Effects Of Different Grazing Systems On Carbon Balance In Stipa Breviflora Desert Steppe

Using field investigation and enclosed chamber method (IRGA), dynamics of biomass and soil respiration rate was determined in Stipa breviflora desert steppe. The effects of grazing systems on carbon input, carbon output and carbon balance was studied in this paper. The results showed that:1) Compared with continuous grazing, community abovebiomass was not superior under rotational grazing, while community abovebiomass was suprrior under non-grazing.2) The abovebiomass of Stipa breviflora was greater in continous grazing plot than that in rotational grazing and non-grazing. The abovebiomass of Cleistogenes songorica decreased in the order was non-grazing plot, rotational grazing plot and continuous grazing plot. While, Allium polyrrizum showed little difference between different grazing systems.3) The seasonal dynamics of belowground biomass was similar between different grazing systems. The belowground biomass was greater in rotational grazing plot and non-grazing plot than that in continous grazing plot.4) The seasonal dynamics of litter fall was mainly affected by the state of grazing. The litter was greater in rotational grazing plot and non-grazing plot than that in continous grazing plot.5) Compared with continous grazing plot, the livestock feed intake was greater in rotational grazing plot. Livestock feed intake changed with the seasonal dynamics of aboveground biomass.6) Non-grazing maintains greater productivity, while continous graing and rotational grazing were no difference.7) The soil respiration rate and effect of environmental factors were similar between rotational grazing and continuous grazing, and there were differences between continuous grazing and non-grazing in daily mean soil respiration rate and effect of environmental factors. The diurnal variation of soil respiration could be expressed as a single peak curve, and the seasonal variation was mainly affected by soil moisture. Correlation of soil respiration diurnal variation with air temperature was greater than that with soil temperature, and water-temperature composite model was better than single-factor model to explain the changes in soil respiration rate. Compared with non-grazing, rotational grazing and continuous grazing elevated the temperature sensitivity of soil respiration (adequate moisture), while reduce the impact of soil moisture on soil respiration.8) Stipa breviflora desert steppe emerged to be carbon sinks under different grazing systems. Carbon sinks decreased in turn from non-grazing, rotational grazing to continous grazing, but with little differences.