that levels of beta-diversity were high and predominantly driven by spatial turnover, particularly for dispersal-limited organisms having relationships with deadwood. Beta-diversity was lowest for the avian group, reflecting their mobility. The lichen and fungal groups were correlated in terms of beta-diversity and turnover likely due to similar resource requirements. Variation in deadwood attributes (volume, decay stage) was significantly related to the local species richness of beetle and lichen communities. We identified occurrences of several threatened (red-listed) species that were similarly associated with deadwood substrates. We suggest that the beta-diversity patterns and habitat associations revealed by our analyses provide baseline data for comparison with managed systems. In particular, our findings highlight the importance of dead trees and logs for biodiversity conservation, suggesting a need for management strategies that retain an abundant and diverse supply of deadwood in forested landscapes.
Forests of the Carpathians are of increasing research interest, as they cover a large area (>9 Mha) within European forests and are influenced by diverse environmental conditions and contrasting historical developments. We reviewed 251 papers dealing with Carpathian forests, their history, and future perspectives. Over 70% of articles and reviews appeared in the last ten years, and 80% refer to the Western and Eastern Carpathians, while the Serbian Carpathians remain a gap in this research field. Forest expansion and species changes have occurred since Holocene deglaciation, influenced by timber use, settlements, cropland development, and, since the Bronze Age, pasture activities. At higher elevations, early conifer successors have been increasingly replaced by Norway spruce (Picea abies), silver fir (Abies alba), European beech (Fagus sylvatica), and hornbeam (Carpinus betulus), while oaks have been present in the Carpathian foothills throughout the whole of history. In the 19th and 20th centuries, Norway spruce afforestation was favored, and timber use peaked. Recent transitions from agriculture to forest land use have led to a further increase in forest cover (+1 to +14% in different countries), though past forest management practices and recent environmental changes have impaired forest vitality in many regions; climate warming already causes shifts in treelines and species distributions, and it triggers pest outbreaks and diseases and affects tree-water relations. The risk of forest damage is the highest in monodominant Norway spruce forests, which often experience dieback after cascade disturbances. European beech forests are more resilient unless affected by summer droughts. In the future, increasing dominance of broadleaves within Carpathian forests and forest management based on a mix of intensive management and ecological silviculture are expected. Maintenance and promotion of silver fir and mixed European beech forests should be encouraged with respect to forest stability, biodiversity, and economic sustainability. As supported by the Carpathian Convention and related institutions and initiatives, connectivity, management, and stakeholder cooperation across administrative borders will be crucial for the future adaptive potential of Carpathian forests.
With accelerating environmental change, understanding forest disturbance impacts on trade-offs between biodiversity and carbon dynamics is of high socioeconomic importance. Most studies, however, have assessed immediate or short-term effects of disturbance, while long-term impacts remain poorly understood. Using a tree-ring-based approach, we analysed the effect of 250 years of disturbances on present-day biodiversity indicators and carbon dynamics in primary forests. Disturbance legacies spanning centuries shaped contemporary forest co-benefits and trade-offs, with contrasting, local-scale effects. Disturbances enhanced carbon sequestration, reaching maximum rates within a comparatively narrow post-disturbance window (up to 50 years). Concurrently, disturbance diminished aboveground carbon storage, which gradually returned to peak levels over centuries. Temporal patterns in biodiversity potential were bimodal; the first maximum coincided with the short-term post-disturbance carbon sequestration peak, and the second occurred during periods of maximum carbon storage in complex old-growth forest. Despite fluctuating local-scale trade-offs, forest biodiversity and carbon storage remained stable across the broader study region, and our data support a positive relationship between carbon stocks and biodiversity potential. These findings underscore the interdependencies of forest processes, and highlight the necessity of large-scale conservation programmes to effectively promote both biodiversity and long-term carbon storage, particularly given the accelerating global biodiversity and climate crises.
Aim
Natural disturbances influence forest structure, successional dynamics, and, consequently, the distribution of species through time and space. We quantified the long-term impacts of natural disturbances on lichen species richness and composition in primary mountain forests, with a particular focus on the occurrence of endangered species.
Location
Ten primary mountain spruce forest stands across five mountain chains of the Western Carpathians, a European hotspot of biodiversity.
Methods
Living trees, snags, and downed logs were surveyed for epiphytic and epixylic lichens in 57 plots. Using reconstructed disturbance history, we tested how lichen species richness and composition was affected by the current forest structure and disturbance regimes in the past 250 years. We also examined differences in community composition among discrete microhabitats.
Results
Dead standing trees as biological legacies of natural disturbances promoted lichen species richness and occurrence of threatened species at the plot scale, suggesting improved growing conditions for rare and common lichens during the early stages of recovery post-disturbance. However, high-severity disturbances compromised plot scale species richness. Both species richness and the number of old-growth specialists increased with time since disturbance (i.e. long-term uninterrupted succession). No lichen species was strictly dependent on live trees as a habitat, but numerous species showed specificity to logs, standing objects, or admixture of tree species.
Main conclusions
Lichen species richness was lower in regenerating, young, and uniform plots compared to overmature and recently disturbed areas. Natural forest dynamics and its legacies are critical to the diversity and species composition of lichens. Spatiotemporal consequences of natural dynamics require a sufficient area of protected forests for provisioning continual habitat variability at the landscape scale. Ongoing climatic changes may further accentuate this necessity. Hence, we highlighted the need to protect the last remaining primary forests to ensure the survival of regionally unique species pools of lichens.
Primary forests, defined here as forests where the signs of human impacts, if any, are strongly blurred due to decades without forest management, are scarce in Europe and continue to disappear. Despite these losses, we know little about where these forests occur. Here, we present a comprehensive geodatabase and map of Europe’s known primary forests. Our geodatabase harmonizes 48 different, mostly field-based datasets of primary forests, and contains 18,411 individual patches (41.1 Mha) spread across 33 countries. When available, we provide information on each patch (name, location, naturalness, extent and dominant tree species) and the surrounding landscape (biogeographical regions, protection status, potential natural vegetation, current forest extent). Using Landsat satellite-image time series (1985–2018) we checked each patch for possible disturbance events since primary forests were identified, resulting in 94% of patches free of significant disturbances in the last 30 years. Although knowledge gaps remain, ours is the most comprehensive dataset on primary forests in Europe, and will be useful for ecological studies, and conservation planning to safeguard these unique forests.
On the basis of long-term surveys of permanent plots and traps, we examined the communities of saproxylic beetles, fungi, herbs, and trees on an untreated 22 ha large beech forest windthrow and asked whether the results lend support to the intermediate disturbance hypothesis (IDH). We studied species richness and the similarity of community composition. Additionally, we grouped species by their frequency trend over time to successional model types to examine whether, corresponding to the IDH, the diversity of these groups explained peak richness at intermediate intervals after the disturbance. In line with the IDH, species richness showed a hump-backed temporal course for alpha and gamma diversity. We found evidence for a linear succession directly after the disturbance. This, however, did not continue, and in all species groups, a partial recovery of the initial community was observed. In the case of fungi, herbs, and trees, but not for saproxylic beetles, alpha diversity was driven by the diversity of the successional model types. Our results underline that the mechanisms driving species richness after disturbances are more complex than the IDH suggests and that these mechanisms vary with species group. We assumed that, besides competition, legacy effects, facilitation, habitat heterogeneity, and random saturation of the species pool are important. In case of trees and herbs, we found indications for strong legacy and competition effects. For fungi and beetles, substrate heterogeneity and microclimate were assumed to be important. We concluded that disturbances contribute to increasing species richness not only by reducing the effectiveness of competitors but also by increasing the amount and diversity of resources, as well as their rate of change over time.
Deadwood plays a crucial role in the maintenance of biodiversity in forest ecosystems. Its quantity and quality are commonly used in ecology and nature conservation as a proxy indicator of forest biodiversity. In this study we exposed 720 logs of wood in a full-factorial experiment, set in a temperate European forest, to test the influence of forest type (three levels), host wood identity (four species) and degree of contact with soil (three levels) on species richness and species composition of wood-inhabiting macrofungi.
