Variation In Fungal Community Composition Research Articles

Endophytic Fungal Diversity in Cirsium kawakamii from Taiwan.

The endophytic fungal diversity of Cirsium kawakamii, a herb indigenous to Taiwan, was analyzed in this study. In addition, some fungal isolates were evaluated for the risk they pose as plant pathogens. In total, 1836 endophytic fungi were isolated from C. kawakamii from Hehuanjian, Puli Township, and Tatachia. They were classified into 2 phyla, 8 classes, 40 families, and 68 genera. Colletotrichum, Fusarium, Phomopsis, and Xylaria, (Ascomycota, Sordariomycetes) were the dominant genera. The genus accumulation curve (based on the bootstrap estimator) was non-asymptotic, with estimated richness significantly exceeding the richness captured by our sampling to date. Considering the collection time, the data indicated significant differences in the proportions of the C. kawakamii endophyte genus from Hehuanjan, Puli Township (across two seasons), and Tatachia. The Shannon and Gini-Simpson indices revealed variations in diversity, with C. kawakamii endophytes (Puli Township in winter) significantly reducing alpha diversity compared with other seasons and locations. Meanwhile, the Gini-Simpson index suggested that there were no significant differences in richness among the four sampling sites. The PCA results unveiled distinct community structures across different locations and seasons, explaining 46.73% of the total variation in fungal community composition significantly affected diversity and richness. In addition, a considerable number of Fusarium isolates exhibited harmful properties towards wheat, potatoes, and apples. It is postulated that these fungi belong to the Fusarium tricinctum species complex (FTSC).

Seasonal consumption of mycorrhizal fungi by a marsupial-dominated mammal community

The temperate forests of Australia support a high diversity of hypogeous fungi and a wide variety of mycophagous mammals, yet many mammal-fungal relationships are still poorly understood. We studied the seasonal fungal diets of eight sympatric mammals (seven marsupials and one rodent) in a remnant montane eucalypt forest. Fifty-five different fungal taxa were identified from 305 scat samples. Swamp wallabies (Wallabia bicolor), yellow-footed antechinus (Antechinus flavipes) and brown antechinus (A. stuartii) were the primary mycophagists in this community, but all mammals consumed fungi, including three species not previously recorded as mycophagous (eastern grey kangaroo, Macropus giganteus;common wallaroo, Osphranter robustus; and common dunnart, Sminthopsis murina). Winter was the peak season for fungal consumption and dietary diversity of fungi, however, the diversity of taxa ingested varied between species and season. Our work supports the idea that a diverse mycophagous mammal community is important for maintaining natural variation in fungal community composition.

Climate-driven shifts in plant and fungal communities can lead to topsoil carbon loss in alpine ecosystems.

Alpine tundra ecosystems suffer from ongoing warming-induced tree encroachment and vegetation shifts. While the effects of tree line expansion on the alpine ecosystem receive a lot of attention, there is also an urgent need for understanding the effect of climate change on shifts within alpine vegetation itself, and how these shifts will consequently affect soil microorganisms and related ecosystem characteristics such as carbon storage. For this purpose, we explored relationships between climate, soil chemistry, vegetation, and fungal communities across seven mountain ranges at 16 alpine tundra locations in Europe. Among environmental factors, our data highlighted that plant community composition had the most important influence on variation in fungal community composition when considered in combination with other factors, while climatic factors had the most important influence solely. According to our results, we suggest that rising temperature, associated with a replacement of ericoid-dominated alpine vegetation by non-mycorrhizal or arbuscular mycorrhizal herbs and grasses, will induce profound changes in fungal communities toward higher dominance of saprotrophic and arbuscular mycorrhizal fungi at the expense of fungal root endophytes. Consequently, topsoil fungal biomass and carbon content will decrease.

