中文摘要：

通过测定科尔沁不同强度放牧后自然恢复的沙质草地的土壤呼吸、碳平衡和碳储量．结果表明．整个生长季平均土壤呼吸速率表现为轻牧后恢复草地（CO2—C0．737g／m^2·d）〉无牧后恢复草地（CO2-C0．704g／m^2·d）〉中牧后恢复草地（CO2-C0．641g／m^2·d）〉重牧后恢复草地（CO2-C0．576g／m^2·d）；无牧和重牧后恢复草地的碳素输人和输出处于平衡状态，轻牧和中牧后恢复草地的碳素输人显著高于输出．净截存碳分别为84．89和76．51g／m^2；植物—土壤系统的碳储量大小为轻牧后恢复草地（1785．39g／m^2）〉中牧后恢复草地（1494．69g／m^2）〉无牧后恢复草地（1483．61g／m^2）〉重牧后恢复草地（1323．39g／m^2）。研究结果表明．不同强度放牧后的退化沙质草地在采取围封恢复措施以后．有益于大气CO2的截存．而适度（轻度和中度）放牧后的恢复更有利于增强沙质草地的碳汇作用。

英文摘要：

Soil respiration, carbon balance and carbon storage of sandy grasslands in natural restoration processes were studied after the grasslands were subjected to different grazing intensities. The mean soil respiration rate in the growing season decreased in the order： post-light-grazed restoration plot （CO2-C 0. 737 g/m^2· d） non-grazed restoration plot （CO2-C 0. 704 g/m^2· d）） post-moderate-grazed restoration plot （CO2-C 0. 641 g/ m^2· d）〉 post-heavy-grazed restoration plot （CO2-C 0. 576 g/m^2· d）. The C balance calculated as the difference between net primary production （sink） and respiration of heterotrophs （source） suggested equilibrium between the input and output of C in the non-grazed restoration plot and post-heavy-grazed restoration plot, and sequestration C of 84.89 and 76.51 g/（m^2· growing season） in the post-light-grazed restoration plot and postmoderate-grazed restoration plot, respectively. The C storage in plant-soil ecosystems decreased in the order： post-light-grazed restoration plot （1 785.39 g/m^2） 〉 post-moderate-grazed restoration plot （1 494.69 g/m^2） non-grazed restoration plot （1 483.61 g/m^2） 〉 post-heavy-grazed restoration plot （1 323.39 g/m^2）. It is concluded that the degraded sandy grassland could contribute to carbon sequestration under exclosure conditions but that, moderate grazing would enhance the C sequestration more significantly.