关键词: 放牧强度, 荒漠草原, 枯落物, 固沙能力

Abstract: Overgrazing is an important cause of grassland degradation and desertification affecting large land areas. The aim of this project was to investigate the effects on soil erosion of seasonal regulation of grazing intensity. Litter biomass, sand collection in winter and spring and the particle size of the soil surface layer were evaluated under six grazing intensity treatments in Stipa breviflora desert steppe in a randomized complete block design. It was found that: 1) The more that litter biomass was preserved in winter and spring, the stronger the sand-fixation ability of the grassland, and the proportion of ‘flow sand' under moderate grazing intensity (45.16%), which was lower than that of heavy grazing. 2) With increase in grazing intensity, the amount of loose sand of various particle sizes increased significantly. Severe grazing increased the proportion of particles of size >0.25 mm and <0.05 mm, compared to that of ungrazed or lightly grazed treatments, while the proportion of particles sized 0.25-0.10 mm was lowest under severe grazing. 3) Heavy grazing in autumn increased the amount of loose sand in grassland. Therefore grazing practice in desert grassland should be to reduce stocking rate in autumn. Based on these results, it was concluded that unreasonable grazing utilization of grassland reduces the windbreak and sand fixation capacity of the vegetation, resulting in surface roughening. In the desert steppe, maintenance of no less than 32.93 g·m^-2 litter in winter and spring was conducive to reducing wind erosion.

Key words: grazing intensity, desert steppe, litter, sand-fixation ability