中文摘要：

内蒙古锡林郭勒草原处于我国典型草原分布区,但部分地区有戈壁针茅（Stipa gobica）等荒漠成分侵入,并与大针茅（S.grandis）和克氏针茅（S.krylovii）共同形成斑块状格局分布,目前尚不清楚群落中优势种之间的相互作用关系。采用2×2列联表,通过方差分析、Pearson相关分析和Spearman秩相关分析等研究方法,对大针茅＋克氏针茅群落的大针茅斑块、克氏针茅斑块和戈壁针茅斑块中的24种主要植物的种间联结动态进行了定量分析。结果表明：1）群落主要成分总体上种间联结呈无关联,种间关联松散;2）3种针茅斑块的种间关联分析,验证了由于干扰、竞争、土壤环境与植物相互作用形成的斑块分布格局,此结果为种对正、负关联理论提供了有力证据;3）同一种对的联结性质（正关联或负关联）或关联程度因斑块不同而发生改变,根据24个优势种群对环境的适应方式和主导生态因素,可将它们划分为3大生态种组。

英文摘要：

Aims Xilin Gol steppe of Inner Mongolia is located in the typical steppe area in China,but some areas have been invaded by desert steppe species such as Stipa gobica,with which S. grandis and S. krylovii mixed to form three types of patches （Stipa grandis,S. krylovii and S. gobica） within the community. It is not known what kinds of relationships exist among the dominant species in the community. Our objective was to investigate how the dominant species in the three patches interact with each other and with other species. Methods Field data were collected in August during 2007 to 2009 in the three different kinds of Stipa patches. Ten plots were set in each patch type and placed at random within the site,giving a total of 90 plots in three years. The 2 × 2 contingency table,variance ratio （VR） of the overall association,Pearson coefficient and Spearman rank correlation coefficient were used in quantitative analysis of the interspecific associations among the 24 plant spe-cies in the three kinds of patches. Important findings The overall inter-specific association among 24 plant species of the community showed no correlation,indicating that species association was weak. The distribution and formation patterns of patches,which were possibly due to interactions among interference,competition,soil environment and plant function,were verified by analyzing species correlation in the three kinds of Stipa patches. These results provide evidence for the theory of species association. We noted that the nature （positive or negative） or degree of association varied with different kinds of patches. According to their adaptability to the environment and relationships between plants and environment,the 24 species were divided into three ecological species groups.