关键词: 红砂, 过牧, 围栏封育, 荒漠草地, 植被演替

Abstract: Desert shrub land with Reaumuria soongrica as the dominant or edificator species is one of the main grassland types in the northwest of China. It plays an important role in environmental protection. Affects of different over grazing intensities and enclosure on vegetation succession of Reaumuria soongrica + Cliestogenes songorica grassland at Alxa region, Inner Mongolia, were reported in this study. The total vegetation coverage had reduced to 8% from 12% during the last 6 years. As grassland degraded (light, medium and heavy degradation), the R. soongrica shrubs were gradually decreased, it s coverage at medium and heavy degraded regions were 74% and 84% of that in the light degraded region respectively, where the cover was 7.5% (P<0.05). Accordingly, the herbs with lower yield or poorer feeding value were increased. The increasing of C. songorica and Peganum nigellastrum could be the indicators for the medium and heavy degradation grasslands, respectively. Significant effects of vegetation restoration were obtained from short time fencing without grazing. One growing season after fencing, the average vegetation cover increased by 1.7% and forage yield increased by 218.8%, compared to that of open grazed, and seed yield of R. soongrica was 371 times of grazed paddock. However, during the fenced period the relative restoration rates of the dominant species R. soongrica were increasingly reduced (P<0.05) both in coverage and yield as the grassland degradation become heavier. And restoration rate was zero at the heavy degraded paddock. Therefore, the fenced non-grazing technique is an effective approach to restore and protect the R. soongrica desert grassland, however, the fencing work need start as early as possible, otherwise, the restoration of R. soongrica vegetation will be either very slow or impossible.

Key words: Reaumuria soongrica, over grazing, fenced non-grazing, desert grassland, vegetation succession