[Research advances in root-derived carbon inputs and stabilization mechanisms in floating marshes.]

Abstract

Lake terrestrialization is a distinctive successional phase through which open-water ecosystems gradually transition into marsh-dominated wetlands. In floating marshes, intertwined roots and rhizomes form buoyant, peat-like mats that underpin marsh formation and persistence while serving as important interfaces for carbon input, transformation, and stabilization. Compared with typical peatlands and freshwater marshes, the input and stabilization mechanisms of root-derived carbon in floating marshes remain poorly understood. We reviewed current know-ledge of floating-marsh root traits and ecological adaptations and analyzed major root-derived carbon inputs arising from fine-root, coarse-root, and rhizome turnover, belowground residue accumulation, and rhizodeposition. We further highlighted three major stabilization mechanisms: 1) the enzyme-latch mechanism, driven by phenol oxidase inhibition and phenolic accumulation under anoxic peat conditions, together with the iron-gate mechanism associa-ted with iron redox cycling; 2) radial oxygen loss-mediated rhizosphere iron plaque formation and the associated "rusty sink" process; and 3) microbial transformation of root exudates into metabolic products and necromass, with implications for rhizosphere priming and microbial entombment. This review would provide a theoretical basis for evaluating the carbon sink function of floating marshes.