乌兰布和沙漠东北部沙区人工林土壤微生物及酶活性研究

Soil Microorganism and Enzyme Activities under Different Artificial Forests in the Northeast of Ulanbuh Desert

以荒漠为对照,对乌兰布和沙漠东北部沙区9种人工林0～20 cm和20～40 cm土层的3大类微生物（细菌、放线菌和真菌）及4种酶活性（蔗糖酶、脲酶、过氧化氢和碱性磷酸酶）的生态分布特征进行了研究.结果表明：（1）各林地三大菌数量级均表现为细菌（106）〉放线菌（105）〉真菌（103）;在0～40 cm垂直剖面内,细菌数在柠条、沙枣和沙棘林地中较多,两白杨林地中放线菌数量最多,真菌数在花棒和柠条林地中较多,微生物总数整体表现为灌木林地多于乔木林地;随土层加深各林地土壤微生物总数量均呈明显减少趋势.（2）在0～40 cm土层中,两白杨林地蔗糖酶活性最高,小美旱林地脲酶活性和过氧化氢酶活性均较高,沙棘和沙枣林地碱性磷酸酶活性较高;土壤酶活性具有明显垂直分异特征,除过氧化氢酶外其余几种酶活性均随土层深度增加而递减,其中脲酶活性降幅最大.（3）4种土壤酶活性间整体正相关性较好,土壤放线菌数量与其蔗糖酶、脲酶和过氧化氢酶活性呈显著正相关.可见,人工乔、灌林地的土壤微生物数量比荒漠地增加,酶活性增强,土壤生物学性质得到改善;不同林地土壤微生物组成、数量、分布和土壤酶活性存在差异.

Take the desert land as the comparison,the soil bacteria,actinomycetes,fungus and sucrase,urease,catalase,alkaline phosphatase activities of 9 kinds of typical artificial forests in 0~20,20~40 cm soil layers in the northeast of Ulanbuh Desert have been studied.The results showed that：（1）microorganism magnitude：bacteria（106）actinomycetes（105）fungi（103）.In the 0~40 cm soil layer,the number of microbes in the surface layer was maximum,and clearly decreased with the soil depth.The number of microbes under the bush forest land was great than that under the tree forest land.The bacteria numbers under Caragana korshinskii Kom.Elaeagnus angustifolia L.and Hippophae rhamnoides Linn.were the largest in 0~40 cm soil layer.The actinomycetes under P.gansuensis had the most numbers.The fungi numbers under Hedysarum scoparium Fisch.and Caragana korshinskii Kom.were bigger than those of others.（2）Soil enzymatic activities varied in different artifical forests.In 0~40 cm soil layer,the activity of soil sucrase under P.gansuensis was higher than those of others.The activities of soil urease and catalase under Populus simonii×（Populus pyramidalis＋Salix matsudana） cv.Poplaris＇ were the highest;Soil alkaline phosphatase under Hippophae rhamnoides Linn.and Elaeagnus angustifolia L.were relatively high.In study region,the soil enzyme activities had obvious vertical distribution characteristics,decreasing with the soil depth except the soil catalase,especially soil urease had the sharpest decrease.（3）Four kinds of soil enzyme activities existed a good positive correlation.The correlations were significant between the number of soil actinomycetes and the activities of sucrase,urease,catalase.Artificial forests were established in study area,soil microorganism quantities increased greatly and soil enzyme activities strengthened significantly,and the soil biological properties were improved obviously.