摘要
用因子分析的方法确定影响沙丘固定程度的主导因素 ,并根据其共同度在总方差中所占比例来确定各主导因素的权重 ,然后对原始数据进行无量纲化处理 ,通过加权平均的方法计算出各样地沙丘固定程度的综合指数α。结果表明 :1流动沙丘的α值一般低于 0 .6,半固定沙丘的α值介于 0 .6～ 0 .7之间 ,固定沙丘的α值大于 0 .7;2单纯以植被盖度或特定植物种作为判断依据是片面的 ;3灌丛和土壤对沙丘的固定和演化起着非常重要的多重积极作用 。
The study area is located in the central part of Naiman Banner,Korqin Sandy Land, a stretch of dunefield where there is a very favorable temperate climate, with the mean annual precipitation of 362 3 mm , for fixing aeolian sand dunes Nevertheless, the fixing extent greatly varies with different sites due to wide and intensive human activities (i e overgrazing, irrational cultivation, cutting woods for fuel, fencing dunes, afforestation, etc ) Therefore, this is an optimal area for studying quantitatively the fixing extent of dunes After deeply analyzing and comparing, vegetation and soil are determined as principal indicators which themselves are intuitive and the most important components of landscape in a certain area Considering the seasonal variation of landscape and the vulnerability of dune ecosystem , the status of local vegetation on dunes in spring must be taken into account Subsequently, based on these considerations, 14 parameters are cautiously chosen as variables in original data matrix, which are thought to be those which strongly affect the fixing extent of dunes and which can be measured in the field or analyzed in the laboratory, rather conveniently and rapidly, with the conventional methods and techniques Of these, 6 edaphic variables are fine sand content, silt and clay content, bulk density, moisture content, organic matter content, pH, and 8 relative to vegetation include coverage, height of dominant layer, species saturation (total sum of seed plants), number of perennial seed plants, biomass measured in the warm seasons, and coverage, height of dominant layer and biomass in the cold seasons, all being measured in quadrats of one square meter with 9 repeats In order to make sure which variables virtually exert very important roles in influencing the fixing extent of dunes and how important, R type factor analysis (FA) is used to determine the key variables and their weights The criterion of covariance contribution percentage is 84% for selecting principal fa
出处
《生态学报》
CAS
CSCD
北大核心
2001年第7期1057-1063,共7页
Acta Ecologica Sinica
关键词
风成沙丘
固定程度
因子分析
综合指数α
植被演替
aeolian sand dune
fixing extent of dunes
factor analysis(FA)
integrated index( α )
vegetation succession
