The vertical distributions of soil microbial biomass and soil organic carbon across terrestrial ecosystems

The data were used for the global synthesis on the topic of the vertical distribution of microbial biomass carbon (MBC). The data were collected from 82 articles, covering 163 observations. To quantify the vertical distribution patterns of MBC and SOC, we used an exponential decay function to fit MBC and SOC with soil depth: log10(Y)= -kd + m where Y is the MBC or SOC density (g cm-3) at depth d (midpoints of depth intervals, cm), k characterizes the relative decrease rate of MBC or SOC with depth, the greater k, the faster MBC or SOC decreases along the soil profile. m indicates the power of ten of MBC content at the soil surface. We used kMBC and kSOC to represent the rates of decrease in MBC and SOC, respectively. We square-root transformed kMBC and kSOC to make these two variables comparable and to facilitate visualization of the relationship.