中文摘要：

以宁夏荒漠草原优势植物短花针茅（Stipa breviflora）、蒙古冰草（Agropyron mongolicum）、甘草（Glycyrrhiza uralensis）、牛枝子（Lespedeza potaninii）、牛心朴子（Cynanchum komarovii）和乳浆大戟（Euphorbia esula）为研究对象,探讨了不同放牧强度对植物的高度、叶性状、生物量、根冠比和根生物量比的影响。结果表明：围封区短花针茅、蒙古冰草、甘草、牛枝子和牛心朴子的株高显著高于重度放牧区。随着放牧强度的增加,短花针茅、蒙古冰草和牛枝子的株高呈降低趋势,而甘草、牛心朴子和乳浆大戟呈先升高后降低趋势;短花针茅、蒙古冰草、甘草和牛心朴子的叶面积和叶干重呈先增加后降低趋势,牛枝子的叶面积和叶干重呈显著降低趋势,而乳浆大戟呈显著增加趋势。重度放牧对短花针茅、蒙古冰草、甘草和牛枝子的比叶面积（SLA）影响显著,而中度和轻度放牧没有影响。重度放牧区短花针茅、蒙古冰草、甘草、牛枝子和牛心朴子的个体生物量、根系生物量和地上生物量均显著低于围封区和轻度放牧区。重度放牧区短花针茅、蒙古冰草和甘草的根系生物量分别比围封区降低了66.5%,88.8%和55.5%。说明放牧干扰影响短花针茅、蒙古冰草、牛枝子和牛心朴子生物量在植物地上和地下的分配模式。

英文摘要：

The effect of grazing on plant height,leaf traits,biomass,root： stem ratio and root biomass ratio of six dominant species was examined in a desert steppe in Ningxia. The results indicated that the height of Stipa breviflora,Agropyron mongolicum,Glycyrrhiza uralensis,Lespedeza potaninii and Cynanchum komarovii in ungrazed land was significant higher than that in the land with higher grazing intensity. With the increase of grazing intensity,the height of Stipa breviflora,Agropyron mongolicum and Lespedeza potaninii decreased,and height of Glycyrrhiza uralensis,Cynanchum komarovii and Euphorbia esula decreased after an initial increase,and had the highest value in light grazing intensity. The leaf area and leaf dry mass of Stipa breviflora,Agropyron mongolicum,Glycyrrhiza uralensis and Cynanchum komarovii showed a slight increase at light or moderate grazing intensity but declined significantly at heavy grazing intensity. The leaf area and leaf dry mass of Lespedeza potaninii significantly decreased with increasing grazing intensity,whereas the leaf area and leaf dry mass of Euphorbia esula significantly increased by grazing at heavy grazing intensity. Grazing increased the specific leaf area of Stipa breviflora,Agropyron mongolicum,Glycyrrhiza uralensis,Lespedeza potaninii at heavy grazing intensity and had no effect on specific leaf area at light and moderate grazing intensity. The individual biomass,root biomass and aboveground biomass of Stipa breviflora,Agropyron mongolicum,Glycyrrhiza uralensis,Lespedeza potaninii and Cynanchum komarovii in high grazing intensity were significant lower than those in ungrazed and light grazing intensity. Compared with ungrazed land,root biomass of Stipa breviflora,Agropyron mongolicum and Glycyrrhiza uralensis in high grazing intensity decreased by 66. 5%,88. 8% and 55. 5%. Grazing disturbance had significant effect on the allocation pattern of above- and belowground biomass of Stipa breviflora,Agropyron mongolicum,Lespedeza potaninii and Cynanchum komarovii.