昼夜不对称增温背景下入侵植物改变土壤氮转化的氨氧化微生物机制及其反馈作用

Many studies have shown that warming affects plant growth and soil Nitrogen (N) transformation and composition and function of related microbes. Our previous results showed that exotic invasive plants have the potential to influence soil N transformation and composition of soil ammonia oxidizers (AOA, AOB). Although asymmetric daytime and night-time warming is predominant in the future, and plant growth has different responses to daytime and night-time warming, few studies consider the effect of asymmetric warming (variations in diurnal temperature range) on plant invasion. The competition between invasive and native species dictates invasion consequence. However, little is known about the effect of the unequal elevations in day versus night temperature on invasive species-native species competition and the dynamics in N cycling in soil. Therefore, we selected several invasive plants, including herbs and vines (commonly occur in Southern China) and their native ones. Four different diurnal temperature range (DTR) were manipulated to explore the potential mechanisms that could affect invasiveness, to probe the mechanisms of soil N transformation from the point view of soil AOA and AOB, and to study the feedbacks of soil N transformation to further invasion under warming with DTR change. This project will be helpful to improve our understanding of the ecological mechanisms on how global warming may influence exotic plant invasion and may provide the basis for invasive plant management and control under the context of asymmetric warming.

大量研究表明增温会影响植物的生长，也会影响土壤氮(Nitrogen, N)转化与相关微生物结构与功能。我们研究发现，外来入侵植物会影响土壤N转化及氨氧化微生物群落结构与丰度。虽然全球昼夜不对称增温现象愈加明显，白天增温和夜间增温对植物生长的影响作用明显不同，但全球变暖对外来入侵植物的研究很少考虑昼夜“不对称增温”的影响。那么，昼夜不对称增温对外来植物的入侵力有何影响，它对土壤N转化与土壤氨氧化微生物有何影响？这种N转化的改变对入侵植物又有何反馈作用？为此，选择华南入侵植物及其近缘本地植物，设置不对称增温模式，拟研究不对称增温对入侵-本地植物竞争关系的影响，揭示不对称增温背景下入侵植物对土壤N转化的氨氧化微生物机制，探索不对称增温背景下土壤N转化对外来植物入侵的反馈作用。本研究不仅能揭示入侵植物改变土壤N转化的氨氧化微生物机制，也能为评估未来增温背景下外来植物的入侵扩散与管理提供科学依据。

以华南主要外来入侵植物薇甘菊（Mikania micrantha）、假臭草（Eupatorium catarium）、白花鬼针草（Bidens pilosa var. radiata, also called Bidens alba）为研究对象，分别采用人工气候箱与野外红外辐射器模拟昼夜不对称增温，以不增温作为对照，比较研究入侵植物与本地植物对昼夜增温的响应差异，研究昼夜增温对它们竞争关系的影响作用，同时研究昼夜增温对土壤氮转化的影响及氨氧化微生物机制。经过4年的研究，完成了预期的任务，获得创新性成果。.研究发现在所有的增温模式下入侵植物的生物量明显大于本地植物。夜间增温通过提高入侵植物根系的竞争影响，从而增强入侵植物的竞争能力，入侵植物-本地植物竞争关系对夜间增温的响应存在明显的物种依赖性。夜间增温更为明显的情况下，增温会促进入侵植物的土壤N转化作用。虽然土壤AOA丰度均明显高于AOB丰度，但昼夜增温没有对土壤AOA丰度产生显著影响，而显著影响了土壤AOB丰度，且AOB对增温的响应更加敏感。.在Biological Invasions, Annals of Botany, Plant and Soil, Weed Research 等发表 SCI 论文11篇，其中二区及以上论文5篇；培养硕士研究生3名。陈宝明副教授（本项目负责人）受Allelopathy Journal (SCI刊物)主编的邀请，担任特邀编委(Guest editors)，2017年组织完成了“入侵植物与化感作用”(Invasive Plants and Allelopathy)的专刊。参加国际会议3人次，项目负责人陈宝明2次在国际学术会议作专题主旨口头报告。