中文摘要：

草食动物采食对草地植物多样性和生态系统功能的影响机制是放牧生态学研究的核心问题。该研究以内蒙古锡林郭勒盟苏尼特右旗荒漠草原的长期放牧控制实验为平台,从既有草地植物多样性和动物偏食性两个层面系统地研究了荒漠草地植物多样性对草食动物采食的响应机制。结果显示：1）荒漠草地植物对草食动物采食呈现4种响应模式：放牧＂隐没种＂、放牧＂敏感种＂、放牧＂无感种＂、＂绝对优势种＂;2）在群落尺度上,物种多样性指数随放牧强度增加而减少,与不放牧小区相比,重度放牧（HG）与适度放牧（MG）小区植物多样性均下降,且这一规律同样适用于功能群多样性,灌木半灌木这一功能群内物种多样性对放牧干扰较敏感;3）在草地既有植物的基础上,以不放牧小区为参考系,草食动物对植物功能群偏食性的排序为：一二年生草本（AB）〉多年生杂类草（PF）〉灌木半灌木（SS）〉多年生禾草（PG）,且偏食性物种主要分布于AB和PF中;4）植物多样性与动物偏食性基本呈显著负相关关系（p〈0.05）。

英文摘要：

Aims The mechanism of herbivore foraging effect on plant diversity and ecosystem functions of grasslands is the core issue of grazing ecology research. This study is aimed to examine 1） how species respond to different grazing intensity in grassland, and how plant diversity responds to different grazing intensity within different organization scales and whether there are cascade effects across multiple organization scales？ 2） How herbivore foraging affects plant diversity. Methods Based on a six-year grazing experiment in Sonid Right Banner, Xilingol, the study attempted to explain the relationships between plant diversity and herbivore foraging from two perspectives, i.e. plant diversity index and herbivore preference index. Important findings Results showed that there were four modes for desert grassland plant in response to herbivore： grazing-hidden species, grazing-sensitive species, grazing-non inductive species and absolute dominant species. At the community scale, species diversity index decreased with an increased grazing intensity. Compared with no grazing, heavy grazing and moderate grazing treatments decreased community plant diversity, and the same principle is applicable to the functional group diversity. Further analysis found that differences of grazing species diversity within a functional group were mainly caused by shrubs and semi-shrubs. Compared to plots without grazing, the herbivore preference degree on the whole species was lower for moderate grazing plots than heavy grazing ones. The foraging preference order on the plant functional groups was annual and biennial forbs（AB）, perennial forbs（PF）, shrubs and semi-shrubs（SS） and perennial grasses（PG）. The preferred species were mainly distributed in AB and PF. The diversity index of plant and preference index of herbivore were basically significant and negatively correlated（p 0.05）.