Organic and inorganic carbon in the topsoil of the Mongolian and Tibetan grasslands: Pattern, control and implications. Biogeosciences Discussions 9

Abstract. Soil carbon (C) is the largest C pool in the ter-restrial biosphere and includes both inorganic and organic components. Studying patterns and controls of soil C help us to understand and estimate potential responses of soil C to global change in the future. Here we analyzed topsoil data of 81 sites obtained from a regional survey across grasslands in the Inner Mongolia and on the Tibetan Plateau during 2006– 2007, attempting to find the patterns and controls of soil inor-ganic carbon (SIC) and soil organic carbon (SOC). The aver-ages of inorganic and organic carbon in the topsoil (0–20 cm) across the study region were 0.38 % and 3.63 %, ranging be-tween 0.00–2.92 % and 0.32–26.17 % respectively. Both SIC and SOC in the Tibetan grasslands (0.51 % and 5.24 % re-spectively) were higher than those in the Inner Mongolian grasslands (0.21 % and 1.61 %). Regression tree analyse