民勤荒漠区霸王群落植物生态位研究

Study on the niche of Zygophyllum xanthoxylumcommunity in Minqin desert area

运用Simpson生态位宽度指数及Pianka生态位重叠指数,对民勤荒漠区霸王群落两大分布区的植物生态位宽度及生态位重叠度进行计算,从生态位角度分析霸王群落内各物种对资源的利用状况,揭示霸王群落的结构及分布格局。结果表明:两大分布区建群种均为霸王,霸王的生态位宽度较其他物种都要宽;建群种霸王与猫头刺、沙生针茅相互之间的重叠度指数相对较高,猫头刺、沙生针茅与霸王相互间对资源利用竞争激烈,对群落的结构共同起着重要的作用。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直接的线性关系,说明植被在演替进化的过程中对资源利用分化严重,环境资源存在着高度的空间异质性。

In order to show resources utilization status and the structural characteristics of Zygophyllum xanthoxy lum community from niche5 view, the niche breadth and niche overlapping were measured by means of Simpson niche breadth and Pianka niche overlapping indexes in the two different distribution area in Minqin desert area. It shows that constructive species is Zygophyllum xanthoxylum in both two different distribution area. The niche breadth of ZygophyUum xanthoxylum is the biggest in community. The niche overlapping are relatively high be tween Zygophyllum xanthoxylum and Oxytropis aciphylla Ledeb, and Stipa glareosa, and they have keen competi tion to utilization for environmental resources, together play important role for structure of community. The spe cies with big niche breadth does not always have big niche overlapping, and the niche breadth and niche overlap ping do not have a direct positive linear relation. It shows that environment and resources have high spatial heter ogeneity during the vegetation succession process.