ELSEVIER Ecological Modelling 83 (1995) 85-96 E[OLOGIfllL mODELLInG Application of the SAFE model to the Soiling spruce site Charlotta J6nsson *, Per Warfvinge, Harald Sverdrup Dept. of Chemical Engineering II, Lund University, P.O. Box 124, 221 O0 Lund, Sweden Accepted 2 January 1995 Abstract A dynamic geochemical simulation model, SAFE, was applied to a Norway Spruce stand in Soiling, Germany. The model performance was evaluated with respect to base saturation, base cation (Ca + Mg + K) and aluminum concentration in soil solution, weathering rate, and soil solution pH. Four acid deposition scenarios were evaluated with respect to base saturation and molar ratio of aluminum to base cations in soil solution. Base cation and aluminum concentrations were in agreement with data, while pH was slightly underestimated. The predicted weathering rate of base cations was close to rates estimated from budget studies and studies of depletion of minerals in the soil column. Release of K was overestimated, possibly because congruent dissolution of illite rich in Mg and K was assumed. The scenario analysis shows that continued acid deposition stress at the 1990 level will cause no further depletion of the soil exchange complex, while 95% reductions in acid deposition would lead to an increase in base saturation from 3% to 10% during the period 1990 to 2050. In this case, the BC to A1 ratio would exceed one at all depths of the soil profile by the year 2012. A scenario based on emission reductions as agreed upon by a number of European countries in the UN-ECE Convention on Transboundary Air Pollution and in national abatement plans would lead to minor improvements in base saturation and BC to AI molar ratio, but the BC to A1 ratio would stabilize at a value as low as 0.3. Keywords: Acidification; Geochemistry; SAFE; Soil; Weathering I. Introduction The dynamic soil chemistry model SAFE was applied to data from a spruce site at Soiling, Germany. The study compares the SAFE model calculations of base saturation, soil solution pH and concentration of aluminum and base cations in soil solution with available measured time se- * Corresponding author (now Charlotta Walse). ries of these parameters. Calculated weathering rates are compared with values derived by budget studies and studies of mineral depletion. Finally, the model was used to predict the development of soil conditions under four acid deposition sce- narios. The model was parameterised using the data available for a workshop on comparison of for- est-soil-atmosphere models. Although the data available did not fully fill the requirements of the model SAFE, especially with respect to geochemi- cal data, it was considered to be a meaningful 0304-3800/95/$09.50 © 1995 Elsevier Science B.V. All rights reserved SSDI 0304-3800(95)00088-7