Maintaining or increasing forest carbon sinks is considered essential for mitigating the rise in atmospheric CO2 concentrations. In contrast, harvesting trees is perceived as having negative consequences for both the standing biomass stocks and the carbon sink strength. However, the forest carbon sink needs to be examined from a forest stand canopy perspective, where assimilation predominantly occurs in temperate forests. Here we show that a threshold of leaf area exists beyond which additional leaves do not contribute to CO2 uptake. The associated biomass can be harvested without affecting the forest carbon uptake. Based on eddy covariance measurements, we show that CO2 uptake (gross primary production - GPP) and net ecosystem exchange (NEE) in temperate forests are of a similar magnitude in both unmanaged and sustainably managed forests, on the order of 1500-1600 gCm-2yr-1 for GPP and 542-483 gCm-2yr-1 for NEE. A threshold located between 3 and 4.5 m2m-2 LAI (leaf area index) can be used for sustainable harvesting with regard to CO2 uptake. Simulations based on the LPJ-GUESS (Lund-Potsdam-Jena General Ecosystem Simulator) model reproduce the saturation of GPP and NEP and the convergence on the LAI threshold range. Accordingly, in temperate managed forests, trees can be harvested while maintaining a high tree biomass and carbon sink of the remaining stand. In this case, competition between neighboring trees in unmanaged forests is replaced by harvest management and provision of wood products. No difference in the LAI productivity response was observed between managed and unmanaged sites.

Besides their symbiotic association with tree rootlets, ectomycorrhizal (EM) fungi have been commonly detected in nature in deadwood and plant debris of various tree species. However, their potential dual roles as symbiotrophs and saprotrophs are still debated. Here, we provide evidence from a series of experiments on the plasticity of symbiotrophic-saprotrophic lifestyles of the ectomycorrhizal fungus Piloderma croceum associated with Quercus robur L. Specifically, we find that P. croceum efficiently colonizes deadwood of oak in an experimental system without living oak. Results based on the productions of hydrolytic enzymes and corticrocin as well as the 14C content in deadwood and mycelium of P. croceum demonstrate its capability of wood decomposition and assimilation of C from the decomposing wood. Our results also show that in presence of wood pieces colonized by saprotrophic mycelium of P. croceum, the roots of oak plants develop true EM symbiosis with Hartig net formation. Collectively, our results indicate a role for mycelium growing in deadwood as an underestimated EM fungus propagule bank, suggesting that deadwood and other decomposing plant material may indirectly influence the productivity of forest ecosystems by contributing to the recruitment of mycorrhizal fungi, thereby enhancing plant nutrient acquisition.

Amplicon sequencing of the nuclear ribosomal 5S RNA gene arrays is highly promising for genotaxonomy, to delineate genetic resources of species and trace their evolution. However, the huge amount of data retrieved with this approach is difficult to manage and prone to redundancy, error, and computational difficulties. Reducing the amount of data per sample without losing molecular-phylogenetic signal is therefore a crucial step for downstream analyses. In this work, we compared operational taxonomic units (OTUs, 100% identity) and amplicon sequence variants (ASVs) from 5S intergenic spacer (5S-IGS) amplicons of seven beech species (Fagus spp.) obtained with two widely used and competing bioinformatics tools, MOTHUR and DADA2. We assessed quantitative (total number of sequences retrieved, proportion of sequences unique or shared across the different data sets) and qualitative (sample diversity, data ruggedness and congruence of the obtained phylogenies) differences among sample data profiles obtained with the two methods, and the capacity of the inferred phylogenies to capture diagnostic 5S-IGS variant types. Over 70% of processed reads were shared between OTUs and ASVs. Despite a strong reduction (> 80%) of the representative sequences, DADA2-ASVs identified all main 5S-IGS variants known for Fagus, reflecting the phylogenetic, taxonomic and diversity patterns expected for each sample. In contrast, MOTHUR generated large proportions of rare OTUs and ASVs that complicated the obtained phylogenies and were inference-wise redundant. We conclude that differences in the sequence variation detected by the two pipelines are minimal and do not result in different phylogenetic information. The more effective and computationally more efficient DADA2 ASVs may thus replace OTUs in future 5S-IGS studies dealing with complex bioecological phenomena such as hybridisation, polyploidisation, drift and inferring evolutionary pathways of species systems, especially when using increasingly large sample sets.

