Hydrology of Montane Forests in the Sierra de San Javier, Tucuman, Argentina

Abstract

In Tucuman Province of Argentina, the subtropical moist montane forests, known as Yungas, reach their southern- most limit, occurring between 400 and 2,800 m. The study area is located on the eastern slopes of the Sierra de San Javier where the forest is strongly affected by human pressure. Eighty percent of the annual rainfall in Tucuman falls largely during thunder- storms between October and March. Three recording rain gauges and two fog catchers were installed at 730, 950, and 1,350 m, re- spectively, to study the effect of altitude on the intensity, duration, distribution, and influence of horizontal precipitation. A stream-gauging station has been constructed to measure discharge, floods, and bed load in a small experimental basin in the basal forest. To measure the amount of surface runoff and soil erosion in the basal forest and piedmont area three experimental test plots were installed. The results confirm that deforestation has notably increased hydrological and erosion risk in summer, but also has led to a reduction of water volumes in winter. It was confirmed that the Tucuman montane forests are actual subtropical mon- tane cloud forests. The additional moisture obtained from passing low clouds during the long dry winter season is important and has not yet been considered in the hydrological budget.