[目的]通过比较外来植物紫茎泽兰不同入侵程度样地的土壤微生物、酶活性及肥力变化,以期揭示外来植物入侵对土壤生态的影响机制.[方法]本文采用传统培养的方法研究了紫茎泽兰对入侵地土壤微生物群落的结构变化;比较了入侵对8种土壤肥力因子和3种土壤酶活性的影响.[结果]紫茎泽兰入侵提高了土壤有机质、NO_3~-N、NH_4~+-N、有效磷、有效钾和土壤脲酶、磷酸酶和蔗糖酶的含量.重度入侵生境中铵态氮含量最高达53.00mg·kg~(-1),分别是空白对照土、混生当地植物土和单一当地植物土的14.1、9.9和5.9倍.脲酶含量在重度为2.87,显著高于当地植物区,并为空白区的3.9倍.培养结果表明紫茎泽兰入侵提高了土壤自生固氮菌、氨氧化细菌和真菌的数量.[结论]紫茎泽兰改变了入侵地土壤微生物群落结构和功能,暗示着微生物的改变引起土壤酶活性的改变进而影响了土壤肥力,形成对自身生长有利的微生态环境以利于入侵扩张.%[Objective] In present study, the structure of soil microbial community, activities of soil-enzyme and changes of fertility in different Ageratina adenophora invaded areas were analyzed for understanding the impacts of alien invasive plant on soil ecosystem. [Method] Soil samples were taken from different communities: heavily-invaded area, medium-invaded area, newly-invaded area, non-vegetation area, single-native-plant area, and multi-native-plants area, which are within similar ecological situations, soil biota were analyzed by traditional cultural methods, soil enzyme activities and fertilities were measured using the traditional chemical-factor analyzing methods. [Result] Compared to non-vegetation and native-plant soils, it was most noticeable that A. adenophora increased soil organic carbon, NO_3~-N, NH_4~+-N, available P, available K content and the activities of urase, phosphatase and invertase. NH4+-N content in the heavily-invaded soil was 53.00 mg·kg~(-1), which was 14.1, 9.9, and 5.9 times as that in the non-vegetation, multi-native-plants and single-native--plant soils, respectively. The activities of urase in the heavily-invaded soil was 2.87, which was 2.9 and 3.9 times more than that in the multi-native-plants and non-vegetation soils, respectively. The quantity of soil fungi, azotobacteria and ammonia oxidizing bacteria were most abundant in the heavily-invaded area. [Conclusion] The results indicate that A. adenophora changed soil microbial communities, especially the soil nutrition cycling and soil enzyme related soil microbe groups, probably creating a favorable soil environment which is of benefit to itself. The invasion-induced changes of soil microbial community and physical and chemical properties may be used by A. adenophora to expand rapidly in invasive ranges.
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