轮牧高寒草甸温室气体排放的季节动态与羊粪的作用

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

用静态箱法测定了藏羊轮牧的高寒草甸温室气体的排放及其季节动态,分析了羊粪的作用。结果显示,高寒草甸土壤为CH4的汇,返青季CH4日吸收量最高,轻牧区为枯黄季最低,适度放牧增强高寒草甸吸收CH4的能力;高寒草甸土壤为CO2的源,牧草生长旺季日排放量最高,枯黄季最低,重牧促进高寒草甸CO2排放;放牧没有改变高寒草甸作为CH4汇/CO2源的功能。分析表明,羊粪具有抑制高寒草甸温室气体排放的趋势,季节对于温室气体排放的作用大于放牧。

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 CH,. 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 CH2 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 CH, sink/ CO2 source. Analyses showed that the sheep dung could inhibit the trend of greenhouse gas emissions in alpine meadow and sea- son 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.