不同干扰荒漠生境中子午沙鼠的繁殖及种群动态特征

子午沙鼠(Merionesmeridianus)广泛分布于我国西北部地区,是荒漠啮齿动物群落的优势鼠种。种群繁殖特征是动物生活史参数中的一个重要组成部分,是种群数量补充的重要来源,而干扰是影响繁殖特征的重要因素。本研究于2012~2014年,在位于蒙古阿拉善左旗南部典型荒漠的野外实验区,设置禁牧、开垦、过牧、轮牧4种不同干扰样地,使用铗日法对实验样地子午沙鼠相对数量及繁殖特征进行调查。4种不同干扰生境中的子午沙鼠种群数量具有显著差异,禁牧过牧轮牧开垦;雌雄性比在轮牧生境中最高,开垦生境次之,禁牧生境最低;4种干扰生境中,轮牧样地子午沙鼠雌鼠怀孕率显著高于禁牧、过牧和开垦样地;雄鼠的睾丸下降率在过牧干扰样地显著高于其他3种干扰方式样地,轮牧样地雄鼠睾丸下降率最低;雌鼠平均胎仔数在4种干扰生境间无显著性差异;轮牧干扰样地繁殖指数显著高于其他3种干扰方式样地;繁殖指数、怀孕率及睾丸下降率对密度的反馈作用最为明显,但在不同的干扰生境中其反馈特征有差异。综上,子午沙鼠在轮牧生境中各繁殖特征指数最高,繁殖能力最强,种群密度相对较高,更适合其生存,其密度制约效应表现最为明显。

The Population Density and Breeding Characteristic of Mid-day Jerbil (Meriones meridianus) in the Desert Habitats with Different Disturbance

The Mid-day Jerbil (Meriones meridianus) distributes in the northwest of China widely and is the dominant species in the desert rodent community.Its breeding characteristic is an important life history parameter which will produce great influence on population abundance.We conducted a 3 years filed study to investigate the population dynamic and breeding characteristics of Mid-day Jerbil in the south of Alxa using trap day method in four different areas with different grazing loads.We got the results as following:the meaning of the sex ratio was 1.09 ± 0.12,testicular decent rate was 0.74 ± 0.01,pregnancy rate was 0.21 ± 0.05,the number of foetus were 4.20 ± 0.32,breeding characteristics was 0.90 ± 0.22 in three years for the Mid-day Jerbil in the whole study area.The population density of Mid-day Jerbil was significant difference in four areas with different grazing load (grazing free ＜ heavy grazing ＜ rotational grazing ＜ farmland) (Fig.1);the highest sex ratio Appears in rotational grazing area,the next higher was recorded in farmland.The sex ratio collected in grazing flee area was with minimum value (Fig.2).The pregnancy rate in rotation grazing areas was significantly higher than those three other area,while the testicular descent ratio was significantly higher in heavy grazing load area than that in the other three areas and the lowest value occurred in the rotational grazing area (Fig.3).No any difference was found between the mean embryo number of Mid-day Jerbil collected in the whole study areas with different grazing load (Fig.4).The value of breeding index was the highest in rotational grazing areas of the four areas with different grazing loading (Fig.5).The breeding characteristic,pregnancy rate and testicular descent ratio showed an obvious feedback for the population density but the feedback degree was difference in each area with different grazing load (Table 1).In conclusion,the Mid-day Jerbil's showed a highest breeding potentials in rotational grazing area where was with the obvious density feedback and most suitability for the Mid-day Jerbil survival.