Soil water soluble organic carbon under three alpine grassland types in Northern Tibet, China

Water soluble organic carbon (WSOC) is the most mobile and reactive soil carbon source available. It plays an important role in many biogeochemical processes. In this study, we assessed WSOC in the upper 0 to 15 cm soil layer, during the growing season of three representative alpine grassland types of Northern Tibet, with an average elevation of over 4500 m. We also evaluated the contributions of soil environmental factors on the three types of grassland. We found that the WSOC was typically higher at the first sampling in May and decreased with subsequent samples. Furthermore, over the short growing season, the alpine meadow steppe ecosystem had significantly higher WSOC content than the alpine meadow and alpine steppe ecosystems. Soil WSOC of alpine grasslands also negatively correlated with both soil temperature and moisture. These results indicated that soil WSOC is considerably different among the different types of grassland in the same alpine area, and we conclude that soil environmental conditions including soil temperature and moisture are important influencing factors that control soil WSOC content.