In this study, nutrient incorporation by gross precipitation and throughfall was evaluated for two forest plantations of Vochysia guatemalensis Donn. Sm. and Vochysia ferruginea Mart. and a secondary forest in La Selva Biological Station, Sarapiquí, Costa Rica. Concentrations, in mg/l, of NH4+, NO3 -, K+, Ca2+ and Mg2+ were analyzed, in addition to the pH and the electrical conductivity (μS/cm). The values for pH and electrical conductivity in the rainwater increased as it passed through the canopy, due mainly to the increase in base cations concentrations, where the lowest values were found to be in the gross precipitation. The secondary forest showed a removal of 23.8% NH4+ of the input, incorporated by the rainfall, while Vochysia ferruginea removed 21% of the NO3- found in the gross precipitation; both reductions can be associated with physiological plant demands during the fructification stage of the dominant trees in both ecosystems and possibly, due to the presence of bacteria and fungi that could modify the forms of nitrogen from complex to simpler forms. The leaching of K+, Ca2+ and Mg2+ from the canopy could be explained by the deposition of aerosol particles on foliage and branches between periods of rain.
