CONICET | Buscador de Institutos y Recursos Humanos

Wetland loss is a process of global concern because wetlands are highly diverse ecosystems that provide important goods and services. Land use and land cover changes in wetlands thus threaten both biodiversity and human well-being. The Paraná River Delta is one of the largest and most important wetland ecosystems of South America. However, cattle and forestry activities are both expanding and intensifying rapidly, accompanied by widespread water control practices (e.g., dams and ditches), with unknown consequences for wetland landscape structure and function. To understand the patterns and drivers of land cover change in the Lower Paraná River Delta, we quantified land cover changes and modeled associated factors. We classified Landsat images from 1999 and 2013 to generate land cover maps for the Lower Delta and identified areas of land cover changes, especially the conversion of freshwater marshes into pastures. We quantified the influence of different socioeconomic (distance to roads, population centers and human activities centers), land management (area behind dams, cattle density and years since last fire),biophysical variables (landscape unit, elevation, soil productivity, distance to rivers) and variables related to extreme system dynamics (flooding and fires)on freshwater marsh conversion with Boosted Regression Trees. We found that one third of the freshwater marshes of the Lower Delta were lost in only 14 years (163,000 ha). The majority (70%) of the losses were due to conversion to pastures and 18% due to conversion to forestry plantations. Cattle density, dammed area and accessibility were the most important factors for freshwater marsh conversion to pastures. These rapid and widespread losses of freshwater marshes have potentially large negative consequences for biodiversity and ecosystem services and the lack of a land use policy to mitigate these losses is of concern. A strategy for sustainable wetland management will benefit from careful analysis of dominant land uses and the related management practices, taking into account the characteristics of the landscape.

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