Carbon (C) assimilation can be severely impaired during periods of environmental stress, like drought or defoliation, making trees heavily dependent on the use of C reserve pools for survival; yet, the dynamics of reserve use during periods of reduced C supply are still poorly understood. We used stem girdling in mature poplar trees (Populus tremula L. hybrids), a lipid-storing species, to permanently interrupt the phloem C transport and induced C shortage in the isolated stem section below the girdle and monitored metabolic activity during three campaigns in the growing seasons of 2018, 2019 and 2021. We measured respiratory fluxes (CO2 and O2), non-structural carbon concentration, the respiratory substrate (based on isotopic analysis and CO2/O2 ratio) and the age of the respiratory substrate (based on radiocarbon analysis). Our study shows that poplar trees can survive long periods of reduced C supply from the canopy by switching in metabolism from recent carbohydrates to older storage pools with a potential mixture of respiratory substrates, including lipids. This mechanism of stress resilience can explain why tree decline may take many years before death occurs.

Poly(butylene succinate-co-adipate) (PBSA), a biodegradable plastic, is significantly colonized and degraded by soil microbes under natural field conditions, especially by fungal plant pathogens, raising concerns about potential economic losses. This study hypothesizes that the degradation of biodegradable plastics may increase the presence and abundance of plant pathogens by serving as an additional carbon source, ultimately posing a risk to forest ecosystems. We investigated (i) fungal plant pathogens during the exposure of PBSA in European broadleaved and coniferous forests (two forest types), with a specific focus on potential risk to tree health, and (ii) the response of such fungi to environmental factors, including tree species, soil pH, nutrient availability, moisture content, and the physicochemical properties of leaf litter layer. Next-generation sequencing (NGS) revealed that PBSA harbored a total of 318 fungal plant pathogenic amplicon sequence variants (ASVs) belonging to 108 genera. Among the identified genera (Alternaria, Nectria, Phoma, Lophodermium, and Phacidium), some species have been reported as causative agents of tree diseases. Plenodomus was present in high relative abundances on PBSA, which have not previously been associated with disease in broadleaved and coniferous forests. Furthermore, the highest number of fungal plant pathogens were detected at 200 days of PBSA exposure (112 and 99 fungal plant pathogenic ASV on PBSA degraded under Q. robur and F. sylvatic-dominated forest, respectively), which was double compared mature leaves and needles from the same forest sites. These findings suggest that PBSA attracts fungal plant pathogens in forests as an additional carbon source, potentially leading to increased disease outbreaks and disrupting the stability of forest ecosystems. The fungal plant pathogenic community compositions were mainly shaped by forest type, PBSA exposure time, site locations, leaf litter layer water content, and N:P ratio from leaf litter layer in both forest types. This study provides valuable insights into the potential risks posed by biodegradable plastic degradation in forests after 200 and 400 days of exposure, respectively. Further comprehensive evaluations of their effects on tree health and ecosystems, ideally on a long-term basis, are needed. These evaluations should include integrating microbial investigation, soil health monitoring, and ecosystem interaction assessments. Nevertheless, it should be noted that our interpretation of plant pathogens is solely based on high-throughput sequencing, bioinformatics, and annotation tools.

Standard models of speciation assume strictly dichotomous genealogies in which a species, the ancestor, is replaced by two offspring species. The reality is more complex: plant species can evolve from other species via isolation when genetic drift exceeds gene flow; lineage mixing can give rise to new species (hybrid taxa such as nothospecies and allopolyploids). The multi-copy, potentially multi-locus 5S rDNA is one of few gene regions conserving signal from dichotomous and reticulate evolutionary processes down to the level of intra-genomic recombination. Here, we provide the first high-throughput sequencing (HTS) 5S intergenic spacer (5S-IGS) data for a lineage of wind-pollinated subtropical to temperate trees, the Fagus crenata – F. sylvatica s.l. lineage, and its distant relative F. japonica . The observed 4,963 unique 5S-IGS variants reflect a long history of repeated incomplete lineage sorting and lineage mixing since the early Cenozoic of two or more paralogous-homoeologous 5S rDNA lineages. Extant species of Fagus are genetic mosaics and, at least to some part, of hybrid origin.

