典型草原开垦弃耕后不同年限群落植物多样性和空间结构特征

Influence of Restoration on Community Plant Diversity and Spatial Structure of Typical Grasslands

本文旨在研究不同退耕年限下典型草原群落空间结构和植物多样性的变化特征。以长武王东沟流域不同退耕年限的典型草原为研究对象,采用空间序列代替时间序列的方法,对植物群落空间结构和植物多样性的变化特征进行了调查和研究,旨在为草地恢复和管理提供一定的理论基础。结果表明,随着退耕年限的增加,群落高度、盖度、多样性指数、地上生物量、平均个体大小和禾草类功能群所占比例均显著增加(P<0.05),而群落均匀度指数、密度均显著降低(P<0.05)。在演替的过程中,群落中主要植物种的优势地位发生了明显的替代变化,由演替初期的冰草(Agropyron cristatum)、散穗早熟禾(Poa subfastigiata),经过中期的异燕麦(Helictotrichon schellianum)、散穗早熟禾,到演替后期的散穗早熟禾。植物群落的空间结构也发生了显著变化,由初期的高密度、小个体分布到后期的低密度、大个体分布。退耕时间对草地群落的物种组成、空间结构及系统功能等方面均存在显著影响。

The objective of this study was to investigate the community spatial structure and plant diversity features of typical grasslands with different restoration years without human activities.In this study,the grasslands with different restoration years were taken as the objects located in Changwu County,Shaanxi Province,China.The community spatial structure and plant diversity had been surveyed and researched using space series to replace time series,which aimed to provide certain theoretical basis for the grassland restoration and management.The results showed that with increasing restoration years,some indices values significantly increased（P〈0.05）,such as height,cover,diversity index,above-ground biomass,mean individual biomass and the ratio of Gramineae.However,the community evenness index and density both significantly decreased（P〈0.05）.During the restoration process,the prominent roles of some species in plant community alternatively changed,from the Agropyron cristatumand Poa subfastigiataat the early stage,to the Helictorichon schellianumand Poa subfastigiataat the later stage,and to the Poa subfastigiata at the last stage.The results suggested that the different restoration years had different effects on species composition,spatial structure and ecosystem functioning in typical grassland.