宁夏盐池荒漠草原区天然草地植物生态位研究

运用Levins生态位宽度指数及Pianka生态位重叠指数，对宁夏盐池无量殿的植物生态位宽度及生态位重叠度进行了计算，从生态位角度揭示了荒漠草原区天然草地的植被生长状况。结果表明:2008年达乌里胡枝子、老瓜头、阿尔泰狗娃花生态位宽度值最大，是该区的优势种；2009年天然草地的优势种是阿尔泰狗娃花、丝叶山苦荬、老瓜头、达乌里胡枝子。2008年和2009年的生态位重叠结果均表明，生态位宽度大的物种不一定和其他物种有大的重叠指数，较高的生态位宽度和较高的生态位重叠度之间并不存在明显的线性关系。相比2008年，2009年6-8月降雨量较大，植物长势好，密度较大，资源利用率较高，植物种间竞争更为激烈，使得生态位宽度和生态位重叠度总体比2008年大。可见，荒漠草原区降雨量的多少是影响植物生长的主要因素。

The Study on Vegetable Niche of Natural Grassland of Desertification Grassland Region in Yanchi County, Ningxia

In order to show growth of plants in natural grassland of desertification grassland region from niche’s view,the niche breadth and niche overlapping of plants are measured by means of Levins niche breadth and Pianka niche overlapping indexes in the grassland of Wuliangdian,Yanchi county,Ningxia.It shows that Lespedezadavurica(Laxm.) Schindl.,Cynanchum komarovⅡ Al.,Heteropappus altaicus which have the biggest niche breadth are dominant species in natural grassland in 2008,while in 2009 Heteropappusaltaicus(Willd.) Novopokr.,Lxeris chinensis var.graminifolia(Ledeb.) H.C.Fu,Cynanchum komarovⅡ Al.,Lespedezadavurica(Laxm.) Schindl.become the dominant species.Meanwhile,the result of niche overlapping in 2008 and 2009 showed that the species with big niche breadth did not always have big niche overlapping,and the niche breadth and niche overlapping did not have an obvious linear relation.Compared with 2008,in 2009 the niche breadth and niche overlapping were bigger on the whole,because the amount of rainfall from June to August are more in 2009,the plants grow well with bigger density and higher use of resources,and interspecific competition of the plants is more fierce.And these indicate that the amount of rainfall is the primary factor for growth of plants.