The forest type did not influence the taxon richness and had limited influence on the composition of deadwood-dwelling mycobiota. The degree of contact with soil was an important factor, with the taxon richness of the subterranean logs extremely low and their fungal composition being a subset of the species pools of logs lying on the soil surface and those hanging above the ground. The host wood identity was the strongest predictor of taxon richness and composition of macrofungi: Carpinus betulus wood hosted the highest, Quercus robur the medium, and Picea abies and Pinus sylvestris ex aequo the lowest taxon richness of fungi. Fungal communities differed significantly between all host wood species with the exception of conifers, which hosted similar mycocoenoses.
Our study indicates that host wood identity and degree of log contact with soil are the most important factors determining macrofungal communities in deadwood, overriding the influence of forest type. Taking into account the degree of wood debris contact with soil revealed that the common practice of leaving subterranean wood biomass (stumps and root systems) in logged forests does not have any importance for the diversity of macrofungi. Thus, a reasonable amount of diverse above ground wood debris needs to be left (or brought from outside) to maintain the diversity of the forest ecosystems.
Pulses of tree mortality caused by drought have been reported recently in forests around the globe, but large-scale quantitative evidence is lacking for Europe. Analyzing high-resolution annual satellite-based canopy mortality maps from 1987 to 2016 we here show that excess forest mortality (i.e., canopy mortality exceeding the long-term mortality trend) is significantly related to drought across continental Europe. The relationship between water availability and mortality showed threshold behavior, with excess mortality increasing steeply when the integrated climatic water balance from March to July fell below −1.6 standard deviations of its long-term average. For −3.0 standard deviations the probability of excess canopy mortality was 91.6% (83.8–97.5%). Overall, drought caused approximately 500,000 ha of excess forest mortality between 1987 and 2016 in Europe. We here provide evidence that drought is an important driver of tree mortality at the continental scale, and suggest that a future increase in drought could trigger widespread tree mortality in Europe.
Primary forests are critical for forest biodiversity and provide key ecosystem services. In Europe, these forests are particularly scarce and it is unclear whether they are sufficiently protected. Here we aim to: (a) understand whether extant primary forests are representative of the range of naturally occurring forest types, (b) identify forest types which host enough primary forest under strict protection to meet conservation targets and (c) highlight areas where restoration is needed and feasible.
We combined a unique geodatabase of primary forests with maps of forest cover, potential natural vegetation, biogeographic regions and protected areas to quantify the proportion of extant primary forest across Europe's forest types and to identify gaps in protection. Using spatial predictions of primary forest locations to account for underreporting of primary forests, we then highlighted areas where restoration could complement protection.
We found a substantial bias in primary forest distribution across forest types. Of the 54 forest types we assessed, six had no primary forest at all, and in two‐thirds of forest types, less than 1% of forest was primary. Even if generally protected, only ten forest types had more than half of their primary forests strictly protected. Protecting all documented primary forests requires expanding the protected area networks by 1,132 km2 (19,194 km2 when including also predicted primary forests). Encouragingly, large areas of non‐primary forest existed inside protected areas for most types, thus presenting restoration opportunities.
Europe's primary forests are in a perilous state, as also acknowledged by EU's “Biodiversity Strategy for 2030.” Yet, there are considerable opportunities for ensuring better protection and restoring primary forest structure, composition and functioning, at least partially. We advocate integrated policy reforms that explicitly account for the irreplaceable nature of primary forests and ramp up protection and restoration efforts alike.
Global sustainability agendas focus primarily on halting deforestation, yet the biodiversity crisis resulting from the degradation of remaining forests is going largely unnoticed. Forest degradation occurs through the loss of key ecological structures, such as dying trees and deadwood, even in the absence of deforestation. One of the main drivers of forest degradation is limited awareness by policy makers and the public on the importance of these structures for supporting forest biodiversity and ecosystem function. Here, we outline management strategies to protect forest health and biodiversity by maintaining and promoting deadwood, and propose environmental education initiatives to improve the general awareness of the importance of deadwood. Finally, we call for major reforms to forest management to maintain and restore deadwood; large, old trees; and other key ecological structures.
Given the short time-frame to limit global warming, and the current emissions gap, it is critical to prioritise mitigation actions. To date, scant attention has been paid to the mitigation benefits of primary forest protection. We estimated tropical forest ecosystem carbon stocks and flows. The ecosystem carbon stock of primary tropical forests is estimated at 141–159 Pg C (billion tonnes of carbon) which is some 49–53% of all tropical forest carbon, the living biomass component of which alone is 91–103% of the remaining carbon budget to limit global warming to below 1.5 degrees above pre-industrial levels. Furthermore, tropical forests have ongoing sequestration rates 0.47–1.3 Pg C yr−1, equivalent to 8–13% of annual global anthropogenic CO2 (carbon dioxide) emissions. We examined three main forest-based strategies used in the land sector—halting deforestation, increasing forest restoration and improving the sustainable management of production forests. The mitigation benefits of primary forest protection are contingent upon how degradation is defined and accounted for, while those from restoration also depend on how restoration is understood and applied. Through proforestation, reduced carbon stocks in secondary forests can regrow to their natural carbon carrying capacity or primary forest state. We evaluated published data from studies comparing logged and unlogged forests. On average, primary forests store around 35% more carbon. While comparisons are confounded by a range of factors, reported biomass carbon recovery rates were from 40 to 100+ years. There is a substantive portfolio of forest-based mitigation actions and interventions available to policy and decision-makers, depending on national circumstances, in addition to SFM and plantation focused approaches, that can be grouped into four main strategies: protection; proforestation, reforestation and restoration; reform of guidelines, accounting rules and default values; landscape conservation planning. Given the emissions gap, mitigation strategies that merely reduce the rate of emissions against historic or projected reference levels are insufficient. Mitigation strategies are needed that explicitly avoid emissions where possible as well as enabling ongoing sequestration.
Reducing the rate of global biodiversity loss is a major challenge facing humanity¹, as the consequences of biological annihilation would be irreversible for humankind2–4. Although the ongoing degradation of ecosystems5,6 and the extinction of species that comprise them7,8 are now well-documented, little is known about the role that remaining wilderness areas have in mitigating the global biodiversity crisis. Here we model the persistence probability of biodiversity, combining habitat condition with spatial variation in species composition, to show that retaining these remaining wilderness areas is essential for the international conservation agenda. Wilderness areas act as a buffer against species loss, as the extinction risk for species within wilderness communities is—on average—less than half that of species in non-wilderness communities. Although all wilderness areas have an intrinsic conservation value9,10, we identify the areas on every continent that make the highest relative contribution to the persistence of biodiversity. Alarmingly, these areas—in which habitat loss would have a more-marked effect on biodiversity—are poorly protected. Given globally high rates of wilderness loss¹⁰, these areas urgently require targeted protection to ensure the long-term persistence of biodiversity, alongside efforts to protect and restore more-degraded environments.
Background:
The majority of wood decomposing fungi are mushroom-forming Agaricomycetes, which exhibit two main modes of plant cell wall decomposition: white rot, in which all plant cell wall components are degraded, including lignin, and brown rot, in which lignin is modified but not appreciably removed. Previous studies suggested that brown rot fungi tend to be specialists of gymnosperm hosts and that brown rot promotes gymnosperm specialization. However, these hypotheses were based on analyses of limited datasets of Agaricomycetes. Overcoming this limitation, we used a phylogeny with 1157 species integrating available sequences, assembled decay mode characters from the literature, and coded host specialization using the newly developed R package, rusda.
Results:
We found that most brown rot fungi are generalists or gymnosperm specialists, whereas most white rot fungi are angiosperm specialists. A six-state model of the evolution of host specialization revealed high transition rates between generalism and specialization in both decay modes. However, while white rot lineages switched most frequently to angiosperm specialists, brown rot lineages switched most frequently to generalism. A time-calibrated phylogeny revealed that Agaricomycetes is older than the flowering plants but many of the large clades originated after the diversification of the angiosperms in the Cretaceous.
Conclusions:
Our results challenge the current view that brown rot fungi are primarily gymnosperm specialists and reveal intensive white rot specialization to angiosperm hosts. We thus suggest that brown rot associated convergent loss of lignocellulose degrading enzymes was correlated with host generalism, rather than gymnosperm specialism. A likelihood model of host specialization evolution together with a time-calibrated phylogeny further suggests that the rise of the angiosperms opened a new mega-niche for wood-decay fungi, which was exploited particularly well by white rot lineages.
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.
We classified mixed mountain forests in Central Europe into nine successional stages using airborne Li DAR . 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.
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.
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.
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.
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.
