青藏高原紫穗槐主要形态特征变异分析

应用数量统计方法,对在西藏拉萨市、曲水县和甘肃玛曲县等青藏高原区首次种植的紫穗槐3个居群的17项形态特征指标进行比较分析。变异系数分析结果表明:不同居群内及居群间的形态特征存在一定程度的变异。采用主成分分析方法,找到了积累贡献率达86.603%的4个主成分,新枝长、新枝直径、老枝直径、主根直径、二级侧根总长5个性状是造成紫穗槐形态变异的主要因素,并分析了其与根际土壤生境的相关性。通过对紫穗槐一级侧根与二级侧根根长频率分布研究,表明:(1)不同居群内及居群间各个阶段根长存在差异;(2)居群3(玛曲)中一级侧根和二级侧根根长≥40 cm的频率明显高于另外两个居群。

Variation in main morphological characteristics of Amorpha fruticosa plants in the Qinghai-Tibet Plateau

This paper investigated the variation in 17 main morphological characteristics of 3 Amorpha fruticosa populations inhabiting three sites(Lhasa,Qushui and Maqu) of the Qinghai-Tibet Plateau.Our results showed that there were striking differences in some of the morphological characteristics within and among A.fruticosa populations when compared the average coefficients of variation in these morphological characteristics.The average coefficients of the variation of 17 main morphological characteristics across the three populations were 0.09—0.37,with the average coefficient of new branch length variation being largest.In addition,the average coefficient of population variation in the Lhasa site greater than that for the other two sites.Principal component analysis(PCA) indicated that the accumulated contribution of the first four principal components was 86.6%,but the contribution of the first principal component was 40.9%,suggesting that the first four principal components explained most of the variation in the morphological characteristics.New branch length,new branch diameter,old branch diameter,taproot diameter and total length of the second-order lateral root explained the majority of the variation in morphological characteristics of A.fruticosa populations.Correlation analysis also indicated that there were complicated relationships between main factors(soil organic carbon,total nitrogen and so on) in the rhizosphere and the above five morphological characteristics.New branch length,taproot diameter showed significant positive or negative correlations(P < 0.05) with the contents of soil nutrients,and in particular the content of soil organic carbon,total nitrogen,total phosphorus were significantly and negatively correlated(P<0.05) with the five morphological characteristics.In addition,our results showed some of the differences in the distribution frequency of the first-order and second-order lateral root lengths of A.fruticosa plants within and among populations.The distribution frequency of the first-order lateral root lengths(10—20 cm and 20—30 cm)was generally larger than that for the other first-order lateral root lengths in the three sites,and the distribution frequency of the second-order lateral root lengths(0—10 cm,10—20 cm,20—30 cm,30—40 cm,≥40 cm) showed a decline trend in the Lhasa and Maqu sites.Moreover,the distribution frequency of the first-order and second-order lateral root lengths(≥ 40 cm) in the Maqu population was significantly greater than that for the populations of the Lhasa and Qushui sites.This study reported in the first time the variation in the main morphological characteristics of A.fruticosa plants in the alpine regions,which may have important implications for the management of such alpine grasslands in China.