中国喀斯特森林群落系统发育多样性的纬度梯度格局及其形成机制研究

Latitudinal gradient pattern of biodiversity and its formation mechanism was a key fundamental theoretical issue, and has remained perplexing to ecologists for long times. To analyze and interpret spatial patterns of species and Phylogenetic diversity on local and regional scales and their drive mechanisms would contribute to reveal the formation and maintenance mechanisms of species diversity as well as the process of community assembly. So far, studies on biodiversity pattern and its drive mechanism of karst forest community are still very limited. To clarify species diversity and phylogenetic diversity patterns of karst forests and their formation mechanisms along a latitudinal gradient in China, this study conduct in four typical karst old-growth forests that lies in different latitudinal area: tropical monsoon forest in Exianling on Hainan Province, tropical monsoon forest in Longgang in Guangxi Province, subtropical evergreen broadleaf forest in Longhushan in Guangxi Province, and subtropical evergreen and deciduous broad-leaved mixed forest in Maolan in Guizhou Province. By establishing the forest plots and investigating the plant species composition and environmental factors (include climate, soil topography and other factors), thus constructing phylogenetic trees, analyzing and calculating phylogenetic structure and phylogenetic alpha and beta diversity index. The main objective of this study is to reveal and resolve the species and phylogenetic diversity patterns of karst forests and their formation mechanisms on local and regional scales along a latitudinal gradient.

生物多样性的纬度梯度格局及其形成机制是一个令人困惑的重大基础理论问题。解析局域和区域尺度上植物群落物种和系统发育多样性空间格局及其成因，有助于揭示物种多样性的形成和维持机制以及群落的构建过程。迄今为止，我们对喀斯特森林群落的生物多样性格局及其驱动机制的研究还很有限。为阐明我国喀斯特森林群落物种和系统发育多样性的纬度梯度格局及其形成机制，本研究以海南俄贤岭的热带季雨林、广西弄岗的热带季雨林、广西龙虎山的南亚热带常绿阔叶林和贵州茂兰的中亚热带常绿落叶阔叶混交林4个不同纬度带典型的喀斯特原生林为研究对象，通过设置样地，测定植物种类组成和环境因子数据，从而构建系统发育树，分析和计算系统发育结构和系统发育alpha与beta多样性指数，从局域和区域尺度上解析喀斯特森林群落物种和系统发育多样性的纬度梯度格局及其形成机制。

生物多样性的多尺度格局及其形成机制是生态学研究的核心问题。探讨局域范围内物种共存和生物多样性的维持机制或者区域范围内不同类型森林群落的构建机制，能够加深对生物多样性格局及其成因的理解。本项目以我国不同纬度带喀斯特植被为研究对象，研究地点包括了广西弄岗、广西三十六弄-陇均和贵州茂兰3个保护区，测定3个研究地植物群落种类组成和环境因子数据，分析了植物区系、群落结构、物种多样性、植物性状，并构建了系统发育树，从局域和区域尺度上分析了物种多样性、系统发育结构和系统发育多样性的格局和形成机制。研究结果表明：（1）弄岗、龙虎山和茂兰的木本植物分别有104科425属936种、99科363属636种和100科352属995种。木本植物区系均以热带亚热带成分为主，其优势科热带性质随纬度升高逐步降低。弄岗和龙虎山保护区的木本植物区系属的热带性质明显，而茂兰保护区植物属的热带性质较弱，温带性质属的比重随纬度升高而增加。弄岗和龙虎山木本植物的亲缘关系较为密切，而茂兰则与两者的亲缘关系较为疏远；（2）不同研究区乔木层、灌木层和草本层群落物种α多样性的纬度格局变化规律不一致。不同研究区植物群落间物种差异程度与纬度差异程度呈正相关。物种Jaccard指数和Sorensen指数之间随纬度梯度呈显著正相关；（3）在弄岗植被的演替过程中，群落构建具有明显的系统发育进化历史。在演替早期，群落的谱系结构表现为谱系聚集，群落内的共存物种亲缘关系较近、生态位相似；在演替后期，群落的谱系结构表现为谱系发散，群落内的共存物种亲缘关系较远。环境过滤在演替早期的群落构建中起主导作用，相似性限制在演替后期群落构建中起主导作用。本项目研究结果有助于深入揭示喀斯特植物群落的物种多样性格局与和群落构建机制，同时对喀斯特地区植被的恢复与重建以及森林管理等具有一定实践指导意义。