中文摘要：

通过对生长季内不同放牧强度下大针茅（Stipa grandis）种群不同土层深度根系生物量的分析,探讨放牧对大针茅根系生物量的影响。结果表明：同一放牧强度下的根系生物量在不同季节有显著性差异（P〈0.05）,0~30cm的根系生物量随季节的变化趋势成＂N＂字形变化趋势,即先增加后降低然后再增加。同一月份内,大针茅根系生物量在不同放牧强度的影响下,有显著差异（P〈0.05）,中度放牧影响下根系生物量在5,6,8三个月增加,比对照增加0.35%~16.52%,重度放牧压力下根系生物量最小。根系生物量在土壤中的垂直分布呈＂T＂字形分布,即根系生物量随土层深度增加而降低。

英文摘要：

Root biomass of Stipa grandis under different grazing intensity was measured for detecting the effect of grazing intensity on root biomass during the growing season.Results showed that the root biomass in different months under the same grazing intensity is significantly different（P0.05）.The 0~30cm root biomass shows a ＂N＂ shape which signifies a July increase,then reduces in August,followed by a second flush in October.The root biomass of Stipa grandis has Significant differences（P0.05） in different grazing intensities under the same month.Compared with the no grazing treatment,moderate grazing intensity increases the root biomass 0.35%～16.52% from May to August.Root biomass reaches its lowest at highest grazing intensity.The root biomass forms a ＂T＂-shape as roots grow deeper in soil.