中文摘要：

摘要：选取内蒙古哈拉沁沟流域中游草本植被进行调查取样和数量分析。通过野外工作获取研究区的植物种、群落特征和环境数据，并将野外所采样品进行实验室内常规分析。分析结果显示，研究区植物群落分为5个群丛：百里香＋羊草＋细叶苔草群丛、蒙古蒿＋细叶苔草＋二裂委陵菜群丛、细叶苔草＋白莲蒿＋光稃茅香群丛、细叶苔草＋硬质早熟禾群丛和蒙古蒿＋鹅绒委陵菜＋光稃茅香群丛。DCCA样方排序的结果与分类结果较吻合，其中排序第一轴主要指示海拔和土壤pH值对群落分布格局的影响，第二轴着重反映年太阳总辐射、相对地形湿润指数（TRMI）和土壤有机质含量对群落分布格局的影响。DCCA结果揭示出各植物群落沿环境梯度的递变规律，表明海拔与土壤的湿润及营养状况是控制研究区群落及物种分布的决定性因素。

英文摘要：

The herbaceous vegetation in the middle reach of Halaqingou Stream Valley, Mt. Daqingshan, Inner Mongolia, were surveyed through quadrat samplings, and quantitatively analyzed with DCCA ordination. The resuits show that the vegetation can be inducted into 5 associations： Ass. Thymus mongolicus ＋ Leymus chinensis ＋ Carex rigescens, Ass. Artemisia mongolica ＋ Carex rigescens ＋ Potentilla bifurca, Ass. Carex rigescens ＋ Artemisia sacrorum ＋ Hierochlae glabra, Ass. Carex rigescens ＋ Poa sphondylodes and Ass. Artemisia mongolica ＋ Potentilla anserine ＋ Hierochloe glabra. The 1st axis of DCCA ordination mainly revealed the environmental influences of altitude, pH value of soil, while the 2nd one reflected the variation of the annual solar radiation, the topographic relative moisture index （TRMI） and the content of soil organic matter In general, elevation, soil moisture and nutrients were the dominant factors deciding the distribution pattern of communities and herbaceous species.