Bulk precipitation and lysimetric waters were monitored during 1996-1999 in two forested (Fagus sylvatica and Picea abies) and one grassland plots situated at altitude of 1500 m in the Western Balkan Range, Bulgaria. Dynamics of pH, nitrates and sulfates in bulk precipitation and dynamics of output/input ratios (values in lysimetric waters to values in bulk precipitation) were assessed using Time Series Analysis. In bulk precipitation, pH ranged 4.45-5.75, nitrates 1.13-3.13 mg/1, and sulfates 2.4-16.6 mg/l. These results suggest that acid precipitation is a common environmental event in the Balkans in the period studied. In most cases, the beech forest increases pH while the spruce forest rather induces additional acidification of the soil solution. The main trends of the pH output/input ratios in the beech (decrease) and the spruce (increase) stands have opposite directions. The grass ecosystem has a pH-increasing effect, which is more similar to this of the beech forest. Nitrates exhibit a trend for increase in soil solution in the beech forest. Such an increase is also observed in the spruce forest and in the grass association, however, with smaller rate. Sulfate leaching from soil under spruce is almost twice as large as compared with that under beech. The grass association exhibits intermediate values compared with the two forests.