外来物种对云南大山包湿地植物群落物种多样性的影响

Effects of Exotic Species on Species Diversity of Plant Communities in Dashanbao Wetland

大山包湿地属于典型的季节性湿地,湿地面积斑块状分布极易受到外界干扰。以大山包沼泽化草甸为研究对象,利用样方法调查大山包湿地外来物种的种类和分布情况,并采用TWINSPAN分类方法将湿地群落划分为有外来物种分布的群落和无外来物种分布的群落,对群落多样性进行分析,研究外来植物对湿地生态系统的影响。结果表明:有外来物种分布的群落为菊状千里光(Senecio laetus)+车前(Plantago asiatica)的Ⅰ群落、小灯心草(Juncus bufonius)+细芒羊茅(Festuca stapfii)的Ⅲ群落、水马齿(Callitriche palustris)+尼泊尔蓼(Polygonum nepalense)的Ⅳ群落;无外来物种分布的群落为尼泊尔蓼+透明鳞荸荠(Heleocharis pellucida)的Ⅱ群落。从多样性指数来看,有外来物种分布的群落(Ⅰ、Ⅲ、Ⅳ)其Shannon-Wener指数、Simpson指数、丰富度指数、均匀度指数均高于无外来物种分布的群落(Ⅱ),有外来物种分布的群落其物种多样具明显优势。白花三叶草在6种外来物种中,扩散能力最强。白花三叶草为豆科植物,改善了湿地的土壤肥力,促进沼泽湿地物种多样性增加。

The Dashanbao Wetland,Zhaotong,Yunnan,is a typical seasonal wetland consisting of several patchy sections,which are susceptible to disturbance from outside.This paper attempts to investigate into the impact from alien invasive floral species on the local wetland ecosystems using a quadrate methodology,including such exotic species and their patterns in distribution around the adjacent swamp meadows.In the process the authors also adopts TWINSPAN classification approach to divide those local wetland communities into ones with exotic species and ones without,which are assessed separately in terms of their diversity for understanding the impact on them.The results show that there do exist communities with alien species in distribution(I Senecio laetus+Plantago asiatica community,ⅢJuncus bufonius+Festuca stapfii community,IV Callitriche palustris+Polygonum nepalense community),and the communities without alien species,i.e.,Polygonum nepalense+Heleocharis pellucida community.Judging from the diversity index,the Shannon-Wener index,the Simpson index,the richness index,and the evenness index of the alien species distribution in I,III,and IV are all higher than the communities without alien species in II communities.There are obvious dominance in the distribution of alien species.For instance,communities dominated by Trifolium repens,an alien species from legume family,may help improve soil fertility and importantly,help promote the diversity on the landscape.