Context-dependence of fungal community responses to dominant tree mycorrhizal types in Northern hardwood forests

Dominant tree community mycorrhizal associations can influence soil biogeochemistry and nutrient cycling, suggesting a prominent role of mycorrhizas in shaping belowground microbial community composition and function. The degree to which the mycorrhizal type of dominant trees interacts with natural environmental gradients to influence belowground microbial communities is, however, unclear. Likewise, it is unknown if community-level mycorrhizal associations can influence the local microbial community encountered by an individual tree through spillover effects. To address these questions, we studied fungal communities from soil, roots, and leaf litter surrounding individual arbuscular (AM) and ectomycorrhizal (ECM) trees embedded in gradients of tree mycorrhizal dominance from three climatically distinct locations in the Adirondack Mountains, NY, USA. We found that dominant tree mycorrhizal types interact with site location to explain more variation in fungal community composition, richness, and function than specific soil properties, such as pH. This finding was consistent for all three sample types, but soil-associated fungi demonstrated the largest amount of explainable variation compared to root- and leaf litter-associated fungi. The relative abundance of plant pathogens was especially responsive to tree mycorrhizal dominance, increasing with AM dominance around individual AM trees but not around ECM trees in the same forests. These “mycorrhizal-spillover” effects on AM trees were also strongest in our warmest, driest site and weakest in our coolest, wettest site, indicating that the strength of mycorrhizal spillover is context-dependent in mixed-mycorrhizal forests.

Host phylogeny is the primary determinant of ectomycorrhizal fungal community composition in the permafrost ecosystem of eastern Siberia at a regional scale

Ectomycorrhizal (EM) fungal communities have been studied worldwide; however, those in the very cold and dry continental climate zone of northern Eurasia remain understudied. We investigated EM fungal community structure on plant roots and its determinants in eastern Siberia. We identified 291 EM fungal taxa belonging to 37 fungal genera from nine sites spanning 2100 km. In a variation partitioning analysis, host plant phylogeny was the primary factor that explained variation in fungal community composition, followed by spatial distance, soil, and climate. Host specificity and preference were attributed to differences in EM fungal community composition among host plants. The EM fungal community on Larix cajanderi, the dominant canopy tree in the region, was characterized by a high proportion of Suillus and Rhizopogon species. This implies that these specialist fungal symbionts have a close ecological relationship with pioneer Larix trees to adapt to the harsh continental climate of Siberia.

Differential Responses of Soil Bacterial and Fungal Community to Short-Term Crop Tree Management in a Larix gmelinii Plantation

Crop tree management (CTM) is a widely applicable silviculture technology that is used to improve the performance of individual trees. However, only little information is available about the effects of the CTM regime on the soil microbial community structure. We conducted a study to explore the effects of short-term (five years) CTM on the soil bacterial and fungal diversity, community composition, and structure in the 0–10 cm soil layer in a Larix gmelinii (Rupr.) Kuzen. plantation. We set out to investigate the differential response of bacterial and fungal communities to variations in soil properties mediated by short-term CTM. Compared with the control plots, the soil microbial biomass carbon and microbial biomass nitrogen in CTM increased significantly by 64.2% and 32.3%, respectively. CTM significantly promoted the content of soil organic carbon, dissolved organic carbon, and nitrate nitrogen, and reduced the content of dissolved organic nitrogen. CTM changed the Shannon and Simpson indices of soil fungi to a remarkable extent but had little effect on the α diversity of bacterial communities. The bacterial β diversity was more sensitive to CTM than fungi. The relative abundance of Verrucomicrobiae (the dominant class of soil bacteria) in CTM was significantly increased by 78.2%, while the relative abundance of Agaricomycetes (dominant class for soil fungi) was reduced by 43.3%. We observed a significantly increased number of unique OTUs for soil fungi in the CTM plots. Redundancy analysis showed that dissolved organic carbon, soil moisture, and total phosphorus content significantly affected the composition of bacterial communities, while soil dissolved organic nitrogen, C/N, and total phosphorus drove the high variation in fungal community composition. Overall, our results emphasize the divergent response of soil bacterial and fungal communities in Larix gmelinii plantations to short-term CTM. We must pay more attention to the functional role of soil microbiota in future forest management.

Site-Dependent Relationships Between Fungal Community Composition, Plant Genotypic Diversity and Environmental Drivers in a Salix Biomass System.

