洞庭湖区鼠类群落的物种多样性分析

通过对洞庭湖区黑线姬鼠褐家鼠主害区桃源的害鼠群落调查，揭示了平原农田生态类型区、丘陵农林复合生态类型区和山区林农复合生态类型区及其不同生境的鼠类群落的物种多样性。在人类干扰程度最高的平原生态类型区，鼠类群落的优势种突出，优势集中性指数最高，丘陵生态区次之，而具有大片森林、受干扰较低的山区林农复合生态区，优势集中性指数最低。物种多样性Shannon—Weiner指数和均匀性指数亦显示同样的规律：适度干扰的山区复合生态区的多样性指数最高，均匀性最好，丘陵生态区居中，平原生态区最低。不论何种生态类型区，农田生境鼠类群落的优势种都较突出，优势集中性指数也较高，群落多样性和均匀性较低；林地生境的优势集中性有较大下降，山区林地内的鼠种比丘陵区要多，优势集中性指数也较低，多样性指数和均匀度都有提高。林缘农田在同一生态类型不同生境内优势集中性最低、多样性指数和均匀性最高。比较不同生境鼠类群落的相似性，最不相似的群落是农田与受人类干扰较小的森林。这些现象说明人类的社会生产活动使害鼠群落的物种多样性降低、优势度下降、优势种突出、均匀性降低，形成了只利于少数几个种群栖息和生产发展的环境，最终导致少数种群的暴发，形成危害。但适度干扰能提高物种多样性。

Species diversity of rodent communities in the Dongting Lake area of China

Rodent communities were studied in the Dongting lake area of China (Taoyuan County, Hunan Province). Approximately 18,400 covered snap traps were employed for one night once every three months (March, June, September, and December of 2001) to survey rodent populations; the plains area of the region was surveyed every month from March to December 2001. In the agricultural ecosystem of the plains (5% of the region), paddy field and dry field are predominant. Hilly areas (50%) are typical agroforestry ecosystems, whereas the mountain area (45%) is mostly occupied by forest. A total of 346 animals from nine species (Rattus norvegicus, R. flavipectus, R. confucianus, R. fulvescens, R. nitidus, R. edwardsi, Mus musculus, Apodemus agrarius and Micromys minutus) was obtained. The highest species richness (all nine species), the lowest dominant concentration (Simpson index), and the highest diversity (Shannon Wiener index) and evenness (Pielou index) were found in mountainous areas dominated by forest with few crops. Four rodent species, the highest dominant concentration, and the lowest diversity and evenness indices were found in the field ecosystem of the plains, the area with highest agricultural disturbance. Diversity in the agroforestry ecosystem of the hills (also with four species) was intermediate, as was the level of agricultural activity. Overall, diversity was lower in habitats with greater disturbance, suggesting that agriculture is an important factor influencing rodent community diversity. In farmland next to woodlands, dominant concentration was lowest and both species diversity index and evenness index were the highest, suggesting an edge effect. However, species richness was lower than in montane forest, which supported the most rodent species of all habitats in the studied ecosystems. Similarity coefficients among habitats were greatest among farmlands of the three ecosystems, and were least comparing farmlands of the three ecosystems with montane forest habitat. Rodent communities of field ecosystems differed fundamentally from rodent communities of other ecosystems or habitats, especially the natural biotopes in montane forest. Agricultural activities reduce rodent diversity, which may facilitate harmful outbreaks of resident rodent populations.