Fungi In Forests Research Articles

Deadwood manipulation and type determine assemblage composition of saproxylic beetles and fungi after a decade

The biodiversity crisis calls for immediate restoration of deteriorated and rare habitat. Due to fire suppression and intensive forest management, boreal pine forests of high conservation value are exceptionally rare. Despite decades of restoration research in boreal forests, relatively few studies have evaluated multi-taxon biodiversity response of restoration measures in pine forests. In a Scots pine experiment, we investigated biodiversity patterns of wood-inhabiting fungi and beetles a decade after restoration (prescribed burning and deadwood creation) and forest management (harvest with varying retention). We found that fungi and beetles develop differently and have distinct preferences in deadwood originating from restoration. Standing deadwood supported more species for beetles and lying deadwood for fungi and for both taxa, standing and lying deadwood harboured different species assemblages. Burned deadwood displayed less variable assemblages than unburned deadwood for both organism groups. We found that, after a decade, deadwood type and not harvest with different retention levels better explained diversity patterns of wood-inhabiting beetles and fungi in pine forests. Pine forests are naturally prone to recurring disturbances creating open light conditions. Pine-associated species are therefore likely resistant to disturbance as long as a variety of deadwood resources are present. To accommodate multiple taxa, a variety of substrate and environment types is required. Beetles benefit from standing deadwood while fungi benefit from lying deadwood. To support assemblages with both rapid and slow turnover rates, a combination of recurring restoration and leaving restored stands in the adjacent landscapes is required.

Impact of invasive alien tree species on symbiotic soil fungal communities in pine-dominated forest ecosystems in central Europe

Biological invasions are a serious threat to nature conservation and sustainable forest management. Invasive trees can reduce biodiversity, modify nutrient cycles and transform native forests into novel ecosystems determined by invaders. Almost all European trees form ectomycorrhizal (ECM) symbiosis with fungi, which is crucial for tree development. However, the impact of invasive trees on ECM fungi in native forests has scarcely been studied.We aimed to determine how an invasion of the widespread alien trees Robinia pseudoacacia (which hosts arbuscular mycorrhizal (AM) fungi), Prunus serotina (which forms AM associations and potentially can ECM symbiosis), and Quercus rubra (ECM-dominated, can form AM associations) influences symbiotic fungi in soil. We collected soil samples along a gradient of increasing density of invasive species in 81 stands in pine-dominated forests in Western Poland, identifying fungi through high-throughput sequencing of the ITS2 rDNA, a barcode region for fungi. Each invasive tree was examined independently.Robinia pseudoacacia had the strongest negative impact, almost eliminating ECM fungi from the soil. Among soil compounds, N-NO3 and N-NH4 significantly influenced diversity and taxa composition of ECM fungal communities. Uninvaded pine stands near R. pseudoacacia had significantly lower richness and abundance of ECM fungi, and several-fold higher N-NO3 concentrations, than uninvaded stands elsewhere. That indicates, that the negative impact of Robinia trees extends beyond stands containing Robinia to influence surrounding forests. Prunus serotina had significant negative impact on ECM taxa abundance, but not on ECM taxa richness and diversity indices, while Quercus rubra enhanced the abundance and richness of ECM fungi, but had no significant influence on the diversity indices.

Plant diversity increases diversity and network complexity rather than alters community assembly processes of leaf-associated fungi in a subtropical forest.

Plant diversity significantly impacts ecosystem processes and functions, yet its influence on the community assembly of leaf fungi remains poorly understood. In this study, we investigated leaf epiphytic and endophytic fungal communities in a Chinese subtropical tree species richness experiment, ranging from 1 to 16 species, using amplicon sequencing to target the internal transcribed spacer 1 region of the rDNA. We found that the community assembly of epiphytic and endophytic fungi was predominantly governed by stochastic processes, with a higher contribution of dispersal limitation on epiphytic than on endophytic fungal communities but a higher contribution of selection on endophytic than on epiphytic fungal communities. The plant-epiphytic fungus interaction network was more complex (e.g., more highly connected and strongly nested but less specialized and modularized) than the plant-endophytic fungus interaction network. Additionally, tree species richness was positively correlated with the network complexity and diversity of epiphytic (α-, β- and γ-diversity) and endophytic (β- and γ-diversity) fungi, but was not associated with the contribution of the stochastic and deterministic processes on the community assembly of epiphytic and endophytic fungi. This study highlights that tree species diversity enhances the diversity and network complexity, rather than alters the ecological processes in community assembly of leaf-associated fungi.

