农田周围杂草带中普通田鼠种群数量的季节变动特征及杂草带年龄和植被之间的关系

本文中我们采用标志重捕方法从2003到2004年11月,对栖息在野花带的普通田鼠种群结构和数量动态进行比较系统的研究.结果表明,这两年中种群密度夏季最大分别达到410个体/ha和641个体/ha,春季最少分别达到166个体/ha和153个体/ha,从7月份开始增长,8月份种群密度减少并在11月份开始重新增长.种群中雌性个体数量比较多,雌性在种群中的居留时间比较长同时存活率比雄性高,这种现象导致种群数量的季节变化.种群周转率比较高,在两个捕鼠期间种群中的80%个体被更新,这表明普通田鼠在野花带中的活动非常活跃,不断与周围的其它种群进行交流,提高种群对环境的适应能力.种群中雌雄个体的领域之间没有年间变化,它们的活动领域比较小,领域长度2003年平均为11米,最长为37.5米,2004年平均为13米,最长为52米.本研究中我们没有找到环境因素和种群数量动态之间的相关关系.

The Seasonal Fluctuation of Microtus Arvalis (Pall.)Population Density and Relationship between the Weed Strips Age and Vegetation

A population of Microtus arvalis Pallas,1779 living in a weed strip area was studied by capture recapture method over a two-year period.Weed strip area is characterized by their shape and high vegetation cover,and are not comparable to the habitats examined in most former studies on M.arvalis.Vole density was found to be high in the strip with a maximum MNA of 410 voles/ha in the first year and 641 vile/ha in the successive year.Population density was minimal in spring and increased until July.A decrease in population density at the beginning of August was followed by a new increase in both years.One difference between the two years was a pronounced peak density at the end of June in the second year.The peak may be related to a shift in sex ratio in favour of females in this year(ratio of males: females of 1:8).Also the time of residency of females was significantly longer in the second year than in the before,and the survival rate of females was greater compared to that of males.The turnover was generally very high and reached maximum values of 80% renewal of the population every two weeks.We could not detect any signs of a multiannual cycle in the population density,and weather variables had no influence on observed densities.