无芒隐子草地上部分功能性状对长期放牧的变异性响应

摘要

植物个体受放牧干扰影响,通过自身权衡不同功能性状,对不同放牧强度干扰做出差异性适应.为研究长期放牧条件下,植物个体各性状对不同放牧梯度的差异性响应,本研究以荒漠草原优势种无芒隐子草(Cleistogenes songorica)为研究对象,分析其个体功能性状对放牧的响应变化、地上生物量与各功能性状间的关系,以及各功能性状对个体地上生物量的影响权重.结果表明:随放牧强度增加,叶片各性状指标、个体生物量、植株高度、冠(丛)幅均有明显变小、变矮的趋势;除茎基部直径和平均叶长外,无芒隐子草个体地上生物量、茎重、叶重与植株茎、叶各表型性状均呈正相关关系,植物个体地上生物量组分具有较大的变异性,变异性较小的表型性状指标与地上生物量组分的相关性系数相对偏低;影响无芒隐子草地上生物量的表型性状中,总叶面积、叶片数和平均叶长的 VIP(variable importance proj ection)值大于1,其对植物个体地上生物量的贡献率达到61.01%.放牧导致无芒隐子草各功能性状出现显著性差异,但并未改变其作为优势种的地位.%Individual plants can react to grazing of different intensities with a variety of adaptions,including trade-offs of several functional traits.In order to study the responses of Cleistogenes songorica individual traits to long-term grazing,this study,conducted in a desert steppe(Inner Mongolia),focused on the individual functional traits,the relationship between individual above-ground biomass and its functional traits,and the effect of the functional traits on the individual above-ground biomass in the dominant species,C.songorica. The results showed that the leaf characteristic index,individual above-ground biomass,plant height,and crow (bundle)decreased significantly with the increase of grazing intensity.Apart from basal stem diameter and av-erage leaf length,we found positive correlations of individual above-ground biomass,stem biomass,leaf bio-mass and phenotypic traits of stem and leaves with grazing intensity.Furthermore,a greater variability was ob-served among individual above-ground biomass components,while only a relatively low correlation coefficient of phenotypic traits with smaller variability,and individual above-ground biomass components was found.A-mong all phenotypic traits of above-ground biomass of C.songorica,the VIP(variable importance proj ection) of total leaf area,the total number of leaves,and the average leaf length was greater than 1,and its contribu-tion rate to individual aboveground biomass approached 61.01%.Grazing resulted in significant difference a-mong all functional traits of C.songorica,however,grazing pressure did not challenge its position as a domi-nant species in this desert steppe.