Temperature governs the community assembly of root-associated ectomycorrhizal fungi in alpine forests on the Qinghai-Tibetan Plateau

Unraveling the assembly processes of ectomycorrhizal (ECM) fungal communities in changing environments is crucial for forecasting the impacts of climate change on forests. However, the assembly processes and key drivers of root-associated ECM fungal communities in alpine coniferous forests remain poorly understood. To address this knowledge gap, we conducted sampling in 65 monodominant alpine coniferous forests, which encompass 11 plant species belonging to three genera (Abies, Pinus, and Picea) within the Pinaceae family, all located on the Qinghai-Tibetan Plateau. We employed a combination of null model and multivariate analyses to elucidate the drivers and assembly processes of ECM fungal communities. Our results revealed significant variation in the composition and diversity of root-associated ECM fungal communities among Abies, Pinus, and Picea, indicating specific preferences for ECM fungi among Pinaceae genera. Importantly, mean annual temperature (MAT) emerged as the primary driver of these variations and regulated the assembly processes within the community of root-associated ECM fungi. As MAT temperature, the α-diversity of these fungi significantly decreased, suggesting that increased temperature may reduce the species diversity of root-associated ECM fungi in alpine forests. Furthermore, stochastic processes, such as dispersal limitation and drift, became more influential as MAT increased. Conversely, the role of deterministic processes, particularly heterogeneous selection, in shaping the ECM fungal community assembly weakened with increasing MAT. This study provides novel theoretical insights into the processes of ECM fungal community assembly in alpine forests, emphasizing the pivotal role of temperature in regulating the assembly processes and compositional dynamics of root-associated ECM fungal communities in these unique environments.

Reticulate evolution and rapid development of reproductive barriers upon secondary contact in a forest fungus

Reproductive barriers between sister species of the mushroom-forming fungi tend to be stronger in sympatry, leading to speculation on whether they are being reinforced by selection against hybrids. We have used population genomic analyses together with invitro crosses of a global sample of the wood decay fungus Trichaptum abietinum to investigate reproductive barriers within this species complex and the processes that have shaped them. Our phylogeographic analyses show that T.abietinum is delimited into six major genetic groups: one in Asia, two in Europe, and three in North America. The groups present in Europe are interfertile and admixed, whereas our crosses show that the North American groups are reproductively isolated. In Asia, a more complex pattern appears, with partial intersterility between subgroups that likely originated independently and more recently than the reproductive barriers in North America. We found pre-mating barriers in T.abietinum to be moderately correlated with genomic divergence, whereas mean growth reduction of the mated hybrids showed a strong correlation with increasing genomic divergence. Genome-wide association analyses identified candidate genes with programmed cell death annotations, which are known to be involved in intersterility in distantly related fungi, although their link here remains unproven. Our demographic modeling and phylogenetic network analyses fit a scenario where reproductive barriers in Trichaptum abietinum could have been reinforced upon secondary contact between groups that diverged in allopatry during the Pleistocene glacial cycles. Our combination of experimental and genomic approaches demonstrates how T.abietinum is a tractable system for studying speciation mechanisms.

Effects of Thinning Practices on Soil Properties and Arbuscular Mycorrhizal Fungi in Natural Pure Oriental Beech Forests

Thinning intensities in Fagus orientalis Lipsky. stands may influence the soil properties, arbuscular mycorrhizal (AM) fungi symbiosis, and their interaction through soil quality enhancement. We aimed to investigate the impact of four thinning intensities—control (no thinning); moderate (15%), moderately intense (35%), and intense thinning (55%)—implemented five years ago in pure oriental beech forests. In this context, the percentage indicates the proportion of trees removed by each thinning intensity, based on the total number of trees before thinning. Our focus encompassed soil physical–chemical properties, AM fungi community composition, and root colonization. At the intense thinning sites, the soil organic carbon, total nitrogen, available potassium, AMF spore density, and root colonization increased by 209.7, 88.9, 115.8, 404.9, and 448.5%, respectively, when compared to the control sites. This suggests a potential rise in AMF spore density and root colonization—a vital aspect for natural regeneration. These findings highlight the importance of considering management practices in forest systems that can enhance the root system in a sustainable manner to improve plant performance, soil fertility, and symbiosis with AM fungi.

