How does climate influence mangrove litterfall production across different species? A case study in Zhanjiang, China

• We revealed distinct phenological differences of mangrove species across organs and climate drivers. • Litterfall production of Rhizophora stylosa and Bruguiera gymnorhiza showed strong correlations, reflecting phylogenetic similarity. • Leaf litterfall was most sensitive to temperature, while flowers and propagules were strongly influenced by wind speed. • Avicennia marina exhibited more stable litterfall dynamics, primarily responding to precipitation variations. • Our findings provide new insights into climate-driven litterfall processes and implications for mangrove management under global change. Mangrove litterfall represents a major pathway of energy and nutrient flux, yet species-specific and organ-specific climatic responses remain insufficiently understood. This study quantified litterfall dynamic of three dominant mangrove species— Avicennia marina, Bruguiera gymnorhiza , and Rhizophora stylosa —compared fresh and dry organ-level phenology, and identified climatic drivers of species- and organ-specific litterfall patterns. Litterfall was monitored sub-monthly for two years (2023–2024) in mature subtropical stands and partitioned into leaves, flowers, propagules, and branches. Across species, annual fresh litterfall ranged from 1675.39 g·m⁻²·in A. marina to 2998.74 g·m⁻²·in B. gymnorhiza , with leaves contributing over 60% of total biomass. B. gymnorhiza and R. stylosa consistently produced more litterfall than A. marina . Pronounced interspecific differences were observed: B. gymnorhiza exhibited the strongest seasonality with sharp mid-year peaks, whereas R. stylosa maintained relatively stable production year-round. Leaf and flower litterfall showed asynchronous seasonal patterns across species, while propagule and branch litterfall displayed distinctly staggered reproductive and structural turnover cycles. To examine climatic effects, we employed Bayesian generalized additive mixed models (GAMMs), which capture nonlinear climate–litterfall relationships and account for hierarchical variation among species and organs. The models revealed clear functional differentiation in climatic sensitivity. Temperature positively influenced leaf and flower litterfall, particularly above 28°C. Precipitation showed unimodal effects, and maximum wind speed strongly promoted flower and propagule litterfall, especially in A. marina and R. stylosa . Relative humidity had generally minor effects. Leaf litterfall showed the strongest climatic response, while branch litterfall was least sensitive. Overall, this study highlights contrasting phenological rhythms and climatic sensitivities among coexisting mangrove species and provide insights to support mangrove restoration, carbon accounting, and climate adaptation in subtropical coastal ecosystems.