Warming alters elevation distributions of soil bacterial and fungal communities in alpine grasslands

Abstract

It is still unknown whether climate warming can change the elevation distribution of soil microbial communities in alpine grasslands. Both species and phylogenetic β-diversity of soil bacterial and fungal communities were investigated at three alpine grasslands (site A: 4300 m, site B: 4500 m, and site C: 4700 m) after 7–8 years of experimental warming. Three main findings were observed. First, warming may increase species β-diversity of soil bacterial community between altitudes, while decrease species β-diversity of soil fungal community between altitudes. This finding may be due to their (species β-diversity of soil bacterial community vs. fungal community) different relationships with environmental factors and different responses of ecological processes in determining the community turnover between elevations to warming. Second, compared to phylogenetic β-diversity, species β-diversity of soil bacterial and fungal communities between elevations had diverse responses to warming. This finding may be related to species and phylogenetic β-diversity had different correlations with environment variables (e.g., soil moisture had the greatest contribution to soil bacterial species β-diversity between elevations, but the ratio of available nitrogen to phosphorus had the greatest contribution to soil bacterial phylogenetic β-diversity between elevations under warming scenes). Third, warming effects on species and phylogenetic β-diversity of soil bacterial and fungal communities between elevations varied with years (e.g., for soil fungal community, the phylogenetic β-diversity between elevation 4300 m and 4500 m was reduced after 7-year of experimental warming, but increased after 8-year of experimental warming), which may be due to interannual variability in climate conditions, relative contributions of ecological processes in determining the community turnover between elevations, and warming effects on the differences of soil variables between elevations. In summary, warming can reconstruct the elevation distribution patterns of soil bacterial and fungal communities, and the reconstruction can vary with β-diversity type (i.e., phylogenetic versus species β-diversity) and year.