Depth dependence of climatic controls on soil microbial community
activity and composition
Abstract
Subsoil microbiomes play important roles in soil carbon and nutrient
cycling, yet our understanding of the controls on microbial communities
in the subsoil is limited. Here, we investigate the direct (mean annual
temperature and precipitation) and indirect (soil chemistry) effects of
climate on microbiome composition and activity throughout the soil
profile across two elevation-bioclimatic gradients in central
California, USA. We show that microbiome composition changes and
activity decreases with depth. Across these sites, the direct influence
of climate on microbiome composition and activity was relatively lower
at depth. Furthermore, we find that certain microbial taxa change in
relative abundance over large temperature and precipitation gradients
only in specific soil horizons, highlighting the depth dependence of the
climatic controls on microbiome composition. Our finding that the direct
impacts of climate are muted at depth suggests that deep soil
microbiomes may lag in their acclimation to new temperatures with a
changing climate.