Global depth distribution of soil carbon inputs inferred from
belowground net primary production and root biomass profiles
Abstract
The depth distribution of carbon inputs to soil has been unquantified
globally, hindering our understanding of belowground carbon dynamics. We
synthesize global observational data to infer the allocation of carbon
inputs to soil depths down to 2 m, and map depth-specific carbon inputs
globally at 1 km resolution. Global average carbon input to the 0–20 cm
soil layer is 1.1 Mg C ha–1 yr–1,
accounting for >50% of total soil carbon inputs. Across
the globe, the depth distribution of carbon inputs shows large
variability, and there are relatively more carbon inputs to deeper
layers in hotter and drier regions. Edaphic, climatic and topographic
properties (in the order of importance) explain >80% of
such variability in soil depths; and the direction and magnitude of the
influence of individual properties are soil depth- and biome-dependent.
Our results provide global benchmarks for prediction of whole-soil
carbon profiles across global biomes.