中文摘要：

以藏北高寒草地为研究对象,探讨不同施肥模式对高寒草地植物物种组成、物种多样性及生产力的影响。结果表明,与不施肥处理相比,施肥处理的草地地上生物量提高幅度为23.6%-199%,其中施氮磷肥（NP）和施氮磷有机肥（ONP）的地上生物量较高,分别是不施肥（CK）的2.99倍和2.11倍,而单施有机肥（O）虽然能够提高草地生产力,但与CK相比无显著差异。高寒草地施肥由于限制了一部分罕见杂类草物种的生长而降低了高寒草地的物种丰富度。与CK相比,施氮磷有机肥（ONP）与单施有机肥（O）的物种数分别降低6.9%和10.3%（P〉0.05）,而施氮磷肥（NP）的物种数则降低了20.7%（P〈0.05）。施肥后草地植物群落的Shannon-Wiener指数和Pielou均匀度指数均有降低趋势。其中施有机肥（O）与施氮磷有机肥（ONP）处理的Shannon-Wiener指数与CK相比并无显著差异,而施氮磷肥（NP）处理的Shannon-Wiener指数与CK相比则降低10.5%（P〈0.05）。综合分析,施氮磷有机肥（ONP）的方式不仅显著提高高寒草地的植物生产力,而且没有引起植物多样性的显著变化,为供试条件下实现藏北草地恢复的最佳途径。

英文摘要：

Effects of different fertilization on species composition, plant diversity and productivity were discussed to explore the optimum improved practice of degraded grassland in alpine grassland in Northern Tibet. The results showed that the aboveground biomass under the treatment of fertilization was increased by 23.6%-199% compared with no fertilization （CK） . The aboveground biomass under the treatments of NP and ONP were 2.99 and 2.11 times of CK and had reached significant level. Even though it improved grassland productivity under the treatment of O, but there was no significant difference with CK. fertilization had limited the growth of some rare species of forbs to a certain extent. Compared with no fertilization,the species richness under the treatment of ONP and O had decreased by 6.9% and 10.3%,while it had decreased significantly by 20.7% under the treatment of NP. The Shannon-Wiener index and Pielou evenness index showed a decreasing trend in the fertilization treatments. The Shannon-Wiener index and Pielou evenness index in the treatments of O and ONP and had no significantly difference with CK. While the Shannon-Wiener index had reduced by 10.5% under the treatment of NP. Comprehensive analysis of different fertilization on species diversity and productivity,the way of ONP had not only increased the productivity significantly,and had no significant effect on plant diversity. It is the optimal approach to rehabilitate Northern Tibet grassland in this study.