Soil fungi are strongly affected by plant species or genotypes since plants modify their surrounding environment, but the effects of plant genotype diversity on fungal diversity and function have not been extensively studied. The interactive responses of fungal community composition to plant genotypic diversity and environmental drivers were investigated in Salix biomass systems, posing questions about: (1) How fungal diversity varies as a function of plant genotype diversity; (2) If plant genotype identity is a strong driver of fungal community composition also in plant mixtures; (3) How the fungal communities change through time (seasonally and interannually)?; and (4) Will the proportion of ECM fungi increase over the rotation? Soil samples were collected over 4 years, starting preplanting from two Salix field trials, including four genotypes with contrasting phenology and functional traits, and genotypes were grown in all possible combinations (four genotypes in Uppsala, Sweden, two in Rostock, Germany). Fungal communities were identified, using Pacific Biosciences sequencing of fungal ITS2 amplicons. We found some site-dependent relationships between fungal community composition and genotype or diversity level, and site accounted for the largest part of the variation in fungal community composition. Rostock had a more homogenous community structure, with significant effects of genotype, diversity level, and the presence of one genotype ("Loden") on fungal community composition. Soil properties and plant and litter traits contributed to explaining the variation in fungal species composition. The within-season variation in composition was of a similar magnitude to the year-to-year variation. The proportion of ECM fungi increased over time irrespective of plant genotype diversity, and, in Uppsala, the 4-mixture showed a weaker response than other combinations. Species richness was generally higher in Uppsala compared with that in Rostock and increased over time, but did not increase with plant genotype diversity. This significant site-specificity underlines the need for consideration of diverse sites to draw general conclusions of temporal variations and functioning of fungal communities. A significant increase in ECM colonization of soil under the pioneer tree Salix on agricultural soils was evident and points to changed litter decomposition and soil carbon dynamics during Salix growth.

Seasonal Variation in Fungal Community Composition Associated with Tamarix chinensis Roots in the Coastal Saline Soil of Bohai Bay, China

Coastal salinity typically alters the soil microbial communities, which subsequently affect the biogeochemical cycle of nutrients in the soil. The seasonal variation of the soil fungal communities in the coastal area, closely associated with plant population, is poorly understood. This study provides an insight into the fungal community's variations from autumn to winter and spring to summer at a well-populated area of salt-tolerant Tamarix chinensis and beach. The richness and diversity of fungal community were higher in the spring season and lower in the winter season, as showed by high throughput sequencing of the 18S rRNA gene. Ascomycota was the predominant phylum reported in all samples across the region, and higher difference was reported at order level across the seasonal variations. The redundancy analysis suggested that the abundance and diversity of fungal communities in different seasons are mainly correlated to total organic carbon and total nitrogen. Additionally, the saprotrophic and pathotrophic fungi decreased while symbiotic fungi increased in the autumn season. This study provides a pattern of seasonal variation in fungal community composition that further broadens our limited understanding of how the density of the salt-tolerant T. chinensis population of the coastal saline soil could respond to their seasonal variations.

Changes in Fungal Community Structure in Freshwater Canals across a Gradient of Urbanization

Fungi are an important, yet often, neglected component of the aquatic microflora, and is responsible for primary decomposition and further processing of organic matter. By comparison, the ecological roles of terrestrial fungi have been well-studied, but the diversity and function of fungi that populate aquatic environments remain poorly understood. Here, the impact of urbanization on fungal diversity and community composition in the canal system of Suzhou was assessed by sequencing the internal transcribed spacer 1 (ITS1) region of the rRNA operon. It was amplified from environmental DNA that has been extracted from water samples and pre-deployed decomposing leaves collected from nine sampling locations (high, medium and low urbanization) over two seasons. The fungal diversity and community composition were determined by bioinformatic analysis of the large DNA sequence datasets generated to identify operational taxonomic units (OTUs) for phylogenetic assignment; over 1 million amplicons were sequenced from 36 samples. The alpha-diversity estimates showed high differences in fungal diversity between water and leaf samples, and winter versus summer. Higher numbers of fungal OTUs were identified in both water and leaf samples collected in the summer, and fungal diversity was also generally higher in water than on colonized leaves in both seasons. The fungal community on leaves was usually dominated by Ascomycetes, especially in winter, while water samples contained more diversity at phylum level with Chytridiomycetes often prominent, particularly in summer. At a genus level, a very high relative abundance of Alternaria on leaves was observed in winter at all locations, in contrast to very low abundance of this genus across all water samples. Fungal community composition also varied between sampling locations (i.e., urbanization); in cluster analysis, samples from high urbanization locations formed a distinct cluster, with medium and low urbanization samples clustering together or in some instances, separately. Redundancy analysis shed further light on the relationships between variation in fungal community composition and water physico-chemical properties. Fungal community diversity variation and correlation with different parameters is discussed in detail, but overall, the influence of season outweighed that of urbanization. This study is significant in cataloguing the impact of urbanization on fungal diversity to inform future restoration of urban canal systems on the importance of protecting the natural aquatic fungal flora.

