贡嘎山东坡的鸟类多样性和区系

经过7年5次野外系统调查并综合有关文献,贡嘎山东坡分布有鸟类336种,其中,留鸟204种(60.7%),夏候鸟89种(26.5%),冬候鸟18种(5.4%),旅鸟25种(7.4%);东洋界物种205种(61.0%),古北界物种105种(31.3%),广布种26种(7.7%);雀形目Passeriformes鸟类245种(72.9%);繁殖鸟类293种(87.2%)。本地区有国家Ⅰ级重点保护鸟类3种,国家Ⅱ级重点保护鸟类29种;横断山-喜马拉雅地区特有鸟类53种;CITES附录Ⅰ鸟类3种,附录Ⅱ鸟类25种;世界自然保护联盟濒危物种红色名录濒危鸟类1种,易危鸟类2种。研究发现,东洋界物种的海拔分布下限平均、上限平均、中点平均和海拔跨度平均都低于古北界物种,但仅海拔分布中点平均和上限平均差异有统计学意义(P<0.05),体现了东洋界和古北界物种对高海拔环境适应能力的不同可能与其不同的生物地理演化历史有关;东洋界占优势的特有种(51/53)海拔分布下限平均、中点平均和上限平均显著高于非特有物种,体现出东洋界特有种对高山环境的适应也许与其特有化过程有关。贡嘎山东坡鸟类丰富度在中海拔1 800~2 800 m的落叶阔叶混交林和针阔叶混交林中最高,在高海拔和低海拔物种丰富度较低,物种丰富度呈中峰模式,鸟类生态群落随植物群落结构变化而呈现一定的垂直生态替代规律。

Elevational patterns of bird species richness on the eastern slope of Mt.Gongga,Sichuan Province,China

Background:In biological systems,biological diversity often displays a rapid turn-over across elevations.This defining feature has made mountains classic systems for studying the spatial variation in diversity.Because patterns of elevational diversity can vary among lineages and mountain systems it remains difficult to extrapolate findings from one montane region to another,or among lineages.In this study,we assessed patterns and drivers of avian diversity along an elevational gradient on the eastern slope of Mt.Gongga,the highest peak in the Hengduan Mountain Range in central China,and a mountain where comprehensive studies of avian diversity are still lacking.Methods:We surveyed bird species in eight 400-m elevational bands from 1200 to 4400 m a.s.l.between 2012 and 2017.To test the relationship between bird species richness and environmental factors,we examined the relative importance of seven ecological variables on breeding season distribution patterns:land area(LA),mean daily temperature(MDT),seasonal temperature range(STR),the mid-domain effect(MDE),seasonal precipitation(SP),invertebrate biomass(IB) and enhanced vegetation index(EVI).Climate data were obtained from five local meteorological stations and three temperature/relative humidity smart sensors in 2016.Results:A total of 219 bird species were recorded in the field,of which 204 were recorded during the breeding season(April–August).Species richness curves(calculated separately for total species,large-ranged species,and smallranged species) were all hump-shaped.Large-ranged species contributed more to the total species richness pattern than small-ranged species.EVI and IB were positively correlated with total species richness and small-ranged species richness.LA and MDT were positively correlated with small-ranged species richness,while STR and SP were negatively correlated with small-ranged species richness.MDE was positively correlated with large-ranged species richness.When we considered the combination of candidate factors using multiple regression models and model-averaging,total species richness and large-ranged species richness were correlated with STR(negative) and MDE(positive),while small-ranged species richness was correlated with STR(negative) and IB(positive).Conclusions:Although no single key factor or suite of factors could explain patterns of diversity,we found that MDE,IB and STR play important but varying roles in shaping the elevational richness patterns of different bird species categories.Model-averaging indicates that small-ranged species appear to be mostly influenced by IB,as opposed to large-ranged species,which exhibit patterns more consistent with the MDE model.Our data also indicate that the species richness varied between seasons,offering a promising direction for future work.