中文摘要：

采用静态暗箱法,比较测定了放牧对内蒙古锡林河流域羊草群落土壤呼吸的影响以及水热等相关环境因子与土壤呼吸的关系。结果表明：放牧没有改变羊草群落土壤呼吸的季节性变化特征,但降低了土壤呼吸速率的年幅度;生长季放牧样地土壤呼吸速率显著低于封育样地,非生长季两样地土壤呼吸强度均处于较低水平,而且出现负通量的现象,放牧使羊草群落土壤呼吸年总量下降了约33.95%;从全年来看,无论是围栏还是放牧样地,封育样地和放牧样地土壤呼吸与温度因子均显著正相关（p〈0.01,n=15）,其中与10cm处地温相关性最好,但放牧降低了土壤呼吸对温度变化的敏感性;生长季水分影响作用高于温度,围栏封育样地0～10cm土壤含水量的变化可以解释土壤呼吸变异的87.4%,放牧样地10～20cm和20～30cm土壤含水量的变化共同可以解释土壤呼吸变异的74.9%。

英文摘要：

Using the static opaque enclosed chamber, the seasonal dynamics and annual total amount of soil respiration in fence-enclosed and grazed Leymus chinensis steppes of Xilin River basin in Inner Mongolia, China, were compared in 2007, and its environmental driving factors were analyzed. The results showed that there was no significant difference between fenced and grazed plots in seasonal dynamics of soil respiration, but the grazed decreased the annual variation range of soil respiration. In growing season, the soil respiration rates were much lower in the grazed plot than in fence-enclosed plot, and annual soil respiration decreased by 33.95% due to the grazing, but in the non-growing season, there was little difference in soil respiration between the two sites. In a year round, soil respiration was positively correlated with the temperature, the Q10 values in fence-enclosed and grazing plots were 3.89 and 2.59, respectively, and grazing decreased the sensitivity of temperature sensitivity of soil respiration, while in the growing season, soil respiration was significantly related to soil moisture. In the fence-enclosed plot, soil respiration was affected by the soil water content at a depth of 0-10 cm, and the change of 0-10 cm soil water content accounted for 87.4% of variation of soil respiration. In the plot with grazing, soil water contents at depths of 10-20 and 20-30 cm were the main factors affecting the change of soil respiration, and the two factors could explain 74.9% of the total variation of soil respiration.