Assessing extraradical mycelium of mycorrhizal fungi in tropical forests using armored in-growth mesh bags

The extraradical mycelium of mycorrhizal fungi is among the major carbon pools in soil that is hard to quantitatively assess in-situ. Established method of in-growth mesh bags in temperate ecosystems is difficult to apply in the tropics, where mesh bags are often damaged by termites. Here we introduce a modification of the in-growth mesh bag technique, in which mesh bags are enforced by stainless steel mesh. Its performance was tested in the Đồng Nai (Cát Tiên) National Park in Vietnam across two monsoon tropical forests, dominated by tree species associated with either ectomycorrhizal (ECM) or arbuscular mycorrhizal (AM) fungi. Armored in-growth mesh bags remained intact, while about 60 % of non-armored mesh bags were damaged by termites after 180 days of exposure. The biomass of extraradical mycelium of ectomycorrhizal fungi estimated by PLFA analysis was similar in the armored and non-armored mesh bags and did not differ between studied forests. However, fungal community composition slightly differed between armored and non-armored mesh bags in the ECM- but not in the AM-dominated forest. Fungal mycelium gathered in the AM-dominated forest was depleted in 15N compared to that collected in the ECM-dominated forest. Overall, our results argue for using armored mesh bags as a robust tool for harvesting the biomass of extraradical mycelium of mycorrhizal fungi in tropical ecosystems.

Long-term nitrogen deposition alters the soil bacterial community structure but has little effect on fungal communities

Subtropical Moso bamboo (Phyllostachys edulis) forests have become hot spots for nitrogen (N) deposition in China. However, the effect of long-term N deposition on the structure of soil microbial communities in different horizons of these forests remains unclear. To investigate the influence of extended N deposition on soil bacteria and fungi, a simulated N deposition field study was conducted in Fujian Province with four N deposition levels (0, 20, 40 and 80 kg N hm−2 a−1). The absolute abundances, diversity, community structure, and potential functions of soil bacteria and fungi were investigated after 10 years of simulated N deposition. The results indicated that there was no significant effect of N deposition on the abundance or diversity of soil microbes in either the organic or mineral horizons of Moso bamboo forests. However, under rates of 40 and 80 kg N hm−2 a−1, long-term N deposition altered the structure of the soil bacterial community in the organic horizon. Specifically, there was a 27.75∼36.40 % increase in the relative abundance of Actinobacteria, while that of Acidobacteria decreased by 24.40∼27.52 %. Redundancy analysis (RDA) demonstrated that soil total carbon (TC) was the key variable influencing the bacterial community structure in the organic horizon. Analysis of potential microbial functions showed that in the organic horizon, the rates of chemoheterotrophy significantly decreased under 80 kg N hm−2 a−1. However, N deposition did not noticeably impact the fungal community structure in either soil horizon. Our study suggested that under 10 years of N deposition, only the bacterial community composition and function in the organic horizon was affected, indicating that soil bacteria are more sensitive to N deposition than fungi in subtropical Moso bamboo forests. Therefore, further research is necessary to fully understand the impact of N deposition on fungal community composition in the soil organic horizon and on the microbial community in the mineral horizon of subtropical bamboo forests. This study provides valuable insights for informing future environmental management and conservation strategies.

Diversity of soil fungi and entomopathogenic fungi in subtropical mountain forest in southwest China

AbstractTill now, the diversity of entomopathogenic fungi in subtropical mountain forest was less studied. Here, the vertical distribution of forest soil fungi, entomopathogenic fungi, and their environmental influencing factors in a subtropical mountain in western China were investigated. Soil samples were collected from four elevations in a subtropical forest in Shaanxi. The results indicated a greater richness of soil fungi at middle elevations and soil fungi were more even at low elevation. Soil pH, available iron, available potassium, total potassium, and available zinc were the most important influencing factors affecting this vertical distribution of fungi. Interestingly, the Isaria genus was predominant while Metarhizium and Beauveria showed decreasing abundance. The presence of Isaria showed a significant positive correlation with both total phosphorus and available iron, while, available zinc was negatively correlated. Metarhizium was influenced by elevation, pH, available phosphorus, and available copper and Beauveria was influenced by soil organic carbon, total nitrogen, total potassium, available potassium, and available zinc. Overall, as environmental factors affecting soil fungi, elevation, and plant species diversity were less important than soil physical and chemical properties. The virulence of isolated entomopathogenic fungi were tested against larvae of Tenebrio molitor, with mortality ranging from 31.11% to 100%. The above findings provide valuable data to deepen our understanding of the diversity of entomopathogenic fungi in subtropical mountain forests.

