Abstract: Grazing is a key human disturbance affecting the structure and function of desert steppe ecosystem. Most of the current studies focus on the response of species or functional groups at a single level， and there is a lack of systematic analysis of the changing patterns of the correlation between the two with the change of disturbance gradient. In this study， Stipa breviflora desert steppe in Inner Mongolia was taken as the object， and four stocking rate gradients were set up. By measuring the characteristics of plant populations and dividing functional groups， the relationship between dominant species （Stipa breviflora， Cleistogenes songorica， Artemisia frigida） and functional groups （life form， photosynthetic type， root type） was analyzed by grey correlation degree. The results showed that： （1） The dominant species had different responses to grazing. Stipa breviflora and Cleistogenes songorica had strong grazing tolerance， and Artemisia frigida decreased significantly with the increase of stocking rate. （2） Perennial grass （PG） was always dominant in the community， C₄ functional group performed the best under moderate grazing， and the axis root system （ARS） was sensitive to grazing. （3） Grazing intensity regulated the association pattern of dominant species and functional groups： the two were the most closely related under light grazing （LG）， the dominant species contributed the most under moderate grazing （MG）， and heavy grazing （HG） led to the weakening of functional group association and community simplification. This study revealed the dynamic response of dominant species and functional groups to grazing， and provided a scientific basis for grassland management in arid areas.

Key words: Desert grassland, Dominant populations, Function groups, Correlation degree

摘要： 放牧是影响荒漠草原生态系统结构与功能的关键人为干扰，目前研究多集中于物种或功能群单一层次的响应，缺乏对二者关联格局随干扰梯度变化的系统解析。本研究以内蒙古短花针茅（Stipa breviflora）荒漠草原为对象，设置4种载畜率梯度，通过测定植物种群特征并划分功能群，采用灰色关联度分析优势种[短花针茅、无芒隐子草 （Cleistogenes songorica）、冷蒿（Artemisia frigida）]与功能群（生活型、光合型、根系型）的关系。结果表明：（1）优势种对放牧响应各异，短花针茅和无芒隐子草耐牧性强，冷蒿随载畜率增加显著衰退；（2）多年生禾草（PG）在群落中始终占主导，C₄功能群在中度放牧时表现最优，主根系（ARS）对放牧敏感；（3）放牧强度调控优势种与功能群的关联格局：轻度放牧（LG）下二者关联最紧密，中度放牧（MG）下优势种贡献最大，重度放牧（HG）则导致功能群关联减弱、群落简化。本研究揭示了优势种与功能群对放牧的动态响应，为干旱区草地管理提供了科学依据。

关键词: 荒漠草原, 优势种群, 功能群, 关联度