紫茎泽兰(Ageratina adenophora)入侵对土壤微生物群落和理化性质的影响

Invasive effects of Ageratina adenophora Sprengel (Asteraceae)on soil microbial community and physical and chemical properties

外来入侵植物与入侵地土壤微生物群落的互作关系是影响外来植物入侵力和生态系统可入侵性的一个重要领域。因此,研究外来植物入侵对入侵地土壤微生物群落及其理化性质的影响不仅可以全面地评估入侵植物对生态系统的影响,而且对于探索外来植物入侵的土壤微生物学机制尤为重要。采用磷脂脂肪酸(PLFAs)和传统培养相结合的方法研究了外来入侵植物紫茎泽兰对入侵地土壤微生物群落结构的影响;同时研究了紫茎泽兰入侵对11种土壤理化因子的影响。结果表明紫茎泽兰入侵改变了土壤微生物群落结构,提高了土壤自生固氮菌、氨氧化细菌和真菌的数量;同时,显著地提高了土壤的有效磷、速效钾、硝态氮、氨态氮和土壤有机碳含量,降低了土壤总钾含量和pH值。土壤微生物不同生理类群的变化与土壤中植物可直接吸收利用养分的变化显著相关。紫茎泽兰在入侵地成功定殖后,可能通过改变土壤微生物群落结构,特别是增加了与土壤养分循环相关的微生物功能类群数量,进而提高了土壤可利用的养分水平,创造对自身生长有利的土壤环境。紫茎泽兰改变土壤微生物群落是其入侵的一部分,这种改变进而加速了土壤养分循环,可能增强了紫茎泽兰的养分吸收,进而促进其生长、竞争和扩张。

Interaction between invasive plant and soil microbial community is an important aspect to understand the plant invasivibility and susceptibility of receptive communities, as a result, studies on effects of plant invasion on soil microbial community and physical and chemical properties are becoming increasingly important to explore the effects of plant invasion on ecosystem and the underground soil biota related invasion mechanism. In present study, soil microbial communities were analyzed using PLFAs （phospholipids fatty acids ） method, and 11 different soil physical and chemical factors were measured following Ageratina adenophora invasion. Compared to non-invaded site and native plant site, invasion of A. adenophora modified soil microbial community composition. It was most noticeable that A adenophora increased soil fungi,azotobacteria and ammonia oxidizing bacteria, but significantly decreased actinomycetes and denitrifying bacteria. Soil organic carbon, NO3^- -N, NH4^＋ -N, available P and available K content were most abundant in heavily invaded site, while soil total K and pH value were lower than non-invaded site. Soil fungi, azotobacteria and ammonia oxidizing bacteria were significantly associated with most of the measured soil physical and chemical properties. The results indicate that A. adenophora changed soil microbial communities, especially the soil nutrition transition related soil microbe groups, probably creating favorable soil environment to benefit itself. Modification of soil biota is an important part of A. adenophora invasion process, and the invasion-induced changes of soil microbial community may lead to high soil available nutrition abundance,through which A. adenophora gains its superority in competition.