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.
Dead wood is a habitat for numerous fungal species, many of which are important agents of decomposition. Previous studies suggested that wood‐inhabiting fungal communities are affected by climate, availability of dead wood in the surrounding landscape and characteristics of the colonized dead‐wood object (e.g. host tree species). These findings indicate that different filters structure fungal communities at different scales, but how these factors individually drive fungal fruiting diversity on dead‐wood objects is unknown.
We conducted an orthogonal experiment comprising 180 plots (0.1 ha) in a random block design and measured fungal fruit body richness and community composition on 720 dead‐wood objects over the first 4 years of succession. The experiment allowed us to disentangle the effects of the host (beech and fir; logs and branches) and the environment (microclimate: sunny and shady plots; local dead wood: amount and heterogeneity of dead wood added to plot).
Variance partitioning revealed that the host was more important than the environment for the diversity of wood‐inhabiting fungi. A more detailed model revealed that host tree species had the highest independent effect on richness and community composition of fruiting species of fungi. Host size had significant but low independent effects on richness and community composition of fruiting species. Canopy openness significantly affected the community composition of fruiting species. By contrast, neither local amount nor heterogeneity of dead wood significantly affected the fungal diversity measures.
Synthesis . Our study identified host tree species as a more important driver of the diversity of wood‐inhabiting fungi than the environment, which suggests a host‐centred filter of this diversity in the early phase of the decomposition process. For the conservation of wood‐inhabiting fungi, a high variety of host species in various microclimates is more important than the availability of dead wood at the stand level.
Determining the drivers of shifting forest disturbance rates remains a pressing global change issue. Large-scale forest dynamics are commonly assumed to be climate driven, but appropriately scaled disturbance histories are rarely available to assess how disturbance legacies alter subsequent disturbance rates and the climate sensitivity of disturbance. We compiled multiple tree-ring based disturbance histories from primary Picea abies forest fragments distributed throughout five European landscapes spanning the Bohemian Forest and the Carpathian Mountains. The regional chronology includes 11 595 tree cores, with ring dates spanning the years 1750 to 2000, collected from 560 inventory plots in 37 stands distributed across a 1000 km geographic gradient, amounting to the largest disturbance chronology yet constructed in Europe. Decadal disturbance rates varied significantly through time and declined after 1920, resulting in widespread increases in canopy tree age. Approximately 75% of current canopy area recruited prior to 1900. Long-term disturbance patterns were compared to an historical drought reconstruction, and further linked to spatial variation in stand structure and contemporary disturbance patterns derived from LANDSAT imagery. Historically, decadal Palmer drought severity index minima corresponded with higher rates of canopy removal. The severity of contemporary disturbances increased with each stand's estimated time since last major disturbance, increased with mean diameter and declined with increasing within-stand structural variability. Reconstructed spatial patterns suggest that high small-scale structural variability has historically acted to reduce large-scale susceptibility and climate sensitivity of disturbance. Reduced disturbance rates since 1920, a potential legacy of high 19th century disturbance rates, have contributed to a recent region-wide increase in disturbance susceptibility. Increasingly common high-severity disturbances throughout primary Picea forests of Central Europe should be reinterpreted in light of both legacy effects (resulting in increased susceptibility) and climate change (resulting in increased exposure to extreme events). This article is protected by copyright. All rights reserved.
Identification of forest stands with priority for the conservation of biodiversity is of particular importance in landscapes with a long cultural and agricultural history, such as Central Europe. A group of species with a high indicator value for the naturalness of forest ecosystems are saproxylic insects. Some of these species, especially within the order Coleoptera, have been described as primeval forests relicts. Here, we compiled a list of 168 “primeval forest relict species” of saproxylic beetles based on expert knowledge. These species can serve as focal and umbrella species for forest conservation in Central Europe. They were selected because of their dependence on the continuous presence of primeval forest habitat features, such as over-mature trees, high amounts of dead wood, and dead wood diversity, as well as their absence in managed Central European forests. These primeval forest relict species showed a moderately strong clumping pattern within the phylogeny of beetles, as indicated by phylogenetic signal testing using the D-statistic. When we controlled for phylogenetic relatedness, an ordinal linear model revealed that large body size and preference for dead wood and trees of large diameter are the main characteristics of these species. This list of species can be used to identify forest stands of conservation value throughout Central Europe, to prioritize conservation and to raise public awareness for conservation issues related to primeval forests.
Questions
How do canopy–understorey interactions respond to variation in disturbance severity over extended periods of time? For forests with different disturbance histories, do light availability and understorey cohort densities converge towards a common old‐growth structure, or do historical legacies influence populations indefinitely?
Locations
Remnants of primary spruce ( Picea abies (L.) Karst.) forests throughout Germany, Slovakia, Ukraine and Romania.
Methods
A disturbance history of >200 yr was reconstructed from 11 278 tree cores collected from forest plots ( n = 520). Understorey tree densities of two size classes and hemispherical photo‐based light availabilities were inventoried and modelled as functions of the severity of the main disturbance and time since the event.
Results
Variation in understorey tree densities had a hump‐shaped distribution through time. Stem densities were approximately static in the least disturbed sites, and declined in relation to disturbance severity over approx. 100 yr. Similar to patterns of stem densities, initially high understorey light availability also reached a minimum at 100 yr, which indicated crown closure. Following this, light availability and stem densities both increased as stands transitioned from stem exclusion to understorey re‐initiation. The effect of disturbance severity on understorey densities and patchiness in light availability persisted for >200 yr.
Conclusions
Long‐term trends in canopy–understorey interactions validate current conceptual models of forest development. Furthermore, we empirically validate that these conceptual models generalized over gradients in disturbance severity. Higher disturbance sites exhibited a more even‐aged character with more pronounced periods of stem exclusion, canopy closure and understorey re‐initiation; forests with low‐severity disturbance histories yielded a more stationary uneven‐aged structure. The model identified the extent of variation in disturbance severity within which these P . abies forests are able to regenerate and retain their monospecific character, which is increasingly relevant as disturbance regimes continue to shift under global climate change.
The coefficient of determination R² quantifies the proportion of variance explained by a statistical model and is an important summary statistic of biological interest. However, estimating R² for generalized linear mixed models (GLMMs) remains challenging. We have previously introduced a version of R² that we called for Poisson and binomial GLMMs, but not for other distributional families. Similarly, we earlier discussed how to estimate intra-class correlation coefficients (ICCs) using Poisson and binomial GLMMs. In this paper, we generalize our methods to all other non-Gaussian distributions, in particular to negative binomial and gamma distributions that are commonly used for modelling biological data. While expanding our approach, we highlight two useful concepts for biologists, Jensen's inequality and the delta method, both of which help us in understanding the properties of GLMMs. Jensen's inequality has important implications for biologically meaningful interpretation of GLMMs, whereas the delta method allows a general derivation of variance associated with non-Gaussian distributions. We also discuss some special considerations for binomial GLMMs with binary or proportion data. We illustrate the implementation of our extension by worked examples from the field of ecology and evolution in the R environment. However, our method can be used across disciplines and regardless of statistical environments.
Logging to “salvage” economic returns from forests affected by natural disturbances has become increasingly prevalent globally. Despite potential negative effects on biodiversity, salvage logging is often conducted, even in areas otherwise excluded from logging and reserved for nature conservation, inter alia because strategic priorities for post‐disturbance management are widely lacking.
A review of the existing literature revealed that most studies investigating the effects of salvage logging on biodiversity have been conducted less than 5 years following natural disturbances, and focused on non‐saproxylic organisms.
A meta‐analysis across 24 species groups revealed that salvage logging significantly decreases numbers of species of eight taxonomic groups. Richness of dead wood dependent taxa (i.e. saproxylic organisms) decreased more strongly than richness of non‐saproxylic taxa. In contrast, taxonomic groups typically associated with open habitats increased in the number of species after salvage logging.
By analysing 134 original species abundance matrices, we demonstrate that salvage logging significantly alters community composition in 7 of 17 species groups, particularly affecting saproxylic assemblages.
Synthesis and applications . Our results suggest that salvage logging is not consistent with the management objectives of protected areas. Substantial changes, such as the retention of dead wood in naturally disturbed forests, are needed to support biodiversity. Future research should investigate the amount and spatio‐temporal distribution of retained dead wood needed to maintain all components of biodiversity.
