利用Shannon-Wiener生态位宽度、生态位相似比例及Pianka生态位重叠值等指标对西鄂尔多斯高原北缘四合木(Tetraena mongolica Maxim.)群落内的11种优势灌木种群进行研究。结果表明,群落中主要种类的生态位宽度均较高,其中绵刺(Potaninia mongolica Maxim.)和四合木的生态位宽度分别为1.702 6和1.532 8;各种类的生态位相似比例均较小;绵刺与其他种类的生态位重叠值较高,四合木和其他种类的生态位重叠值较低。表明四合木群落内许多耐干旱灌木逐渐占据较宽的生态位,群落层次结构比较单一,四合木与其他种类间的相互作用强度不高,整个群落抵御外来干扰的能力较弱,四合木种群有衰退的趋势。

The niche characteristics of eleven shrub populations in Tetraena mongolica Maxim. community on the North Ordos Plateau were analyzed by using Shannon-Wiener coefficient of niche breadth, similarity of niche breadth and Pianka of niche over lap. The results showed that main species in the community had broad niche breadth, in which niche breadth values of Potanini amongolica Maxim. and T. mongolica were 1.702 6 and 1.532 8 respectively. Niche similarity of inter species was lesser. The niche over lap value between P. mongolica and other species was bigger than that of T. mongolica. It indicated that niche breadth of some shrubs which endure arid environment in the community were more and more broad, the hiberarchy of T. mongolica community was single, and the competition between T. mongolica and other species was weaker. It was concluded that the ability to resisted disturbance of whole community was weaker, and the population of T. mongolica inclined to decay.