千岛湖岛屿小型兽类群落的多样性

Analysis of the small mammals community diversity in the Qiandao Lake region

2007年秋季和2008年春季,选取千岛湖地区14个岛屿和2个半岛作为样地,采用夹夜法进行小型兽类群落组成调查。两季度共布夹20400个,捕获小型兽类1141只,隶属2目3科9属13种,啮齿目(Rodentia)鼠科(Muridae)10种和仓鼠科(Cricetidae)1种,食虫目(Insectivora)鼩鼱科(Soricidae)2种。利用以上结果分析其群落多样性,结果显示:14个岛屿小型兽类群落春、秋两季的多样性指数、均匀度指数和优势度指数均呈现极显著差异且优势种发生变化;对可能影响岛屿小型兽类群落多样性的岛屿面积、距最近陆地距离、距最近大岛距离和植物丰富度等因素进行逐步回归分析,发现只有植物丰富度对小型兽类群落的物种丰富度有显著影响;对16个样地按照物种组成比进行聚类,许源半岛样地与14个岛屿聚为一类,姚家半岛样地单独归为一类,相似性指数比较结果亦显示姚家半岛样地与其它样地的相似性指数偏低。结论:景观破碎化导致千岛湖岛屿小型兽类群落的稳定性下降,物种多样性季节变化强烈;随岛屿面积的增加,小型兽类物种丰富度并非总是增加的,而是出现反复,呈现明显的小岛效应;14个岛屿的物种与许源半岛样地物种构成比接近,推断在水库未形成前属同一生境。

During autumn 2007 and spring 2008, we surveyed 14 islands and 2 peninsulas, sampling with a total of 20 400 traps, for small mammals in Qiandao Lake, Zhejiang to determine their community diversity of mammals. The captured small mammals belonged to 13 species, 9 genera, 3 families and 2 orders, including 10 species of murids （Muridae） , 1 species of cricetid （Cricetida） and 2 species of soricids （ Soricdae）. The results showed that there were significant between-season differences in the diversity index, evenness index, and dominance index, and the preponderant species changed among the 14 islands as well. Through an analysis of stepwise linear regression on factors that could influence spe- cies diversity on islands such as area, distance to the nearest mainland, distance to the nearest bigger island and plant species richness, we discovered that only plant species richness had significant effect on the species richness of small mammals. The 16 sample sites were classified by the eonstituent proportion of species, with Xuyuan and 14 islands being the same category., and Yaojia the separated one. This result was also supported by the similarity index. Our conclusions are （ 1 ） in Qiandao Lake, habitat fragmentation has resulted in a decline of ecosystem stability yielding dramatic seasonal changes in species diversity ; （ 2 ） with the increase of island size, the species richness of the small mammals doesn＇ t always increase but shows a small island effect; （3） Xuyuan and 14 islands had been a continuous habitat before the reservoir was formed because the proportion of species within the communities was similar in these two regions.