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Abstract:
The Gran Chaco ecoregion is South America's largest remaining continuous stretch of dry forest. However, the region has been subject to intensive deforestation, mainly in the western part known as Dry Chaco. In this region, the highest rate of dry forest loss in the world occurred in the 2000-2012 period. Removing natural vegetation modifies biophysical properties at the surface, affecting the heat and water fluxes on the surface, which in turn modify the atmospheric fluxes and the local and nonlocal climate state. WRF model simulations are performed to investigate the local and nonlocal effects that could have resulted from the dominant LULCCs in Dry Chaco from 2001 to 2015. The analysis is focused on the austral summer months when land-atmosphere interactions become stronger. In areas identified as deforested, decreases in LAI, increases in albedo, and reductions in stomatal resistance are found. The changes in surface properties lead to energy balance variations that influence the temperature and the terrestrial hydrological cycle. The consequence is a general reduction of precipitation, soil moisture, evapotranspiration, and runoff, both locally and non-locally. Assuming that a continued and intensive agricultural expansion within Dry Chaco continues, the outcome from model simulations suggests a continued decrease of the same hydrologic variables for the Gran Chaco, leading to austral summers with lower precipitation and drier, warmer soils.
