根据新疆塔里木河中游植物样地的监测数据,计算了19种主要植物在土壤含水率与土壤盐分资源维上的生态位宽度及生态位重叠值,作出了反映它们相似程度的最小生成树图;探讨了19种植物的生态位特征及各物种在二维环境因子上的相似关系。结果表明:建群种对环境变化的生态适应性较强,在二维生态因子上的生态位宽度值较大,乔灌植物普遍具有较大的生态位宽度(个别物种除外),草本植物除建群种外生态位宽度相应较小,并对个别物种生态位的变化进行了分析。由于环境条件的影响和胁迫,塔里木河中游物种间的生态位重叠值普遍较低。根据最小生成树图分析了19种植物在二维环境因子上的生态相似关系

The Tarim River is the longest inland river in China. There are natural species belts composed of Arbors, Shrubbery and Herbage along the River The species distribution of natural species is affected by soil water, soil salt content, human activities and so on In this paper, based on the investigation data in the middle reaches of the Tarim River, niche breadths and overlaps of the 19 main species on two environmental dimensions were calculated and analyzed The minimal spanning tree revealing ecological similarity was drawn on the basis of the niche overlaps The results showed that niche breadths of community building species were bigger than that of the others, because they could acclimatize themselves to some changed environmental conditions Niche breadths of Shrubs and Arbor were generally big except for individual species, and niche breadths of Herbage were small except for community building species The above analysis shows the ecological characters of different species in the middle reaches of the Tarim River, it also shows that the niche overlaps among different species are generally low in the middle reaches of the Tarim River, that is, different species need different nutrient which can enable different kinds of species live together for a long time The ecological character of different species in a same family is more similar, and the niche overlaps among them are also small The reason is that the ecological character among different species in a same family is more similar The needs of these species are different, which lower the degree of niche overlaps and make these species live together in a small ecological environment Based on the minimal spanning tree, the ecological similarity of 19 species was analyzed on two environmental dimensions According to different ecological needs among the 19 species, they could be divided into four categories when the niche overlap is greater than 0 278 These species could also be divided into three categories according to the soil salt content when the niche overlap is greater than 0 190 These phenomena show the importance of the ecological character in the niche evolution