Rhizosphere microbial communities reflect genotypic and trait variation in a salt marsh ecosystem engineer.

There is growing recognition that intraspecific genetic variation in plants can influence associated soil microbial communities, but the functional bridges linking plant genotype with microbial community structure are not well understood. This deficit is due in part to a prevailing focus on characterizing relationships between microbial communities and functional trait variation among plant species or across plant communities, rather than within a single species. We examined whether and how spatiotemporal variation in salt marsh rhizosphere microbial communities reflect plant provenance (genotypic variation) and associated trait variation within an ecosystem engineer, Spartina alterniflora. We planted S. alterniflora from four genetically distinct source populations in replicate sets of experimental plots across a shoreline in southeastern Louisiana, USA. After 2 years, we measured functional plant traits and profiled microbial communities. Bacterial and fungal α-diversity and richness were significantly higher in winter than in summer and corresponded to plant trait variation associated with provenance. Notably, 20% of the variation in fungal community composition was explained by trait differences while bacterial community structure did not reflect plant provenance or trait variation. However, evidence was found suggesting that bacterial communities are indirectly shaped by the influence of plant provenance on soil physicochemical properties. This study illustrates that intraspecific genetic and corresponding trait variation in an ecosystem engineer can shape rhizosphere microbial communities, with fungal communities being more responsive than bacteria to the influence of plant provenance and associated trait variation. Our results highlight the potential relevance of plant intraspecific variation in plant-microbe-soil feedbacks shaping naturally depauperate ecosystems like salt marshes.

Limited effects of depth (0–80 cm) on communities of archaea, bacteria and fungi in paddy soil profiles

AbstractMost current microbial studies in paddy soils have focused on the top (0–20 cm) layer where rice roots are concentrated. To better understand the vertical distribution of microorganisms in paddy soils, we investigated the abundances, diversities and community compositions of archaea, bacteria and fungi in six geographically and climatically distinct paddy soil profiles from 0–80‐cm depth. Although microbial abundances and operational taxonomic unit (OTU) diversities largely decreased with soil depth, only the community composition of archaea (not bacteria or fungi) was associated with soil depth, echoing that only one archaeal OTU, but no bacterial or fungal OTUs, differed significantly in relative abundance between depth intervals. Mean annual temperature, precipitation and soil iron and manganese concentrations were significantly correlated with the ordinations of microbial communities for all three domains. Besides these common environmental factors, bacterial and archaeal community structures were also influenced by soil chloride and sulphate concentrations, whereas the concentrations of organic matter and total nitrogen were important explanatory factors for the variation in fungal community composition. Further analyses on putative bacterial functions showed significant differences between sampling sites rather than depth intervals, and suggested that bacterial OTUs that significantly varied in relative abundance across sampling sites might be functionally related to organic matter decomposition, sulphur oxidation and reduction, as well as nitrate reduction. Altogether, in the studied paddy soil profiles, the community composition and putative functions of bacteria were largely the same between different vertical layers, each with a thickness of 20 cm. This study suggests that the community compositions of archaea, bacteria and fungi are mainly driven by different soil chemical properties rather than soil depth, which could be linked to the ecological traits of the three microbial domains.Highlights Communities of archaea, bacteria and fungi were investigated in six paddy soil profiles. Soil depth was only correlated with archaeal community structure Environmental factors influenced community composition differently for different domains. Bacterial OTUs contributing to variation in community composition among sites were functionally linked to C, N and S cycling.

