Neo-humedales en las llanuras agrícolas del Chaco Seco-Espinal argentino: ¿Cómo son, dónde se originan y qué hacer con ellos?

Abstract

In the last decades and as a result of the rapid transformation of the terrestrial ecosystems, a new category called ‘neo-ecosystems’ has emerged. In the dry plains of Argentina, the agricultural expansion replacing forests, woodlands and natural grasslands has generated water surpluses at the regional scale. This water excess has favoured the development of neo-wetlands characterized by shallow water tables, frequent waterlogging and progressive salinization. In this work, we characterize these neo-ecosystems that spontaneously occupy these degraded environments by reviewing bibliography in the Dry Chaco-Espinal area and by taking the El Morro basin in the province of San Luis as a case of study. Through a temporal analysis of high-resolution images, we found that in the last 13 years, the neo-wetlands of the El Morro basin have tripled their extension, covering more than 15% of the lower basin, mainly in depressed areas of the landscape where salinization has been more widespread. These neo-wetlands showed lower NDVI-LANDSAT values than the surrounding forests (0.44±0.04 vs. 0.35±0.09) but similar to the annual crops (neo-wetlands 0.35±0.09 and crops 0.37±0.13). Compared to the crops, the neo-wetlands presented longer growing seasons (241±54 days vs. 194±54 days, for neo-wetlands and crops, respectively), showing revegetation with saline tolerant species adapted to the new environment. Finally, we propose guidelines for the restoration and use of these neo-ecosystems in order to recover their functionality but also their ecological-productive value.