黄土沟壑区不同坡位白羊草群落物种多度分布研究

物种多度分析是研究群落结构和分析群落生态学机制的重要方法,以黄土沟壑区地带性白羊草群落为对象,研究了坡位对白羊草群落物种多度分布格局的影响。结果表明:(1)坡位对白羊草群落物种多样性有显著性影响,坡中的Shannon指数、Simpson指数、Patrick指数显著低于坡上和坡下(p<0.05),坡上和坡下上述指数无显著差异(p>0.05)。坡上、坡中和坡下的群落Pielou均匀度指数和Alatalo均匀度指数无显著差异(p>0.05);(2)采用Zipf、Zipf-Mandelbrot、几何序列、分割线段、优势优先5种生态位模型对不同坡位上白羊草群落的物种多度分布格局进行模拟,发现仅前两个模型能很好地拟合白羊草群落在坡上、坡中和坡下的多度分布格局。说明尽管在不同坡位上白羊群落的物种多样性不同,但不同坡位上群落的形成过程和机理基本一致。本研究支持了Zipf模型和Zipf-Mandel-brot模型能较好的描述演替后期群落分布格局的观点。

Distribution Pattern of Species Abundance in Bothriochloa ischaemun Community at Different Slope Positions in the Loess Gully Region,China

Analysis of species abundance(SA) is an important way to understand community structure and the underlying mechanism of community ecological processes.This paper analyzed the SA of Bothriochloa ischaemun L.Keng community at different slope positions in the Loess Gully Region of China.We fitted the SA with five niche models,including Zipf model,Zipf-mandelbrot model,niche preemption model(NPM),broken stick model(BSM) and dominance preemption model(DPM).We found out that:(1) indices of Shannon,Simpson and Patrick at the intermediate position of the slope were significantly smaller than the upland and lowland,whereas upland and lowland had no significant difference in terms of these indices;Evenness indices of Pielo(Jsw and Jsi) and Alatalo showed no difference among these slope positions;(2) Zipf model,Zipf-mandelbrot model described the species abundance distribution(SAD) pattern of Bothriochloa ischaemun L.Keng community well.All these results indicated that the community formation under different slope positions shared a similar mechanism,though its diversity indices varied among these slope positions.The results of this study confirmed that the Zipf model,Zipf-mandelbrot model can successfully reproduce the community SAD at the later succession stage.