三种嵩草群落中若干植物种的生态位宽度与重叠分析

本文利用Ｌｅｖｉｎｓ和Ｐｉａｎｋａ公式，在多维生态因子梯度上测定了海北地区高寒草甸三种嵩草（Ｋｏｂｒｅｓｉａ）群落中若干植物种的生态位宽度和生态位重叠。结果表明：三种嵩草群落中优势种群的生态位宽度都较大，其中小嵩草（Ｋ．ｐｙｇｍａｅａ）在土壤水势、光照强度和坡向等三维因子上的生态位宽度分别是０．９１８、０．８９６和０．９１０；矮嵩草（Ｋ．ｈｕｍｉｌｉｓ）和藏嵩草（Ｋ．ｔｉｂｅｔｌｃａ）在土壤水势维上的生态位宽度分别是０．８７５和０．８６６；植物种如具有较大的生态位，则种间的生态位重叠亦较高；植物种对间若有相似的生物学－生态学特征，生态位重叠有降低的趋势；小嵩草和矮嵩草在三维上的重叠值分别是０．６７１、０．７１９和０．６８６；某些杂类草与优质牧草之间存有较大的重叠，这主要与长期过度放牧、优良牧草受到抑制以及生境退化有关。

ANALYSES OF NICHE BREADTHS AND OVERLAPS OF SEVERAL PLANT SPECIES IN THREE KOBRESIA COMMUNITIES OF AN ALPINE MEADOW

This paper concerns the analyses of niche breadths of and overlaps bet-ween several plant species in 3 Kobresia communities in the Haibei Research Station using the formula described by Levins and Pianka. Our results show that the dominant species in the three Kobresia communitites have greater ni-che breaths than their companion species. Kobrcsia pygmaea have niche brea-dths of 0.918,0.896 and 0.910 on the gradients of soil water potential, inci-dent light intensity and slope aspect,respectively.K. humilis and K. tibeticahave niche breadths of 0.875 and 0.866,respectively,on the soil water pote-ntial gradient. The niche overlaps are higher between the species that havegreater niche breadths than between those that have relatively narrower nichebreadths.The niche overlaps show a decreasing trend among congeneric spe-cies that have similar biological and ecological characteristics.The nicheoverlaps between K pygmaea and K. kumilis are 0.671,0.719 and 0.686 on thegradients of soil water potential,incident light intensity and slope aspect,respectively.Our results also show that the niche overlaps between someweeds and high-quality grasses are rather high.This might have been attri-butable to the suppression of high-quality grasses due to long-term overgrazingand habitat degradation.