Climate and vegetation together control the vertical distribution of soil carbon, nitrogen and phosphorus in shrublands in China

Carbon (C), nitrogen (N) and phosphorus (P) in soil are characterized by decreasing patterns with soil depth. However, these patterns and their driving factors have rarely been investigated in shrublands. We conducted extensive sampling of the top 100 cm of soil in 1120 shrublands across China to measure the soil organic C (SOC), total N (STN) and total P (STP) concentrations and densities. We found that in shrublands, the geometric means (and geometric standard errors) of SOC, STN and STP concentrations were 5.62 (0.09), 0.66 (0.07), and 0.31 (0.07) mg g−1, respectively, and those of their densities were 5.46 (0.08), 0.67 (0.08), and 0.30 (0.08) kg m−3, respectively. The decrease along soil depth for nutrients could be parameterized by a power function. The rates of decrease with depth differed between shrubland types and were negatively correlated with temperature but positively correlated with biomass. Climatic factors tended to have a relatively stronger effect than vegetation factors on the vertical distribution patterns of soil nutrients. Our findings reveal nutrient limitations in shrublands in terms of the total pools, suggest the necessity of soil protection for vegetation conservation and restoration, and provide an important supplement for the accurate prediction of terrestrial element cycles.