海南热带山地云雾林苔藓植物多样性与谱系结构

Tropical montane cloud forests represent a rare ecosystem which harbours concentrations of endemic and threatened species, but they are in the most serious survival dangers in many parts of the world. The bryophyte diversity is the important component of tropical montane cloud forest ecosystems, for bryophytes and cloud forests are all particularly sensitive to environmental changes especially climatic conditions, they are very fragile and difficult to recover after degradation or destruction. But with the impacts of deforestation, climatic warming and habitat fragmentation, they are facing more and more severe threats to their existence, thus the investigation of bryophytes is an essential and very important complement for cloud forests. In this study, we will collect and determine the species composition, probe the distribution patterns and detect endemism and threatened species of bryophytes in five cloud forest distribution areas. Then we will provide the bryophyte species checklists of tropical montane cloud forest in Hainan Island, and on this basis, make a classification revision on the bryophyte flora of the island. In the meantime, we will establish sampling transects in different cloud forest distribution regions and with different vegetation types to survey bryophyte species diversity, measure DNA barcode information and environmental factors. By reconstruction of the phylogenetic trees using DNA barcoding information for each and overall the five cloud forests which represent local and island scale, the relationships of the phylogenetic diversity of both within- and among-communities will be analysed to detect the mechanisms that explain how the bryophyte communities were organized. The results are expected to reveal the species diversity and phylogenetic structure of bryophytes in the tropical montane cloud forest in Hainan Island, which will be helpful from an evolutionary perspective to understand the relationships among bryophyte species and to learn about the formation and maintenance mechanisms of bryophyte biodiversity in the cloud forests.

热带山地云雾林是特有种和濒危种最丰富的森林类型，也是世界上受威胁最严重的生态系统之一。苔藓植物是热带山地云雾林生态系统的重要组成部分，二者对环境变化均十分敏感而易被破坏难以恢复，开展苔藓植物多样性调查是对云雾林生物多样性研究和保护工作的一项必要和重要的补充。本项目拟在海南岛5个热带山地云雾林分布区全面调查苔藓植物的物种组成和分布，发现特有种和濒危种，编制海南热带山地云雾林苔藓植物名录，并在此基础上对海南岛苔藓植物区系展开分类修订；选取不同分布区和植被类型的云雾林样地，测定样地内苔藓植物群落物种多样性、DNA条形码信息及环境因子，构建本地群落和全岛尺度物种库谱系树，比较不同群落内及群落间的谱系多样性，探讨苔藓植物群落构建机制。本项目将揭示海南热带山地云雾林苔藓植物的物种多样性和群落谱系结构特征，有助于从进化角度深入认识云雾林中苔藓植物物种间的关系以及苔藓植物多样性的形成和维持机制。

海南热带山地云雾林孕育着丰富且对环境变化十分敏感的苔藓植物，在维持热带森林生态系统中具有重要功能。研究内容主要包括三个方面：（1）全面调查海南热带山地云雾林苔藓植物的物种多样性和地理分布；（2）探究云雾林不同微生境苔藓植物的群落多样性以及与环境因子关系；（3）构建云雾林苔藓植物群落系统发育树，揭示群落谱系结构。 . 主要研究结果：. （1）苔藓植物区系研究，共采集标本5375份，鉴定确认苔藓植物59科135属313种(含种以下分类单位)，包括苔类植物门22科50属156种、藓类植物门36科84属156种、角苔植物门1科1属1种，细鳞苔科和锦藓科分别为苔类与藓类中物种数量最多的优势科。发现濒危和国家重点保护苔藓植物7种，中国和海南特有种5种，海南新记录1科、8属、15种。地理成分中热带成分达57.68%。5种微生境类型以树附生苔藓比例最高，占苔藓物种的68.91%，其次为倒朽木生苔藓。. （2）在云雾林样地内选取2130个含不同类型生境的微样方，调查苔藓植物物种的组成、盖度、宿主乔木的胸径、粗糙度，以及测定了8个样方环境因子。根据重要值排序，树生和地面生苔藓的优势种有一定差异。树生苔藓群落的α多样性指数均高于地面生群落，其次为倒朽木群落，土生群落的多样性最低；地面生苔藓群落β多样性指数高于树生群落。树生苔藓盖度受到宿主乔木胸径、水汽压的显著影响，地面生苔藓盖度主要受到植被覆盖度影响。. （3）基于核基因ITS、叶绿体基因trnL-F、rbcL及rps4分别构建霸王岭、尖峰岭和黎母山苔藓植物群落系统发育树，谱系多样性PD、MPD显示，树基、树干及倒朽木苔藓群落之间无显著性差异，三者与石生、土生苔藓群落差异显著。NRI和NTI在5个微生境及3个云雾林样地群落中的谱系均表现为聚集结构，表明生境过滤在这些群落的构建中起主导作用。. 科学意义：本项目推动了我国热带山地云雾林生物多样性研究，丰富了海南苔藓植物区系成果，对于开展热带森林生态系统完整性保护及深入探讨热带雨林植物多样性的形成和维持机制具有重要意义。