Linking microbial-mediated methane production in wetlands to invasive plants

Abstract

Plant invasion has risen in recent decades due to climate change and land-use alterations, profoundly impacting biodiversity and ecosystem functioning. Belowground, invasive plants disrupt native microbial networks, altering nutrient cycling and soil organic matter dynamics. In wetlands, such disruptions can enhance methane (CH₄) fluxes by reshaping both production and oxidation processes. Methanogenic archaea (methanogens) are the primary producers of biogenic CH₄, but they differ in metabolic strategies (acetoclastic, hydrogenotrophic, or methylotrophic methanogenesis), depending on available substrates and environmental conditions. This review explores how invasive plants influence CH₄ emissions through changes in plant–soil feedbacks (PSFs), root exudation, microbial community composition, and methanogenic pathways. Invasive plants often restructure soil microbial communities by releasing species-specific metabolites, enhancing labile carbon inputs, and modifying rhizosphere conditions that favor methanogens. These shifts can elevate CH₄ emissions; however, the effects are highly context-dependent, some invasions lead to increased emissions, others show negligible change, and some even reduce CH₄ fluxes. In addition, the formation of aerenchyma in invasive wetland plants may bypass the methane filter formed by surface-dwelling methanotrophs, thus leading to higher net CH₄ emissions even if production remains unchanged. These variable outcomes depend on plant traits, microbial selection, soil hydrology, and interactions with climate-driven stressors. We propose that invasive plants, microbial communities, and climate change form a self-reinforcing PSF triangle that can amplify CH₄ emissions. Understanding the mechanisms behind these dynamics, including root exudate-driven microbial colonization and rhizosphere priming, could support predicting climate impacts of biological invasions in wetland ecosystems.