Zhang Zhibin, Xu Lei, Guo Cong, Wang Yong, Guo Yongwang
State Key Laboratory of Integrated Pest Management in Agriculture, Institute of Zoology, Chinese Academy of Sciences, Beijing, ChinaAgricultural Technology Extension Center, Ministry of Agriculture, Beijing, ChinaGraduate School of Chinese Academy of Sciences, Beijing, ChinaInstitute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, ChinaCollege of Life Science, Sichuan University, Chengdu, China.
Integr Zool. 2010 Jun;5(2):176-184. doi: 10.1111/j.1749-4877.2010.00199.x.
The Yangtze vole (Microtus fortis Buechner, 1889) is a small herbivore species that inhabits lake beaches in the Dongting Lake region along the Yangtze River in Southern China. Its population shows strong oscillations during the wet season due to summer precipitation-induced immigration away from the lake into adjacent rice fields. The effect of El Niño-Southern Oscillation-driven precipitation on population abundance and growth of the vole species is not fully understood. We undertook an analysis of the combined data of 4 time series covering 1981-2006 from 4 different sites and a separate analysis on a single time series (1981-2006) from one site. Our results demonstrate that a dual effect of El Niño-Southern Oscillation-driven precipitation on the population abundance of voles is time-dependent: precipitation in the current year has a positive effect, whereas precipitation in the previous year has a negative effect. The dual effect of precipitation on vole population is well explained by the unique interactions among vole population, precipitation water level and the lake beach habitat around Dongting Lake. We found that drier than average weather of the previous year benefited voles because their breeding habitats, lake beaches, were exposed for long stretches of time. Wet weather was found to increase the number of voles inhabiting rice fields because as the water level of the lake rose they were forced from beaches into surrounding rice fields. Summer precipitation in the Dongting Lake region was found to be positively associated with the sea surface temperature (SST) of the eastern tropical Pacific Ocean of the previous year and winter SST and spring SST of the current year. Annual rates of increase in the vole population of the reconstructed time series are negatively associated with the vole abundance and autumn precipitation of the previous year and winter precipitation of the current years. These results suggest that both extrinsic and density-dependent intrinsic factors may affect population dynamics of the Yangtze voles.
长江田鼠（Microtus fortis Buechner，1889）是一种小型食草动物，栖息于中国南方长江沿岸洞庭湖地区的湖滩。由于夏季降水导致其从湖边迁移至邻近稻田，其种群数量在雨季呈现强烈波动。厄尔尼诺 - 南方涛动驱动的降水对该田鼠种群数量和增长的影响尚未完全明晰。我们对来自4个不同地点的涵盖1981 - 2006年的4个时间序列的合并数据进行了分析，并对来自一个地点的单个时间序列（1981 - 2006年）进行了单独分析。我们的结果表明，厄尔尼诺 - 南方涛动驱动的降水对田鼠种群数量的双重影响具有时间依赖性：当年降水具有正向影响，而前一年降水具有负向影响。降水对田鼠种群的双重影响可以通过田鼠种群、降水水位以及洞庭湖周边湖滩栖息地之间独特的相互作用得到很好的解释。我们发现，前一年比平均天气更干燥对田鼠有利，因为它们的繁殖栖息地湖滩长时间裸露。潮湿天气会使栖息在稻田中的田鼠数量增加，因为随着湖水水位上升，它们被迫从湖滩进入周边稻田。发现洞庭湖地区夏季降水与前一年东热带太平洋的海表温度（SST）以及当年冬季和春季的SST呈正相关。重建时间序列中田鼠种群的年增长率与前一年的田鼠数量和秋季降水以及当年冬季降水呈负相关。这些结果表明，外在因素和密度依赖的内在因素都可能影响长江田鼠的种群动态。
