[Biophysical effects of wetland vegetation changes on land surface temperature: Research progress and prospects.]

Abstract

Wetland vegetation regulates surface energy balance through biophysical processes and modulates land surface temperature. However, a systematic understanding of such effect remains insufficient. We systematically reviewed the effects of wetland vegetation changes on land surface temperature from three perspectives: distribution patterns, vegetation coverage, and phenological dynamics. The regulation of key biophysical processes such as evapotranspiration, surface albedo, and turbulent exchange by wetland vegetation changes exhibits pronounced spatiotemporal heterogeneity, thereby leading to divergent surface energy partitioning and temperature feedbacks. Changes in vegetation distribution patterns can alter surface roughness and evaporation potential, thereby modifying the spatial configuration of turbulent exchange and water-heat fluxes, with consequences on land surface temperature. Increases in vegetation coverage drive daytime cooling by enhancing evapotranspiration, but this effect displays marked spatial variability. For example, it is more pronounced in semi-arid regions than in humid ones, and reverses to a warming effect during winter at high latitudes. Seasonal variations in the physiological activity of wetland vegetation can regulate the intensity of water vapor exchange, alter the temporal allocation of surface energy, and thus drive seasonal fluctuations in land surface temperature. There are some limitations of current research: inadequate differentiation and mechanistic quantification of the coupled interactions between wetland vegetation dynamics and hydrological processes, and insufficient process-based attribution of energy balance components, particularly latent, sensible and ground heat fluxes. The improved parameterization and ground validation of models that simulate wetland vegetation-hydrology-energy exchange processes are critically needed. In the future, it is necessary to integrate multi-source data and models, quantitatively separate the contributions of radiative and non-radiative processes, and couple biogeochemical processes to construct a unified framework for assessing climate effects, which will provide theoretical support for wetland conservation and restoration and accurate prediction of wetland climate-regulation functions under the background of global change.