城市郊区外来杂草生态位特点及对生物多样性影响研究

Niche characteristic of exotic weeds in suburb and the impacts on biodiversity

采用样方法调查金华市郊春夏季节非农田生境的外来杂草和主要"土著性"杂草的种类和分布,分析外来杂草和其他主要杂草的生态位关系,定量分析了外来杂草对城市郊区植物多样性的影响。结果表明:(1)50个样地中共出现21种外来杂草,其中以野塘蒿、一年蓬、北美车前的生态位宽度最大,分别达到0.7819、0.6915、0.5237;(2)大致可将50种杂草分成3大类,其中21种外来杂草根据其对环境资源利用的差异又可分为4组;(3)人为干扰因素和土壤水分条件是影响外来杂草分布、危害的主要因素;(4)样地聚类群VI、I、III、II的外来杂草丰富度递增,并与物种丰富度成正比,说明外来杂草在一定程度上丰富了局部环境的物种多样性;(5)外来杂草重要值与物种丰富度呈线性显著负相关,表明金华市郊外来杂草的入侵对生物多样性有不利的影响;(6)外来杂草重要值较外来杂草丰富度更为适合衡量外来杂草对生物多样性的影响。

A survey of species and distribution of exotic weeds was conducted with quadrat plot method in non-filed habitats in late spring and early summer in Jinhua suburb. The ecological similarity of exotic weeds and native companion weeds was analyzed, and the quantitative influence of exotic weeds on biological diversity was studied. The results showed： （1） Conyza bonarinisis, Erigeron annuus, and Plantago virginica had wider niche breadths, with 0. 781 9,0. 691 5 and 0. 523 7 respectively spring and early summer in suburb. （2）Based on the niche overlaps,50 weeds in suburb could be divided into three groups, and the 21 exotic weeds could be divided into four groups according to their differences in deploying environmental resources. （3）The Detrended Canonical Correspondence Analysis （DCCA） revealed that the human disturbance intensity and soil humidity were the most important factors affecting the occurrence and distribution of exotic weeds. （4）Positively correlation existed between species richness and exotic weed species richness in sites group Ⅵ ,Ⅰ, Ⅲ,Ⅱ. This phenomenon showed that the exotic weeds enriched the biodiversity in a certain extent at the present time in local habitats. （5）The correlation between important value（x）of exotic weeds and species richness（y）showed significant negative correlation（y=-14.36x＋27.48,R= 0. 928, P〈0. 05）. With the increase of the important value of exotic weeds, Shannon-Wiener index（H） and evenness index（E） declined, while Audair and Goff index（D）increased. The results showed that invasion of exotic weeds had a harmful influence on biological diversity. （6）Importsnt value of exotic weeds was a suitable criterion for evaluating the effect of exotic weeds on biodiversity than species richness of exotic weeds.