Sequence and structure analyses of lytic polysaccharide monooxygenases mined from metagenomic DNA of humus samples around white-rot fungi in Cuc Phuong tropical forest, Vietnam

Background White-rot fungi and bacteria communities are unique ecosystems with different types of symbiotic interactions occurring during wood decomposition, such as cooperation, mutualism, nutritional competition, and antagonism. The role of chitin-active lytic polysaccharide monooxygenases (LPMOs) in these symbiotic interactions is the subject of this study. Method In this study, bioinformatics tools were used to analyze the sequence and structure of putative LPMOs mined by hidden Markov model (HMM) profiles from the bacterial metagenomic DNA database of collected humus samples around white-rot fungi in Cuc Phuong primary forest, Vietnam. Two genes encoding putative LPMOs were expressed in E. coli and purified for enzyme activity assay. Result Thirty-one full-length proteins annotated as putative LPMOs according to HMM profiles were confirmed by amino acid sequence comparison. The comparison results showed that although the amino acid sequences of the proteins were very different, they shared nine conserved amino acids, including two histidine and one phenylalanine that characterize the H1-Hx-Yz motif of the active site of bacterial LPMOs. Structural analysis of these proteins revealed that they are multidomain proteins with different functions. Prediction of the catalytic domain 3-D structure of these putative LPMOs using Alphafold2 showed that their spatial structures were very similar in shape, although their protein sequences were very different. The results of testing the activity of proteins GL0247266 and GL0183513 show that they are chitin-active LPMOs. Prediction of the 3-D structures of these two LPMOs using Alphafold2 showed that GL0247266 had five functional domains, while GL0183513 had four functional domains, two of which that were similar to the GbpA_2 and GbpA_3 domains of protein GbpA of Vibrio cholerae bacteria. The GbpA_2 - GbpA_3 complex was also detected in 11 other proteins. Based on the structural characteristics of functional domains, it is possible to hypothesize the role of chitin-active GbpA-like LPMOs in the relationship between fungal and bacterial communities coexisting on decomposing trees in primary forests.

The Diversity and Floristic Analysis of Rust Diseases in the Sanjiangyuan Forest Plants.

Between 2020 and 2023, rust fungus specimens were collected from the primary forested regions of the Sanjiangyuan area in Qinghai Province, resulting in over 300 samples. A taxonomic and phylogenetic study of the rust fungi from these forests was conducted using morphological and molecular biological techniques. The investigation identified rust fungi from 7 families, 12 genera, 56 species and varieties, including 10 new host records, 1 new record for China, and 2 novel species. The host plants involved belonged to 26 families, 48 genera, and 78 species. Pucciniaceae and Coleosporiaceae were the dominant families, with the genera Puccinia, Melampsora, and Gymnosporangium being prevalent. The rust fungi in the Sanjiangyuan forests showed a biogeographical affinity with the North Temperate Zone. Floristic comparisons revealed a higher similarity with rust fungi from Inner Mongolia, Gansu, and Tibet and a lower similarity with those from Hainan. An analysis of the life forms of rust fungus host plants indicated that herbaceous plants were the most common, followed by shrubs and trees. In different regions of Sanjiangyuan, rust fungi were found as follows: Golog Prefecture with 6 families, 9 genera, and 28 species; Yushu Prefecture with 5 families, 8 genera, and 31 species; Huangnan Prefecture with 5 families, 9 genera, and 26 species; and Hainan Prefecture with 4 families, 5 genera, and 10 species. The families Pucciniaceae, Melampsoraceae, and Coleosporiaceae were common across all four regions. Moreover, the families Rosaceae, Asteraceae, Ranunculaceae, Salicaceae, and Caprifoliaceae were shared among the host plants in these regions.

Entomopathogenic Fungi in Forest Habitats of Ixodes ricinus.

