Global patterns and drivers of soil microbial biomass C, N, and P in terrestrial ecosystems

Soil microbes play key roles in driving and regulating nutrient cycling in terrestrial ecosystems. However, a lack of global-scale information regarding the distribution of soil microbial biomass C (SMB C), N (SMB N), and P (SMB P) in terrestrial ecosystems has limited our ability to incorporate the broad-scale soil microbial nutritional properties and the associated processes into biogeochemical models. Here, we synthesized a global dataset including 3,801 observations for SMB C, 3,154 observations of SMB N, and 2,429 observations of SMB P in the top 0–30 cm soil depth. Based on this comprehensive global dataset, we generated quantitative and spatially explicit maps of SMB C, N, and P across terrestrial ecosystems using a random forest approach. In general, the global mean values of SMB C, N, and P concentrations were 693.0 mg kg-1, 89.5 mg kg-1, and 35.5 mg kg-1, respectively. These mean values belie a significantly spatial heterogeneity of these concentrations across biomes and a cle...