Soil microbial diversity-biomass relationships are driven by soil carbon content across global biomes

The relationship between biodiversity and biomass has been a long standing debate in ecology. Soil biodiversity and biomass are essential drivers of ecosystem functions. However, unlike plant communities, little is known about how the diversity and biomass of soil microbial communities are interlinked across globally distributed biomes, and how variations in this relationship influence ecosystem function. To fill this knowledge gap, we conducted a field survey across global biomes, with contrasting vegetation and climate types. We show that soil carbon (C) content is associated to the microbial diversity-biomass relationship and ratio in soils across global biomes. This ratio provides an integrative index to identify those locations on Earth wherein diversity is much higher compared with biomass and vice versa. The soil microbial diversity-to-biomass ratio peaks in arid environments with low C content, and is very low in C-rich cold environments. Our study further advances that the reductions in soil C content associated with land use intensification and climate change could cause dramatic shifts in the microbial diversity-biomass ratio, with potential consequences for broad soil processes.

Automated summary

Based on a global field survey, it was found that soil carbon content is closely associated with the relationship and ratio between microbial diversity and biomass in soils across different ecosystems and climate types. Particularly, the ratio of soil microbial diversity to biomass is higher in arid environments and lower in C-rich cold environments. The study indicates that reductions in soil carbon content due to land use intensification and climate change could lead to significant shifts in the microbial diversity-biomass ratio, impacting various soil processes.