中文摘要：

人工封育是恢复退化草场的重要措施之一.为了研究北方农牧交错带不同封育时间与不同封育措施对植被的结构特征与多样性的影响,研究选取宁夏盐池柳杨堡人工封育地区,采用样方调查法对封育区植被生长状况进行调查.结果表明,长期封育初期对草场植被的生物多样性与生产力产生有益效果,但随着封育年限的增加,长期的完全封育不利于改善半干旱沙地草场植被的生产力及其放牧功能.样方中主要种群的重要值呈先增加后降低趋势;边缘区的丰富度指数（R）和综合多样性指数D、H的最大值分别为18、9.62、2.44,外围区的分别为18、9.74、2.48.封育区植被的盖度和生物量都是外围区最大,说明适当的利用是有利于草场植被恢复的.带状翻耕明显是不适合的,不能起到很好的作用,建议进行适当的放牧或刈割.

英文摘要：

Artificial fencing is one of the important measures for the restoration of degraded pasture.To study the effect of artificial fencing on the structural characteristics and diversity of vegetation of different fencing time in the farming-pastoral ecotones in northern China,artificial fenced areas of Yanchi County of Ningxia Hui Autonomous Region were selected to investigate the vegetation growth status by quadrate method.The results showed that fencing had a beneficial effect on the biological diversity and productivity of pasture plants in the early stages.With the increase of the enclosure years,full fencing was not conducive to improve the productivity of semi-arid sandy pasture vegetation and grazing function.The main plants＇ importance value in quadrats increased first and then descended.The maximum richness index and comprehensive diversity index of the edge areas was 18,9.62,and 2.44,while that of the peripheral areas was 18,9.74,and 2.48,then decreased.The vegetation cover and biomass in outside areas were the largest indicated that appropriate use was conducive to the restoration of pasture vegetation.The strip tillage did not have a very good effect and grazing or cutting should be used in this region.