中文摘要：

采用围栏放牧控制试验,研究了不同放牧强度和放牧方式对封育9年荒漠草原地上生物量及种间关系的影响。结果显示,1）放牧强度对生长季不同时期牧草地上生物量的影响不同,中度自由放牧小区的牧草地上生物量在整个生长季都高于封育小区;2）环境条件对牧草地上生物量的影响较大,在光热水等资源充足时,自由放牧区3种牧压梯度下的牧草地上生物量均高于封育禁牧小区,当遭遇高温干旱胁迫时,自由放牧区的牧草地上生物量的增长量均比封育禁牧小区低,中度轮牧草场表现出较好的抗胁迫能力;3）放牧能够减小荒漠草原年内牧草地上生物量的时间变异,而其空间变异对不同放牧制度的响应较为复杂,在不同强度、不同方式以及植被生长季的不同时期都有所不同;4）轻度自由放牧不会改变植物的种间关系和群落之间的关系,而重度自由放牧不仅加剧了群落间的资源竞争,还会引起研究区3种群落发生不同程度的逆向演替,中等强度的4区轮牧方式为研究区最优的放牧模式,它一方面减缓了群落界面上的资源竞争,另一方面促进了本氏针茅群落的顺行演替。以上结果表明,合理地调控人类放牧制度能够促进草地生态系统功能,从而起到恢复和保护草原的作用。

英文摘要：

The best grazing system characteristics in desert steppe were probed in a controlled grazing experiment in desert grassland under 9-year exclosure in Yanchi county,Ningxia province and the effects of different grazing systems on aboveground biomass of pasture and interspecific relationships were studied.Results showed that,1） The grazing intensities had different effects on aboveground biomass of pasture in different growing seasons,and the biomass was lower in moderately grazed,fenced plots than in continuously grazed ones throughout the growing season.2） The environment had a great impact on aboveground biomass which was lower in fenced than in rotationally grazed plots with different intensities under adequate natural conditions,while fenced plots had more biomass in rotationally grazed plots under high temperature,drought environments.The grassland of rotationally grazed plots with moderate intensity showed better anti-stress ability than ungrazed.3） Grazing reduced the temporal heterogeneity of aboveground biomass in desert steppe throughout the growing season,however the spatial heterogeneity of aboveground biomass was complex： it had different responses in different grazing systems and different growing seasons.4） The interspecific relationships and those between communities were not changed by continuous low intensity grazing,while continuous grazing with heavy intensity not only increased the resource competition between different communities but also caused varying degrees of regressive succession in three communities.The four-course system with moderate intensity was the best grazing system in this area,as it eased the resource competition at the interface between communities and also improved the forward succession of Stipa bungeana.Therefore,the desert steppe could be protected and restored by regulating the grazing systems.