高寒草地城镇对周边鸟类影响范围评估方法

Survey Method on the Impact Distance of Town to Alpine Grassland Birds

城镇化占用了大面积的土地,对鸟类的影响巨大。然而,城镇对鸟类的影响范围却一直缺乏有效的评估方法。本文以若尔盖高寒草地这种较为简单的单一生境为例,探讨了评估城镇对周边鸟类分布影响范围的方法。在若尔盖县唐克镇周边草地设置6条样线开展鸟类调查,并对距城镇不同距离的鸟类种类、数量与生物量进行了分析。相关分析表明,黑耳鸢Milvus lineatus、家燕Hirundo rustica和麻雀Passer montanus的数量与距城镇距离呈显著负相关,是喜城镇型的鸟类,而地山雀Pseudopodoces humilis、角百灵Eremophila alpestris和白腰雪雀Montifringilla taczanowskii等草地物种则呈显著正相关,表现出对城镇的躲避,其他物种的分布与距城镇距离相关性不显著。分段回归分析显示,随着距城镇距离的增加,鸟类的数量和生物量都呈先下降后缓慢上升的格局。研究发现,距城镇339~630 m存在一个鸟类分布的低谷带,在这个地带鸟类的数量和生物量都达到最低值,而鸟类物种丰富度的低谷带在367~955 m。城镇周边存在的鸟类低谷带可能是由于该区域的环境处于从城镇到草地的过渡带上,对喜城镇的鸟类物种而言,这一区域距城镇过远,而对于草地物种而言,这一区域受到的城镇干扰又太大。

b A large area of land has been occupied during the process of urbanization, which has a tremendous impact on bird. The method to estimate the distance of impact of urban or town on birds is still lack. This study investigated the method to estimate the impact of the distance of urban and town on birds in Zoige alpine grassland, a simple and monotonous habitat.We set 6 transect lines in grassland beside Tangke town, Zioge. The species richness, counts and biomass of birds at different distances from towns were analyzed. Correlation analysis showed that the counts of Milvus migrans, Hirundo rustica and Passer montanus were negatively correlated with the distance from the town. This suggested that those species prefer to habitat near town. The distributions of Pseudopodoces humilis, Eremophila alpestris and Montifringilla taczanowskii were significantly posi-tive correlated with the distance from the town, indicating that those species prefer to habitat grassland away from town. How-ever, other species showed no significant preference between habitats near and far away from town. Piecewise regression analy-sis revealed the patterns of the numbers, biomass and richness of birds changing along the distance from town, which charac-terized by first decreasing and then rising slowly. The results showed that, the counts and biomass of bird bottomed between 339 -630 m away from town, while the richness bottomed between 367 -955 m. The environmental factors changed from town to grassland habitat along those transect lines. Possibly, the distribution patterns of birds formed due to the habitat in the bot-tom regions was too far from town for the birds prefer town, while was too close for the grassland birds.