根田鼠栖息地选择的影响因素

2002年7～9月在中国科学院海北高寒草甸生态系统定位站地区对根田鼠的栖息地选择进行了研究。对根田鼠栖息地利用强度变量(一定面积内的跑道长度、跑道分叉数、洞口数)与12个栖息地特征变量进行多元线性逐步回归分析表明：显影响跑道长度的变量为灌丛高度、竞争性啮齿类、电线杆、早熟禾、围栏、灌丛间距和双子叶植物生物量；显影响跑道分又数的变量为灌丛高度、竞争性啮齿类、电线杆、早熟禾和围栏；显影响洞口数的变量为灌丛高度、土壤含水率和围栏。对影响利用强度变量的因素进行综合生态学分析表明，在小生境尺度上，研究期间影响根田鼠栖息地选择的因素主要为捕食风险和种间竞争，食物资源和土壤硬度也有一定程度的影响。

Factors Influencing Habitat Selection of Root Voles (Microtus oeconomus)

We studied habitat selection of root voles (Microtus oeconomus) at Haibei Alpine Meadow Ecosystem Research Station,the Chinese Academy of Sciences,July-September 2002. Stepwise regression indicated that shrub height, dicotyledon biomass, number of competing rodent species, Poa density, and distances from power line poles, pasture fences, and shrubs significantly influenced runway length. Significant factors influencing runway branch number were shrub height, number of competing rodent species, Poa density, and distances from power line poles, and pasture fences.Factors significantly influencing burrow number were shrub height, soil moisture, and distance from pasture fences. The influences of most habitat variables on vole habitat selection were directly or indirectly related to interspecific competition and predation risk. Risk of predation increased and habitat utilization decreased with decreased shrub height and Poa dominance, and with increased proximity of pasture fences and power lines. The presence of plateau pikas (Ochotona curzoniae) resulted in increased habitat openness, thus increased risk of predation and decreased habitat utilization by root voles. Overall, at a microhabitat scale, risk of predation and inter-specific competition were the main factors which influenced habitat selection by root voles during the study period.