土壤生物，包括微生物和线虫等，直接或间接（通过影响地上昆虫）调控植物扩散和入侵，而后者可改变土壤生物群落结构和功能。申请人前期研究了土壤生物对入侵植物喜旱莲子草和本土植物莲子草的调控，结果表明：土壤生物可能直接或间接促进喜旱莲子草入侵，不同纬度来源土壤生物的作用存在差异，但尚需严谨论证。本研究在此基础上，拟沿纬度梯度开展野外调查、同质园实验和移植实验，结合微生物高通量测序等，探讨：1）土壤生物对植物入侵的直接和间接调控，解析关键调控路径和生物类群；2）土壤生物群落结构、土壤生物-植物-地上昆虫等多级营养关系沿纬度变化规律和驱动机制；3）土壤生物对气候变化下入侵和本土植物扩散的调控和机理；4）植物入侵对土壤生物群落结构和功能的影响。项目的实现，有助于从多级营养关系、生物地理学等视角，剖析土壤生物对植物入侵的调控及其纬度格局，为预测气候变化下物种扩散提供依据，为治理喜旱莲子草提供潜在生物资源。

Soil biota, including microbes and nematodes, can directly and indirectly via herbivore influence plant range expansion and invasions, which in turn could alter soil biota community structure and function. With greenhouse experiment, the project applicant has tested soil biota’s impacts on the invasive plant Alternanthera philoxeriodes and its native congener A.sessilis and found that: soil biota might directly and indirectly facilitate A. philoxeriodes invasion and soil biota’s impacts might change as a function of latitude of soil collection, but needs further clarify. Based on this finding, this project plans to investigate: 1) how soil biota directly and indirectly affects A. philoxeriodes invasion, and to identify the dominant functional groups of and the key pathways via those soil biota affecting A. philoxeriodes invasion; 2) how soil biota’s impacts on A. philoxeriodes invasion, and multitrophic interactions of soil biota, plants and aboveground herbivores change with latitude and what is the underlying mechanism; 3) how soil biota affects range expansion of the native and invasive plants under warming climate and what is the underlying mechanism; 4) how A. philoxeriodes invasion affects soil biota community structure and function. Realization of this project will improve our understanding on the role of soil biota in plant invasions from the perspectives of biogeography and multitrophic interactions. The results will provide empirical information for predicting plants range expansion under warming climate and potential soil enemies for managing A. philoxeriodes.