Long-term grazing exclusion greatly improve carbon and nitrogen store in an alpine meadow on the northern Qinghai-Tibet Plateau

摘要

Grazing management is known to be one of the most important strategies for regulating plant community structure and soil carbon and nitrogen content for alpine meadows, but very few studies about the effect of long-term grazing management on soil and plant characteristics. In this study, biomass and soil samples were collected during the grazing and grazing-exclusion periods to determine the biomass and soil properties, two-way ANOVA was used to examine the effects of grazing management on plant and soil properties. Our results show that the aboveground biomass was reduced during the grazing period but increased during the grazing exclusion period. Furthermore, the response of plant functional groups to grazing management was different. Whereas the belowground biomass increased during the grazing period but decreased during the grazing-exclusion period. Interestingly, the 0-10 cm and 30-40 cm soil organic carbon (SOC) increased significantly during grazing and grazing exclusion period, respectively. The 0-30 cm total nitrogen (TN) and 0-40 cm available nitrogen (AN) increased significantly during the grazing-exclusion period but showed no significant change during the grazing period. The 0-40 cm SOC and TN were both significantly affected by the year, with grazing management ex- erting only a marginal effect on SOC. 0-40 cm AN was significantly affected by grazing management and the interaction between year and grazing management. Our results suggest that long-term grazing exclusions could greatly improve both above vegetation biomass and soil condition such as soil carbon and nitrogen content.