(1) Background: In addition to the microclimate, host availability, and tick microbiota, soil environmental microorganisms can affect tick populations. This study aimed to (1) determine the presence and diversity of entomopathogenic fungi (EF) in forests, where ticks are abundant, and (2) estimate the effectiveness of the isolated EF strains against Ixodes ricinus. (2) Methods: EF were isolated using the trap insect method from soil collected from tick sites. A bioassay was used to estimate the effectiveness of EF against ticks. (3) Results: The presence of EF was found in all tested forest habitat types. A total of 53 strains belonging to the genera Metarhizium, Beauveria, and Isaria were isolated. All the six strains subjected to the bioassay showed potential efficacy against both adult and nymphal stages of I. ricinus; however, the strains differed in their effectiveness. The most effective isolate against I. ricinus was the soil environmental strain of Metarhizium anisopliae. (4) Conclusion: The study indicates that tick habitats can be the source of entomopathogenic fungi, which have a lethal effect on ticks, as demonstrated in preliminary laboratory tests with I. ricinus. However, for practical use, extensive field tests and further research on application methods and long-term effects are necessary to develop effective and sustainable tick management strategies.

Community Assembly Processes of Deadwood Mycobiome in a Tropical Forest Revealed by Long-Read Third-Generation Sequencing

Despite the importance of wood-inhabiting fungi on nutrient cycling and ecosystem functions, their ecology, especially related to their community assembly, is still highly unexplored. In this study, we analyzed the wood-inhabiting fungal richness, community composition, and phylogenetics using PacBio sequencing. Opposite to what has been expected that deterministic processes especially environmental filtering through wood-physicochemical properties controls the community assembly of wood-inhabiting fungal communities, here we showed that both deterministic and stochastic processes can highly contribute to the community assembly processes of wood-inhabiting fungi in this tropical forest. We demonstrated that the dynamics of stochastic and deterministic processes varied with wood decomposition stages. The initial stage was mainly governed by a deterministic process (homogenous selection), whereas the early and later decomposition stages were governed by the stochastic processes (ecological drift). Deterministic processes were highly contributed by wood physicochemical properties (especially macronutrients and hemicellulose) rather than soil physicochemical factors. We elucidated that fine-scale fungal-fungal interactions, especially the network topology, modularity, and keystone taxa of wood-inhabiting fungal communities, strongly differed in an initial and decomposing deadwood. This current study contributes to a better understanding of the ecological processes of wood-inhabiting fungi in tropical regions where the knowledge of wood-inhabiting fungi is highly limited.

Nitrogen addition changed soil fungal community structure and increased the biomass of functional fungi in Korean pine plantations in temperate northeast China

Nitrogen (N) deposition is a global environmental issue that can have significant impacts on the community structure and function in ecosystems. Fungi play a key role in soil biogeochemical cycles and their community structures are tightly linked to the health and productivity of forest ecosystems. Based on high-throughput sequencing and ergosterol extraction, we examined the changes in community structure, composition, and biomass of soil ectomycorrhizal (ECM) and saprophytic (SAP) fungi in 0–10 cm soil layer after 8 years of continuous N addition and their driving factors in a temperate Korean pine plantation in northeast China. Our results showed that N addition increased fungal community richness, with the highest richness and Chao1 index under the low N treatment (LN: 20 kg N ha−1 yr−1). Based on the FUN Guild database, we found that the relative abundance of ECM and SAP fungi increased first and then decreased with increasing N deposition concentration. The molecular ecological network analysis showed that the interaction between ECM and SAP fungi was enhanced by N addition, and the interaction was mainly positive in the ECM fungal network. N addition increased fungal biomass, and the total fungal biomass (TFB) was the highest under the MN treatment (6.05 ± 0.3 mg g−1).Overall, we concluded that N addition changed soil biochemical parameters, increased fungal activity, and enhanced functional fungal interactions in the Korean pine plantation over an 8-year simulated N addition. We need to consider the effects of complex soil conditions on soil fungi and emphasize the importance of regulating soil fungal community structure and biomass for managing forest ecosystems. These findings could deepen our understanding of the effects of increased N deposition on soil fungi in temperate forests in northern China, which can provide the theoretical basis for reducing the effects of increased N deposition on forest soil.

The influence of tree genus, phylogeny, and richness on the specificity, rarity, and diversity of ectomycorrhizal fungi.

