栖息地荒漠化对蜥蜴群落组成的影响

栖息地改变往往对动物群落及其物种多样性有重要影响,但是目前关于栖息地荒漠化如何影响蜥蜴的群落组成鲜有研究。在内蒙古自治区鄂尔多斯市准格尔旗和达拉特旗地区通过样线法调查了三类不同荒漠化程度样地上的蜥蜴群落组成差异,用典范对应分析探究了关键的影响因素。结果表明,栖息地荒漠化使蜥蜴的群落组成发生显著变化,从固定沙丘、半固定沙丘到流动沙丘,草原沙蜥均是蜥蜴群落的优势物种,密点麻蜥逐渐减少,丽斑麻蜥则消失于荒漠化严重的半固定沙丘和流动沙丘中。随栖息地荒漠化程度的增加,蜥蜴的数量显著减少,密度显著降低,蜥蜴物种的丰富度、香农-威纳(Shannon-Weaver)多样性指数和皮洛(Pielou)均匀性指数均逐次显著下降,而辛普森(Simpson)优势度指数则逐次显著升高。这说明荒漠化不仅使蜥蜴群落组成变得简单,同时造成了蜥蜴物种多样性的下降甚至丧失。荒漠化也使蜥蜴的栖息条件发生显著变化。植被高度、油蒿比例、裸地比例、隐蔽度、表层土壤含水量和表层土壤孔隙度在三类栖息样地之间均存在极显著差异。典范对应分析结果表明,这些环境因子与蜥蜴群落组成的变化密切相关。总体而言,草原沙蜥偏好裸地,密点麻蜥偏好隐蔽性好且土壤湿润又疏松的区域,而丽斑麻蜥则偏好植被高的区域。

Effects of habitat desertification on the community composition of lizards

Habitat alteration often has important impacts on animal community and species diversity, but only a few studies have been conducted on how habitat desertification affects community composition of lizards at present. In this study, we investigated the differences in the community composition of lizards among three types of sampling fields with different stages of desertification using the line transect method in Jungar Banner and Dalad Banner in the Erdos region of Inner Mongolia, China. Subsequently, we explored their key influencing factors through canonical correspondence analysis (CCA). The results of our investigations showed that habitat desertification led to significant changes in the community composition of lizards. From the fixed and semi-fixed dunes to mobile dunes, the toad-headed lizard (Phrynocephalus frontalis) was the dominant species of the lizard communities, the multiocellated racerunner (Eremias multiocellata) showed gradual reduction in its population density, and the Mongolian racerunner (E. argus) disappeared in the semi-fixed and mobile dunes of severe desertification. With increasing habitat desertification in the three types of dunes, the population sizes and densities of different lizard species decreased gradually; the richness, Shannon-Weaver diversity index, and Pielou''s evenness index of lizard species declined gradually; and the Simpson''s dominance index increased significantly. These results indicated that desertification not only simplified the community composition of lizards, but also led to a decrease in lizard species diversity. Furthermore, desertification led to significant changes in the inhabited conditions of lizards. Significant differences were observed in vegetation height, proportion of Artemisia ordosica, bare ground and shelter percentages, and surface soil porosity and water content among the three sampling fields. The CCA results showed that these environmental factors were closely related to the changes in lizard community composition. In general, P. frontalis preferred the areas dominated by bare ground, while E. multiocellata preferred the region with sufficient shelter and loose moist soil. As for E. argus, this lizard species was frequently found in habitats with high vegetation.