Recovery of soil pH, cation-exchange capacity and the saturation of exchange sites from stemflow-induced soil acidification in three Swedish beech (Fagus sylvatica L.) forests

Stemflow water acidifies the soil in beech stands impacted by atmospheric d eposition. To investigate whether the soil recovers from acidification, ste mflow was experimentally removed. A horizon material was sampled at a dista nce of 10-250 cm From the stems. Before the onset of the experiment, there were stemflow-induced gradients in the saturation of exchange sites with K, H+ and Na+ that were larger near the stems, while the pH(KCl), the cation -exchange capacity, and the saturation with Ca2+, Mg2+ and Mn2+ were smalle r. After 8 yrs of recovery, the pH(KCl) and the saturation with Ca2+ and Mg 2+ had increased close to the stems, while the saturation with Na+, H+, Mn2 + and Fe2+ and the C/N ratio had decreased. With some exceptions, e.g. base saturation, the recovery was not complete after 8 yrs. Soil far from stems had also changed similarly, probably because of the ongoing decrease in ov erall deposition in southern Sweden.