阿拉善荒漠连续放牧对三趾跳鼠巢区的影响

三趾跳鼠(Dipus sagitta)是内蒙古西部荒漠草原和沙地的优势害鼠,巢区研究对了解探讨其繁殖策略和种群动态规律有着重要的理论和实践意义。本研究通过2012~2014年的野外标志重捕实验,对三趾跳鼠的巢区在连续放牧和禁牧条件下的变动特征进行了分析。结果表明,连续放牧区雌性三趾跳鼠在6月的巢区范围显著大于禁牧区(P0.05);禁牧区雄性三趾跳鼠的巢区仅在7月份显著大于连续放牧区(P0.05),其他季节没有显著差异(P0.05)。放牧对雄性巢区无显著影响(P0.05),但连续放牧使雌性三趾跳鼠巢区范围显著大于禁牧区。雌性与雄性三趾跳鼠巢区均与一年生草本生物量存在正相关关系。这些结果表明,相对于雄性三趾跳鼠来说,雌性对由放牧导致的食物资源变化比较敏感,这种现象在哺乳期更为显著;繁殖是影响雄性三趾跳鼠巢区的因素之一。因此,保卫资源假说的理论可能是放牧导致三趾跳鼠巢区变化的重要原因之一。

The Effect of Successive Grazing on the Home Range of Northern Three Toed Jerboa (Dipus sagitta) in Alax Desert

Northern Three Toed Jerboa (Dipus sagitta) is one of dominant rodent pests in the western desert in Inner Mongolia.Study on home range ofD.sagitta have theoretical and practical significance in exploring rodent reproductive strategies and the population dynamics.An experiment was conducted in Alax desert in order to investigate home range ofD.sagitta subjected to successive grazing during April to October between the year of 2012 to 2014.Rodent was captured by living trapping method.The influence of grazing treatment on the home range of Northern Three Toed Jerboa between each gender and seasons,were tested using mixed effect model.Relation between plant factors and body mass within the home range was analyzed by partial redundancy analysis method.The results showed that the population density of D.sagitta in grazing exclusion sites was higher than that in successive grazing sites (Fig.1).Successive grazing decreased height,coverage,density and biomass of herbage and shrub height significantly (Fig.2).The home range of females in the field with successive grazing was larger significantly than that in grazing exclusion sites only on the month June (P ＜ 0.05,Fig.3a).The home range of males in grazing exclusion sites was significant larger than that in successive grazing sites on July (P ＜ 0.05,Fig.3b).No any remarkable difference was found between the habitat treatments in other seasons (P ＞ 0.05,Fig.3b).Although the treatment of successive grazing had no significant effect on the male's home range (P ＞ 0.05),it did extended the female's home ranges (P ＜ 0.05,Fig.4,Table 2).Meanwhile,home ranges,both male and female were positive associated with the biomass of annual herbage (Fig.5).It indicated that the home range of female jerboas was more sensitive to the food availability decreasing than males,especially during lactation period.While breeding was one important factors influencing the home range size for males.The Resources defending Hypothesis could be one for the home range change ofD.sagitta due to grazing reducing the food availabilty.