Abstract: Traditional carbon cycle research in estuarine wetlands has mostly been confined to static observations of interannual total precipitation and total carbon, struggling to reveal the hidden risks of carbon destabilization triggered by extreme hydrological pulses. Recently, studies have achieved critical transitions from macroscopic factors to microscopic mechanisms, and from single interfaces to multi-interface coupling. We examined the cascading feedback theories of seasonal rainfall variation on soil organic carbon dynamics in estuarine wetlands. The academic community has gradually clarified its core evolutionary pathways. At the carbon input end, drying-rewetting pulses drive the spatiotemporal decoupling of above- and below-ground primary productivity, reshaping the carbon supply pattern. At the carbon emission end, moisture fluctuations prompt shifts in resource acquisition strategies of plants to regulate autotrophic respiration and reorganize microbial niches to trigger pulsed greenhouse gas releases. Regarding fractions and chemical structure, drying-rewetting cycles accelerate the phase transformation between labile and stable carbon and the selective enrichment of micro-molecules. Finally, from the perspective of sources and stability, the deterioration of physicochemical stabilization mechanisms, such as microaggregate breakdown and the failure of iron-carbon complexation, acts as the core pivot triggering fundamental carbon source-sink transitions. Although the theoretical outline has emerged, there are significant deficiencies in quantitative analysis and mechanistic coupling of multi-interface ecological processes. Future research should focus on: identifying the critical drought thresholds that trigger carbon source-sink abrupt shifts, unraveling the response mechanisms of deep carbon dynamics to plant carbon allocation decoupling, exploring the ecological buffering roles of multi-trophic interaction networks in maintaining carbon stability, and developing process-based predictive models coupling fine carbon fractions with multiple stabilization mechanisms.

Key words: coastal wetland, carbon sink-source transition, decoupling of aboveground-belowground allocation, stability mechanism