Dynamics of leaf litter decomposition and nutrient release in mangroves under different control conditions:...

Mangrove litter decomposition is a critical land-sea coupling process, regulating carbon sequestration and nutrient cycling. However, the interactive effects of litter diversity and mixing effects, fauna and environmental contexts on decomposition and associated biogeochemical processes in mangrove ecosystems remain inadequately quantified. An in-situ litterbag experiment was employed to investigated the effects of litter species, litter mixtures and benthic fauna on decomposition rates and elemental release in mangroves. The results revealed that litter quality (particularly cellulose, lignin, and hemicellulose content) was the primary factor controlling the decomposition rate (k). The k rate of Sonneratia apetala was higher than that of Kandelia obovata, while the mixing of litter and the presence of benthic fauna accelerated mass loss. The microorganisms, acting through extracellular enzymes, played a central role throughout the process. Regardless of treatment, a net release of litter carbon and phosphorus were observed, while nitrogen dynamics were species-specific. This indicates that fast-decomposing species enhance nutrient turnover but may compromise long-term carbon storage, while mixed-species inputs， especially high quality understory vegetation, can modulate decomposition through non-additive effects. These findings clarify how litter traits, biodiversity, and decomposer communities jointly drive mangrove decomposition processes, which is critical for predicting blue carbon dynamics and nutrient cycling, and can also guide mangrove restoration through optimized species selection and biodiversity conservation strategies.