太白山北坡夏秋季鸟类物种多样性

2006年5月～7月(夏季),9月～10月(秋季)在秦岭主峰太白山的北坡根据海拔和典型植被划分生境类型,在6种生境中选择典型样区划定样线并采用样线法对鸟类进行调查,根据鸟类的绝对数量和估算面积计算鸟类的绝对密度,并根据密度等级划分各生境类型中优势物种和常见物种。共观察到鸟类144种,其中留鸟102种,夏候鸟41种,冬候鸟1种。不同的海拔和不同生境类型中的鸟类物种丰富度和多度有较大差异,而且同一生境中鸟类多样性的季节性变化也很明显。无论是夏季还是秋季,低海拔农田带生境中鸟类的总密度最高,而高山灌丛草甸生境中的鸟类总密度最低。优势物种和常见物种在不同的生境类型组成也不相同,而且在不同季节也有变化。夏秋季的鸟类食性组成在农田带有显著差异,而其它生境类型中的鸟类食性夏秋季无明显差异,但是秋季植食性鸟类在各个生境类型中都有增多的趋势。物种丰富度和海拔梯度的关系显示在中海拔地区的鸟类丰富度最高。总体上,和20世纪80年代相比,太白山北坡的鸟类已经发生了明显的变化。

Bird diversity in summer and autumn on the north slope of Taibaishan Mountain

In 2006,a bird survey was performed on the north slope of Taibaishan Mountain,the summit of the Qinling range in the center of China,during two time periods:from May to July in the summer and from September to October in the autumn.Based on elevation and vegetation,six types of habitat were categorized,and characteristic sample plots were selected within each habitat type.The birds in each sample plot were counted using a line transact methodology.The absolute density of species was calculated and ranked based on the absolute abundance and estimated area,and dominant and common avian species in each habitat type were defined according to ranks within species density.We encountered 144 bird species total,including 102 residents,41 summer breeders and 1 winter migrant.Species richness,abundance and the constitution of dominant and common species showed significant variation across the six types of habitat.Even within given habitat types,the diversity of bird species and the constitution of dominant and common species exhibited obvious seasonal change.The highest and lowest total densities were found in cropland habitat and alpine meadow habitat,respectively.A significant seasonal difference in diet of birds was only found in cropland habitat.When correlated to elevation,the highest bird species richness was found in those habitats occurring primarily at mid-elevation.In general,our results indicate a complex,and habitat specific,distribution of avian populations and obvious change on the north slope of Taibaishan Mountain.