Microbial invasions in living soils: Mechanisms, consequences, and roles in ecosystem functions and services

Microbial invasion triggered by microorganism dispersal represents an ever-present phenomenon that has attained unprecedented levels, primarily as a result of human activities and global climate changes within soil ecosystems. On a large geographic scale, microbial invasion in the soil can significantly change the resident community composition and functionality. On a smaller scale, microbial invasion can frequently occur in soil agroecosystems, where microbial inoculants/consortia are deliberately introduced into the soil to achieve more efficient bioremediation, biocontrol, and bio-fertilization. Despite the importance, our understanding of the role of microbial invasions in soil ecosystems and the underlying mechanisms has gaps. Here, we employed article syntheses to conceptually gain insights and build the framework, performed meta-analysis to grab empirical evidence broadly, and utilized invasion models in soil microcosms to obtain experimental observations precisely. First, this thesis argues conceptually and empirically for integrating microbial invasion with community assembly and ecological succession. It proposes a corresponding theoretical framework to guide microbial invasion studies. Second, this thesis investigates the mechanisms and impacts of microbial invasion in soils, completes an essential piece of the blueprint for microbial invasion - community coalescence - and proposes a mechanistic model that can unify different invasion scenarios. Third, this thesis demonstrates the critical role of microbial invasion in soil (agro)ecosystems and the implications for human management of soil ecosystems. These studies provide advanced insights into microbial invasions.