Abstract: Studies have been made on three main traits of communities’ composition and structure in 18 abandoned lands of abandondment to analyze the species number-area curves, species diversity indices and species abundance pattern of communities. The results show that both power and exponent function could be used to fit the curves of species number-area. As the land abandoned time advances, the land community evenness decrease and the dominance index increase, the species diversity indices Simpson、Shannon、Brilliouin and Dahl decrease, but the Whittaker index steadily increase. The species patterns of initial succession stage effect logarithmic series distribution, which implies that niche pre-emption is the main factor in controlling the structure of the initial succession community. The species patterns of the middle and the later stage are arranged in lognormal distribution, their community structures could be affected by niche pre-emption, seed invasion stress of the nearby community, interspecies competition and other factors concurrently. Besides the above situations, some community patterns are of neither distributions . More statistical and theory models are needed to explain all this.

Key words: Loess hilly region, Succession, Species diversity

摘要： 对陕北黄土丘陵区18块不同年限撂荒样地调查分析。结果表明:指数函数和幂函数均可对种数-面积曲线进行拟合;随着撂荒年限的增加,群落组成均匀度下降,Simpson、Shannon、Brilliouin和Dahl多样性指数减小,但优势度多样性指数-Whittaker则随着撂荒年限的增加而稳定上升;撂荒演替前期的样地群落基本属于对数级数分布,说明该阶段种的组成主要是生态位预占模式起作用,演替中后期属于对数正态分布,可能是生态位预占、周围繁殖体的侵入压力、种间竞争和其它因素共同作用的结果。

关键词: 黄土丘陵区, 演替, 多样性