Organic and inorganic carbon in the topsoil of the Mongolian and Tibetan grasslands: pattern, control and implications

作者：Yue Shi, Frank Baumann, Yuqing Ma, Chao Song, Peter Kühn, Thomas Scholten, Jin He · 发表于：Biogeosciences · 年份：2012 · DOI：10.5194/bg-9-2287-2012 · 研究领域：Soil Carbon and Nitrogen Dynamics、Soil Geostatistics and Mapping、Geochemistry and Geologic Mapping

Abstract. Soil carbon (C) is the largest C pool in the terrestrial 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 inorganic carbon (SIC) and soil organic carbon (SOC). The averages of inorganic and organic carbon in the topsoil (0–20 cm) across the study region were 0.38% and 3.63%, ranging between 0.00–2.92% and 0.32–26.17% respectively. Both SIC and SOC in the Tibetan grasslands (0.51% and 5.24% respectively) were higher than those in the Inner Mongolian grasslands (0.21% and 1.61%). Regression tree analyses showed that the spatial pattern of SIC and SOC were controlled by different factors. Chemical and physical processes of soil formation drive the spatial pattern of SIC, while biotic processes drive the spatial pattern of SOC. SIC was controlled by soil acidification and other processes depending on soil pH. Vegetation type is the most important variable driving the spatial pattern of SOC. According to our models, given the acidification rate in Chinese grassland soils in the future is the same as that in Chinese cropland soils during the past two decades: 0.27 and 0.48 units per 20 yr in the Inner Mongolian gras...