Effect Of Enclosure Management On Soil Respiration Of Desert-steppe In Ningxia

In this study, we selected the desert steppes which were enclosed against grazing in different years, in Ningxia as the research sample plot. The soil respiration rate, soil water content, soil temperature, soil organic carbon and total nitrogen at 0-10cm depth, aboveground biomass, underground biomass and litter accumulation were measured to explore the effects of enclosure on soil respiration in desert steppe. The main results were as follows:(1) The diurnal variation of soil temperature appeared to be rising from 7:00 to 16:00, which was the lowest at 7:00, and gradually increased to the highest at 16:00. The soil temperature increased from May to August, the dairy mean temperature up to 31.71℃, and then decreased gradualry to the lowest in October, which was consistent with the changing trend of air temperature. The soil water contents at 0-10cm depth showed as up-down trends, which were consistent with the changing trend of rainfall.(2) The soil respiration rates increased from7:00 to 16:00. which were the lowest at 7:00, and gradualry increased to the highest at 16:00. The soil respiration rates showed increasing-decreasing trends in the whole growing season. The soil respiration rates increased slowly from May to July and then rapidly reached peak values in August. From August to September, they were relatively stable and then decreased rapidly from September to October. The soil respiration rates of the enclosed grasslands in each month were all significantly higher than those of unenclosed grassland (P<0.05).(3) The soil respiration rate and soil temperature presented significantly exponential regression relationship of the enclosed grasslands. The soil respiration rate presented significantry linear regression relationship with soil moisture. The Q10 presented significantly linear regression relationship with soil moisture. Compared with single factor model, the water and heat complex model can better explain the changes of soil respiration.(4) The content of soil organic carbon, aboveground biomass, underground biomass and litter accumulation increased with the enclosure time prolonging. The soil respiration significantly correlated with soil organic carbon and underground biomass, while which poorly correlated with total nitrogen, aboveground biomass and litter accumulation.