腾格里沙漠东南缘植被恢复过程中土壤微生物量及酶活性

土壤微生物量和酶活性是反映土壤功能的关键指标，也是土壤恢复和环境变化的指示器。以流动沙丘为对照，研究了腾格里沙漠东南缘人工固沙植被区表层0~5、5~10、10~20 cm土壤微生物量碳氮和酶活性随植被恢复的变化特征。结果显示：土壤微生物碳氮含量和脲酶、多酚氧化酶、碱性磷酸酶、过氧化氢酶、淀粉酶、纤维素酶、蔗糖酶活性均随植被恢复年限延长而增大，随土层深度增加而减小，不同年代植被区及不同土层间差异均显著（P<0.05）。其中0~5 cm土层变化最明显，经过62年植被恢复后土壤微生物碳氮量和脲酶、多酚氧化酶、碱性磷酸酶、过氧化氢酶、淀粉酶、纤维素酶、蔗糖酶活性分别增加了16.44、8.79、3.99、3.01、2.54、19.35、0.77、0.65、16.61倍，年平均变化速率分别为1.55、0.21 mg·kg^-1和6.14×10^-4、1.25×10^-2、9.32×10^-4、6.05×10^-2、8.22×10^-5、9.07×10^-5、4.24×10^-3 mg·g^-1·h^-1。土壤微生物量和酶活性与土壤理化性质高度相关，除与沙粒、容重呈负相关关系外，与土壤粉粒、黏粒、pH、电导率、有机碳、无机碳、全氮、碱解氮、速效磷和速效钾含量呈正相关关系。这表明种植旱生灌木能够有效促进沙地土壤功能恢复并改善沙区环境。

Soil Microbial Biomass and Enzyme Activities during Revegetation Process in the Southeastern Fringe of the Tengger Desert

Soil microbial biomass and soil enzyme activities are key indicators of soil function and indicators of soil recovery and environmental changes. The dynamic patterns of soil microbial biomass carbon and nitrogen and soil enzyme activities in different soil layers (0-5, 5-10 and 10-20 cm) at revegetated areas in the southeastern fringe of the Tengger Desert, respectively, were investigated by taking moving sand dune as control. The results showed that:The soil microbial biomass carbon, microbial biomass nitrogen, urease, polyphenol oxidase, alkaline phosphatase, catalase, amylase, cellulase and sucrase all increased with the increasing restoration age, and decreased with the increasing soil depth, significant differences were found among different revegetated areas and different soil layers (P<0.05). And 0-5 cm soil layer changes most obviously. After 62-year-revegetation,the soil microbial biomass carbon, microbial biomass nitrogen, urease, polyphenol oxidase, alkaline phosphatase, catalase, amylase, cellulase and sucrase increased by 16.44, 8.79, 3.99, 3.01, 2.54, 19.35, 0.77, 0.65 and 16.61 times,and their average annual rate of change is 1.55, 0.21 mg·kg^-1 and 6.14×10^-4, 1.25×10^-2, 9.32×10^-4, 6.05×10^-2, 8.22×10^-5, 9.07×10^-5, 4.24×10^-3 mg·g^-1·h^-1 respectively. The soil microbial biomass carbon and nitrogen and soil enzyme activities were highly positive correlated with silt and clay content, pH, electronic conductivity, the concentrations of organic carbon, inorganic carbon, total nitrogen, available nitrogen, available phosphorus and available potassium, while negatively correlated with sand and bulk density. The results showed that planting xerophytic shrubs can effectively promote the restoration of sandy soil function and improve the environment in the sandy area.