食物、捕食和种间竞争对东方田鼠种群动态的作用

Effect on population dynamics of reed voles Microtus fortis by food,predation and interspecific competition

采用2×2×2析因实验设计,在野外围栏条件下,测定食物、捕食和竞争物种黑线姬鼠(Apodemus agrarius)对东方田鼠(Microtus fortis)种群动态作用的格局。食物可利用性、捕食及种间竞争的独立作用对种群最小存活数均具有极显著的效应,除捕食与种间竞争的交互作用接近显著水平外,食物与种间竞争、食物与捕食者以及三者间的交互作用均不显著;三类外部因子对种群补充量的独立作用效应均达到极显著水平,且对种群补充量的作用具有累加效应;食物可利用性、捕食及种间竞争对种群繁殖成体的比例具有极显著的作用;三类外部因子对种群幼体与成体的比例具有极显著的作用。对种群年龄结构而言,与捕食者及种间竞争比较,食物可利用性是相对较弱的影响因子,在任何捕食与种间竞争交互作用条件下,食物的作用均不显著;三类外部因子均能显著地影响东方田鼠的体重增长率,但三者的交互作用对其影响不显著;MANOVA结果表明,捕食对成体存活率的作用最强烈,其次,为食物可利用性,种间竞争的作用最弱,但三者的交互作用效应不显著。对幼体的存活时间,除捕食的作用接近显著水平外,食物可利用性及种间竞争的作用均不显著。结果提供了食物可利用性、捕食和种间竞争对东方田鼠种群动态作用的充分证据,验证了食物、捕食和种间竞争对田鼠类种群动态具有独立或累加效应的总假设。

Effect patterns of food,predation and Apodemus agrarius as competition species on population dynamics of reed voles,Microtus fortis were measured using 2×2×2 factorial experiment design under the field enclosure. The independent effects of food availability,predation and interspecific competition on population MNKA were extremely significant. Except the marginally significant effect of interaction between predation and interspecific competition,the effects of other interaction between two or among three external factors on population density were all not significant; The independent effects of three external factors on population recruitment were all significant and the effects were additive; The different combination of food availability,predation and interspecific competition had extremely significant effects on proportions of reproductive females in the population; Three external factors had also extremely significant effect on proportions of juveniles and adults in the population Comparing to the effects of predation and interspecific competition,the effects of food availability on age structure were weaker because they were all not significant in any combination of predation and interspecific competition; All of three external factors had significant effects on the growth rate of body mass in reed voles while their interactions had not; Results of MANOVA showed that the effects of predation on adult survival were most intense,those of food availability were less and those of interspecific competition were least,but the effects of interaction among three external factors were not significant. Except that the effects of preadation were marginally significant,the effects of food availability and interspecific competition on survival time of juvenile were not significant. the results of this dissertation provided sufficient evidence for the effects of food availability,predation and interspecific competition on population dynamics,and thus supported hypothesis that there were independent and additive effects of food availability,predation and intespecific competition on population dynamics.