The response of carbon reserves of plants and soils to different grassland managements on alpine meadow of three headwater source regions

Knowledge about carbon and nitrogen in plants and soils and response to fence and graze in alpine ecosystems is still rudimentary because of extremely geographic situation.The purpose of this study was to compare the difference among carbon concentration,and content of unit area and dynamics of above-and below-ground biomass,soil organic carbon and total nitrogen between fencing and grazing alpine meadow.The results showed that the total carbon and C:N ratio in the aboveground tissue were significantly higher in fenced and ungrazing grassland(FU) than those in free grazing grassland(FG).In addition,the order of total carbon concentration of aboveground tissue of different function groups were not identical between them;The total carbon storage(TCS) per unit of aboveground tissue,roots and 0~30 cm soil layer increased after being fenced for 5 years from free grazing grassland(9 255.17 g/m2) to fenced and ungrazing grassland(1 2637.10 g/m2) by 26.79%.However there were no significant differences between fenced and ungrazing grasslands of 10 years and 5 years.Therefore fenced to exclude grazing by Tibetan sheep and yaks was an alternative approach to sequester C from the soil in alpine meadow systems.