宁夏贺兰山东麓荒漠草原区地衣物种多样性研究

Desert steppe region in the eastern foothills of Helan Mountain,located between Helan mountain and Yinchuan plain irrigation oasis, is mainly composed of Helan mountain proluvial and Yellow River alluvial,and is a special part of Helan mountain ecosystem. In this region,the climate is droughty, little rain, strongly windy and dusty,vegeration is sparse, soil surface is mainly covered by biological soil crusts. There are lots of lichens in biological soil crusts and rocks'surface.These desert lichens,as the important part of the desert ecosystem, play important roles in soil surface stabilization, moisture maintaing and have great signification in desert restoration and succession. Due to the shortage of investigations on lichens of Northwest desert region,lichens in desert steppe region in the eastern foothills of Helan Mountain were not studied in any detail.We intend to investigate lichen species composition, flora characteristics and lichen species diversity variation in connection to different habitats and substrates.It is the objective of this study to provide comprehensive information on lichen species diversity in desert steppe region in the eastern foothills of Helan Mountainto. The data obtained from this research could provide the theoretical basis for effective species diversity protection and scientific management of desert ecosystems, accumulate data for predicting lichen community evolution trends in this region and the futher systematic study of desert lichens.

宁夏贺兰山东麓荒漠草原区位于贺兰山与银川平原灌溉绿洲之间，主要是由贺兰山洪积和黄河冲积而成，是贺兰山生态系统中较为独特的重要组成部分。这一地区干旱少雨，风大沙多，植被稀疏，地表景观主要为生物土壤结皮所覆盖。在该地区的生物土壤结皮层及裸露岩石上存在大量的地衣。这些荒漠区地衣是荒漠生态系统重要的组成部分，对荒漠区土表的保护，水分的保持及荒漠的恢复和演替发挥着重要的作用。本项目针对我国西北荒漠地区地衣研究方面的不足，对目前尚未涉足的宁夏贺兰山东麓荒漠草原区地衣开展研究，拟通过对宁夏贺兰山东麓荒漠草原区地衣的物种组成、区系特征及不同生境和基物上地衣物种多样性的分析研究，获得该地区地衣物种多样性的综合资料。不仅为该地区有效的开展地衣物种多样性的保护，对荒漠生态系统进行科学管理提供理论依据，而且为预测该地区地衣群落的演替趋势提供理论参考，为中国荒漠区地衣的系统学研究积累基础资料。

本项目为了查明宁夏贺兰山东麓荒漠草原区地衣的物种多样性和区系特征，在贺兰山东麓荒漠草原区由南到北设立典型样地，对地衣开展样方调查，标本采集，并结合形态、化学和分子手段对标本进行鉴定，进而对贺兰山东麓荒漠草原区地衣的区系成分和生态学特征进行了分析。综合目前的研究结果，宁夏贺兰山荒漠草原区共有地衣149种，隶属于51属15科，其中中国新纪录种42个，宁夏新记录属11个，新记录种24个。优势科为微孢衣科，优势属为微孢衣属。贺兰山东麓荒漠草原区地衣区系地理成分共划分为世界广布、广泛分布、北温带分布、欧亚分布、温带亚洲，环北极高山，东亚成分及中国特有成分等八个区系成分，其中以北温带成分占优势，反映了贺兰山北温带植物区系的特征。该地区地衣主要以壳状地衣为主，其次为叶状地衣和鳞片状地衣，枝状地衣稀少，生长型体现了地衣物种对当地干旱环境的适应特性。通过对不同干扰条件下地衣物种多样性的比较分析发现，随着人为干扰程度的加剧，地衣物种种类组成显著减少，丰富度降低。其中平茶渍属和微孢衣属的物种对干扰最为敏感，Psora decipens, Collema coccophorum和Endocarpon adscendens抗干扰能力最强，但是种群数量显著变小。此次研究结果为贺兰山荒漠区地衣的系统学研究和开展地衣物种多样性保护积累了基础资料。