古尔班通古特沙漠生物结皮中微生物量与土壤酶活性的季节变化

研究了古尔班通古特沙漠生物结皮土壤中微生物N量与酶活性的季节变化。结果表明：微生物N量及蔗糖酶、碱性磷酸酶、脲酶、过氧化物酶和多酚氧化酶的活性在不同月份差异极显著；微生物N量春季>夏季>秋季>冬季，在3月达到最高值；蔗糖酶在4-9月均保持较高的活性，酶活性在4月份最高；碱性磷酸酶、脲酶、多酚氧化酶、过氧化物酶的活性均呈单峰曲线变化，其峰值分别出现在3-7月；土壤有机质和全N含量在3月和9月明显高于其他月份；微生物N量与碱性磷酸酶、脲酶之间，蔗糖酶、多酚氧化酶及过氧化物酶与土壤温度之间，蔗糖酶、脲酶和过氧化物酶与土壤水分之间均具有极显著的正相关关系。微生物N量的增加为脲酶和碱性磷酸酶提供反应底物或能源物质从而增加酶的活性。土壤酶活性的季节变化可能是由土壤水分和温度共同影响的。

Seasonal Variations of Microbial Biomass and Soil Enzyme Activity in Biological Soil Crusts in the Gurbantunggut Desert

In the Gurbantunggut Desert, seasonal variations of microbial biomass and soil enzymes were measured with 60 soil samples collected from the inter-dune of the sand dune. The results indicated that: significant seasonal differences were observed in microbial biomass and the activity of invertase, alkaline phosphatase, urease, polyphenol oxidase, peroxidase of biological soil crusts. The changing trends of microbial biomass N in different season was spring>summer>autumn>winter; the value of microbial biomass N reached the highest point in March; two peaks were found for the invertase activity in a year; invertase activity was higher from April to September than in the other months and was the highest in April; the changing trends of alkaline phosphatase, urease, polyphenol oxidase, and peroxidase acitivity all presented single-peaked curve and their highest values were observed in different month from March to July; organic matter and total N of the soil in March and September were higher than in the other months; microbial biomass N was significantly and positively correlated with alkaline phosphatase activity and urease activity, respectively; significant positive correlations were observed between soil temperature and invertase, polyphenol oxidase, peroxidase acitivity; soil moisture was significantly correlated with invertase, urease and peroxidase activity; increasing microbial biomass offered substrate or energetic substance for urease and alkaline phosphatase activities and then increased enzymatic activities; the seasonal change of soil enzyme may be impacted by direct roles and indirect roles of soil moisture and temperature.