Partner specificity is a well-documented phenomenon in biotic interactions, yet the factors that determine specificity in plant-fungal associations remain largely unknown. By utilizing composite soil samples, we identified the predictors that drive partner specificity in both plants and fungi, with a particular focus on ectomycorrhizal associations. Fungal guilds exhibited significant differences in overall partner preference and avoidance, richness, and specificity to specific tree genera. The highest level of specificity was observed in root endophytic and ectomycorrhizal associations, while the lowest was found in arbuscular mycorrhizal associations. The majority of ectomycorrhizal fungal species showed a preference for one of their partner trees, primarily at the plant genus level. Specialist ectomycorrhizal fungi were dominant in belowground communities in terms of species richness and relative abundance. Moreover, all tree genera (and occasionally species) demonstrated a preference for certain fungal groups. Partner specificity was not related to the rarity of fungi or plants or environmental conditions, except for soil pH. Depending on the partner tree genus, specific fungi became more prevalent and relatively more abundant with increasing stand age, tree dominance, and soil pH conditions optimal for the partner tree genus. The richness of partner tree species and increased evenness of ectomycorrhizal fungi in multi-host communities enhanced the species richness of ectomycorrhizal fungi. However, it was primarily the partner-generalist fungi that contributed to the high diversity of ectomycorrhizal fungi in mixed forests.

DYNAMICS OF HEAVY METAL ACCUMULATION IN TROPHIC LEVELS OF FOREST ECOSYSTEMS

The aim of the study is to examine the accumulation of heavy metals (HMs) in trophic levels (soil, wood, tree leaves and fungi of various evolutionary origin) of forest ecosystems.
 Materials and Methods. The authors examined soil, wood, leaves and fungi in forests with different anthropogenic load intensity. The collecting grounds were selected according to forest management materials. In total, 26 grounds were examined. Sampling of soil and fungi of various trophic levels was carried out on different substrates, in different forest conditions and under different levels of technogenic impact. Leaf and wood samples were taken from phytopathogen-affected and healthy trees. Chemical sample analysis was carried out using a Kvant atomic absorption spectrophotometer.
 Results. The total heavy metal content in fungi is higher than in wood, but lower than in soil. The total heavy metal content in leaves of Norway maple affected by Rhytisma acerinum is higher compared to the leaves from heathy trees. Iron predominates among the heavy metals found in the fungi under consideration; cadmium content is minimal.
 Conclusion. The largest amount of accumulated heavy metals was found in the fruiting bodies of the facultative saprotroph, and the smallest amount was in the bodies of the facultative parasite. The forest type and growing conditions affect the heavy metal content in ecosystems.

Morpho-phylogenetic characterizations reveal a new species of Coccomyces on Cunninghamia lanceolata from China

Specimen of Coccomyces collected on Cunninghamia lanceolata, from Huangshan Mountain in Anhui Province, China, was identified as a new species, named here as Coccomyces cunninghamiae. Although multi-gene (ITS, nrLSU, mtSSU) phylogenetic analysis showed that the new species was closely related to C. anhuiensis, it differs significantly from C. anhuiensis in morphology by intraepidermal or subepidermal ascomata, well-developed paraphyses forming epithecium and shape of ascospores. Moreover, the ITS sequence similarity between them is only 87.86%. Specimens studied are deposited in the Reference Collection of Forest Fungi of Anhui Agricultural University, China (AAUF).

Diversity of Mycorrhizal fungi in Eastern Hemlock stands will significantly change with the effects of Hemlock Woolly Adelgid infestation in southwestern Nova Scotia, Canada

A foundation tree species, eastern hemlock (Tsuga canadensis) is threatened by the invasive hemlock woolly adelgid (Adelges tsugae) (HWA) in southwestern Nova Scotia, Canada. The loss of this key species and its heavily shaded ecosystems may alter the diversity of important mycorrhizal fungi in hemlock forests. Mycorrhizal fungi share a vital mutualistic relationship with their host trees; consequentially, understanding if and how the predicted eastern hemlock decline will affect mycorrhizal diversity is paramount. Using available literature, we discuss three major consequences of HWA on eastern hemlock ecosystems – changing forest composition, loss of old-growth trees, and increased insect stress on host trees – and how they will likely influence mycorrhizal communities as adelgid infestations intensify. Environmental variables are also discussed as another major influence on fungal diversity. We conclude that the mycorrhizal community of eastern hemlock forests will likely change significantly as old-growth hemlock is replaced with mixed forest. We also suggest that mycorrhizal community composition will shift in favour of generalist mycorrhizae which form symbioses with multiple tree species. These conclusions illuminate the future of hemlock forest fungi in southwestern Nova Scotia and underline the importance of conserving old-growth eastern hemlock forests and their unique fungal communities.

