中国热带-亚热带常绿阔叶林群落交错区  

Ecotones in the tropical-subtropical vegetation transition at the tropical margin of southern China

作　　者：朱华[1] Peter Ashton Hua Zhu;Peter Ashton(Center for Integrative Biology,Xishuangbanna Tropical Botanical Garden,Chinese Academy of Sciences,Mengla 666303,China;Arnold Arboretum,Harvard University and Royal Botanic Gardens,Kew,London TW93AE,UK)

机构地区：[1]中国科学院西双版纳热带植物园,保护生物学中心,勐腊666303 [2]Arnold Arboretum,Harvard University and Royal Botanic Gardens,Kew,London TW93AE,UK

出　　处：《科学通报》2021年第28期3732-3743,共12页Chinese Science Bulletin

基　　金：国家自然科学基金(41471051,31170195,41071040,31970223);生态环境部生物多样性调查、观测和评估项目(2019-2023)资助。

摘　　要：在中国南部热带北缘,热带森林向亚热带常绿阔叶林转变过渡,它们之间存在群落交错区.本文主要通过对中国热带北缘地区的4个永久样地植被的群落结构、生态外貌和植物区系组成分析,论证了热带-亚热带常绿阔叶林群落交错区的存在和其识别特征.由于中国南部西高东低的地势,西南部群落交错区主要体现在沿海拔的转变过渡,东南部则是沿纬度的转变过渡.西南部热带北缘存在两个明显的群落交错区.在海拔800~1200 m,热带低地季节性雨林与热带低山常绿阔叶林交错过渡,森林群落的外貌、结构和林冠层树种明显改变:由具有3个乔木亚层和散生巨树、典型混交热带树种组成林冠层的热带低地季节性雨林转变为具有2个乔木亚层、缺乏散生巨树、林冠趋于平整、主要由热带山地分布的壳斗科和茶科植物为林冠层优势树种的热带低山常绿阔叶林.在海拔1800~2100(2200)m,热带低山常绿阔叶林向亚热带常绿阔叶林交错过渡,林冠层树种发生了替换,群落的植物区系性质也发生了改变,由热带性质的植物区系变成亚热带-暖温带性质的植物区系.在中国东南部低地,约22°30′N及两侧附近,存在一个明显的常绿森林群落交错区:热带北缘低地季节性雨林向(南)亚热带低地常绿阔叶林交错过渡,群落的外貌、结构和林冠层树种明显改变.我们认为,热带-亚热带常绿阔叶林群落交错区与霜冻情况有关,霜冻对热带低地季节性雨林的林冠树种是致命的.我们建议,西南部的热带低山常绿阔叶林与亚热带常绿阔叶林的群落交错区和东南部的低地热带季节性雨林与亚热带常绿阔叶林的群落交错区为热带森林分布的北界.超越热带北界,林冠树种在西南部替换为亚热带-温带分布的中国-喜马拉雅和中国特有种,在东南部替换为主要是亚热带分布的中国特有种.中国东南部的亚热带气候地区存在Tropical evergreen forests are transitional to subtropical evergreen forests at the tropical margin of southern China,where ecotones exist.Forest structure,physiognomy and canopy tree flora,mainly from 4 permanent plots in the transitional area in southern China,are studied here,and the ecotones and their recognition features are clarified.Due to the different topography in southwestern and southeastern China,the forest ecotones occur along altitudinal gradients in the southwestern mountains of China,while the ecotone occurs along the latitudinal gradient in the southeastern lowlands.Two ecotones evidently exist in the southwestern mountains:At 800−1200 m asl,the tropical lowland seasonal rain forest with 3 tree layers and typical emergent tropical trees in the canopy changes to tropical lower montane evergreen broad-leaved forest with 2 tree layers and with mainly tropical southeastern Asian and tropical margin distributed Fagaceae and Theaceae canopy trees constituting their flattening canopy;at 1800−2100(2200)m asl,the tropical lower montane evergreen broad-leaved forest changes to subtropical(warm temperate)evergreen broad-leaved forest with a largely subtropical(warm temperate)Himalayan and Chinese endemic tree flora.In southeastern lowland China,the evergreen forest ecotone occurs at 22°30′N and nearby,where tropical-margin lowland seasonal rain forest changes to subtropical lowland evergreen broad-leaved forest.In the latter,the subtropical endemic Chinese and eastern Asia trees dominate the flattening canopy.We consider that the ecotones of the tropical-subtropical evergreen forest transition could be limited by air frost,because typical tropical canopy trees could be damaged and can survive only in the frost-free habitats.The ecotone between the tropical lower montane evergreen forest and subtropical(warm temperate)evergreen forest in southwestern China and the one at 22°30′N and nearby between the tropical margin lowland seasonal rain forest and the subtropical lowland evergreen broad-leaved f

关 键 词：热带北缘 群落交错区 热带-亚热带森林过渡 中国南部 

分 类 号：S718.54[农业科学—林学]