Species diversity of rodent communities in the Dongting Lake area of China
洞庭湖区鼠类群落的物种多样性分析

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.