Extreme weather events are occurring more frequently, and research has shown that plant diversity can help mitigate the impacts of climate change by increasing plant productivity and ecosystem stability. Although soil temperature and its stability are key determinants of essential ecosystem processes, no study has yet investigated whether plant diversity buffers soil temperature fluctuations over long-term community development. Here we have conducted a comprehensive analysis of a continuous 18-year dataset from a grassland biodiversity experiment with high spatial and temporal resolutions. Our findings reveal that plant diversity acts as a natural buffer, preventing soil heating in hot weather and cooling in cold weather. This diversity effect persists year-round, intensifying with the aging of experimental communities and being even stronger under extreme climate conditions, such as hot days or dry years. Using structural equation modelling, we found that plant diversity stabilizes soil temperature by increasing soil organic carbon concentrations and, to a lesser extent, plant leaf area index. Our results suggest that, in lowland grasslands, the diversity-induced stabilization of soil temperature may help to mitigate the negative effects of extreme climatic events such as soil carbon decomposition, thus slowing global warming. Plant diversity stabilizes grassland soil temperature by boosting soil organic carbon and increasing plant leaf area, according to an 18-year plant diversity experiment.

We propose a long-overdue subgeneric classification of Fagus and revision of its western Eurasian taxa based on population-level sampling of morphological and molecular data. The molecular sequence data bolstering this classification derive from nuclear-encoded genetic markers. Fagus subg. Fagus comprises twelve species, of which two occur in North America, four in western Eurasia, and six in EastAsia. Fagus subg. Englerianae Denk & G. W. Grimm comprises three East Asian species. Application of a new species concept using fine-scale data justifies the recognition of previously overlooked cryptic taxa. Beech trees from western Eurasia are currently treated as one species, F. sylvatica L., with two subspecies. Despite this, several previous studies pointed out distinct differences between beech populations from Europe, Turkey, the Caucasus region, and the Hyrcanian forest region including the Talysh Mountains of Azerbaijan and the forests south of the Caspian Sea in Iran. All newly generated data indicate that the various Oriental beeches reflect divergences and speciation processes predating the split between the European beech and its eastern siblings. Therefore, based on morphological and molecular differences, we recognize four species in western Eurasia, the European F. sylvatica L., the chiefly northwestern Turkish F. orientalis Lipsky, the Caucasian F. hohenackeriana Palib., and the Hyrcanian F. caspica Denk & G. W. Grimm. Diagnostic genotypic characteristics are included in the descriptions.

Recently, a new annotation tool “FungalTraits” was created based on the previous FUNGuild and Fun Fun databases, which has attracted high attention in the scientific community. These databases were widely used to gain more information from fungal sequencing datasets by assigning fungal functional traits. More than 1500 publications so far employed FUNGuild and the aim of this study is to compare this successful database with the recent FungalTraits database. Quality and quantity of the assignment by FUNGuild and FungalTraits to a fungal internal transcribed spacer (ITS)–based amplicon sequencing dataset on amplicon sequence variants (ASVs) were addressed. Sequencing dataset was derived from leaves and needles of 12 temperate broadleaved and coniferous tree species. We found that FungalTraits assigned more functional traits than FUNGuild, and especially the coverage of saprotrophs, plant pathogens, and endophytes was higher while lichenized fungi revealed similar findings. Moreover, ASVs derived from leaves and needles of each tree species were better assigned to all available fungal traits as well as to saprotrophs by FungalTraits compared to FUNGuild in particular for broadleaved tree species. Assigned ASV richness as well as fungal functional community composition was higher and more diverse after analyses with FungalTraits compared to FUNGuild. Moreover, datasets of both databases showed similar effect of environmental factors for saprotrophs but for endophytes, unidentical patterns of significant corresponding factors were obtained. As a conclusion, FungalTraits is superior to FUNGuild in assigning a higher quantity and quality of ASVs as well as a higher frequency of significant correlations with environmental factors.

