外来菊科植物入侵介导的AMF与植物群落的互作反馈作用

Based on the phenomenon of the competitive exclusion of native species and rapidly form a single community, three Chinese typical invasive composite plants Ambrosia artemisiifolia,Flaveria bidentis and Bidens pilosa were taken as examples to study their interactions between arbuscular mycorrhizal fungi(AMF) and plant community during their invasion in common garden experiment for many years. Arbucsular mycorrhizal fungi was focused on studying by ecology and microbe molecule biology. The effect of the invasion of composite plant on the plant community was studied. AMF community in the soil and colonized in plant roots was focused on exploring how AMF was changing.The effects of AMF that enriched in rhizosphere soil of the mixed planting in the different time during the invasion on the photosynthesis and the absorption of nitrogen were compared.The role of AMF in the competitive growth between the invasive plants and native plants and its merchanism were clarified.The contribution of different AMF community to the invasion of plant growth and competition was explored. Combined with the changes of plant community and AMF in the common garden,the relationship between the change of AMF community and plant community succession was discussed.The results will help to support and enrich the hypothesis of soil microbial feedback of exotic plant invasion and can provide theoretical basis for habitat restoration by soil microbial.

利用野外同质园试验，以豚草、黄顶菊、三叶鬼针草3种重要外来菊科植物为研究对象，基于其竞争排斥本地物种而迅速形成单一群落的现象，以植物与AMF互作为切入点，经过多年定点采样与调查，采用传统生态学和微生物分子生物学方法，重点研究外来菊科植物入侵对入侵域植被和入侵域土壤和植物根系AMF群落的影响，探究外来菊科植物入侵域AMF变化的普遍规律；采用同位素标记方法，通过人工接种盆栽试验，比较不同植物、入侵不同时间入侵植物和本地植物混种处理根际土壤聚集的AMF对入侵植物和本地植物光合作用和氮吸收的影响，明确AMF在入侵植物竞争生长过程中所起的作用及其作用机制，探究不同AMF群落在入侵植物入侵过程中的贡献，并结合同质园试验中植被和AMF群落变化，进一步探讨入侵植物入侵过程中AMF变化与植物群落演替间的关系。研究结果将有助于支持和丰富外来植物入侵的土壤微生物反馈假说，可为入侵生境土壤微生物修复提供理论依据。

本研究以黄顶菊（Flaveria bidentis）、豚草（Ambrosia artemisiifolia）、三叶鬼针草（Bidens pilosa）3种入侵菊科植物为研究对象，根据入侵植物土壤微生物反馈假说，以植物与AMF互作为切入点，采用生态学与微生物分子生物学方法，研究外来菊科植物入侵对AM真菌群落结构的影响及其反馈作用。研究结果大大丰富了外来植物入侵的土壤微生物反馈假说，该研究可为入侵生境土壤微生物修复提供理论依据。具体结果如下：. 1、3种入侵植物根际AM真菌的群落结构多样性不同，但是3种入侵植物聚集的AM真菌均偏利于入侵植物的竞争生长。其主要机理为（1）侵染率与植物的根冠比呈显著的正相关，三种入侵植物在与本地植物竞争生长过程中通过增加入侵植物AM真菌的侵染率或降低本地植物的侵染率增强其竞争能力；（2）AM真菌侵染促进了入侵植物对土壤中氮、磷的吸收，因而促进了入侵植物的生长；（3）本研究表明在入侵植物与本地植物竞争生长过程中，AM真菌菌丝桥介导的碳、氮转移与入侵植物的竞争能力非正相关关系，且这种转移与本地植物种类有关。. 2、三种外来菊科植物随入侵时间变化对土壤酶活性的影响存在相近的规律：三种外来植物入侵域的脲酶和碱性磷酸酶活性随入侵时间增加都表现出升高趋势；三种植物对土壤酸性磷酸酶的影响呈现出先升高后降低的变化趋势。三种外来菊科植物随入侵时间变化对土壤养分的影响规律不尽相同。三叶鬼针草和黄顶菊入侵域的速效磷含量随入侵时间变化持续升高，而豚草入侵域的速效磷含量随入侵时间变化出现先降低后升高的变化趋势；三叶鬼针草和黄顶菊对入侵域根际土壤铵态氮含量的影响呈现出先降低后升高的变化趋势，而豚草单种处理根际土壤铵态氮含量连续四年都未发生显著变化，豚草混种处理根际土壤铵态氮含量随时间持续降低。