Variations in fungal community structure along elevation gradients in contrasting Austrian Alpine ecosystems

Abstract

Soil fungi, as a major decomposer of organic matter, govern carbon (C) cycle and act as crucial regulators of the soil C and nutrient balance in terrestrial ecosystems. Climate change and parent material alter important environmental conditions that may affect fungal community. However, very little is known about the diversity and community structure of soil fungi along elevation gradients with distinct parent material properties. We investigated the effects of climate and vegetation changes on soil fungal diversity and community structure at two Austrian alpine sites with different bedrock properties (limestone at the Hochschwab site and silicate at the Rauris site), but with similar climatic conditions. At these sites we sampled soils from 0 to 25 cm depth along three elevation gradients ranging from 900 to 2100 m above sea level and examined how the fungal communities vary by using Illumina MiSeq sequencing. Our results show that the fungal community structures at the Hochschwab and the Rauris site were defined by elevation-induced changes in vegetation and associated differences in soil pH. In forest soils, symbiotrophic fungi (mainly belonging to the class Agaricomycetes, phylum Basidiomycota) were dominant at the Hoschwab site, while at the Rauris site the Ascomycota were the most dominant phyla. The change to grass dominated vegetation generally increased the contribution of saprotrophic fungi (mainly belonging to various classes of the phylum Mucoromycota) at both elevational sites. Prevalence of ectomycorrhizal fungi and associated lignolytic enzymes induced soil C loss might explain lower soil organic C stocks at the Rauris site compared to the Hochschwab site. Our results suggest that parent material can modulate fungal communities indirectly via vegetation (e.g., litter quality) adapted to particular soil conditions. Therefore, changes in fungal structural composition might exert important consequences on ecosystem C balances.