Variations of organic carbon storage in vegetation-soil systems during vegetation degradation in the Gahai wetland, China.

Abstract

Qinghai-Tibet Plateau wetland, an important component of terrestrial ecosystem, plays an essential role in global carbon cycling. To understand the variation of organic carbon storage in vegetation-soil system during vegetation degradation in the Gahai wetland we examined aboveground litter, root biomass and soil organic carbon content in different degradation stages (CK: no degradation, SD: light degradation, MD: moderate degradation, HD: heavy degradation). The results showed that except for HD, carbon storage of aboveground biomass was 99.58-205.64 g·m-2 and that of root biomass (0-40 cm) was 56.96-754.37 g·m-2. The carbon stocks of aboveground and roots decreased significantly with degradation. Soil bulk density increased first and then decreased with degradation. Soil bulk density of each layer under degraded wetland was greater than that of the control. The carbon storage of litter was 17.29-35.69 g·m-2, which was significantly higher in CK than in MD and HD. The carbon storage in the soil (0-40 cm) was 7265.06-9604.30 g·m-2, with the order of MD＞CK＞SD＞HD. The carbon storage in CK and MD as significantly higher than that in SD and HD. The total carbon storage in the vegetation-soil system was 7265.06-10389.94 g·m-2 under different degradation stages. The largest was in CK, followed by MD, SD, and HD. Organic carbon was mostly stored in soil, which accounted for over 90% of the storage. Moderate interference might benefit carbon sequestration of the alpine wetland ecosystems.