中文摘要：

在一个生长季内，对贝加尔针茅草甸草原不同强度放牧地段（非牧段，轻牧段，中牧段和重牧段，以放牛为主）土壤呼吸作用强度与土壤微生物数量和部分土壤理化性状进行了测定和相关性分析。结果表明，不同强度放牧对土壤呼吸作用和土壤微生物数量均产生不同程度影响，即在非牧段，土壤呼吸作用和土壤微生物数量最强（多）；其余各放牧段，随着放牧强度增加，土壤呼吸作用减弱，微生物数量增加，但在各放牧段间均未达到差异显著水平（P〉0．05）。土壤呼吸强度与土壤温度和相对含水量间具有显著的相关性（P〈0．05），与土壤微生物数量和土壤pH值之间相关性不显著（P〉0．05）。说明在该草地放牧较重时首先对土壤物理环境造成不利影响，进而影响土壤微生物的呼吸作用，对微生物数量未产生实质性改变。

英文摘要：

During a growing season, soil respiration intensities, quantities of soil microorganism and part of soil physical ＆ chemical characteristics in different areas around a typical residential site in theStipa baicalensis steppe, Hulunbeir, were measured and analyzed. The data came from four grazing gradient units that represented four grazing intensities, non - grazing, light - grazing, moderate - grazing and heavy - grazing （ grazed meanly by cattle）. The results showed that the above mentioned items under different grazing intensities varied regularly, where the soil respiration and soil microorganism＇s quantity were the highest in the non - grazing area, and had no significant difference between the different areas of grazing intensities （ p 〉 0.05）. The intensity of soil respiration and soil temperature as well as soil moisture positively correlated notably （p 〈 0.05）. but had no significant correlation with the quantity of soil microorganism and soil pH value （ p 〉 0.05 ）, This indicated that the impact of grazing was mainly on the soil physical characteristics that limited soil microorganism＇ s activity. The change of soil respiration intensity was not caused by the number change of soil microorganism in this kind of steppe.