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 deposition. To investigate whether the soil recovers from acidification, stemflow was experimentally removed. A horizon material was sampled at a distance 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 smaller. After 8 yrs of recovery, the pH(KCl) and the saturation with Ca2+ and Mg2+ 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 overall deposition in southern Sweden

Zur NH_4"+-Sorption und NH_4"+-Fixierung in europaeischen Waldboeden

The relevance of inorganic nitrogen forms as sinks for deposited or mineralized NH_4"+ was discussed. Plant availability of NH_4"+ and NH_4"+ transport were also considered. Nonexchangeable NH_4"+ in silicate minerals was determined by the method of Silva and Bremner (1966). Exchange isotherms of NH_4"+ in competition with the cations K"+, H"+, Ca"2"+, Mg"2"+ and Al"3"+ were determined using a batch technique. For NH_4"+ exchange, several evaluation methods were used and their applicability was discussed. For some soils, the effect of soil structure on NH_4"+ exchange was determined. Besides soils from the German Fichtelgebirge-region, soils from France, Denmark and Sweden were included in the experiments. Most of the studied soils are characterized by low pH-values. (orig.)Die Bedeutung anorganischer N-Speicherformen in sauren Waldboeden zur Speicherung von deponiertem NH_4"+ oder NH_4"+ aus Mineralisation wurde besprochen. Neben der Speichermoeglichkeit wurde auf Konsequenzen fuer die Pflanzenverfuegbarkeit von NH_4"+ und den NH_4"+-Transport eingegangen. Nichtaustauschbares NH_4"+ der Silikate wurde mit der Methode von Silva und Bremner (1966) bestimmt. Zur Untersuchung des NH_4"+-Austauschs wurden batch-Versuche unter Konkurrenz von NH_4"+ zu K"+, H"+, Ca"2"+, Mg"2"+ und Al"3"+ durchgefuehrt. Auf den NH_4"+-Austausch wurden verschiedene Auswertungsmethoden angewandt und ihre Eignung diskutiert. Der Einfluss der Bodenstruktur auf den NH_4"+-Austausch wurde fuer einen Teil der Boeden erfasst. Neben Waldboeden des Fichtelgebirges wurden Boeden aus Frankreich, Daenemark und Schweden untersucht. Die Mehrzahl der Boeden zeichnet sich durch niedrige pH-Werte aus. (orig.)SIGLEAvailable from TIB Hannover / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekBundesministerium fuer Bildung, Wissenschaft, Forschung und Technologie, Bonn (Germany); Commission of the European Communities (CEC), Brussels (Belgium)DEGerman