| In this study,soil respiration,soil physical properties,chemical properties and biological properties were analyzed between free grazing and grazing exclusion treatments in a potentially desertifying steppe of Xilingol League in Inner Mongolia.The results showed that(1)variations of soil respiration were unimodal curves in both treatments in the whole growing season;and among all environmental factors determined seasonal patterns of soil respiration,temperature was the most important,and soil moisture is the second.(2)Compared with free grazing treatments,grazing exclusion increased soil respiration by 20.76%.Meanwhile,plant above-and below ground biomass,litter,carbon and nitrogen of microbe biomass increased accordingly(p<0.05).Responses of enzyme activity to grazing varied with kinds of enzymes.Both activities of urease and sucrase were stimulated(p<0.05),while activity of catalase was depressed(p<0.05)by grazing exclusion;however,there was no significant difference existed in protease activity between two treatments.Total carbon and nitrogen of soil were higher in grazing treatments than in grazing exclusion treatments(p<0.05),but pH value was not affected by grazing(p>0.05).As for volume weight of soil,it was significantly higher in grazing treatments than in grazing exclusion treatments.(3)Exponential function could fit for relationship between soil respiration and temperature.and linear function could fit for relationship between soil respiration and moisture for both treatments(p<0.01).Both temperature sensitivity and water content sensitivity of soil respiration were depressed by grazing(p<0.05).These findings indicated that organism activities in soil might be decreased by overgrazing.As an important index of nutrient transformation and supply,soil respiration could be employed to discover the internal cause of overgrazing induced desertifying processes in grassland.And it could be served as a useful reference for desertification control. |
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