Wetland vegetation zoning as a response to groundwater complex systems

This research investigates the interplay between groundwater flow systems and the zoning of wetland species. We aimed to elucidate the relationship between these factors through comprehensive field evaluations encompassing plant composition, piezometric levels, and flow direction; groundwater chemistry, vertical and horizontal, at different depths (0.15 m, 2 m, 4 m, and 6 m) during both rainy and dry seasons. Our findings reveal distinct patterns. The plant diversity in the FP site was related to low ion concentration. In contrast, the dominance of T. geniculata in the TH site correlated with species adapted to sulfate and chloride (SO₄^2- and Cl^-) tolerance. In the CTC site, the dominance of C. jamaicense was linked to local groundwater flow and significant surface water inflows. At the same time, T. domingensis prevailed in the TC site due to sodium chloride facie inhibiting C. jamaicense seed germination. Our study highlights the role of groundwater chemical composition in shaping wetland ecosystems by influencing species tolerance and how the spatial distribution of groundwater discharge and seasonal changes contribute to distinct vegetation patches within wetlands. The relationship between groundwater systems, the water's chemical composition, and vegetation is strongly dependent. This can explain mortality and changes in vegetation composition in wetlands in different parts of the world, stressed by climate change effects (rain pattern alteration).