Following disturbances, early-seral stages of forests provide a variety of structures. Whether this variety is a short-term phenomenon or influences forest succession for several decades or even longer is not known. We tested the hypotheses that after spruce dieback caused by bark beetles, a high spatial heterogeneity of stand structures will persist within stands and among stands even in advanced early-seral stages and that species taxonomical and functional diversity measures will reflect this heterogeneity. We used a chronosequence of unmanaged forests in the Berchtesgaden National Park (Germany) consisting of mature undisturbed spruce stands (control), stands belonging to an initial early-seral stage (~3 years after disturbance) and stands in an advanced early-seral stage (~20 years after disturbance). We analysed diversity and heterogeneity of these forest stands including stand structure, species density, species composition and functional–phylogenetic diversity of vascular plants, wood-inhabiting fungi and saproxylic beetles within plots, among plots of the same successional stage and among stages. Stands of the advanced early-seral stage were characterized by a high spatial heterogeneity of structural attributes, such as crown cover, regeneration density and spatial distribution of trees. Among-plot taxonomic beta diversity was highest in the advanced early-seral stage for beetles, but lowest for fungi, while beta diversity of plants among plots remained unchanged during succession. The mosaic of successional stages initiated by bark beetles increased the gamma diversity of the study area, especially for fungi and beetles. Our findings support the hypothesis that structural heterogeneity continues for at least two decades at stand and landscape scales and that species turnover among successional stages is a major mechanism for gamma diversity in forests after bark beetle disturbance.
An intact forest landscape (IFL) is a seamless mosaic of forest and naturally treeless ecosystems with no remotely detected signs of human activity and a minimum area of 500 km². IFLs are critical for stabilizing terrestrial carbon storage, harboring biodiversity, regulating hydrological regimes, and providing other ecosystem functions. Although the remaining IFLs comprise only 20% of tropical forest area, they account for 40% of the total aboveground tropical forest carbon. We show that global IFL extent has been reduced by 7.2% since the year 2000. An increasing rate of global IFL area reduction was found, largely driven by the tripling of IFL tropical forest loss in 2011–2013 compared to that in 2001–2003. Industrial logging, agricultural expansion, fire, and mining/resource extraction were the primary causes of IFL area reduction. Protected areas (International Union for Conservation of Nature categories I to III) were found to have a positive effect in slowing the reduction of IFL area from timber harvesting but were less effective in limiting agricultural expansion. The certification of logging concessions under responsible management had a negligible impact on slowing IFL fragmentation in the Congo Basin. Fragmentation of IFLs by logging and establishment of roads and other infrastructure initiates a cascade of changes that lead to landscape transformation and loss of conservation values. Given that only 12% of the global IFL area is protected, our results illustrate the need for planning and investment in carbon sequestration and biodiversity conservation efforts that target the most valuable remaining forests, as identified using the IFL approach.
Wood-inhabiting fungi as indicators of nature value in European beech forests
Morten Christensen1, Jacob Heilmann-Clausen1, Ruben Walleyn2 & Slavomir Adamcik3
1The Royal Veterinary and Agricultural University, Denmark
2Institute for Forestry and Game Management, Belgium
3Institute of Botany, Slovak Academy of Sciences, Slovakia,
Abstract
Wood-inhabiting fungi represent a highly species rich and ecologically important organism group in natural forest. Due to exploitation of forest resources most wood-inhabiting organisms have declined in Europe, and many specialised species are severely threatened on the continental scale. This paper presents a preliminary evaluation of a set of fungal indicator species assumed to be usable in conservation priorities in European beech forests. Information on fungal species diversity from 106 beech forest reserves in Europe is analysed and 21 fungal species are proposed as indicators for biotic integrity of old grown beech forests. The presence of the indicator species is compared to the actual amount of dead wood per hectare in a subset of the sites, and it is shown that the presence of indicator species is only weakly related to the absolute dead wood amounts. Accordingly, it is suggested that the fungal indicator species can add valuable information relevant in the prioritisation in forest conservation.
Keywords: dead wood, biodiversity, forest reserves, habitat quality
One of the frequent questions by users of the mixed model function lmer of the lme4 package has been: How can I get p values for the F and t tests for objects returned by lmer? The lmerTest package extends the 'lmerMod' class of the lme4 package, by overloading the anova and summary functions by providing p values for tests for fixed effects. We have implemented the Satterthwaite's method for approximating degrees of freedom for the t and F tests. We have also implemented the construction of Type I - III ANOVA tables. Furthermore, one may also obtain the summary as well as the anova table using the Kenward-Roger approximation for denominator degrees of freedom (based on the KRmodcomp function from the pbkrtest package). Some other convenient mixed model analysis tools such as a step method, that performs backward elimination of nonsignificant effects - both random and fixed, calculation of population means and multiple comparison tests together with plot facilities are provided by the package as well.
ContextDistribution and connectivity of suitable habitat for species of conservation concern is critical for effective conservation planning. Capercaillie (Tetrao urogallus), an umbrella species for biodiversity conservation, is increasingly threatened because of habitat loss and fragmentation. Objective
We assessed the impact of drastic changes in forest management in the Carpathian Mountains, a major stronghold of capercaillie in Europe, on habitat distribution and connectivity. Methods
We used field data surveys with a forest disturbance dataset for 1985–2010 to map habitat suitability, and we used graph theory to analyse habitat connectivity. ResultsClimate, topography, forest proportion and fragmentation, and the distance to roads and settlements best identified capercaillie presence. Suitable habitat area was 7510 km2 in 1985; by 2010, clear-cutting had reduced that area by 1110 km2. More suitable habitat was lost inside protected areas (571 km2) than outside (413 km2). Habitat loss of 15 % reduced functional connectivity by 33 % since 1985. Conclusions
Forest management, particularly large-scale clear-cutting and salvage logging, have substantially diminished and fragmented suitable capercaillie habitat, regardless of the status of forest protection. Consequently, larger areas with suitable habitat are now isolated and many patches are too small to sustain viable populations. Given that protection of capercaillie habitat would benefit many other species, including old-growth specialists and large carnivores, conservation actions to halt the loss of capercaillie habitat is urgently needed. We recommend adopting policies to protect natural forests, limiting large-scale clear-cutting and salvage logging, implementing ecological forestry, and restricting road building to reduce forest fragmentation.
Microclimatic conditions in dead wood influence fungal growth and hence also species composition, but it remains unclear how they influence species richness in nature. We analysed fungal species richness based on the occurrence of fruit bodies on 2 m long segments of both standing and lying trunks of Norway spruce (Picea abies). The number of non-red-listed species was related positively to moisture, and negatively to both temperature extremes and fluctuations. The numbers of both red-listed and non-red-listed species were further differently influenced by trunk diameter and by trunk properties related to the progression in wood decay. These results indicate that the richness of fungal communities in dead wood is shaped by an interaction of wood decay, moisture and temperature fluctuations.
Concerted political attention has focused on reducing deforestation, and this remains the cornerstone of most biodiversity conservation strategies. However, maintaining forest cover may not reduce anthropogenic forest disturbances, which are rarely considered in conservation programmes. These disturbances occur both within forests, including selective logging and wildfires, and at the landscape level, through edge, area and isolation effects. Until now, the combined effect of anthropogenic disturbance on the conservation value of remnant primary forests has remained unknown, making it impossible to assess the relative importance of forest disturbance and forest loss. Here we address these knowledge gaps using a large data set of plants, birds and dung beetles (1,538, 460 and 156 species, respectively) sampled in 36 catchments in the Brazilian state of Pará. Catchments retaining more than 69-80% forest cover lost more conservation value from disturbance than from forest loss. For example, a 20% loss of primary forest, the maximum level of deforestation allowed on Amazonian properties under Brazil's Forest Code, resulted in a 39-54% loss of conservation value: 96-171% more than expected without considering disturbance effects. We extrapolated the disturbance-mediated loss of conservation value throughout Pará, which covers 25% of the Brazilian Amazon. Although disturbed forests retained considerable conservation value compared with deforested areas, the toll of disturbance outside Pará's strictly protected areas is equivalent to the loss of 92,000-139,000 km(2) of primary forest. Even this lowest estimate is greater than the area deforested across the entire Brazilian Amazon between 2006 and 2015 (ref. 10). Species distribution models showed that both landscape and within-forest disturbances contributed to biodiversity loss, with the greatest negative effects on species of high conservation and functional value. These results demonstrate an urgent need for policy interventions that go beyond the maintenance of forest cover to safeguard the hyper-diversity of tropical forest ecosystems.
