库布齐沙漠北缘不同人工灌木林地土壤肥力质量状况

在库布齐沙漠北缘杭锦旗段选择柠条、沙柳、花棒和杨柴等4种人工灌木林为对象，以流动沙地为对照，研究不同人工灌木林下土壤理化性质、微生物数量和酶活性特征及其相互间的关系，并运用综合指数法对各人工灌木林土壤综合质量进行评价。结果表明:1）总体上，各人工灌木林地土壤容重、蒸发速率和pH值低于流沙地，土壤含水量、入渗率、田间持水量、总孔隙度、速效N、速效P、速效K和有机质含量高于流沙地，土壤盐分与流沙地无显著差异，不同人工灌木林对土壤理化特性的改善存在差异。2）各人工灌木林地土壤酶活性均强于流沙地，总体而言，柠条林地和沙柳林地的建植对土壤酶活性影响较大，花棒林地和杨柴林地的建植对土壤酶活性影响较小。磷酸酶与脲酶、蔗糖酶、多酚氧化酶呈极显著正相关，蔗糖酶与脲酶、多酚氧化酶间极显著正相关。3）各人工灌木林土壤微生物数量均显著多于流沙地，柠条和沙柳林地土壤微生物数量多于花棒和杨柴林地；各类人工灌木林地和流沙地土壤中放线菌数量最多，细菌数量次之，真菌数量最少。细菌、真菌和放线菌间无显著相关性；细菌除了与脱氢酶相关性较低外，与其他酶均极显著正相关；真菌仅与多酚氧化酶显著负相关；放线菌与脲酶、蔗糖酶、磷酸酶显著正相关。 4）各人工灌木林地和流沙地土壤肥力高低为柠条林地＞沙柳林地＞花棒林地＞杨柴林地＞流沙地，人工灌木林的营造改善了土壤理化特征和生物学性质，显著地提高了流沙地土壤肥力质量，营造柠条林效果最佳。

Soil Quality Assessment in Different Artificial Shrub Plantations in Northern Margin of Kubuqi Desert,China

Four types of artificial shrub plantations,including Salix psammophila,Hedysarum scoparium,Caragana korshinskii,Hedysarum fruticosum,were selected in the northern margin of Kubuqi Desert to study soil physicochemical properties,quantity of soil microorganisms,enzymatic activities and the relations among these variables.Bare sandy land was taken as the control.Meanwhile,a synthetic index method was used to evaluate the soil comprehensive quality.The results were as follows 1) generally,soil bulk density,evaporation rate and pH of three shrub plantations were lower than those of bare sandy land.Soil moisture content,infiltration rate,field capacity,total porosity,available N,available P,available K and organic matter content of the shrub plantations were higher than those of bare sandy land.No significant differences were found in soil salts between the shrub soil and bare sandy land.Differences existed in the needs of the improvement of soil physicochemical properties among different shrub plantations.2) Soil enzymatic activities of the shrub plantations were stronger than those of bare sandy land.In general,the impacts of afforestation of C.korshinskii and S.psammophila on soil enzymatic activities was relatively stronger than H.scoparium and H.fruticosum.There were extremely and significantly positive correlations between phosphatase and other three enzymes,i.e.,invertase,urease,and polyphenol oxidase,as well as between invertase and other two enzymes (urease,polyphenol oxidase).3) The quantities of soil microorganisms of the shrub plantations were significantly more than that of bare sandy land,the quantities of soil microorganisms of C.korshinskii and S.psammophila were more than those of H.scoparium and H.fruticosum; the quantities of soil actinomycetes of the shrub plantations and bare sandy land were the largest,followed by bacteria and fungi.There were no significant correlations among actinomycetes,bacteria and fungi; bacteria presented significantly positive correlation with all the enzymes except for dehydrogenase; fungi only had significantly negative correlation with polyphenol oxidase; actinomycetes had significantly positive correlations with invertase,urease,phosphatase.4) The order of soil comprehensive quality of the shrub plantations and bare sandy land was C.korshinskii＞S.psammophila＞H.scoparium＞H.fruticosum＞bare sandy land,soil physicochemical properties and biological properties were improved and soil fertility qualities of bare sandy land were remarkably enhanced by afforestation of shrub plantation,the effect of afforestation of C.korshinskii was the best.