The objective of the study was to determine the seasonal dynamics of soil microbial biomass contents and enzymes activities in Caragana microphylla plantations for sand-fixation in the Horqing sandy land.Soil samples at the depths of 0-10 cm,10-20 cm,20-30 cm,30-40 cm,and 40-50 cm were collected from the C.microphylla plantations with an age sequence of 6,11,and 24 years and from the natural community.The activities of soil urease,protease,saccharase,phosphomonoesterase,dehydrogenase and polyphenol oxidase ...