陕北黄土丘陵区退耕地植物群落演替特征

为了解黄土丘陵区侵蚀地貌退耕地植物群落演替模式及其基本特征,以陕北安塞纸坊沟流域的20块不同年限退耕地和荒坡为研究对象,采用空间代替时间序列的方法进行植物群落的调查和演替特征的分析。结果表明:退耕地植物群落大致经历了茵陈蒿群落—杂类草—狗尾草群落—长芒草群落—铁杆蒿群落—茭蒿群落的演替过程。植物群落的Shannon-Wiener指数、Simpson多样性指数、Margalef丰富度指数和Pielou均匀度指数均表现出随演替进行而上升的变化规律,但上升的速率各异;演替前期和中期的群落基本上属于对数级数分布,说明该阶段的物种组成主要是生态位预占模式起作用,演替后期的群落属于对数正态分布,可能是生态位预占、周围繁殖体的侵入压力、种间竞争和其他因素共同作用的结果;群落盖度变化与演替时间符合二次函数变化规律。

Characteristics of plant community succession on abandoned farmland in the Hilly-Gully Region of Loess Plateau

In order to understand the characteristics and model of plant communities succession in the Hilly-Gully Region of northern Shaanxi Province,an investigation in 20 abandoned farmlands with different ages was carried out through the approach of substituting the temporal serial with spatial serial at Zhifanggou Watershed.The results showed that the abandoned farmland successive phases were affirmed.The successive phases were as follows： Artemisia capillaries community—Weeds—Setaira viridis community—Stipa bungeana community—Artemisia sacrorum community—Artemisia giraldii community.The Shannon-Wiener index,Simpson index,Margalef index and Pielou index also increased in the succession process,but the rising rates of them were different.The species patterns of initial and middle succession stage appeared as logarithmic series distribution,which implies that niche pre-emption was the main factor in controlling the structure.The species patterns of the later stage performed as 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.Coverage change and community succession time were related to the quadratic function.