Hydrological impacts of afforestation in the semi‐arid Patagonia: a modeling approach

MILKOVIC, MAYRA; PARUELO, JOSÉ M; NOSETTO, MARCELO D.

ECOHYDROLOGY

JOHN WILEY & SONS INC

Lugar: New York; Año: 2019

1936-0584

Afforestation has been widely encouraged with different goals, including as a strategy to tackle global warming. However, the side-effects of this land-use transformation have been in many cases underestimated. Particularly, the hydrological impacts may become relevant in (semi)arid regions where water is a key element. In this work, we evaluated the hydrological effects triggered by afforestation with ponderosa pine in the semi-arid Argentine Patagonia that is currently a focus of afforestation programs. For this purpose, we used complementary approaches that included hydrological modeling (DINAQUA model), satellite image analysis, and soil wetness data. All analysis provided convergent results into hydrological effects of afforestation. The modeling results showed that afforestation significantly increased transpiration in relation to native grass?]shrub steppe. In the steppe in degraded condition, transpiration accounted for only 10% (40 mm y-1) of total water flux, while in adult pine plantations it accounted for up to 73% (277 mm y-1). Deep drainage was also severely affected by afforestation as it decreased from 182 mm y-1 in the steppe to zero in adult plantations, according to model simulations. Estimates from Landsat images also showed that evapotranspiration was higher in plantations compared to the steppe. Soil wetness data also revealed significantly drier soils in plantations. Our results indicate that pine plantations in the semi-arid Patagonia evaporate all rainfall inputs, resulting in zero deep drainage and groundwater recharge. If the afforested area in the region increases, downstream meadow ecosystems, which are hot-spots of primary productivity, may be negatively impacted