关键词: 荒漠草原, 放牧制度, 净初级生产, 土壤呼吸, 碳平衡

Abstract: 【Objective】Taking Stipa breviflora desert steppe in Inner Mongolia as the research object, carbon input, carbon output and carbon balance features in plots that affected by fencing, rotational grazing and continuous grazing for ten years (1999-2009) were determined.【Method】Using field investigation and enclosed chamber method (IRGA), the dynamics of biomass and soil respiration rate were determined in Stipa breviflora desert steppe. The effects of grazing systems on carbon input, carbon output and carbon balance was studied in this paper. 【Result】 Compared with continuous grazing, the litter fall, livestock feed intake and below-ground biomass were increased by rotational grazing, while no significant difference the community above-ground biomass was found in between continuous grazing and rotational grazing. Litter fall, above ground and below ground biomass were increased by non-grazing. Compared with continuous grazing, rotational grazing and non-grazing increased the soil respiration rate in dry months. Stipa breviflora desert steppe emerged to be carbon sinks under different grazing systems, and the net ecosystem production was, respectively, 413.78, 401.45, and 416.80 gC•m-2•a-1.【Conclusion】There was little difference between different grazing systems, and carbon sinks decreased in turn from non-grazing, rotational grazing to continuous grazing.

Key words: desert steppe, grazing systems, NPP, soil respiration, carbon balance