1. The ongoing changes to climate challenge the conservation of forest biodiversity. Yet, in thermally limited systems, such as temperate forests, not all species groups might be affected negatively. Furthermore, simultaneous changes in the disturbance regime have the potential to mitigate climate-related impacts on forest species. Here, we (i) investigated the potential long-term effect of climate change on biodiversity in a mountain forest landscape, (ii) assessed the effects of different disturbance frequencies, severities and sizes and (iii) identified biodiversity hotspots at the landscape scale to facilitate conservation management.
2. We employed the model iLand to dynamically simulate the tree vegetation on 13 865 ha of the Kalkalpen National Park in Austria over 1000 years, and investigated 36 unique combinations of different disturbance and climate scenarios. We used simulated changes in tree cover and composition as well as projected temperature and precipitation to predict changes in the diversity of Araneae, Carabidae, ground vegetation, Hemiptera, Hymenoptera, Mollusca, saproxylic beetles, Symphyta and Syrphidae, using empirical response functions.
3. Our findings revealed widely varying responses of biodiversity indicators to climate change. Five indicators showed overall negative effects, with Carabidae, saproxylic beetles and tree species diversity projected to decrease by more than 33%. Six indicators responded positively to climate change, with Hymenoptera, Mollusca and Syrphidae diversity projected to increase more than twofold.
4. Disturbances were generally beneficial for the studied indicators of biodiversity. Our results indicated that increasing disturbance frequency and severity have a positive effect on biodiversity, while increasing disturbance size has a moderately negative effect. Spatial hotspots of biodiversity were currently found in low- to mid-elevation areas of the mountainous study landscape, but shifted to higher-elevation zones under changing climate conditions.
5.Synthesis and applications. Our results highlight that intensifying disturbance regimes may alleviate some of the impacts of climate change on forest biodiversity. However, the projected shift in biodiversity hotspots is a challenge for static conservation areas. In this regard, overlapping hotspots under current and expected future conditions highlight priority areas for robust conservation management.
The species richness and composition of macrofungi on huge fallen trunks of silver fir (Abies alba) were monitored during a case study in the well-preserved Boubínský prales virgin forest in Czechia. A detailed survey of all macrofungal groups recorded 200 species on 30 trunks within the diameter range of 85-190 cm. This number is very high in the overall context and includes many rare and threatened species. The species-richest groups were corticioids and fleshy saprotrophic fungi. Individual trunks were inhabited by 4-33 species. The species richness was negatively correlated with trunk decay and positively with bark cover, moss cover and trunk length. Simultaneously, it was negatively correlated with increasing time since tree fall, time since tree death and the way of fall, namely its category 'broken'. Species composition was significantly influenced by decay, bark cover, moss cover, and, to a lesser degree, also by canopy cover, time since fall and time since death. The best trunks in terms of mycobiota rarity and nature conservation were those which died a long time ago but fell to the ground only recently. They have gone through a long phase of slow decay and gradual succession in standing position. As a result, they are inhabited by many distinctive fungi, especially those preferring natural forests. Durandiella gallica, Hohenbuehelia josserandii, Panellus violaceofulvus, Phellinus pouzarii and Pseudoplectania melaena can be considered almost exclusive fir specialists. All these fir-associated fungal species are immediately threatened by the gradual disappearance of firs resulting mainly from ungulate overpopulation, requiring the urgent implementation of appropriate conservation measures. A list of fungi characteristic of wood of silver fir and Norway spruce is presented.
Threats to fungi and fungal diversity throughout the world have prompted debates about whether and how fungi can be conserved. Should it be the site, or the habitat, or the host that is conserved? All of these issues are addressed in this volume, but coverage goes beyond mere debate with constructive guidance for management of nature in ways beneficial to fungi. Different parts of the world experience different problems and a range of examples are presented; from Finland in the North to Kenya in the South, and from Washington State, USA in the West to Fujian Province, China in the East. Equally wide-ranging solutions, are put forward, from voluntary agreements, through land management techniques, to primary legislation. Taken together, these provide useful suggestions about how fungi can be included in conservation projects in a range of circumstances.
The influence of forest management on fungal diversity and community composition has been the subject of a wide number of studies over the last two decades. However, the difficulty of studying the complex kingdom of fungi under real forest conditions has led to rather scattered scientific knowledge. Here, we provide the current state of knowledge suggesting future research directions regarding (i) stand structure attributes (age, tree cover, stand density, tree species composition), (ii) management history (managed vs unmanaged), (iii) silvicultural treatments (thinning, clearcutting, shelterwood methods, selective cutting) and (iv) other anthropogenic disturbances (mushroom picking, salvage logging, prescribed burning, fertilization) affecting fungal diversity and community composition. The reviewed studies reported a positive correlation between fungal diversity and stand structure variables such as canopy cover, basal area of the stand and tree species diversity, particularly for mycorrhizal species. Abundance and diversity in size, tree species and decomposition stage of deadwood are reported as positively related to richness of wood-inhabiting fungi. The main findings about the effects of silvicultural practices suggest that the higher is the management intensity the lower is the diversity of ectomycorrhizal and wood-inhabiting species, at least in the short term. We have therefore reported those silvicultural practices which may reduce trade-offs between timber harvesting and fungal diversity conservation. Indeed, fungal diversity can be conserved in managed forests if (i) low impact logging operations are performed; (ii) stand structural complexity and late-successional forest characteristics are enhanced; (iii) deadwood amount and diversity is promoted, (iv) landscape heterogeneity and connectivity is improved or maintained.
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.
The retrospective study of abrupt and sustained increases in the radial growth of trees (hereinafter 'releases') by tree-ring analysis is an approach widely used for reconstructing past forest disturbances. Despite the range of dendrochronological methods used for release-detection, a lack of in-depth comparison between them can lead researchers to question which method to use and, potentially, increases the uncertainties of disturbance histories derived with different methods. Here, we investigate the efficacy and sensitivity of four widely used release detection methods using tree-ring width series and complete long-term inventories of forest stands with known disturbances. We used support vector machine (SVM) analysis trained on long-term forest census data to estimate the likelihood that Acer rubrum trees experiencing reductions in competition show releases in their tree-ring widths. We compare methods performance at the tree and stand level, followed by evaluation of method sensitivity to changes in their parameters and settings. Disturbance detection methods agreed with 60-76% of the SVM-identified growth releases under high canopy disturbance and 80-94% in a forest with canopy disturbance of low severity and frequency. The median competition index change (CIC) of trees identified as being released differed more than twofold between methods, from −0.33 (radial-growth averaging) to −0.68 (time-series). False positives (type I error) were more common in forests with low severity disturbance, whereas false negatives (type II error) occurred more often in forests with high severity disturbance. Sensitivity analysis indicated that reductions of the detection threshold and the length of the time window significantly increased detected stand-level disturbance severity across all methods. Radial-growth averaging and absolute-increase methods had lower levels of type I and II error in detecting disturbance events with our datasets. Parameter settings play a key role in the accuracy of reconstructing disturbance history regardless of the method. Time-series and radial-growth averaging methods require the least amount of a priori information, but only the time-series method quantified the subsequent growth increment related to a reduction in competition. Finally, we recommend yearly binning of releases using a kernel density estimation function to identify local maxima indicating disturbance. Kernel density estimation improves reconstructions of forest history and, thus, will further our understanding of past forest dynamics.
