西藏东部高寒草甸苔藓植物群落数量分类与排序

Abstract

为探讨高寒草甸苔藓植物群落分布格局及其与环境因子之间的关系, 按网格法在西藏东部的林芝市和昌都市设置了28个高寒草甸样地, 采用双向指示种分析(TWINSPAN)、除趋势对应分析(DCA)和典范对应分析(CCA)的方法对群落进行数量分类和排序。结果显示, 共记录有苔藓植物19科30属60种, 均为藓类植物；其中, 丛藓科和真藓科的物种数占总种数的55%。群落优势种为北地对齿藓(Didymodon fallax)、垂枝藓(Rhytidium rugosum)、山羽藓(Abietinella abietina)、厚角绢藓(Entodon concinnus)、尖叶对齿藓芒尖变种(Didymodon constrictus var. flexicuspis)和短叶对齿藓(Didymodon tectorus)。根据TWINSPAN分析结果可将西藏东部高寒草甸苔藓植物群落划分为9个群丛, 分别为沙氏真藓(Bryum sauteri)群丛、细枝羽藓(Thuidium delicatulum)+狭网真藓(Bryum algovicum)+羽枝青藓(Brachythecium plumosum)群丛、尖叶对齿藓芒尖变种群丛、山羽藓+厚角绢藓+垂枝藓群丛、扭口藓(Barbula unguiculata)+垂枝藓+山羽藓群丛、垂枝藓+曲尾藓(Dicranum scoparium)群丛、厚角绢藓群丛、北地对齿藓群丛、短叶对齿藓群丛, 分类结果反映了群丛类型与环境之间的关系。CCA分析结果表明, 影响西藏东部高寒草甸苔藓植物群落分布的首要环境因子是纬度, 其次是归一化植被指数(NDVI), 再次是黏土比例, 海拔和太阳辐射也有一定影响。;To explore the distribution pattern of bryophyte communities in the alpine meadow and their relationships with environmental factors in eastern Tibet, 28 sample plots were set up in Nyingchi and Changdu based on the grid sampling method. Two-way indicator species analysis (TWINSPAN), detrended correspondence analysis (DCA) and canonical correspondence analysis (CCA) were applied to the quantitative classification and ordination of bryophyte communities. The results showed that 60 species of bryophytes in 30 genera and 19 families were recorded, which all belonged to mosses. The number of species belonging to Pottiaceae and Bryaceae accounted for 55% of the total species richness. The dominant species of the communities were Didymodon fallax, Rhytidium rugosum, Abietinella abietina, Entodon concinnus, Didymodon constrictus var. flexicuspis, and Didymodon tectorus. According to the TWINSPAN analysis, bryophyte communities were classified into nine associations (i.e. Bryum sauteri association, Thuidium delicatulum + Bryum algovicum + Brachythecium plumosum association, Didymodon constrictus var. flexicuspis association, Abietinella abietina+Entodon concinnus+Rhytidium rugosum association, Barbula unguiculata+Rhytidium rugosum+Abietinella abietina association, Rhytidium rugosum+Dicranum scoparium, Entodon concinnus association, Didymodon fallax association, Didymodon tectorus association), which reflected the relationships between vegetation types and the environmental factors. CCA analysis revealed that latitude was the predominant environmental factor, followed by Normalized Vegetation Index (NDVI), percentage of soil clay, influencing the distribution pattern of bryophyte communities in the alpine meadow of eastern Tibet. In addition, altitude and solar radiation were the other two environmental factors which significantly affected the distribution pattern of bryophyte communities.