Estimación de la evapotranspiración en la región montañosa central de Veracruz, México

The global, regional and local hydrological cycle is strongly linked to vegetation distribution. The hydrological cycle is composed by precipitation, infiltration, runoff, transpiration and evaporation. Evaporation is influenced by high temperatures, high winds and low relative humidity. This work is focused on the study of evapotranspiration (ET) as the main variable of water loss in the water balance in the central mountain region of Veracruz, Mexico. ET was estimated using the Penman-Monteith model, which requires environmental (net radiation, vapor pressure deficit, air temperature and wind intensity) and physiological (stomatal and canopy resistances and leaf area index) variables. These variables were measured in two sites within the region: La Joya and La Orduña, comparing different ecosystems: pine-oak, pine forests and grassland, and cloud forest and sugarcane crop, respectively. Results show that both, the estimated and real ET, are high; although, we found net surplus related to precipitation at both sites (533.8 and 526.5 mm) from September 2006 to August 2007. Apparently, no water deficits in either location were found; however, in the dry season water gain was very low, zero or negative. March and April were the months presenting the lowest water contribution to the system. The forests in the central mountain region of Veracruz can provide ecosystem services favoring evapotranspiration and regulating water balance, although the lack of information on the magnitude and value of this variable has hindered recognition and understanding of these forests.