荒漠破碎化生境中长爪沙鼠集合种群野外验证研究

近年来，人类活动和自然干扰，导致内蒙古阿拉善荒漠区生境的破碎化，出现了长爪沙鼠在不同斑块间的不连续分布，每一斑块内可能存在一个局域种群，而集合种群建立的前提条件，是局域种群斑块状分布在离散的栖息地环境中。2002~2012年每年的4~10月，在阿拉善荒漠区禁牧、轮牧、过牧和开垦4种人为不同利用方式形成的生境斑块中，采用标志重捕法对长爪沙鼠（Meriones unguiculatus）种群进行定点监测。通过分析长爪沙鼠种群动态，计算各局域种群的灭绝风险，利用Spearman秩相关系数检验种群动态的空间同步性，同时以种群周转率对长爪沙鼠扩散能力进行评估，以检验阿拉善荒漠区长爪沙鼠种群空间结构是否具有经典集合种群的功能。结果表明：（1） 不同生境斑块可被长爪沙鼠局域种群占据，11年间捕获长爪沙鼠2~7次不等；（2） 长爪沙鼠所有局域种群均具有灭绝风险，在轮牧区和禁牧区灭绝率高达1.000 0，开垦区灭绝率最低，也达到0.333 4，而本研究期间最大局域种群（2008年过牧区，26只/hm²），在2010年发生了局域灭绝；（3） 不同生境斑块间没有明显的空间隔离而阻碍局域种群的重新建立，长爪沙鼠扩散能力较强，绝大部分月份的种群周转率在50.0%以上，特别是周转率达到100.0%的月份较多；（4） 不同生境斑块间仅轮牧区和禁牧区中长爪沙鼠种群密度显著正相关（P<0.05），而其他生境斑块间相关性均不显著（P >0.05），长爪沙鼠局域种群整体显示出明显的非同步空间动态。阿拉善荒漠区长爪沙鼠种群满足作为经典集合种群物种区域续存的4个条件，具有作为研究小哺乳动物集合种群的潜在价值。

The Mongolian Gerbils Meta-population in Habitat Fragmentation in Alxa Desert: A field Verification Study

Recently, Influence of human activities and natural disturbances the habitat of Alxa desert in Inner Mongolia was fragmentized, it was lead to the discontinuous distribution of Mongolian Gerbils (Meriones unguiculatus) between habitat patches which might be exist a local population in each one. The precondition of metapopulation establishing was that local population was patchy distribution in discrete habitats. Population dynamics of Mongolian Gerbils were investigated by mark-and-recapture method from 2002 to 2012. This study was conducted in four different habitat patches by different use patterns including a prohibited-grazing site, a rotational-grazing site, an over-grazing site and a farmland. The population spatial structure of Mongolian gerbil was tested whether it had the function of a classical metapopulation, respectively, analysis the population dynamics of Mongolian gerbil, calculation the risk of extinction of local population, Spearman correlations used for determines the degree of population spatial synchrony, and the population turnover rate was evaluated for the dispersal ability of Mongolian gerbil. The results showed that: first, this region was suitable habitats for Mongolian gerbils and the different habitat patches can be occupied by local population, and it was captured two to seven times in eleven years. Second, all the local population had a risk of extinction, and rate of extinction reached 1.000 0 in prohibited-grazing site and rotational-grazing site was higher, the lowest rate of extinction in farmland which was 0.333 4. In the 2008, the largest local population had 26 individuals per hectare in over-grazing site, however, it also suffered from extinction in the 2010. Third, the habitat patches was not too isolated to prevent recolonization of the local population. The Mongolian Gerbils had strong ability of dispersal which the population turnover rate more than 50.0% at most month and especially it reached 100.0% was much more month. Fourth, there was significant positive correlation between rotational-grazing site and prohibited-grazing site in the population density of Mongolian gerbil (P<0.05), but between the others habitat patches had no significant correlation(P >0.05). The Mongolian gerbils population fulfills exceptionally well the four conditions of regional persistence of a species as a classical metapopulation in Alxa desert which has a potential value in small mammal metapopulation research.