Unraveling Resilience Amidst Degradation: Recurring Loss of Freshwater Marshes in the Paraná River Delta, Argentina

摘要: Wetland ecosystems have experienced several ecological and hydrological impacts in recent decades determined not only by human activities, but also by natural disturbances. The Lower Delta of the Paraná River, one of the most important wetland ecosystems of South America, has experienced significant losses in both the structural and functional components of wetland vegetation. These losses promoted not only a widespread conversion of freshwater marshes into grasslands between 1997 and 2013, but also a decline in ecosystem functional diversity between 2001 and 2015. The consequences of the aforementioned processes reflected on non-monotonic vegetation activity trends, a distorted, spatially heterogeneous relationship with the hydrologic regime and altered plant communities at the local scale. Nevertheless, it remained to be clarified whether hypothetical phases or regimes were guiding an either cyclic, sustained or absolute loss of freshwater marshes. To answer the aforementioned question, we studied land use and land cover conversions (LULCCs) through an object-based supervised classification of yearly Landsat composites between 1985 and 2023, trained on 935 ground-truth points. To study the spatial and temporal patterns of wetland gain and loss, we implemented an Intensity Analysis (IA), a quantitative method to analyze cross-tabulation matrices, as well as complementary analyses that capture both frequency-specific variations and identify significant shifts in linear trends. We produced a total of 39 land cover maps. The IA revealed non-stationarity at all levels of analysis. In particular, significant and increasingly …