Poly(butylene succinate-co-adipate) (PBSA) degradation and its plastisphere microbiome in cropland soils have been studied; however, such knowledge is limited in the case of forest ecosystems. In this context, we investigated: i) the impact of forest types (conifer and broadleaved forests) on the plastisphere microbiome and its community assembly, ii) their link to PBSA degradation, and iii) the identities of potential microbial keystone taxa. We determined that forest type significantly affected microbial richness (F = 5.26-9.88, P = 0.034 to 0.006) and fungal community composition (R2 = 0.38, P = 0.001) of the plastisphere microbiome, whereas its effects on microbial abundance and bacterial com-munity composition were not significant. The bacterial community was governed by stochastic processes (mainly homogenizing dispersal), whereas the fungal community was driven by both stochastic and deterministic processes (drift and homogeneous selection). The highest molar mass loss was found for PBSA degraded under Pinus sylvestris (26.6 +/- 2.6 to 33.9 +/- 1.8 % (mean +/- SE) at 200 and 400 days, respectively), and the lowest molar mass loss was found under Picea abies (12.0 +/- 1.6 to 16.0 +/- 0.5 % (mean +/- SE) at 200 and 400 days, respectively). Important fungal PBSA decomposers (Tetracladium) and atmospheric dinitrogen (N2)-fixing bacteria (symbiotic: Allorhizobium- Neorhizobium-Pararhizobium-Rhizobium and Methylobacterium and non-symbiotic: Mycobacterium) were identified as potential keystone taxa. The present study is among the first to determine the plastisphere microbiome and its commu-nity assembly processes associated with PBSA in forest ecosystems. We detected consistent biological patterns in the forest and cropland ecosystems, indicating a potential mechanistic interaction between N2-fixing bacteria and Tetracladium during PBSA biodegradation.

We studied the peat stratigraphy of the Mukhrino peatland, which is a typical ombrotrophic bog for the Middle Taiga zone of Western Siberia, to gain insights into its history, hydrology, and carbon fluxes. For the first time in Western Siberia, seven cores were collected from locations that were chosen to represent the typical present-day vegetation types, and this was performed for the dating of the separated dissolved (DOC) and particulate organic carbon (POC) fractions, which were determined using the Accelerator Mass Spectrometer (AMS) radiocarbon (14C) method. The oldest peat was found at the bottoms of an underlying lake (10,053 cal. year BP) and an ancient riverbed (10,989 cal. year BP). For the whole history of the peatland, the average peat accumulation rate was estimated to be 0.067 ± 0.018 cm yr−1 (ranging from 0.013 to 0.332 cm yr−1), and the carbon accumulation rate was 38.56 ± 12.21 g m−2 yr−1 (ranging from 28.46 to 57.91 g m−2 yr−1). There were clear age differences between the separated samples of the DOC and POC. The DOC was older than the POC in the uppermost 150 cm of the peat deposit and younger in the deeper layers. The difference in age increased with depth, reaching 2000–3000 years at the bottom of the peat deposit (depth of 430–530 cm). Following the consideration of a range of factors that could potentially cause the dating discrepancy, we hypothesised that the DOC continuously moves down into the mineral sediment beneath the peat, as an additional carbon flux that results in the mixing of younger and older carbon. On this basis, we estimated the apparent rate of the DOC’s downward movement and the associated rate of carbon loss. The first estimate of the average rate of the DOC’s downward movement in Western Siberia was 0.047 ± 0.019 cm yr−1, causing carbon loss in the range of 28–404 mg m−2 yr−1.

