Abstract

To assess the effects of acid deposition on the soil acidity of Swedish forests, six sets of forest soils were analysed for pH, and the values obtained compared with measurements made during 1951-1963. In one of the sites in southwest Sweden, the contents of extractable anions were also compared. It was found that the forest soils of southern Sweden exhibited large pH decreases of around one pH unit throughout the soil profile, with forest soils in northern Sweden relatively unaffected. For most sites, including the northernmost site, the soil pH values seem to have approached a steady-state value. Acid deposition was the major cause of the observed pH decreases in southern Sweden. Elevated atmospheric inputs of sulphur and selenium, along with the recorded pH decreases would, in theory, have increased the adsorption of sulphate and selenite. It was found, however, that phosphate-extractable sulphate and selenite have not increased significantly between 1951 and 1989 in the spodic horizons of southwest Swedish forest soils. Instead, the pool of adsorbed organic anions, measured as NH4F/HCl-extractable C, increased significantly in the forest. Increased adsorption of organic anions probably explains the fact that sulphate and selenite have not increased to any considerable degree, because organic anions exert a negative influence on the adsorption of the other anions. These findings have implications for the prediction of recovery times in response to decreased acidic inputs to watersheds, as reversibly adsorbing sulphate would act to delay the recovery.

Published in

Agriculture, Ecosystems and Environment
1993, Volume: 47, number: 2, pages: 103-115
Publisher: ELSEVIER SCIENCE BV

UKÄ Subject classification

Soil Science


Publication identifier

DOI: https://doi.org/10.1016/0167-8809(93)90105-X

Permanent link to this page (URI)

https://res.slu.se/id/publ/69513