Vegetable niche of enclosed grassland in Yanchi county of Ningxia

In order to find the vegetable niche pattern in arid and semi-arid grassland region,the niche breadth and niche overlapping in Yanchi county of Nixia in 2002 and 2003 are measured by means of Levins niche breadth and Pianka niche overlapping indexes of enclosed grassland.The results showed that,the biological and ecological characteristics of Artemisia capillaris Thunb determined its predominant station in this(region),and its niche breadth in 2002 and 2003 were bigger than other species(0.758 and 0.868) continuing to keep rising trend.The results of niche overlapping in 2002 and 2003 also showed that the species with big niche breadth didn't always have big niche overlapping,and the niche breadth and niche overlapping did not have a positive direct linear relation.The higher Pianka niche overlapping in 2002 and 2003 both appeared in the species with low niche breadth,which showed from another point of view that environment and resources have high spatial heterogeneity during the vegetation restoration process.