中文摘要：

于2011年植物生长旺季（8月）在围封禁牧（NG）、轻度放牧（LG）、中度放牧（MG）和重度放牧（HG）区分别随机选取荒漠草原优势植物甘草（Glycyrrhiza uralensis）和牛心朴子（Cynanchum komarovii）各15株为研究对象,对比分析其生长特征、各植物构件生物量及生物量资源分配差异对不同放牧强度的响应机制,为退化草原的恢复演替提供依据。结果表明：（1）甘草株高和地径、牛心朴子株高均随放牧强度的增加呈先升高后下降的趋势,而且均在轻度放牧条件下最高,重度放牧时则显著降低。（2）甘草和牛心朴子的总生物量、茎生物量和叶生物量随着放牧强度的增加呈先升高后降低的趋势,且不同放牧强度间差异显著;甘草和牛心朴子根系生物量随放牧强度的加强变化趋势不同。（3）甘草和牛心朴子生物量分配的总体格局为：根〉叶〉茎;随着放牧强度的增加,甘草根生物量比呈先升高后降低趋势,茎生物量比呈下降的趋势,叶生物量比呈上升趋势,而牛心朴子根生物量比呈先下降后升高的趋势,茎生物量和叶生物量呈先增加后下降的趋势。研究认为,不同放牧强度下两种植物形态可塑性和生物量分配格局的差异反映出植物生态适应策略的不同。

英文摘要：

The plant growth,tissues biomass and biomass allocation of two dominant species （Glycyrrhiza uralensis and Cynanchum komarovii） were observed under different grazing intensities in desert steppe.The results showed that：（1）The plant height and ground diameter of G.uralensis,and plant height of C.komarovii were decreased after an initial increase with increasing of grazing intensities,with the highest values under light grazing,and there were significantly decreased under heavy grazing.（2）Stem biomass,leaf biomass and total biomass of G.uralensis and C.komarovii were significantly affected by grazing,and decreased after an initial increase with increasing of grazing intensities.The root biomass of G.uralensis and C.komarovii showed different trends under different grazing intensities.（3）The biomass allocation patterns of G.uralensis and C.komarovii were roots〉leaves〉stems.With increasing of grazing intensities,the root biomass ratio of G.uralensis decreased after an initial increase,but stem biomass ratio tended to decreased and leaf biomass ratio tended to increased;while the root biomass ratio of C.komarovii increased after an initial decrease,contrary to stem biomass ratio and leaf biomass ratio.It suggests that differences in morphological plasticity and biomass allocation patterns of these two species indicated that they had different ecological strategies to grazing.