栖息地荒漠化对草原沙蜥食性的影响

Effects of habitat desertification on the diet of Phrynocephalus frontalis

栖息地退化会使环境中蜥蜴的可利用食物资源发生改变。采用剖胃法对内蒙古自治区鄂尔多斯市准格尔旗和达拉特旗地区采集的草原沙蜥样本进行了食性分析。对固定沙丘、半固定沙丘和流动沙丘三类样地中77个实胃样本的652只(套)食物进行鉴定和分析的结果表明,这些食物主要为节肢动物,分为35类,隶属3纲11目32科;也在少部分个体(4.69%)的胃容物中发现少量(1.95%)植物碎片。上述三类栖息地中,草原沙蜥对蚁科、蚜科、瓢虫科、叶蝉科和茧蜂科昆虫均有较大的捕食比例;但相比固定沙区栖息地,草原沙蜥在半固定及流动沙丘中增减的食物种类均比较多,导致草原沙蜥在流动沙区与其他两类样地之间有较大的食物相异性。从固定沙丘、半固定沙丘到流动沙丘,随栖息地荒漠化程度的增加,草原沙蜥捕食食物类群的丰富度逐步减少,辛普森优势度指数相应地下降,但营养生态位宽度、香农威纳多样性指数和皮洛均匀性指数却在流动沙丘栖息地上明显增大。这表明鄂尔多斯地区的草原沙蜥是以捕食昆虫等节肢动物为主、兼食极少量植物的杂食性动物。栖息地荒漠化所致的环境变化显著地影响草原沙蜥的食物组成,使其觅食的食物种类逐步减少。

Habitat degradation changes available food resources for lizards in their environment. We studied the diet of the toad-headed lizard （Phrynocephalus frontalis ） through stomach content analysis. Lizards were collected in Jungar Banner and Dalad Banner in the Erdos region of Inner Mongolia, China. Experiments identified and analyzed 652 suits of food in 77 stomach samples from three fields including a fixed dune, semi-fixed dune, and mobile dune. Food primarily consisted of 35 groups of arthropods belonging to 3 classes, 11 orders, and 32 subjects. In addition, we also found a small amount of plant debris （1.95%） in the stomach contents of a few individuals （4.69%）. Among the three dune habitats, Formicidae were the most important items in the diet, followed by Aphididae, Coccinellidae, Cicadellidae, and Braconidae. However, toad- headed lizards changed food preferences more frequently in the semi-fixed and mobile dunes compared to food in the fixed dune habitat, leading to a large food dissimilarity between the mobile dune and the other two habitats. With increasing desertification of habitats from the fixed dunes, semi-fixed dunes, and mobile dunes, the abundance of prey groups for toad- headed lizards is decreasing, and the Simpson＇s dominance index fell accordingly. However, the niche breadth, the Shannon-Weaver diversity index, and the Pielou＇s evenness index significantly increased in the mobile dune habitat. This result shows toad-headed lizard in the Erdos region is an omnivorous animal and mainly preys upon insects and eats a very small number of plants. Habitat desertification significantly affected food composition of the toad-headed lizard, and gradually reduced the type of foraged food.