Hydrological effects of cloud forest conversion in central Veracruz, Mexico

The provision and regulation of water flows in catchments is probably the most important ecosystem service of cloud forests; however, its hydrological behavior and impacts associated with forest conversion remain very poorly understood. The present study aimed at evaluating the hydrological effects of land use change for a cloud forest region on volcanic soils in Veracruz, Mexico. For this, micrometeorological, ecophysiological and hydrological measurements combined with stable isotope data were used. The findings showed higher annual water yields in pasture, as well as young and mature Pinus patula pine plantations due to lower evapotranspiration rates as compared to mature and secondary cloud forests. Total annual and seasonal flows were found very similar in both cloud forests, suggesting catchment hydrological functioning can be restored within 20 years of natural regeneration. Conversely, the pasture catchment showed higher annual streamflow (10 %), however 50 % on average lower baseflow at the end of the dry season, associated probably with more gentle slopes in combination with lower soil infiltration capacity. Further, it was shown that the conversion of cloud forest to pasture can promote major increases in overland flow in response to maximum rainfall events, despite the high permeability of the volcanic soils characterizing this environment. The ultimate effect of P. patula reforestation at catchment scale is still unknown, though higher rainfall infiltration rates, compared to pasture, suggest a soil hydrological recovery in the short to medium term.