中国南北过渡带东段样带植被序列与气候分界问题

国家科技基础资源调查专项“中国南北过渡带综合科学考察”将秦岭—大巴山定义为中国南北过渡带的主体,秦巴山地植被南北变化研究,对于揭示中国南北过渡带地域结构的过渡性、多样性和复杂性具有重要意义。基于植物群落实地调查数据,本文将中国南北过渡带东段分为：东秦岭北麓（EQMN）、东秦岭南麓（EQMS）、东大巴山北麓（EBMN）和东大巴山南麓（EBMS）4个地理单元,从植物物种、群落结构和物种多样性三个层面,对区域气候分界问题进行研究。结果表明：① 植物种类层面,EQMN主要为北方植物,EQMS出现常绿树种且北方植物减少,东大巴山以喜湿喜热的南方植物为主。② 群落结构层面,EQMN群系有4个（北方群系3个,南方群系0个,广布群系1个）、EQMS有6个（北方群系3个,南方群系1个,广布群系2个）、EBMN群系有4个（北方群系0个,南方群系2个,广布群系2个）、EBMS群系3个（北方群系0个,南方群系3个,广布群系0个）,只有EQMS群系出现南北性质混合;③ 丰富度层面,随着纬度增加,科、属、种3个分类群物种多样性均减小,但南北方植物混合现象开始在EQMS出现。本文对植被变化序列的研究增加了对东秦巴山地南北分界线判断的科学性,东秦岭南麓更适合作为暖温带—北亚热带的分界线。

North-south transect series in vegetation of eastern China's north-south transitional zone and their significance for determining climate dividing line

The National Basic Resources Investigation Program "Integrated Scientific Investigation of the North-South Transitional Zone" introduced the concept of north-south transitional zone(Qinling-Daba Mountains). Variation of north-south series in vegetation of the Qinling-Daba Mountains is of great significance to reveal the transition, diversity and complexity of the regional structure of China’s north-south transitional zone. Based on the survey data of plant communities, in this study, the eastern Qinling-Daba Mountains is divided into four geography units: north flank of eastern Qinling Mountains(EQMN), south flank of eastern Qinling Mountains(EQMS), north flank of eastern Daba Mountains(EBMN), south flank of eastern Daba Mountains(EBMS). The regional climate divisions on levels of plant species, plant community structure and species richness are explored. The results show that:(1)On plant species level, there are mainly north plants in EQMN, evergreen species and fewer north plants in EQMS. Then to the eastern Daba Mountains, there are mainly south plants which like wetness and heat.(2) On plant community structure level, there are 4 formations(3 northern formations, 0 southern formation, 1 widespread formation) in EQMN, 6 formations(3 northern formations, 1 southern formation, 2 widespread formations) in EQMS, 4 formations(0 northern formation, 2 southern formations, 2 widespread formations) in EBMN, 3 formations(0 northern formation, 3 southern formations, 0 widespread formation) in EBMS. In terms of the numbers and properties of formation, there is a mixture of northern and southern formations only in EQMS. On species richness level, the diversity of family, genus and species decreases with the increase of latitude, but the mixture of north and south plants occurred in the south flank of eastern Qinling Mountains. This paper studies the variation of series in vegetation,which increases the scientificity of determining north-south dividing line, and shows that the south flank of eastern Qinling Mountains is more suitable as the warm temperate-subtropical zones dividing line.