Heterogeneity in forests might promote biodiversity not only through an increase in niche volume but also through other processes, such as an increase in resources and their spatial distribution. However, negative relationships between heterogeneity and biodiversity have also been observed, which may indicate that heterogeneity acts as a filter for some species. This study examined the effects of different facets of heterogeneity in forest stands, i.e. deadwood, plant diversity, forest stand structure, and micro-scale topography, on the ecological (functional-phylogenetic) diversity and redundancy of nine animal groups: moths, true bugs, different functional groups of beetles, spiders, birds, and bats. Overall, we found positive effects of heterogeneity on ecological diversity and redundancy. Although the effect of heterogeneity at the local scale was moderate compared with the general effect of region, greater heterogeneity could be beneficial to some species groups and lead to more resilient species communities.

Deadwood provides important ecological and biogeochemical functions in forest ecosystems. These functions rely on tree species-specific decay dynamics, but only few studies investigated how exogenous parameters affected the decay of deadwood at the regional scale. Here, we explore the influence of climate, soil traits and forest structure on decay dynamics and mass loss of logs of 13 tree species in 29 plots across three regions in Germany. This long-term experiment (BELongDead) comprises 1,066 logs of 9 angiosperms and 4 gymnosperms and covers a decay time of almost 10 years. Mass loss of logs was relatively high for the temperate climate with partly different half-lives ranging from 6 to 13 years (mean 8.9 ± 2.2 years). Diffuse-porous angiosperms lost 70 ± 13% of their initial mass, followed by gymnosperms (49 ± 16%) and ring-porous angiosperms (46 ± 12%) within the study period. We applied three different mathematical models to fit mass loss in time and found that a linear model is most appropriate for 10 tree species. A sigmoidal model best described the mass loss of Fraxinus, Quercus and Pinus logs. A multivariate analysis revealed a significant effect of soil, temperature and precipitation on mass loss at the plot level. Mass loss increased with decreasing soil nutrient content, possibly as a result of enhanced bidirectional element translocations between nutrient-poor soils and logs by fungal hyphae. Temperature had a positive effect on mass loss, whereas increasing precipitation and soil moisture were negatively related to mass loss. The region with warmer, moderately humid climate and unfavourable soil properties led to overall higher mass loss (66 ± 4%) whereas the other two regions were indifferent (both 57 ± 3%). Forest structure, including canopy cover, share of coniferous trees and the stock of deadwood in the vicinity of the logs explained only a small part of the variability in mass loss. High variability within individual tree species suggests that other factors such as organismic diversity and microbial activity have stronger impact on the decay process at the regional scale than exogenous factors.

Abstract Background and Aims Cork oaks (Quercus section Cerris) comprise 15 extant species in Eurasia. Despite being a small clade, they display a range of leaf morphologies comparable to the largest sections (>100 spp.) in Quercus. Their fossil record extends back to the Eocene. Here, we explore how cork oaks achieved their modern ranges and how legacy effects might explain niche evolution in modern species of section Cerris and its sister section Ilex, the holly oaks. Methods We inferred a dated phylogeny for cork and holly oaks using a reduced-representation next-generation sequencing method, restriction site-associated DNA sequencing (RAD-seq), and used D-statistics to investigate gene flow hypotheses. We estimated divergence times using a fossilized birth–death model calibrated with 47 fossils. We used Köppen profiles, selected bioclimatic parameters and forest biomes occupied by modern species to infer ancestral climatic and biotic niches. Key Results East Asian and Western Eurasian cork oaks diverged initially in the Eocene. Subsequently, four Western Eurasian lineages (subsections) differentiated during the Oligocene and Miocene. Evolution of leaf size, form and texture was correlated, in part, with multiple transitions from ancestral humid temperate climates to mediterranean, arid and continental climates. Distantly related but ecologically similar species converged on similar leaf traits in the process. Conclusions Originating in temperate (frost-free) biomes, Eocene to Oligocene ranges of the primarily deciduous cork oaks were restricted to higher latitudes (Siberia to north of Paratethys). Members of the evergreen holly oaks (section Ilex) also originated in temperate biomes but migrated southwards and south-westwards into then-(sub)tropical southern China and south-eastern Tibet during the Eocene, then westwards along existing pre-Himalayan mountain ranges. Divergent biogeographical histories and deep-time phylogenetic legacies (in cold and drought tolerance, nutrient storage and fire resistance) thus account for the modern species mosaic of Western Eurasian oak communities, which are composed of oaks belonging to four sections.

