Seasonal dynamics of greenhouse gas emission from alpine meadow grazed by Tibetan sheep and effects of sheep dung

A static boxesgreenhouse gas analyzer was used to measure the seasonal dynamics of greenhouse gas emission in alpine meadow where Tibetan sheep were grazed. The effects of sheep dung on greenhouse gas emission were also compared. The results showed that herding alpine meadow was the sink of CH4. Under light grazing condition the highest daily absorption of CH4 in alpine meadow was in the turning green season and the lowest was in the withered and yellow season. Meanwhile, moderate grazing could enhance the ability of absorbing CH4 of alpine meadow. On the other hand, herding alpine meadow was the source of CO2. The highest daily emission of CO2 in alpine meadow was in the growing season and the lowest was in the withered and yellow season. Heavy grazing could promote the emission of CO2 in alpine meadow. Herding did not change the function of alpine meadow as CH4 sink/ CO2 source. Analyses showed that the sheep dung could inhibit the trend of greenhouse gas emissions in alpine meadow and season might have greater influence on greenhouse gas emissions than herding. Our results may be important for improving the management of carbon balance in alpine meadow.