Interactions of Microhabitat and Time Control Grassland Bacterial and Fungal Composition

Dryland grasslands are vast and globally important and, as in all terrestrial ecosystems, soil microbial communities play fundamental roles in regulating dryland ecosystem function. A typical characteristic of drylands is the spatial mosaic of vascular plant cover surrounded by interspace soils, where biological soil crusts (biocrusts)—a complex community of organisms including bacteria, fungi, algae, mosses, and lichens—are common. The implications of this heterogeneity, where plants and biocrust cover co-occur, are often explored in the context of soil fertility and hydrology, but rarely has the impact of these multiple microhabitat types been simultaneously explored to determine the influence on bacterial and fungal communities, key biological players in these ecosystems. Further, our understanding of the temporal dynamics of bacterial and fungal communities in grasslands, and of how these dynamics depend on the microhabitat within the ecosystem, is notably poor. Here we used a temporally and spatially explicit approach to assess bacterial and fungal communities in a grassland on the Colorado Plateau, and to link variation in these communities to edaphic characteristics. We found that microhabitat (e.g., vascular plant rhizosphere, biocrust, and below biocrust)was the strongest driver of differences in bacterial and fungal community richness, diversity, and composition. Microhabitat type also significantly mediated the impact of temporal change in shaping community composition. Taken together, 29% of the variation in bacterial community composition could be explained by microhabitat, date, and microhabitat-by-date interactions, while only 11% of the variation in fungal community composition could be explained by the same factors, suggesting important differences in community assembly processes. Soil microbial communities dictate myriad critical ecosystem functions, thus understanding the factors that control their compostition is crucial to considering and forecasting how terrestrial ecosystems work. Overall, this case study provides insights for future studies on the spatial and temporal dynamics of bacterial and fungal communities in dryland grasslands.

Mycological Insights Into Wetland Fungal Communities: The Mycobiome of Camassia in the Pacific Northwest

Fungal communities in ephemeral wetland habitats of the Pacific Northwest (PNW) are poorly understood. Because Camassia (camas) populations are a distinctive component of native plant communities in wetland areas of the PNW, camas plant tissue, seed, and associated soil samples were taken from populations growing in wetland habitats in Oregon, Idaho, and Washington. Enumeration of fungal taxa from above- and below-ground camas tissues was accomplished using high-throughput sequencing of fungal internal transcribed spacer genes. Operational taxonomic units (OTUs) affiliated with at least 200 fungal families were found in root, tunic, leaf, rhizosphere, and proximal soil samples (n = 2,984 OTUs). Significant variation in fungal community composition was explained by sample type, habitat of origin, and their interaction. Taxa related to Cladophialophora, Cadophora, and Exophiala, believed to be dark septate endophytes, together with Penicillium, Ceratobasidium, and Ilyonectria were differentially abundant in roots compared with the rhizospheres. Seed-associated communities comprised just 127 OTUs but were highly diverse with at least 50 families detected. Comparison of communities from camas seeds, leaves, roots, and rhizospheres revealed 68 fungal taxa in common, including Alternaria, Fusarium, Selenophoma, Cladosporium, Cryptococcus, and Sporobolomyces. This study provides a baseline understanding into the composition and diversity of fungal communities associated with camas growing in wetland habitats in the PNW.

Detecting Symbioses in Complex Communities: the Fungal Symbionts of Bark and Ambrosia Beetles Within Asian Pines.

Separating symbioses from incidental associations is a major obstacle in symbiosis research. In this survey of fungi associated with Asian bark and ambrosia beetles, we used quantitative culture and DNA barcode identification to characterize fungal communities associated with co-infesting beetle species in pines (Pinus) of China and Vietnam. To quantitatively discern likely symbioses from coincidental associations, we used multivariate analysis and multilevel pattern analysis (a type of indicator species analysis). Nearly half of the variation in fungal community composition in beetle galleries and on beetle bodies was explained by beetle species. We inferred a spectrum of ecological strategies among beetle-associated fungi: from generalist multispecies associates to highly specialized single-host symbionts that were consistently dominant within the mycangia of their hosts. Statistically significant fungal associates of ambrosia beetles were typically only found with one beetle species. In contrast, bark beetle-associated fungi were often associated with multiple beetle species. Ambrosia beetles and their galleries were frequently colonized by low-prevalence ambrosia fungi, suggesting that facultative ambrosial associations are commonplace, and ecological mechanisms such as specialization and competition may be important in these dynamic associations. The approach used here could effectively delimit symbiotic interactions in any system where symbioses are obscured by frequent incidental associations. It has multiple advantages including (1) powerful statistical tests for non-random associations among potential symbionts, (2) simultaneous evaluation of multiple co-occurring host and symbiont associations, and (3) identifying symbionts that are significantly associated with multiple host species.

