摘要
根据对西藏阿里地区163个植物群落样地资料进行的多元分析——排序、数量分类与环境解释,给出了该地区植被的基本类型、生态梯度及其与环境因子的定量关系。基本分析方法包括3个步骤:1)通过无倾向对应分析(DCA)的两个排序向量揭示了阿里植被的两个主要生态梯度;2)由该梯度的二维散点图及二元指示种分析(TWINSPAN)分别产生非等级制与等级制的植物群落分类系统;3)以多元回归分析将排序值与环境及地理参数相联系而给出各类型的环境指标——定量环境解释。分析表明,阿里植被类型及其分布主要取决于热量与湿度梯度,前者可通过地理参数,后者则通过土壤特征的数学表达式来定量地确定。两梯度包含的类型、种类与生境差异颇大,由低山暖性荒漠直到高山冰缘植被,从隐带性沼泽与盐生草甸到高原地带性荒漠与草原均各得其位,各有其值。表明该数量分析法对于处理高度生态多样性的植物群落生态信息是十分有效的。
Basing on the multivariate analysis--ordination, quantitative classifi-cation, and environmental interpretation of 163 plant community samplescollected from Ngari, Xizang, the primary vegetation types, ecologicalgradients, and their quantitative relations with environmental factors ofNgari are given. The basic analysis contains the following three steps; 1)the two principal ecological gradients are brought to light by two vectorsof ordination scores produced by detranded correspondence analysis (DCA);2) the nonhierarchical and hierarchical classification systems of plant com-munities are produced from the 2-dimensional scatter polt of DCA ordina-tion and two-way indicator species analysis (TWINSPAN), respectively;3) environmental indexes (quantitative interpretation) of various vegetationtypes are given by the multivariate regression analysis which connects theordination scores with environmental and geographical parameters. it isshown by the analysis that the vegetation types of Ngari and their distri-bution are mainly determined by the thermal and moisture gradients. Theformer could be expressed quantitatively with the mathematic expressionof geographical parameters, the latter with the soil characteristics. Thetwo gradients contain quite different vegetation types, species, and habi-tates, ranging from low montane warm desert to alpine periglacial vegeta-tion, and from intrazonal bog and saline meadow to tonal plateau desertand steppe with their paricular position and ordination scores. That showsthat the quantitative analysing method used here for handling the ecolo-gical data of plant communities with great ecological diversity is highlyefficient.
关键词
植物群落
梯度分析
数量分类
西藏
Gradient analysis
Quantitative classification
Environmental interpretation
Plant communities
Tibet
