Long-Term Soil Reaction Changes in a Temperate Beech Forest Subject to Past Alkaline Pollution

Changes in deposition exert effects on forests. Some evidence for a slow recovery of strongly alkalised forest soils after a reduction in alkaline pollution exists, but the recovery rate is little known. The objective of this study was to estimate temporal soil reaction changes. For this purpose, measurements of soil reaction under a beech forest near magnesite works in Central Slovakia were taken in 1991 and 2006, following the alkaline pollution reduction in 1992. As a result, the mean active soil reaction decreased from pH 7.8 to 6.6. Beyond the range of beech stemflow, which amplifies water and acid pollution inputs into soils locally, soil reaction dropped from pH 7.8 to 6.8. The effect of stemflow on local exchangeable reaction minima was detected even before the pollution reduction. The logarithmic function fitted on the pH data indicates considerable differences between neutralisation rates within and outside the stemflow zone.