从秦岭蕨类植物区系地理成分论秦岭山地生态分界线的划分

依据2007~2008年野外实地调查以及相关文献资料,运用植物区系地理学和数量生态学方法,分析了秦岭蕨类植物区系的物种组成和地理分布特征,划分了秦岭蕨类植物的垂直带谱,并以此为基础探讨了秦岭山地生态分界线的划分,得出以下主要结论:(1)秦岭共有蕨类植物36科85属311种,优势科为鳞毛蕨科、蹄盖蕨科和水龙骨科,优势属为鳞毛蕨属和耳蕨属;在科属水平上,以热带成分占优势;而种的水平则以温带成分占绝对优势。(2)根据秦岭蕨类植物南北坡垂直带谱的对比分析,南坡海拔1000m左右应该是一条重要的生态分界线。(3)南坡1000m以下蕨类植物区系组成更接近亚热带区系,而其他地带则与温带蕨类植物区系更为接近,DCA排序很好地证明了此结果。综合来看,将南坡海拔1000m作为秦岭山地亚热带与暖温带的生态分界线较为科学。

Division of the geo-ecological boundary in Qinling Mountain Range based on the composition and geographical elements of its Pteridophyta flora

The Qinling Mountain Range is considered as an important geo-ecological boundary between the warm temperate and the subtropical zones in eastern China, however, the specific line of the boundary has been controversial among the academic circles. Several studies based on vegetation ecology and flora geography have been done on discussing the division of this boundary, but in all of which Pteridophyta is not included. Pteridophyta is a transitional link between different flora groups in plant evolution, and thus is more sensitive to the environment that fosters it than other plant groups. It is conducive to and necessary for a better understanding of the division of the geo-ecological boundary in Qinling Mountain Range to research into the Range's Pteridophyta flora. In this paper, the composition and geographical elements of the flora of Pteridophyta were studied, and the division of the vertical Pteridophyta spectrum and the further division of the geo-ecological boundary in Qinling Mountain Range were also discussed, by applying the principles of classical florology and using quantitative ecology method as TWINSPAN and DCA into the analyses, based on comparison between the field investigation data and the relevant literatures. The results of our research have shown and revealed: 1) There are 311 species of Pteridophyta, belonging to 85 genera and 36 families in the Qinling Mountain Range; in which the dominant families are Dryopteridaceae, Athyriaceae, and Polypodiaceae, and the dominant genera Dryopteris and Polystichum; meanwhile, the main areal-types of family and genera are tropical elements, while the areal-types of species is dominated by the temperate elements. 2) The altitude of 1000 m a.s.l. at the southern piedmont of the Range should be an important ecological boundary, since the floristic composition of the Pteridophyta below this elevation showed more similar features to the subtropics, while above it the features of the composition and the vertical vegetation spectrum of the Pteridophyta are much closer to the temperate zones. 3) DCA ordination of FER (floristic element ratio) among 15 regions in northern and southern China and the both sides of Qinling Mountain Range strongly supported the hypothesis mentioned above. Based on these results, we tend to deem that the geo-ecological boundary between the subtropical and warm temperate zones lies around the altitude of 1000 m a.s.l. at the southern piedmont of the Range.