Ecosystem Services of Freshwater Swamp Forests: Mechanisms of Hydrological Regulation and Impacts of Global Environmental Change

Abstract

Freshwater swamp forests (FSFs) are flood-prone ecosystems on nutrient-rich alluvial soils that provide important ecosystem services, yet remain underrepresented in wetland research and management. This integrative review synthesizes current knowledge on FSFs with emphasis on three interconnected themes: (i) ecological definition, classification, and hydrological dynamics; (ii) the role of microtopography and evapotranspiration in regulating water storage and fluxes; and (iii) potential responses of these coupled processes to climate change. Although the “sponge” metaphor is seldom explicitly applied to FSFs, the reviewed literature consistently shows that water retention, delayed release, and vegetation-mediated fluxes are functionally linked, albeit often studied separately. Fine-scale surface heterogeneity, particularly hummocks and depressions, emerges as a key mechanism promoting water redistribution, groundwater recharge, and the persistence of localized refugia and microhabitats. At the same time, climate change-driven shifts in precipitation, drought frequency, heat stress, and disturbance regimes may weaken these regulatory functions and reduce ecosystem resilience. We therefore propose the “sponge–pump framework” as a conceptual model linking hydrological storage (“sponge”) and vegetation-driven water fluxes (“pump”) to explain how FSFs regulate water movement, support biodiversity, and contribute to ecosystem services across spatial and temporal scales. The framework also highlights the need for standardized quantification, broader geographic coverage, and greater integration of microtopographic processes in wetland conservation, restoration, and climate adaptation strategies.