Extreme weather events are occurring more frequently, and research has shown that plant diversity can help mitigate impacts of climate change by increasing plant productivity and ecosystem stability 1,2 . Although soil temperature and its stability are key determinants of essential ecosystem processes related to water and nutrient uptake 3 as well as soil respiration and microbial activity 4 , no study has yet investigated whether plant diversity can buffer soil temperature fluctuations. Using 18 years of a continuous dataset with a resolution of 1 minute (∼795,312,000 individual measurements) from a large-scale grassland biodiversity experiment, we show that plant diversity buffers soil temperature throughout the year. Plant diversity helped to prevent soil heating in hot weather, and cooling in cold weather. Moreover, this effect of plant diversity increased over the 18-year observation period with the aging of experimental communities and was even stronger under extreme conditions, i.e., on hot days or in dry years. Using structural equation modelling, we found that plant diversity stabilized soil temperature by increasing soil organic carbon concentrations and, to a lesser extent, by increasing the plant leaf area index. We suggest that the diversity-induced stabilization of soil temperature may help to mitigate the negative effects of extreme climatic events such as soil carbon release, thus slow global warming.

BackgroundTree mycorrhizal types (arbuscular mycorrhizal fungi and ectomycorrhizal fungi) alter nutrient use traits and leaf physicochemical properties and, thus, affect leaf litter decomposition. However, little is known about how different tree mycorrhizal species affect the microbial diversity, community composition, function, and community assembly processes that govern leaf litter-dwelling microbes during leaf litter decomposition. MethodsIn this study, we investigated the microbial diversity, community dynamics, and community assembly processes of nine temperate tree species using high-resolution molecular technique (Illumina sequencing), including broadleaved arbuscular mycorrhizal, broadleaved ectomycorrhizal, and coniferous ectomycorrhizal tree types, during leaf litter decomposition.Results and discussionThe leaves and needles of different tree mycorrhizal types significantly affected the microbial richness and community composition during leaf litter decomposition. Leaf litter mass loss was related to higher sequence reads of a few bacterial functional groups, particularly N-fixing bacteria. Furthermore, a link between bacterial and fungal community composition and hydrolytic and/or oxidative enzyme activity was found. The microbial communities in the leaf litter of different tree mycorrhizal types were governed by different proportions of determinism and stochasticity, which changed throughout litter decomposition. Specifically, determinism (mainly variable selection) controlling bacterial community composition increased over time. In contrast, stochasticity (mainly ecological drift) increasingly governed fungal community composition. Finally, the co-occurrence network analysis showed greater competition between bacteria and fungi in the early stages of litter decomposition and revealed a contrasting pattern between mycorrhizal types.ConclusionOverall, we conclude that tree mycorrhizal types influence leaf litter quality, which affects microbial richness and community composition, and thus, leaf litter decomposition.

As the Guest Editor I want to dedicate this Special Issue in memory of my university professor Natalya Nikolaevna Vygodskaya (Figure 1) [...]

