黄顶菊入侵对土壤微生物、土壤酶活性及土壤养分的影响

通过采样分析，研究了外来植物黄顶菊入侵对非耕地和耕地，以及对玉米根系土壤微生物、土壤酶活性、土壤速效养分的影响，旨在揭示黄顶菊入侵农田和贫瘠荒地的机制。本试验比较了距根系不同距离土壤的微生态变化；分析了根系土壤3大微生物类群结构、5种土壤理化性质以及5种土壤酶活性之间的相关性。结果表明，非耕地黄顶菊根表速效氮、速效磷、速效钾的含量分别为对照的4.44、6.88、2.64倍，耕地中分别为对照的5.31、13.78、7.56倍；非耕地黄顶菊根表土壤细菌、真菌、放线菌数量分别为对照的13.23、6.67、21.40倍，耕地中分别为对照的9.27、2.15、2.24倍，可见黄顶菊对非耕地土壤中可培养的细菌、真菌、放线菌数量的影响更为明显；非耕地中黄顶菊根表土壤碱性磷酸酶、酸性磷酸酶、脲酶、脱氢酶、蔗糖酶的活性分别为对照的19.44、5.39、1.64、1.74、4.62倍，说明细菌非常活跃。耕地中分别为对照的2.26、3.45、1.53、0.95、4.89倍。另外在玉米与黄顶菊互作时，其根表土壤速效氮、磷、钾分别为非互作条件下的63.54%、64.70%、80.71%、，黄顶菊入侵明显降低了玉米根表速效养分。综上，黄顶菊入侵增加了其根系周围可培养土壤微生物数量、土壤酶活性及土壤速效养分含量；降低了附近玉米根表土壤中可培养微生物数量、土壤酶活性和速效养分含量。

Effects of Flaveria bidentis invasion on soil microbial communities, enzyme activities and nutrients

Through the analysis of sampling,the effects of exotic species Flaveria bidentis invasion on soil microbial communities,enzyme activities and nutrients around their roots in non-cultivated land and cultivated land and around maize roots were studied in order to reveal the mechanism of Flaveria bidentis invading farmland and barren land successfully.Our experiment analyzed the cultivable soil microbe populations,soil available nutrients and soil enzyme activities around the roots in both non-cultivated land and cultivated land when Flaveria bidentis invaded.In Flaveria bidentis root surface in the non-cultivated land and cultivated land,the contents of available N,P and K are 4.44,6.88 and 2.64,and 5.31,13.78 and 7.56 times as those in the nude land(CK) respectively.The numbers of cultivable bacteria,fungi and actinomycetes in root surface are 13.23,6.67 and 21.40,and 9.27,2.15 and 2.24 times as those in the nude land respectively.The alkaline phosphatase,acid phosphatase,urase,dehydrogenase,invertase activities are 19.44,5.39,1.64,1.74 and 4.62,and 2.26,3.45,1.53,0.95 and 4.89 times as those in the nude land respectively which can indicate that bacteria are so active.In soil of maize root surface,the contents of available N,P,K,nutrients at non-interactional root surface are 63.54%,64.70% and 80.71% of that at interactional root surface.The above-mentioned results suggest that the root secretion of Flaveria bidentis increases the quantity of cultivable soil microbe groups,soil enzyme activities and available nutrients contents around their roots,reduces the quantity of cultivable soil microbe groups,soil enzyme activities and available nutrients contents around maize roots growing nearby under the natural environment,which may be one of main factors making Flaveria bidentis invading farmland and barren land successfully.