拉萨河流域植物群落的数量分类与排序

青藏高原植物群落空间分异格局是异质生境条件下物种性状、种间相互作用等生态学过程共同作用的结果,对其分析有助于深入理解群落形成与环境因子之间的关系。基于拉萨河流域自然植被样带调查,采用双向指示种分析(TWINSPAN)和典范对应分析(CCA)等方法,探讨了群落的结构组成及影响其结构分异的主导环境因子。结果表明:(1) TWINSPAN数量分类将拉萨河流域草地系统划分成12个群系类型,即圆叶合头菊+唐古拉翠雀花群系;紫花针茅群系;青藏臺草群系;雪层杜鹃+鲜卑花-西藏嵩草群系;高山嵩草群系;小叶金露梅群系;硬叶柳+杯腺柳群系;水栒子+拱枝绣线菊-高山嵩草群系;绢毛蔷薇-冷蒿+白草群系;大果圆柏-垂穗披碱草群系;铺地柏-藏橐吾+高原荨麻群系;醉鱼草+砂生槐群系。12种群系类型包含了较多的植被类型,包括高寒灌丛草甸、高寒灌丛草原、稀树草原、高寒草甸和高寒草原等。(2) CCA排序表明:影响拉萨河流域植物群系分布的主要环境因子是年均温度、海拔和经度和纬度,其次是年均降雨量。(3) TWINSPAN分类与CCA排序结合反映了群系分布格局变异与环境因子之间的关系,可为拉萨河流域草地的保护和可持续利用,以及相关的植被群落研究提供参考。

Quantitative classification and ordination of grassland communities on the Lhasa River Basin

To predict the influences of environmental change on the composition of communities, it is indispensable to also understand the regional drivers underlying the structuring of these communities. The goal of this study was to investigate the natural vegetation in the Lhasa River Basin of Qinghai-Tibet Plateau, and TWINSPAN and Canonical Correspondence Analysis (CCA) were used to explore the relationship between the community composition and the dominant environmental factors. The TWINSPAN quantitative classification divides the vegetation surveyed into 12 formation types. The 12 formation types include several vegetation types, including alpine shrub meadows, alpine shrubs, sparse grassland, alpine meadows, and alpine grasslands. The environmental factors explained a total of 20.4% of the community distribution variation, in which the average annual temperature of climatic factors, the altitude, and the latitude of spatial factors had a larger interpretation rate for the community distribution variation than did the topographic factors, such as slope and slope position. However,the average annual rainfall had no prominent impact on the change in community composition. The comprehensive analysis of spatial variation in the vegetation community could help us to understand the relationships between community formation and environmental factors.