横断山区树线以上区域种子植物的标本分布与物种丰富度

Distribution of specimens and species richness of seed plants above timber line in the Hengduan Mountains, southwest China

植物标本是植物空间分布信息的重要来源,也是估算物种丰富度的主要数据资料。本文收集了有关数据库和标本馆的标本资料,以分析横断山区树线以上区域种子植物标本的采集现状和物种丰富度。将树线以上区域(4,100–5,500m)划分成14个100m海拔带,将每号标本的海拔信息记录到相应的海拔带内。共收集8,316号标本信息,记载种子植物1,820种,其中横断山区特有种655种。这些标本在物种间的分布极不均匀,仅有1–2号标本的物种最多,共974种,占53.5%。各海拔带内标本总数、种均标本数和物种丰富度随海拔的增加而下降,但物种稀疏曲线不能很好地描述物种丰富度沿海拔梯度的分布格局。因此,需要开展更多的样地调查和标本采集工作,为物种丰富度的估算积累更多的资料。

Herbaria can provide important information about the spatial distribution of plants, and are important data sources for estimating species richness. In this study we described elevational patterns of specimen frequencies and species richness of seed plants above timber line in the Hengduan Mountains and discussed the impact of specimen data on the estimation of species richness. Specimen data came from the online database （http：//hengduan.huh.harvard.edu） and herbaria. Elevations above timber line were divided into fourteen 100-m belts, and the frequencies of specimens in each elevational belt were recorded. There were 1,820 species and 8,316 specimens with elevational information, of which 655 species were endemic to this region. Distribution of specimens among species was extremely uneven. For example, 974 species （about 53.5% of total species） were represented by 1-2 specimens. Total and average number of specimens in elevational belts decreased linearly with the increasing elevation. Species richness also decreased with the increasing elevation, but species rarefaction curves were not useful for describing elevational patterns in species richness. We suggest that more field plot-sampling and specimen collections are needed to accurately estimate species richness.