中文摘要：

应用Levins和Shannon-weiner生态位宽度指数,以及Pianka生态位重叠指数、简化Morisita生态位重叠指数对晋西黄土区和土石山区交错地带29个主要灌木树种的生态位特征进行了研究,并对各树种的DCA排序分析结果与生态位特征进行了对比分析。结果表明：（1）灰栒子（Cotoneaster acutifolius）、土庄绣线菊（Spiraea pubesceus）、黄刺玫（Rosa xanthina）等物种的生态位宽度明显大于其他物种。（2）多数灌木种之间存在较小的生态位重叠,只有少数种对间生态位重叠值较大。以Pianka生态位重叠指数为例,406个种对之中,有116个种对间不存在生态位重叠,占总种对数的28.57%;指数值在0-0.5间的种对数为276对,占总种对数的67.98%;指数值在0.5-1时种对数只有14对,仅占总种对数的3.45%。（3）物种DCA排序图第一轴反映了各物种分布生境的水分条件。对比分析表明,生态位宽度小的物种多位于DCA排序图的边缘区域,而生态位宽度较大的种则多位于排序图的中心区域。

英文摘要：

In order to probe into the range of distribution of the shrub species in the ecotone between the loess hilly area and bedrock area in the Zhongyang county of west Shanxi province, the niche breadth （Levins, Shannon weiner index）, niche overlap （pianka, simple Morisita） and Detrended Correspondence Analysis（DCA） of 29 species were calculated in this paper. The result of niche characteristic and DCA analyse were also compared. The results showed that the niche breadth of some species were bigger than that of other species, including Cotoneaster acuti folius , Spiraea pubesceus , Rosa xanthina , Viburnum mongolica etc. These species were widely distributed in the study area and had better eco-climate adapt ability than other species which could be used to silviculture in the future. Most Of the species couples had less niche overlap index value, while only few of the species couples had great niche overlap index value. As the Pianka niche overlap index, among the 406 species couples, there were 116 couples which niche overlap value were zero. The niche overlap value of 276 couples were between 0 and 0.5 which was 67.98% of all the couples, and the he niche overlap value of 14 couples were between 0.5 and 1 which was 3.45% of all the couples. The classification of 29 shrub species based on the method of DCA was also rational and actual. The DCA figure of shrub species reflected the spatial pattern of all the species and the eco- logical adaptability of species. The axis 1 of DCA reflected the environmental moisture gradient where the species located. The species which enjoyed moisture environment lied on shade slope and the left of axis 1. The species which could bear dry environment lied on the right of the figure. Diagonal line of the two-dimensional ordination diagram of species DCA reflects the spatial pattern of species. The species which lied on the bottom right of DCA figure numerously distributed in the loess hill area, while the species lied on the top left of the figure mainly distributed in the