Isolation of habitats in space and time affects species globally and in a multitude of ecosystems. It is however often difficult to assess the level of isolation from the point of view of the focal species. Indicator species are often used to assess 'conservation value' of habitats. One such approach involves the use of wood-decaying fungal species as indicators of near-natural forests, continuity in old-forest characteristics over time, and/or presence of red-listed species, but not of spatial connectivity. The indicator species were commonly assigned based on expert opinions, but few scientific evaluations have been performed of what these species actually indicate. Building on previous classifications of wood-decaying fungal indicator species on Norway spruce, we hypothesized that indicator species would differ from non-indicator species in how they respond to local temporal connectivity (forest age, the intensity of historical selective logging and the presence of well-decomposed large logs), and to local and landscape-scale spatial connectivity (local forest area, local amount of deadwood and the connectivity to old forest in the surrounding landscape). Based on fungal occurrence data from a fixed number of spruce logs at 28 sites distributed across the Scandinavian Peninsula, we explored the spatiotemporal scales at which the local communities were affected by connectivity. Indicator species showed the strongest response to connectivity of old forest (≥80 years) within 100 km, while non-indicator species depended on connectivity of younger forest (≥40 years) at a smaller spatial scale (≤25 km). Indicator species increased and non-indicator species decreased in total abundance with the increasing age of the local forest stand. Landscape-scale old-forest connectivity was beneficial for indicator species in all sites except those with relatively low amount of deadwood, while non-indicator species showed the opposite pattern. We identify a threshold of around 29 m 3 ha −1 in the amount of spruce logs where indicator species become abundant enough to influence non-indicator species through competitive interactions. There was a pronounced uniformity within each species group in the connectivity responses. We conclude that the studied indicator species indicate high forest age, high amount of resources and, given that the resources are plentiful, also high old-forest connectivity, but they do not indicate a long history without any logging operations or local deadwood continuity. The studied non-indicator species did not indicate any of the studied spatiotemporal connectivity variables. Indicator species are usually red-listed and may continue to decline in the future without habitat restoration efforts.
The book is written in German.
Teil 1. Makromyzeten.
Zusammenfassung
Dieses Buch ist ein Verzeichnis aller in Österreich bisher festgestellten Basidienpilze (Basidiomycota) mit Ausnahme der Rost- und Brandpilze und zudem der Becherpilze (Pezizales) aus der Abteilung der Schlauchpilze (Ascomycota). Diese Pilzgruppen bilden mit freiem Auge gut sichtbare Fruchtkörper und werden deshalb als „Makromyzeten“ (Großpilze) bezeichnet. Ein solches Artenverzeichnis kann keinen Anspruch auf Vollständigkeit erheben. Jedoch wurde durch aufwändige Recherchen, die Zuarbeit vieler Datenbringer und eine hohe Sorgfalt bei der Erstellung der Liste versucht, eine annähernde Vollständigkeit zu erzielen.
Das Verzeichnis beinhaltet insgesamt über 4.450 Pilztaxa (4.100 Arten, 260 Varietäten und 100 Formen) und dokumentiert damit den hohen Anteil der Pilze an der Artenvielfalt Österreichs. Es ist der erste Artenkatalog für Großpilze Österreichs in diesem Umfang.
Das Verzeichnis basiert auf der „Datenbank der Pilze Österreichs“ mit exakt 475.013 gespeicherten Pilznachweisen von 13.652 Fundorten in Österreich bzw. aus 443 Datenquellen (Stand vom September 2016). Weniger als 1.000 Pilzarten (21 %) sind in Österreich „häufig bis sehr häufig“, etwa 1.700 Arten (38 %) sind „verbreitet bis mäßig häufig“, etwa 1.300 Arten (30 %) sind „selten“ und beinahe 500 Arten (11 %) sind in Österreich nur von einem einzigen Nachweis bekannt.
Im Verzeichnis werden für jede Pilzart neben dem wissenschaftlichen und dem deutschen Pilznamen folgende Informationen angeführt: Zuordnung zu einer Formengruppe und zu einer ökologischen (trophischen) Gruppe, allfällige Bindung an eine Pflanzengattung, Häufigkeit in Österreich innerhalb bzw. außerhalb des Alpenraums, Vorkommen in den Bundesländern, Anzahl der älteren (vor 1990) und der neueren Fundorte (seit 1990). Eine umfangreiche Liste von synonymen Pilznamen mit der Referenz zum jeweils aktuellen Pilznamen im Verzeichnis ist angefügt. Das Literaturverzeichnis inkludiert alle vorliegenden und ausgewerteten Datenquellen zu Pilznachweisen in Österreich.
Gleichzeitig wird in diesem Buch eine völlig neu bearbeitete Version der Roten Liste gefährdeter Pilze Österreichs vorgelegt. Von den über 4.450 Pilzarten im vorliegenden Verzeichnis müssen ca. 1.300 Arten (= 29 %) als gefährdet, stark gefährdet oder vom Aussterben bedroht gelten, weitere 790 Arten (= 17 %) als potentiell gefährdet. Die aktuelle Rote Liste umfasst daher insgesamt 2.086 Arten (= 46 %) und ist direkt in das Gesamtverzeichnis aller Pilzarten integriert.
Für jede gefährdete Pilzart werden steckbriefartig die Naturräume (Regionen in Österreich) sowie die gefährdeten Lebensräume aufgezählt, in denen die Art vorkommt, für jede stark gefährdete Pilzart werden außerdem die einzelnen Nachweise (Funde) in Österreich exemplarisch angeführt und die Gefährdungssituation kommentiert. Viele der gefährdeten Pilzarten sowie ihre gefährdeten Lebensräume werden mit Farbfotos abgebildet.
Die Gefährdungsgrade werden sowohl nach dem herkömmlichen und bewährten System mit den Kategorien 0 bis 4 angegeben, als auch mit IUCN-Kategorien. Die Hauptkriterien für die Bewertung des Gefährdungspotenzials sind, neben verschiedenen anderen Risikofaktoren, die Verbreitungsdichte in Österreich (Anzahl der neueren Fundorte) sowie die Bindung an gefährdete Lebensräume (entsprechend der „Liste der gefährdeten Biotoptypen Österreichs“).
Die Pilzarten der Kategorien 0 bis 3 verteilen sich auf neun Gruppen von Lebensraum-Typen wie folgt: 1. Lebensräume der Auen (180 Arten), 2. Moore und weitere Feuchtlebensräume (230 Arten), 3. Grasländer und Offenland-Lebensräume (200 Arten), 4. Laubwälder der kollinen und submontanen Stufe (200 Arten), 5. Mischwälder der montanen Stufe (140 Arten), 6. Lebensräume der hochmontanen und subalpinen Stufe (110 Arten), 7. Lebensräume der alpinen Stufe (100 Arten), 8. Synanthrope Gehölz-Lebensräume (wenige Arten), 9. Weitere Lebensräume (80 Arten).
Als hauptsächliche Ursachen für die Gefährdung der Pilzarten Österreichs werden folgende Faktoren erläutert: Gefährdungsfaktoren, Eutrophierung (Überangebot an Nährstoffen), Vernichtung von Lebensräumen, verminderte ökologische Wertigkeit von Lebensräumen, Zufallsereignisse und Auswirkungen der Klimaerwärmung.
Der Schutz gefährdeter Pilzarten betrifft verschiedene Ebenen, drei Bereiche werden besonders hervorgehoben und diskutiert: Strukturelle Maßnahmen am Standort (besonders in Wäldern), Artenkenntnis, Bildung und Öffentlichkeitsarbeit sowie Internationale Schutzbestrebungen.
In Bezug auf die in Österreich gerne gesammelten Speisepilze wird festgestellt, dass – unter Berücksichtigung der maßgeblichen Kriterien – für die gängigen und beliebtesten Speisepilzarten (mit Ausnahme des Kaiserlings) aktuell keine Gefährdung im Sinne der Roten Liste besteht.
Einen umfangreichen Teil dieses Buches nehmen schließlich statistische Auswertungen ein. Dabei wird die Anzahl der Pilzarten in Österreich, sowie speziell die Anzahl der Rote Liste-Arten, nach zahlreichen verschiedenen Parametern analysiert: Systematische Gruppen, Jahrzehnte (Dekaden), Jahre, Bundesländer, biogeografische Regionen, naturräumliche Regionen, Höhenstufen, Meereshöhen, Klimatypen, Niederschlag, Temperatur, Gesteinsuntergrund (Karbonat bzw. Silikat), ökologische Gruppen, assoziierte Pflanzengattungen insgesamt bzw. speziell für substratgebundene Pilzarten, Monate und Wochen im Jahresverlauf. Am Beispiel von Schutzgebieten, einschließlich aller Nationalparks Österreichs, wird dargestellt, wie sehr die Anzahl der nachgewiesenen Arten (speziell die Zahl der aus einem Gebiet bekannten gefährdeten Pilzarten) von einer hohen oder geringen Untersuchungsintensität abhängen.
Eine Liste von über 100 Personen ist angefügt, die bei einer größeren Anzahl von Pilznachweisen als Finder (Beobachter, Sammler) genannt sind; sie haben maßgeblich zur Entstehung dieses Verzeichnisses beigetragen.