Fungal community homogenization, shift in dominant trophic guild, and appearance of novel taxa with biotic invasion

AbstractInvasion by non‐native plants may fundamentally restructure the soil fungal community. The invasive plant, Alliaria petiolata, produces secondary compounds suppressive to mycorrhizal fungi and may therefore be expected to have generally negative effects on other components of the fungal community. Here, we compared fungal biomass, diversity, community composition, and the relative abundance of fungal trophic guilds, along with edaphic properties of soils collected from uninvaded and invaded plots across six temperate forests. Invaded plots were differentiated from uninvaded plots by lower variation in fungal community composition (beta diversity) and soil properties, higher fungal richness and community evenness (alpha diversity), and a suite of novel saprotrophic and pathotrophic fungi that were consistently present across the invaded landscape and absent from uninvaded forest patches. Invaded plots also had lower ectomycorrhizal but higher saprotrophic and pathotrophic relative abundance, despite there being no difference in fungal biomass between invasion statuses. We hypothesize that shifts in the fungal community with invasion may directly impact plant disease response, soil nutrient cycling processes, and plant performance of the invasive and native plant communities.

Bacterial and fungal communities and contribution of physicochemical factors during cattle farm waste composting.

During composting, the composition of microbial communities is subject to constant change owing to interactions with fluctuating physicochemical parameters. This study explored the changes in bacterial and fungal communities during cattle farm waste composting and aimed to identify and prioritize the contributing physicochemical factors. Microbial community compositions were determined by high‐throughput sequencing. While the predominant phyla in the bacterial and fungal communities were largely consistent during the composting, differences in relative abundances were observed. Bacterial and fungal community diversity and relative abundance varied significantly, and inversely, over time. Relationships between physicochemical factors and microbial community compositions were evaluated by redundancy analysis. The variation in bacterial community composition was significantly related to water‐soluble organic carbon (WSOC), and pile temperature and moisture (p < .05), while the largest portions of variation in fungal community composition were explained by pile temperature, WSOC, and C/N (p < .05). These findings indicated that those parameters are the most likely ones to influence, or be influenced by the bacterial and fungal communities. Variation partitioning analyses indicated that WSOC and pile temperature had predominant effects on bacterial and fungal community composition, respectively. Our findings will be useful for improving the quality of cattle farm waste composts.

Plant diversity represents the prevalent determinant of soil fungal community structure across temperate grasslands in northern China

Fungi play an important regulating role in terrestrial ecosystem functioning. However, their biogeographic distribution patterns along combined gradients of plant communities and environmental variables across regional spatial scales remain poorly understood. This knowledge gap is particularly pronounced in arid and semi-arid grassland ecosystems, which occupy one third of the terrestrial surface of China. Here, a regional-scale field investigation was conducted to collect soil samples from 290 plots at 52 sites along a 4000 km transect in temperate grasslands of northern China to assess the distribution patterns of fungal communities. The high-throughput Illumina sequencing revealed that soil fungal communities were dominated by Ascomycota, Basidiomycota and Zygomycota across the temperate grasslands. Fungal richness increased with plant species richness and mean annual precipitation (MAP). Bray-Cutis dissimilarities in soil fungal community composition between sites were significantly correlated with plant community composition, geographical distance, and abiotic factors including MAP, mean annual temperature, soil pH, and soil organic carbon. Variation partitioning analysis revealed that variation in fungal community composition was mainly explained by plant community composition, followed by geographical distance and abiotic factors. Structural equation models further highlighted the significant role of plant species richness in determining soil fungal richness. Taken together, these results suggest that the regional-scale distribution pattern of soil fungal communities is predominantly mediated by plant community composition, and also by abiotic factors and geographical distance in arid and semi-arid temperate grasslands.

