Abstract: In order to clarify the response characteristics and laws of individual morphological characteristics and individual diversity of Stipa breviflora to stocking rate， the Stipa breviflora steppe in Siziwang Banner， Wulanchabu City， Inner Mongolia was taken as the research object. The single factor randomized block experimental design of stocking rate was adopted. Each block was set up with four experimental treatments： enclosed non-grazing area （CK）， mild grazing area （LG）， moderate grazing area （MG） and severe grazing area （HG）. The stocking rates were 0， 0.91， 1.82 and 2.71 sheep units·hm^-2·（0.5 a）^-1， and based on the sampling method of representative plots in representative areas， combined with two factor analysis of variance， diversity index calculation， and corresponding analysis methods， the results as following. Heavy grazing leads to a decrease in the basal area， projected area， and height of Stipa breviflora individuals； the basal area， projected area， and height of Stipa breviflora individuals all increase with age-class increasing. The individual richness of Stipa breviflora increases with the increase of stocking rate. Under moderate grazing， the Shannon-Wiener diversity index and Pielou evenness index of Stipa breviflora individuals are higher， while the Simpson dominance index is lower. The C₂-C₄ age-class is of great significance in resisting grazing disturbance. In conclusion， heavy grazing leads to the reduction of individual morphology （base area， height and projection area） of Stipa breviflora， and the population maintains coverage by increasing density but aggravates the risk of patchy death in dry years. At the same time， it supplements the loss of species diversity through age class transition and individual diversity， thereby buffering grazing interference and maintaining the stability of community structure and function.

Key words: Stipa breviflora, Stoking rates, Morphological characteristics, Individual diversity

摘要： 为明确短花针茅（Stipa breviflora）个体形态特征及个体多样性对载畜率的响应特点和规律，本研究以内蒙古乌兰察布市四子王旗短花针茅草原为研究对象，采用载畜率单因素随机区组试验设计，每一区组设置围封不放牧区（CK）、轻度放牧区（LG）、中度放牧区（MG）和重度放牧区（HG）4个试验处理，载畜率分别为0，0.91，1.82，2.71羊单位·hm^-2·（0.5a）^-1，基于代表区代表性样地取样方法，结合双因素方差分析、多样性指数计算以及对应分析方法，得到如下结果：（1）重牧导致短花针茅个体基部面积、投影面积、高度下降；（2）短花针茅个体基部面积、投影面积和高度均伴随龄级增大而增大。（3）短花针茅个体丰富度伴随载畜率增大而增大，适度放牧下短花针茅个体Shannon-Wiener多样性指数和Pielou均匀度指数较大，Simpson优势度指数较小；（4）C₂~C₄龄级对抵御放牧干扰具有重要意义。总之，重牧导致短花针茅个体形态缩减（基部面积、高度、投影面积下降），种群通过密度增加维持盖度但加剧干旱年斑块性死亡风险；同时，其通过龄级跃迁和个体多样性补充物种多样性损失，从而缓冲放牧干扰，维持群落结构与功能稳定。

关键词: 短花针茅, 载畜率, 形态特征, 个体多样性