Effects of forest management on the key fungal decomposer Fomes fomentarius in European beech forests – Lessons from a large-scale experiment

Fomes fomentarius (L.) Fr., (commonly known as Tinder fungus) is an abundant fungus in European beech old-growth forests and is important for nutrient cycles, food web dynamics, and biodiversity. The species was heavily reduced during the last centuries by forestry. Modern silviculture strategies in Central Europe aim to balance both the extraction of wood and promoting dead wood habitats. Such an approach is key to sustaining Fomes fomentarius as well as up to 600 saproxylic arthropods associated with the fungus. The aim of this study was to assess how dead wood type in combination with microclimate, resulting from different forest management strategies, affect the presence (occupancy) and abundance (percent cover occupied) of Fomes fomentarius fruit bodies at the stand- and dead wood object-scale. We experimentally extracted a standardized proportion of trees within 50 m by 50 m patches creating stumps, logs, snags, and logs with snags under two microclimate treatments (open canopy gap versus closed canopy) in a random block design. As a control, we defined cut stumps under closed canopies, as this is the common thinning approach in mature beech production forests. We tested the effects of alternative management strategies against the control using Generalized Linear Mixed-effects Models. At the stand-scale, our model revealed a significantly lower occupancy of Fomes fomentarius in control stands compared to treatments in which dead wood was not removed. The average cover of Fomes fomentarius on snags under a closed canopy, at both the stand- and dead wood object-scale, was higher than in control plots. However, effect size was weak at the object-scale. To increase this principal decomposer and boost important microhabitats for many arthropods, silviculture should aim to increase snags while maintaining dense forest canopies. Yet, at landscape scale, diversifying dead wood types and light conditions may boost overall saproxylic diversity.

Cortinarius and Tomentella Fungi Become Dominant Taxa in Taiga Soil after Fire Disturbance.

Fungi have important ecological functions in the soil of forests, where they decompose organic matter, provide plants with nutrients, increase plant water uptake, and improve plant resistance to adversity, disease, and disturbance. A forest fire presents a serious disturbance of the local ecosystem and can be considered an important component affecting the function of ecosystem biomes; however, the response of soil fungi to fire disturbance is largely unknown. To investigate the effects of fire disturbance on the community composition and diversity of soil fungi in a taiga forest, we collected soil from plots that had undergone a light, moderate, and heavy fire 10 years previously, with the inclusion of a fire-free control. The present soil fungi were characterized using Illumina MiSeq technology, and the sequences were analyzed to identify differences in the community composition and diversity in response to the changed soil physicochemical properties. The results showed that the Chao1 index, which characterizes the alpha diversity of the fungi, did not change significantly. In contrast, the Shannon index increased significantly (p < 0.05) and the Simpson index decreased significantly (p < 0.05) following a light or heavy fire disturbance compared to the control. The relative abundance of Basidiomycota was significantly higher in the soil of the fire sites than that in the control (p < 0.01), and the relative abundance of Ascomycota was significantly lower (p < 0.01). The results of principal coordinates analyses (PCoAs) showed that fire disturbance highly significantly affected the beta diversity of soil fungi (p < 0.001), while the results of canonical correlation analysis (CCA) indicated that the available nitrogen (AN), moisture content (MC), pH, available potassium (AK), and total nitrogen (TN) contents of the soil significantly affected the compositional structure and diversity of the soil fungal communities. The results of functional prediction showed that the majority of the detected soil fungi were symbiotrophs, followed by saprotrophs and saprotroph-symbiotrophs, with ectomycorrhiza being the dominant functional taxon. Fire disturbance significantly reduced the relative abundance of ectomycorrhiza (p < 0.05). This study illustrates that fire disturbance alters the structural composition, diversity, dominance, and relative abundance of the guilds of soil fungal communities in taiga forest, and strongly affected the beta diversity of soil fungi, with AN, MC, pH, AK, and TN being the most important factors affecting their community structure. The results may provide a useful reference for the restoration and rehabilitation of taiga forests after fire disturbance.