Simulated response of an acid forest soil to acid deposition and mitigation measures.

Abstract

A modified version of the soil-water acidification model ILWAS was applied to an acid forest soil in the 'Hackfort' experimental forest in the Netherlands. Monthly observations of the chemistry of atmospheric and soil water between April 1981 and April 1987 were used. ILWAS overestimated water uptake reduction, which caused overestimation of soil water fluxes by 20%, compared with values predicted by the hydrological model SWATRE. ILWAS does not simulate capillary rise which may lead to overestimation of solute concentrations. Chemical calibration of the ILWAS model to field data was mainly confined to adjustment of the rate constants for nitrification and gibbsite dissolution. Calibration of these rate constants was complicated by effects of cation exchange. ILWAS was too crude to simulate the N-dynamics, which led to a relatively strong variation of simulated NO₃ concentration near the end of the growing season. After calibration the ILWAS model was used to predict the effects of 50% reduction of (NH₄)₂SO₄ deposition, of a fertilization experiment with 2.6 kmol_c/ha K₂SO₄ and 8.6 kmol_c/ha MgSO₄, and of removal of the forest vegetation. (Abstract retrieved from CAB Abstracts by CABI’s permission)