Contribution of spatial and environmental variables to fungal community structure in soils and litter across a mixed temperate forest landscape in central Europe
Soil fungi are an ecologically diverse group of organisms that include growth forms of single-cells to long-lived hyphal networks. They are pervasive in the soil environment and are key contributors to many essential soil processes including decomposition and nutrient cycling. While some group-specific studies (eg. Mycorrhizal fungi) have indicated the importance of dominant vegetation and abiotic factors (eg. pH) in structuring the community, we lack a broader picture. Here we examine factors influencing the fungal community in litter and soil of a mixed temperate-forest, specifically looking to address the influence of space.
In September of 2013 we carried out a one-time spatially explicit sampling of a 100km2 area, collecting soil and litter at a total of 64 sites on a 1km2 point-grid. Vegetation surveys were also conducted at the sites. Samples were analysed for soil properties including C:N ratio, organic matter, pH, and ergosterol. Extracted DNA was amplified using general eukaryotic primers targeting the internal transcribed spacer 2 region (ITS2) and sequenced on the Illumina platform. The resulting fungal community composition was analysed using PCNM and variation partitioning methods as described by S.Dray et al (2012) to assess the importance of space on community structure.
Soil and litter communities differed significantly in community composition but not in richness with 1261 and 1337 species in litter and soil respectively (total 2598). The 64 sites covered a range of above ground diversity in vegetation structure varying from open sites to coniferous and deciduous-dominated site with 98% cover (eg. richness 4-42spp; tree cover 10-98%; herb cover 1-60%).
Both soil and litter communities exhibited spatial dependency in the site-to-site variation in taxonomic composition across the study area (soil 8.5%; litter 12% of variation). In soils PCNM detected patterns of spatial autocorrelation at a coarse scale and moderate scale (likely two to three times the minimum inter-site distance). In litter PCNM detected patterns at a moderate scale and one at a much finer scale being an order of magnitude finer (likely approximating minimum inter-site distances of 1 km). Further insights may be gained from analysis and comparison of specific functional groups of fungi with differing life history strategies (such as saprotrophs versus mycorrhizal taxa or hyphal growth forms versus yeasts). Such comparisons will improve our understanding of how these different ecological groups respond to spatial and environmental factors