Foliar fungi of Betula pendula: impact of tree species mixtures and assessment methods

Foliar fungi of silver birch (Betula pendula) in an experimental Finnish forest were investigated across a gradient of tree species richness using molecular high-throughput sequencing and visual macroscopic assessment. We hypothesized that the molecular approach detects more fungal taxa than visual assessment, and that there is a relationship among the most common fungal taxa detected by both techniques. Furthermore, we hypothesized that the fungal community composition, diversity, and distribution patterns are affected by changes in tree diversity. Sequencing revealed greater diversity of fungi on birch leaves than the visual assessment method. One species showed a linear relationship between the methods. Species-specific variation in fungal community composition could be partially explained by tree diversity, though overall fungal diversity was not affected by tree diversity. Analysis of specific fungal taxa indicated tree diversity effects at the local neighbourhood scale, where the proportion of birch among neighbouring trees varied, but not at the plot scale. In conclusion, both methods may be used to determine tree diversity effects on the foliar fungal community. However, high-throughput sequencing provided higher resolution of the fungal community, while the visual macroscopic assessment detected functionally active fungal species.

Patterns of natural fungal community assembly during initial decay of coniferous and broadleaf tree logs

AbstractCommunity assembly processes do not only influence community structure, but can also affect ecosystem processes. To understand the effect of initial community development on ecosystem processes, we studied natural fungal community dynamics during initial wood decay. We hypothesize that fungal community assembly dynamics are driven by strong priority effects of early‐arriving species, which lead to predictable successional patterns and wood decay rates. Alternatively, equivalent colonization success of randomly arriving spores has the potential to drive stochastic community composition and wood decay rates over time. To test these competing hypotheses, we explored the changes in fungal community composition in logs of two tree species (one coniferous and one broadleaf) during the early stages of wood decomposition in a common garden approach. Initial communities were characterized by endophytic fungi, which were highly diverse and variable among logs. Over the first year of decomposition, there was little evidence for priority effects, as early colonizers displaced the endophytic species, and diversity fell as logs were dominated by a few fungal species. During this period, the composition of colonizing fungi was related to the decomposition rates of sapwood. During the second year of decomposition, fungal community composition shifted drastically and the successional dynamics varied considerably between tree species. Variation in fungal community composition among coniferous (Larix kaempferi) logs increased, and there remained no evidence for any priority effects as community composition became stochastic. In contrast, early colonizers still dominated many of the deciduous (Quercus rubra) logs, with a temporally consistent impact on community composition. For both tree species, wood decay rates levelled off and the relationship with fungal community composition disappeared. Our results indicate that priority effects are relatively minimal in naturally occurring fungal community assembly processes. Instead, fungal successional dynamics are governed predominantly by combative abilities of colonizing fungi, and factors that shape fungal communities over time can differ considerably between tree species. Our results indicate that an increased focus of competitive strength among species, rather than priority effects, may be key to predict community assembly and the ecosystem process they provide.

Soil Characteristics Driving Arbuscular Mycorrhizal Fungal Communities in Semiarid Mediterranean Soils.

We investigated communities of arbuscular mycorrhizal fungi (AMF) in the roots and the rhizosphere soil of Brachypodium retusum in six different natural soils under field conditions. We explored phylogenetic patterns of AMF composition using indicator species analyses to find AMF associated with a given habitat (root versus rhizosphere) or soil type. We tested whether the AMF characteristics of different habitats or contrasting soils were more closely related than expected by chance. Then we used principal-component analysis and multivariate analysis of variance to test for the relative contribution of each factor in explaining the variation in fungal community composition. Finally, we used redundancy analysis to identify the soil properties that significantly explained the differences in AMF communities across soil types. The results pointed out a tendency of AMF communities in roots to be closely related and different from those in the rhizosphere soil. The indicator species analyses revealed AMF associated with rhizosphere soil and the root habitat. Soil type also determined the distribution of AMF communities in soils, and this effect could not be attributed to a single soil characteristic, as at least three soil properties related to microbial activity, i.e., pH and levels of two micronutrients (Mn and Zn), played significant roles in triggering AMF populations. Communities of arbuscular mycorrhizal fungi (AMF) are main components of soil biota that can determine the productivity of ecosystems. These fungal assemblages vary across host plants and ecosystems, but the main ecological processes that shape the structures of these communities are still largely unknown. A field study in six different soil types from semiarid areas revealed that AMF communities are significantly influenced by habitat (soil versus roots) and soil type. In addition, three soil properties related to microbiological activity (i.e., pH and manganese and zinc levels) were the main factors triggering the distribution of AMF. These results contribute to a better understanding of the ecological factors that can shape AMF communities, an important soil microbial group that affects multiple ecosystem functions.