水沙过程对洞庭湖区东方田鼠种群动态及群发致害的影响

Effects by silt process on Microtus fortis calamorum population trends and complex calamities of Dongting Lake

洞庭湖区的东方田鼠群发致灾频繁,给当地农林牧业造成了巨大的经济损失。从水沙过程与东方田鼠栖息繁殖环境之间的关系这一深层因子,探讨了东方田鼠种群数量消长及群发致灾的行为特征。研究表明:周而复始的江湖水沙交换过程,一方面导致了洞庭湖泥沙淤积循环,促使着洲滩发育、扩展,为东方田鼠提供了适宜的栖息场所;另一方面支撑着湖泊水位的涨落交替循环,进而形成了东方田鼠被迫外迁和主动内迁的循环。正是这两种循环关系的不断交织,导致了洞庭湖区东方田鼠种群数量及群发致害行为的延续,显然,东方田鼠群发致害行为是泥沙淤积循环、洲滩扩展、种群数量积累和水位涨落等因素长期积累或放大过程的结果。在这一过程中泥沙淤积是基础,水位涨落交替是动力。

A series of complex calamities caused by Microtus fortis calamorum population of Dongting Lake give rise to enormous economic loss on agricultural outputs. The paper that bases on the deep factor of the relation between silt process and Microtus fortis calamorums＇ living circumstances probes into their population varieties and behaviour characters when a series of complex calamities happen. The results show that the continuous silt change processes, on one hand ,lead to Dongting Lake＇ s silt deposit circulations, bring about the development and expansion of islet and provide a comfortable habitat for Microtus fortis calamorums, on the other hand, keep the alternative circles on lake stage verieties, lead a circle of Microtus fortis calamorums＇ migration on passive moving out and positive moving in. The two circles lead to the continuity on Microtus fortis calamorums＇ population amounts and series of complex disastrous behaviours. Apparently, Microtus fortis calamorums＇ disastrous behaviours lead to silt deposit cycles, islet expansion, population amount accumulations and long-time accumulation or enlargement on water level varieties. In this process, silt deposits are base and water level alternative varieties are driving force.