Abstract:
part 1. Macromycetes
This book presents a list of almost all basidiomycetes (Basidiomycota), which have been found in Austria, except rust and smut fungi, and discomycetes (Pezizales, Ascomycota). These fungal groups form fruit bodies well-visible with the naked eye and are therefore referred to as "macromycetes" (large mushrooms).
The list contains a total of 4,450 Pilztaxa (4,100 species, 260 varieties and 100 forms), thus documenting the high percentage of the fungi within the species biodiversity of Austria. It is the first species catalogue for macromycetes in Austria to this extent.
The list is based on the "Database of fungi in Austria" with exactly 475,013 fungal records from 13,652 localities in Austria and from 443 data sources (as of September 2016). In Austria, less than 1,000 species (21%) are "frequent to very frequent", about 1,700 species (38%) are "widespread to moderately frequent", about 1,300 species (30%) are "rare" and almost 500 species (11 %) are only known from one single record.
In addition to the scientific and the German fungus name, the following information is given for each species: allocation to a systematic group in broad sense and an ecological (trophic) guild, possible binding to a plant genus, frequency in Austria within or outside the Alpine area, occurrence in the federal states, number of older (before 1990) and more recent localities (since 1990). An extensive list of synonyms with reference to the current fungal name in the list is attached. The literature lists all available and evaluated data sources of fungal records in Austria.
At the same time, this book presents a completely revised version of the Red List of endangered fungi in Austria. Of the more than 4,450 species of fungi in the present list, approximately 1,300 species (= 29%) are vulnerable, endangered, critically endangered or regionally extinct, while 790 species (= 17%) are near threatened. The actual red list thus comprises a total of 2,086 species (= 46%) and is integrated directly into the list of all macromycetes.
For each endangered fungus species, the natural habitats (regions in Austria) as well as the vulnerable habitats are listed, in which the species occurs, for each endangered or critically endangered species the individual records (finds) in Austria are exemplarily given and the threat situation is commented. Many of the endangered species and their endangered habitats are illustrated with colour photos.
The categories are indicated both by the conventional and proven system with the categories 0 to 4, as well as with IUCN categories. In addition to various other risk factors, the main criteria for the assessment of the potential threat are the distribution density in Austria (number of recent localities) and their binding to endangered habitats (according to the "list of endangered biotope types in Austria").
The fungal species of categories 0 to 3 are distributed among nine groups of habitat types as follows: 1. Habitats of the floodplain (180 species), 2. Bogs and other moist habitats (230 species), 3. Grasslands and open land habitats (200 species), 4. Deciduous forests of the colline and submontane altitudinal zone (200 species), 5. Mixed forests of the montane zone (140 species), 6. Habitats of the upper montane and subalpine zone (110 species), 7. Habitats of the alpine zone (100 species), 8. Synantrop bosk habitats (few species), 9. Other habitats (80 species).
The following factors are elucidated as the main reasons of threat to Austria's fungal species: risk factors, eutrophication (over-supply of nutrients), destruction of habitats, reduced ecological value of habitats, random events and effects of climate warming.
The protection of endangered fungal species affects different fields; three of them are highlighted and discussed: Structural measures at the site (especially in forests), species awareness, education and public relations as well as international conservation efforts.
With regard to the edible mushrooms collected in Austria, it can be stated that - given the relevant criteria - there is currently no danger for the most popular mushrooms in the sense of the red list (except Amanita caesarea).
Finally, a comprehensive section of this book contains statistical evaluations. The number of fungal species in Austria, as well as the number of red list species, is analysed according to numerous different parameters: systematic groups, decades, years, federal states, biogeographical regions, nature regions, altitudinal zones, altitude, climate types, rainfall, temperature, bedrock (carbonate or silicate), ecological groups, associated plant genera in general or especially for substrate-bound fungi, months and weeks in the course of the year. Using the example of protected areas, including all national parks in Austria, it is shown to which extent the number of species reported (especially the number of endangered fungal species known from a locality) depends on a high or low intensity of investigation.
A list of more than 100 persons is attached, which are recorded as a finder (observer, collector) for a larger number of fungal data; they have contributed significantly to the development of this list.
Limited knowledge of dispersal for most organisms hampers effective connectivity conservation in fragmented landscapes. In forest ecosystems, deadwood-dependent organisms (i.e., saproxylics) are negatively affected by forest management and degradation globally. We reviewed empirically established dispersal ecology of saproxylic insects and fungi. We focused on direct studies (e.g., mark-recapture, radiotelemetry), field experiments, and population genetic analyses. We found 2 somewhat opposite results. Based on direct methods and experiments, dispersal is limited to within a few kilometers, whereas genetic studies showed little genetic structure over tens of kilometers, which indicates long-distance dispersal. The extent of direct dispersal studies and field experiments was small and thus these studies could not have detected long-distance dispersal. Particularly for fungi, more studies at management-relevant scales (1-10 km) are needed. Genetic researchers used outdated markers, investigated few loci, and faced the inherent difficulties of inferring dispersal from genetic population structure. Although there were systematic and species-specific differences in dispersal ability (fungi are better dispersers than insects), it seems that for both groups colonization and establishment, not dispersal per se, are limiting their occurrence at management-relevant scales. Because most studies were on forest landscapes in Europe, particularly the boreal region, more data are needed from nonforested landscapes in which fragmentation effects are likely to be more pronounced. Given the potential for long-distance dispersal and the logical necessity of habitat area being a more fundamental landscape attribute than the spatial arrangement of habitat patches (i.e., connectivity sensu strict), retaining high-quality deadwood habitat is more important for saproxylic insects and fungi than explicit connectivity conservation in many cases.
Mixed-severity disturbance regimes are prevalent in temperate forests worldwide, but key uncertainties remain regarding the variability of disturbance-mediated structural development pathways. This study investigates the influence of disturbance history on current structure in primary, unmanaged Norway spruce (Picea abies) forests throughout the Carpathian Mountains of central and eastern Europe, where windstorms and native bark beetle outbreaks are the dominant natural disturbances. We inventoried forest structure on 453 plots (0.1 ha) spanning a large geographical gradient (\>1,000 km), coring 15–25 canopy trees per plot for disturbance history reconstruction (tree core total n = 11,309). Our specific objectives were to: (1) classify sub-hectare-scale disturbance history based on disturbance timing and severity; (2) classify current forest structure based on tree size distributions (live, dead, standing, downed); (3) characterize structural development pathways as revealed by the association between disturbance history and current forest structural complexity. We used hierarchical cluster analysis for the first two objectives and indicator analysis for the third. The disturbance-based cluster analysis yielded six groups associated with three levels of disturbance severity (low, moderate, and high canopy loss) and two levels of timing (old, recent) over the past 200 years. The structure-based cluster analysis yielded three groups along a gradient of increasing structural complexity. A large majority of plots exhibited relatively high (53\%) or very high (26\%) structural complexity, indicated by abundant large live trees, standing and downed dead trees, and spruce regeneration. Consistent with conventional models of structural development, some disturbance history groups were associated with specific structural complexity groups, particularly low-severity/recent (very high complexity) and high-severity/recent (moderate complexity) disturbances. In other cases, however, the distribution of plots among disturbance history and structural complexity groups indicated either divergent or convergent pathways. For example, multiple disturbance history groups were significantly associated with the high complexity group, demonstrating structural convergence. These results illustrate that complex forest structure – including features nominally associated with old-growth – can be associated as much with disturbance severity as it is with conventional notions of forest age. Because wind and bark beetles are natural disturbance processes that can induce relatively high levels of tree mortality while simultaneously contributing to structural complexity and heterogeneity, we suggest that forest management plans allow for the stochastic occurrence of disturbance and variable post-disturbance development trajectories. Such applications are especially appropriate in conservation areas where biodiversity and forest resilience are management objectives, particularly given projections of increasing disturbance activity under global change.
