Spatiotemporal vegetation dynamics in a highly urbanized Chilean coastal wetland: Insights on long-term natural and anthropogenic influences

• We used 884 Landsat images and ground samples to assess vegetation dynamics in a highly urbanized coastal wetland. • The vegetation exhibited seasonal behavior aligned with the Austral winter, occasionally disrupted by natural disturbances such as floods and tsunamis. • The replacement of native vegetation, leading to a sustained increase in NDVI, is mainly attributed to urbanization, and grazing. • The vegetation in undisturbed areas responds to natural variables, including temperature, precipitation, and evapotranspiration. This study analyzes the spatiotemporal dynamics of the vegetation of a highly urbanized coastal wetland in the 2000–2020 period, considering natural disturbances and anthropogenic stressors. The wetland system was stratified into four domains: Coastal, Intertidal, Freshwater, and Urban, differentiated by their geomorphological, topographical, and water salinity characteristics, which were validated by ground vegetation sampling. In these domains, spectral indicators of vegetation were used on 884 Landsat images in the Google Earth Engine to determine vegetation types, trends, and phenology. The start of the growing season coincides with the beginning of the Austral winter, exhibiting seasonal behavior, which was interrupted by abrupt natural disturbances such as floods and tsunamis. In addition, a progressive trend associated with the replacement of native species by exotic species was reported in areas with significant anthropogenic stressors (e.g., highways, city edges, and grazing areas), with 45 % presenting an increase in the normalized difference vegetation index. Areas far from anthropogenic stressors maintained their behavior, which is explained by natural factors such as precipitation, temperature, and evapotranspiration. The proposed method strengthens our understanding of the interrelationship between factors that modify the behavior of vegetation in coastal wetlands pressured by anthropogenic stressors and contributes to their management and protection.