The biodiversity of mycorrhizal and wood-inhabiting macrofungi (basidiomycetes) is declining, and many species are threatened in forests. Based on data from a 30-year fruiting body survey from 1988 to 2017 in the region of the city of Jena (100,000 inhabitants, 4500 ha forest), Germany, we evaluated the role of the urban environment with a variation of ownership, property size, associated management, and high diversity of woody species for the presence of non-red list and red-list fungal species. We found that (i) the urban area hosted 1172 mycorrhizal and wood-inhabiting basidiomycete macrofungi, identified on 64 woody host genera, representing 23% of the total German basidiomycetes on 0.4 parts per thousand of the German forest area. Among these species, 194 species (16%) are threatened according to the German Red List; (ii) a few common forest tree genera (Fagaceae and Pinaceae) hosted 90% of the total and red-list fungal species detected in this study; (iii) plant identity and host functional groups rather than plant phylogeny shaped the community composition and richness of mycorrhizal and wood-inhabiting macrofungi; (iv) conifers contributed 66% and 51% and broad-leaved trees 80% and 74% to total and red-list fungal diversity, respectively; (v) red-list species occurred mainly on common forest trees and shrubs from Fagaceae, Pinaceae, Betulaceae, Salicaceae, and Oleaceae, especially on native ones; and (vi) a few exotic trees (Robinia pseudoacacia and Pseudotsuga menziesii) supported a diverse native fungal flora. We conclude that urban areas can serve as an important zone for maintaining mycorrhizal and wood-inhabiting macrofungi by promoting a high heterogeneity of land use, ownership, and a high diversity of woody species.

Despite the abundance of observations of foliar pathogens, our knowledge is severely lacking regarding how the potential fungal pathobiome is structured and which processes determine community assembly. In this study, we addressed these questions by analysing the potential fungal pathobiome associated with the senescing leaves and needles of 12 temperate tree species. We compared fungal plant pathogen load in the senescing leaves/needles and demonstrated that healthy-looking leaves/needles are inhabited by diverse and distinct fungal plant pathogens. We detected 400 fungal plant pathogenic ASVs belonging to 130 genera. The fungal plant pathogenic generalist, Mycosphaerella, was found to be the potential most significant contributor to foliar disease in seedlings. The analyses of assembly process and co-occurrence network showed that the fungal plant pathogenic communities in different tree types are mainly determined by stochastic processes. However, the homogenising dispersal highly contributes in broadleaf trees, whereas ecological drift plays an important role in coniferious trees. The deterministic assembly processes (dominated by variable selection) contributed more in broadleaf trees as compared to coniferous trees. We found that pH and P level significantly corresponded with fungal plant pathogenic community compositions in both tree types. Our study provides the first insight and mechanistic understanding into the community assembly, networks, and complete taxonomy of the foliar fungal pathobiome in senescing leaves and needles.

Forest management has been shown to affect biodiversity, but the effects vary among taxa and studies. Due to their host-tree preferences, many saproxylic, i.e. deadwood-dependent, beetle species are likely affected by forest management via changes in tree species composition. However, further structural differences caused by forest management, such as microclimatic conditions, may interfere with effects of tree species. We lack a more detailed understanding of how forest management intensity influences saproxylic beetles through tree species composition and structural properties.We analyzed the effect of forest management on saproxylic beetles using an eight-year dataset collected from 379 experimental logs of 13 different tree species, which were exposed in forests of different management intensity in three regions of Germany. To quantify forest management intensity, we first used a composite index (ForMI) which considers the share of locally non-native tree species, the origin of deadwood and the harvesting rate and then replaced it by five forest structural and compositional properties. This two-step approach allowed to assess the overall effects of management summarizing different aspects and to identify the main forest attributes driving these overall effects. We further investigated whether the effects differ between beetle assemblages emerging from conifer and broadleaf logs (host level), and between generalists, conifer-specialists, and broadleaf-specialists (beetle specialization level).Abundance and species richness increased with increasing ForMI for all beetles, generalists, and conifer-specialists, but not for broadleaf-specialists.Effects of ForMI were stronger for assemblages emerging from conifer than broadleaf logs. Among the evaluated structural and compositional variables, strongest effects were observed for conifer share at stand level and canopy cover. Conifer share positively affected the species richness of all beetles, generalists and conifer specialists, but not of broadleaf specialists. Canopy cover negatively affected all beetles, generalists and conifer specialists, but did not affect broadleaf specialists.Our results show that major drivers behind effects of forest management on saproxylic beetles are differences in tree species composition and canopy cover. Effects differ between beetle groups depending on their host specialization. Forest management decisions regarding tree species composition should therefore more strongly consider their effects on saproxylic beetle diversity to meet conservation goals also in the future.