摘要
望天树是我国热带季节性雨林的标识性树种,其原生境热带森林群落是我国植物热带性最强烈、种类组成最复杂、雨林特征最浓厚的植被类型,但现存分布区域狭窄.近期广西弄岗热带喀斯特峰丛洼地森林发现高72.4m的望天树,打破了我国喀斯特区域和华南地区的最高树纪录,刷新了以往对热带喀斯特森林植被特征的认知.本文基于弄岗望天树原生境森林群落调查样方,展示了其群落的林层结构、物种组成及生态特征,与我国其他望天树群落对比分析探讨了其植被生态学意义.结果表明:(1)该群落有高50m以上望天树巨树散生乔木冠层之上;连续乔灌层可分为4层,平均高度分别为36.9、25.6、9.5和2.7m;在2400m2样方内乔、灌、藤、草和附生植物分别有64、24、31、26和8种;(2)林冠上层优势种有望天树、人面子等典型热带区系树种,蚬木、肥牛树等喀斯特专性树种,岭南酸枣、白头树等落叶树种;(3)在乔木层的物种中,热带亚洲(印度-马来)分布型占65.6％,大高位芽植物占15.6％,常绿植物占85.9％,复叶植物占39.1％,革质叶片占60.9％,典型喀斯特植物占28.1％;(4)该区域群落乔木层优势属与我国其他望天树群落的相似性从高到低依次为广西那坡县、云南马关和勐腊县、广西巴马、田阳和大化县;群落结构组成差异与气候环境条件显著相关.综上,广西弄岗望天树原生境群落是在热带喀斯特峰丛洼地的局域封闭生境条件下发育形成的巨树散生、林层复杂的热带季节性雨林植被,孕育着丰富的耐旱型的典型喀斯特植物.
Abstract
Parashorea chinensis is a symbolic tree species in tropical seasonal rain forests in China.Its primeval habitat forest communities show clear adaptations to a tropical seasonal environment,and have the greatest diversity of tree species and the highest proportion of tropical flora,in China.Recently,a P.chinensis with a height of 72.4 m was discovered in the primeval forest of tropical karst peak cluster depression in Nonggang,Guangxi.This tree broke the record for the tallest tree in China's karst areas.Here we examine the properties of the forests that can support such remarkable trees,in order to update our understanding of the vegetation characteristics of tropical karst forests.We draw on four primeval forest community survey plots of P.chinensis in Nonggang,in order to summarize the characteristics of layer structure,species composition,plant areal types,leaf features,ecological habits,and dominant genera of these forest communities.The characteristics of the region around the tall tree were compared with those of other communities of P.chinensis in China.The results were as follows:(1)Giant trees exceeding 50 m in height are scattered across the canopy of the tallest tree's community.The continuous arbor and shrub layer can be divided into four layers,approximately 36.9 m,25.6 m,9.5 m,and 2.7 m high.There are 64 tree species,24 shrub species,31 vine species,26 grass species,and 8 epiphyte species within the 2400 square meter plots.(2)The arbor layer is dominated by tropical flora plants such as P.chinensis and Dracontomelon duperreanum,karst endemic plants such as Excentrodendron tonkinense and Cephalomappa sinensis,and deciduous trees such as Garuga forrestii and Allospondias lakonensis.(3)Species of tropical flora account for 93.7％of the trees in the arbor layer,with species from tropical Asia(Indo-Malay)accounting for 65.6％.Mega-phanerophytes account for 15.6％;evergreen plants account for 85.9％;compound leaf plants account for 39.1％;leathery leaf plants account for 60.9％;and typical karst plants account for 28.1％.(4)The greatest similarity to the dominant tree forest is shown by Napo County in Guangxi.Maguan and Mengla Counties in Yunnan,Bama,Tianyang,and Dahua Counties in Guangxi are progressively less similar.These relationships indicate that the influence of tropical climate on community forest structure is greater than that of their geology.In summary,the primeval forest communities of P.chinensis in Nonggang thrive in the closed habitat environment of the tropical karst peaks cluster depressions,benefiting from the relatively humid and warm local climate.Characterized by the presence of iconic tropical giant trees such as P.chinensis and Dracontomelon duperreanum,these forests exhibit the intricate forest layers of a tropical seasonal rain forest.Due to the combined influence of the tropical northern margin's geographical location and karst landform,these communities'forest canopies contain a certain proportion of deciduous tree species,with relatively low proportions of mega-phanerophytes and epiphytic plants.The communities are rich in drought-resistant plants with features such as leathery leaves,microphyll leaves,compound leaves,and typical karst plants.
基金项目
国家自然科学基金(32260276)
国家自然科学基金(32271599)
广西喀斯特植物保育与恢复生态学重点实验室项目(22-035-26)
弄岗喀斯特生态系统广西野外科学观测研究站项目(桂科23-026-273)
NETL
NSTL
万方数据