By taking 20 shrubs (including Caragana korshinskii et al.) in Tibetan Plateau as the tested materials, their total root system characteristics values such as length(TRL), surface area(TRSA), volume(TRV), number of tips(TRTN), number of branches(TRBN), and their micro-fine roots (diameter≤2 mm) eigenvalues such as length(SFRL), surface area(SFRSA), volume(SFRV), number of tips (SFRTN) were measured respectively by field experiments in the early stage of growth (May) and the exuberant period (July), and the cluster analyses were conducted according to the characteristics of root system. The results show that there were significant differences among the characteristics values of the total roots and micro-fine roots of the shrub species both in May and July, the order of each characteristics value of roots was different during the same period, and characteristic values of roots in July showed different order rules from that in May. The characteristic values of total roots and micro-fine roots in July were all increased with different amplitude compared with that in May, and TRV(175.14%) and SFRTN (74.56%) respectively increased the most among the characteristic values of total roots and micro-fine roots. The 4 characteristic values of total roots and 5 characteristic values of micro-fine roots both showed significant positive correlation, and there was a positive correlation on characteristic values of total roots and that of small fine roots, only the correlation between TRV and all characteristic values of the micro-fine roots was not significant. The results of principal component analysis showed that all factors loading in July was higher than that in May, and the factors loading of characteristic values of small fine roots were relatively higher than that of total roots, so the characteristics of shrub roots could be better reflected through determining the characteristics values of small fine roots of shrub in July. From comprehensive evaluation of root characteristics, 20 shrub species could be divided into 5 types (drought resistance in turn weakened):Potentilla fruticosa was taken into first categories for its the strongest drought resistance; Berberis julianae, Caragana arborescens were taken into second categories; Caragana korshinskii, Elaeagnus pungens, Rosa multilfora, Spiraea salicifolia were taken into third categories;Caryopteris tangutica, Sorbaria kirilowii were taken into fourth categories;the remaining 11 shrub species were taken into fifth categories.%以青藏高原地区各地的柠条Caragana korshinskii等20种灌木树种为试材，通过田间试验测定此20种灌木在生长初期（5月）和生长旺期（7月）的全根系特征值（长度、表面积、体积、根尖数、分叉数）和微细根（直径≤2 mm）特征值（长度、表面积、体积、根尖数），研究灌木在生长初期和旺期根系特征，并根据根系特征进行聚类分析。研究结果表明：（1）5月和7月灌木树种之间全根系和微细根系特征值指标均存在显著性差异，同一时期灌木树种各根系特征值大小顺序有所不同，并且7月灌木树种根系特征值大小顺序规律与5月不一致。（2）与5月相比，灌木7月全根系和微细根特征值均呈不同幅度增加，其中全根系和微细根特征值中增幅最大的分别是全根体积（175.14%）和微细根根尖数（74.56%）。（3）全根系特征值4个指标之间和微细根系特征值5个指标之间均呈显著正相关，而全根系特征值和微细根特征值之间总体呈显著正相关，仅5月全根体积与各微细根特征值相关性不显著。（4）主成分分析结果表明，7月各项指标载荷均比5月份对应指标高，并且7月微细根特征值指标载荷相对高于对应全根系指标，测定灌木7月的微细根系特征值，能更好地反映灌木根系特征。（5）从根系特征角度综合评价，20种灌木大致可以分为5种类型(抗旱能力依次减弱）：金露梅Potentilla fruticosa为第1类，抗旱性最强；三颗针Berberis julianae、树锦鸡儿Caragana arborescens为第2类；柠条Caragana korshinskii、胡颓子Elaeagnus pungens、蔷薇Rosa multilfora和绣线菊Spiraea salicifolia为第3类；唐古特莸Caryopteris tangutica和珍珠梅Sorbaria kirilowii为第4类；其余11种灌木为第5类。
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