西藏半干旱区苔藓植物多样性及其对环境的响应

Bryophyte plays a key role in maintaining the structures and functions of ecosystems and is sensitive to environment. But since the 1980s, the researches of bryophyte diversity in Tibet Plateau are fewer. And the researches of spatial distribution and response of environment changes are not generally appreciated. On the basis of our previous research, the bryophytes distributed in semi-arid region of Xizang where lies in the main zone of business activities, farming and stock breeding, will be selected as a study case in order to further examine the relationships between the diversity of bryophyte species and community and habitats and different environments. We plan to collect bryophyte specimens and record ecological information in field investigation from east to west, southeast to northwest, south to north and investigate the 5 main alpine vertical strip. And there are methods of classification, observation, measure and compare should be use. To achieve the research goals, we will carry out field samplings to collect bryophytes at present locations for richness analysis, and will gather all necessary environmental data, such as local climatic conditions, topographic features, local vegetation types, and anthropologic variables. The importance of environmental variables will be obtained through DCCA ordination, and regression analysis will be used to quantify the relationships of the presence probability of bryophytes and their richness to environmental variables. Species distribution models (Maxent) will be constructed to predict the potential spatial pattern and richness of bryophytes. Understanding the current richness and spatial distribution pattern. By the study of bryophytes diversity in semi-arid area in Tibet and the response to environment, in different levels from species to populations and to community, the projection will give a new sight into the study of bryophyte diversity and response of environment changes. And improve the theories of life history strategies of bryophyte in the regional scale. Add the geography distribution information of Chinese bryophyte. Besides, it is important to species diversity protection and monitor of environmental changes in Tibet Plateau.

苔藓植物既是生态系统功能维持的重要组成部分，又是敏感的环境指示物，但自上世纪80年代以来，对青藏高原苔藓物种多样性的研究较少，对其空间分布以及环境响应机制的研究也未引起重视。本研究将以西藏经济活动最多的半干旱区为研究区域，在申报人前期工作基础上，拟在东-西、东南-西北、南-北、高山垂直样带上开展苔藓植物野外采集和样方调查，以及相关环境要素的测定和获取，采用鉴定、观察、测量、比较、关联、回归和排序等方法，并借助遥感影像和GIS 平台进行空间分布建模，通过对物种多样性、群落特征、个体性状及其与环境关系的分析，阐明研究区苔藓植物物种多样性组成特征，物种和群落的空间分布规律及其对环境的响应。该研究将充实西藏苔藓物种多样性及环境响应机制的研究，丰富和完善气候变化环境下区域苔藓的生活史对策理论，增加我国苔藓植物地理分布信息，且对利用青藏高原苔藓植物来监测环境变化及其多样性保护都具有重要意义。

本团队根据项目研究内和研究计划，在西藏半干旱区域内沿东南到西北二条样带和北到南三条样带开展了系统的采集和群落调查。共获得苔藓植物标本1万余号，调查样方1043个。获得以下主要结果：. （1）物种丰富、特点突出、新种和新分布多. 西藏半干旱区有苔藓植物59科164属581种，其中优势科有丛藓科、真藓科、紫萼藓科等，仅丛藓科就有28属，132种，占全国该科总属数的73%和总种数的70%，而对齿藓属、墙藓属、红叶藓属、赤藓属为优势属。发现并发表新种11个，即卡若拉大帽藓、拟边红叶藓、藏红叶藓、黎氏对齿藓、半边疣对齿藓、吉氏对齿藓、无疣对齿藓、高山对齿藓、西藏对齿藓、钝头对齿藓、西藏卵叶藓，以及中国新纪录种（Bryoerythrophyllum latinervium）1个。. （2）温度、海拔和植被是苔藓植物物种和群落分布的主要影响因子. 对分布最为广泛和物种最多的丛藓科进行相关分析，发现在西藏干旱区物种分布呈现出单峰模式，即在海拔4000-4500 m范围内分布的物种数量最多，其次是高海拔区，低海拔区域相对较少。对齿藓属植物分布最为广泛，其中尖叶对齿藓广泛分布于本研究区内，主要受温度、植被盖度、海拔等因素的影响。土壤含水量和土壤有机质可能是影响物种分布的因素。. （3）植物形态特征是反映生境条件的敏感指标。. 对西藏广泛分布的真藓和尖叶对齿藓进行了形态测定，并与环境进行相关分析。结果表明植株和叶片比细胞水平对环境的响应更为明显，海拔、年均温度、年降水量、坡度、太阳辐射和基质均可影响植物形态；不同物种在相应环境变化时，在某些形态特征上表现一致，但也存在一些性状有自身的独特性。. （4）物种空间分布格局与环境密切相关. 蒸发量、年均温和雨热同期的平均气温以及海拔等因素是影响物种空间分布格局的主要因子；随着气候变暖，对齿藓属和红叶藓属的分布范围将继续扩张。. 本项目的研究结果对增加西藏苔藓植物多样性信息、了解苔藓植物在环境变化检测中的作用以及对全球气候变化的研究均具有重要意义和参考价值。