关键词: 相对密度, 优势种, 物种数, 海拔

Abstract

Taibai Mountain, located in southwestern Shaanxi, is a major summit in the Qinling Mountains of central China. To analyze changes to its avifauna over the past 20 years, we performed bird surveys from May to July (summer) and from September to October (autumn) in 2007 on the south slope of Taibai Mountain. Based on elevation and vegetation, five habitat types were categorized (afforested area, broadleaved forest, broadleaved coniferous mixed forest, coniferous forest, and alpine meadow), and characteristic sample area were selected within each habitat type. Birds were counted in each sample area using line transects. The relative density of species was calculated and ranked based on the relative abundance and estimated area, and dominant and common bird species in each habitat type were defined according to ranks of species density. We recorded a total of 122 bird species, including 85 residents, 31 summer breeding migrant, 1 winter migrant and 5 passing migrant. Species richness, relative abundance, and identity of dominant and common species varied across habitat types. Even within a given habitat type, bird species diversity and the identity of dominant and common species exhibited obvious seasonal changes. In the afforested area, 60 species were recorded in summer, of which two tits Parus monticolus and P. venustulus and a warbler Phylloscopus reguloides were dominant species. In autumn 59 species were recorded, of which the tit Parus major was dominant. In the broadleaved forest, 40 species were recorded in summer of which the tits Parus monticolus, P. venustulus and the warbler Cettia flavolivaceus dominated, and 37 species were recorded in autumn with the tits Parus venustulus, P. rubidiventris and Aegithalos fuliginosus being dominant. In the broadleaved coniferous mixed forest, 46 species were recorded in summer of which the warblers Phylloscopus borealis, P. proregulus and the tit Parus rubidiventris were dominant, and 37 species were recorded in autumn with the minivet Pericrocotus ethologus, the tits Parus dichrous and P. rubidiventris dominating. In the coniferous forest, 36 species were recorded in summer with the warbler Phylloscopus proregulus and the tit P. rubidiventris being dominant and 27 species were recorded in autumn of which the tit P. rubidiventris and the pheasant Ithaginis cruentus were dominant. In alpine meadows, 7 species were recorded in summer and 7 species in autumn. Species seasonal turnover rates and bird species richness decreased with increasing elevation. Bird species diversity was highly similar between the north and south slope. Based on the comparison between current and historical data, our results indicate obvious changes of bird diversity on Taibai Mountain in 20 years, though the composition of dominant and common species in each habitat is similar.

Key words: relative density, dominant species, species richness, elevation