洞庭湖区东方田鼠种群动态及其危害预警

Population dynamics of Microtus fortis in Dongting Lake region and its forecasting

洞庭湖区东方田鼠以湖滩沼泽为最适栖息地 .秋末洞庭湖水位回落 ,湖滩出露 ,东方田鼠从农田迁回到湖滩生活、繁殖 ,种群数量呈逐月上升趋势 .春末夏初 ,洞庭湖水位上涨 ,湖滩被淹 ,东方田鼠被迫越过大堤迁入垸内农田 .其种群动态由“水位影响东方田鼠的栖息地变换”主导 .每年迁入农田的数量首先取决于东方田鼠在湖滩生活繁殖时期的长短 ,亦即枯水期的天数 ;其次 3月降雨量对东方田鼠在湖滩上的繁殖有较大的影响 .东方田鼠迁入垸内后 ,种群数量呈逐月下降趋势 .在分析影响洞庭湖区东方田鼠种群数量动态的主要因子的基础上 ,提出了东方田鼠种群迁入垸内农田的迁入量预警模型 .经过几年的实际预测 。

The population dynamics of Microtus fortis in Yueyang, Hunan Province was studied from 1991 to 1996. M. fortis lived on the beach of the lake from early autumn to next spring, but moved to the farmland in summer when the beach was flooded. When lived on the beach, its population increased gradually. Usually, M. fortis made great damage on the crops when moved to the farmland. The population dynamics of M. fortis was different on the beach and on the farmland, and the key affecting factors were also different. Lake beach was the most suitable habitat for M. fortis. When it emerged in autumn, M. fortis moved back on it. The main breeding season of M. fortis inhabited on the beach was from October to May, and its population density increased gradually. The period between the beach emerged and been flooded determined the population size of the animal moved to farmland. Another factor was the rainfall in March. Farmland was not the suitable habitat for M. fortis. Because of the low breeding potential, high mortality and dispersal on farmland, its population density kept decreasing, and was very low in winter. The population density on farmland dropped dramatically when the lake beach emerged. The animal population was forecasted by means of regression analysis, and a linear regression equation was obtained. The predicted values matched with the real population densities of the animal in the field.