The increasing demand for wood products increases the anthropogenic pressure on biodiversity in forests. Thereby integrative nature conservation strategies, allowing for both, wood production and biodiversity conservation, increase in importance. While many of such strategies are now implemented, the success is often unclear. We evaluated the success of a deadwood enrichment strategy in a large hardwood production forest shortly (four and nine years) after its implementation. We compared plot wise data of deadwood amounts in managed stands of an even aged high forest and forest nature reserves before and after the implementation of the strategy, and used generalized additive boosting models to identify major drivers of deadwood amounts and deadwood enrichment. Deadwood amounts before and after the implementation of the strategy were affected by stand age, natural tree mortality and tree species composition. The highest amounts of deadwood were found in stands around 100 years old, with a high natural mortality and a high percentage of deciduous trees. Harvesting intensity was a strong driver of deadwood enrichment. Besides that we found smaller differences between managed and unmanaged forests after the implementation. We conclude that active deadwood enrichment can be a valuable tool to increase deadwood amounts in production forests.
Spatial heterogeneity is an inherent property of any living environment and is expected to favour biodiversity due to a broader niche space. Furthermore, edges between different habitats can provide additional possibilities for species coexistence. Using computer simulations, this study examines metacommunities consisting of several trophic levels in heterogeneous environments in order to explore the above hypotheses on a community level. We model heterogeneous landscapes by using two different sized resource pools and evaluate the combined effect of dispersal and heterogeneity on local and regional species diversity. This diversity is obtained by running population dynamics and evaluating the robustness (i.e., the fraction of surviving species). The main results for regional robustness are in agreement with the habitat heterogeneity hypothesis, as the largest robustness is found in heterogeneous systems with intermediate dispersal rates. This robustness is larger than in homogeneous systems with the same total amount of resources. We study the edge effect by arranging the two types of resources in two homogeneous blocks. Different edge responses in diversity are observed, depending on dispersal strength. Local robustness is highest for edge habitats that contain the smaller amount of resource in combination with intermediate dispersal. The results show that dispersal is relevant to correctly identify edge responses on community level.
The Red-belted Bracket (Fomitopsis pinicola) is one of the major decomposers of coniferous wood in Europe and can reach high densities after outbreaks of bark beetles. However, factors of dead wood type and decay stage, which determine the growth of reproductive biomass, i.e. basidiomes, remain unclear. In 2013, we surveyed 1280 dead wood objects and vital trees in spruce stands killed by the bark beetle Ips typographus in 2012, 2002, 1992 and in undisturbed stands for the presence, number, mean basidiome size and total volume of basidiomes. Living basidiomes were equally abundant on dead wood 1, 11, and 21 y after bark beetle outbreak, but were lacking on living trees. Our results indicate that F. pinicola is an effective early colonizer of the huge resource pulse of dead wood caused by the outbreak of bark beetles and basidiomes can persist for 21 y.
Diversity of forest macrofungal communities is strongly influenced by various management approaches. These effects have so far only been studied in certain types of forest stands and with limited sampling effort. Here we studied the fruit bodies of all macrofungal trophic groups on 80 permanent plots (2500 m² each) in forest stands differing in tree species composition and management practice. Unmanaged forests were shown to be the species-richest at the plot scale and also when the total fungal species richness of the studied forest types was compared. Diversity patterns varied between functional groups – unmanaged forests stand out in richness of wood-inhabiting fungi, while ectomycorrhizal species were more diverse in managed stands. Terrestrial saprotrophic species were similarly highly diverse in both managed and unmanaged mixed forest stands. The highest number of indicator species, predominantly wood-inhabiting fungi, was associated with unmanaged stands. We discuss a list of the most faithful indicator species along with their substratum preferences.
In order to gauge ongoing and future changes to disturbance regimes, it is necessary to establish a solid baseline of historic disturbance patterns against which to evaluate these changes. Further, understanding how forest structure and composition respond to variation in past disturbances may provide insight into future resilience to climate-driven alterations of disturbance regimes.
We assessed how environmental drivers influence the occurrences of wood-inhabiting macrofungi in European beech forests, using an extensive dataset of fruit body records collected in 53 reserves across twelve European countries. We found that the 105 species included in this study varied greatly in their responses to covariates related to resource quality, climate and forest connectivity, both in the strength and direction of the observed effects. Climate was the most important driver for some species, while others responded more to connectivity, or simply to the presence of high quality substrates within the reserves. Species occurrences varied also across geographical regions, especially between the UK and the rest of Europe. Our results show that wood-inhabiting fungi in European beech forests respond individualistically to habitat filters and differ in their biogeographical distribution patterns, and they thus provide a detailed perspective of how wood-inhabiting fungal communities are structured across Europe.
Mountain forests are among the most important ecosystems in Europe as they support numerous ecological, hydrological, climatic, social, and economic functions. They are unique relatively natural ecosystems consisting of long-lived species in an otherwise densely populated human landscape. Despite this, centuries of intensive forest management in many of these forests have eclipsed evidence of natural processes, especially the role of disturbances in long-term forest dynamics. Recent trends of land abandonment and establishment of protected forests have coincided with a growing interest in managing forests in more natural states. At the same time, the importance of past disturbances highlighted in an emerging body of literature, and recent increasing disturbances due to climate change are challenging long-held views of dynamics in these ecosystems. Here, we synthesize aspects of this Special Issue on the ecology of mountain forest ecosystems in Europe in the context of broader discussions in the field, to present a new perspective on these ecosystems and their natural disturbance regimes. Most mountain forests in Europe, for which long-term data are available, show a strong and long-term effect of not only human land use but also of natural disturbances that vary by orders of magnitude in size and frequency. Although these disturbances may kill many trees, the forests themselves have not been threatened. The relative importance of natural disturbances, land use, and climate change for ecosystem dynamics varies across space and time. Across the continent, changing climate and land use are altering forest cover, forest structure, tree demography, and natural disturbances, including fires, insect outbreaks, avalanches, and wind disturbances. Projected continued increases in forest area and biomass along with continued warming are likely to further promote forest disturbances. Episodic disturbances may foster ecosystem adaptation to the effects of ongoing and future climatic change. Increasing disturbances, along with trends of less intense land use, will promote further increases in coarse woody debris, with cascading positive effects on biodiversity, edaphic conditions, biogeochemical cycles, and increased heterogeneity across a range of spatial scales. Together, this may translate to disturbance-mediated resilience of forest landscapes and increased biodiversity, as long as climate and disturbance regimes remain within the tolerance of relevant species. Understanding ecological variability, even imperfectly, is integral to anticipating vulnerabilities and promoting ecological resilience, especially under growing uncertainty. Allowing some forests to be shaped by natural processes may be congruent with multiple goals of forest management, even in densely settled and developed countries.
Severe natural disturbances are common in many forest ecosystems, particularly in the Northern
Hemisphere. Attempts to minimize their effects through forest management include salvage logging.
In the Bohemian Forest, one of Central Europe’s largest continuous forests, windstorms and bark beetle
outbreaks have affected stands of Norway Spruce for centuries. Over the past decades, these natural
disturbances and their management in the Bavarian Forest National Park and the adjacent Šumava
National Park in the central part of the Bohemian Forest have been scientifically studied. Owing to a
benign-neglect strategy, both windstorms and bark beetle outbreaks have increased stand structural
heterogeneity, the amount of dead wood and light availability, which contribute to increased populations
of nearly-extinct forest specialists. However, the response of a particular taxonomic group or species
strongly depends on its relationship to specific legacies that persist after disturbances. Stand climate
but not dead wood appears to greatly influence the diversity of epigeal bryophytes, whereas both factors
determine the diversity of epixylic bryophytes. Both the amount and heterogeneity of dead wood seems
to be more important than stand climate in determining assemblages of wood-inhabiting fungi and
lichens. To reduce the population density of bark beetles in the management zones of both national parks,
storm-felled spruces are salvage logged, which alters a variety of these legacies and natural successional
pathways. Consequently, the numbers of species of wood-inhabiting fungi, saproxylic beetles and
epixylic lichens are reduced. Natural levels of biodiversity in salvage-logged areas can be preserved by
(1) preserving root plates of storm-felled trees with partly retained trunks; (2) avoiding soil disturbance
by using cable yarding instead of harvesters; (3) retaining sun-exposed dry branches of storm-felled trees
and snags of beetle-killed spruces; (4) avoiding logging damage of natural regeneration and of large trees
that survive disturbances; and (5) bark scratching instead of debarking to avoid bark beetle outbreaks
while maintaining biodiversity. Windstorms and bark beetle outbreaks could be utilized to restore
intensely managed forests of Central Europe to their natural composition and structure. Furthermore,
experimentally mimicked natural disturbances might help in gaining a mechanistic understanding of
how natural disturbances affect biodiversity.