ACIDIFICATION STATUS OF NORWEGIAN FOREST SOILS AS EVIDENT FROM LARGE-SCALE STUDIES OF HUMUS SAMPLES

The acidification status of forest soils in seven counties in Norway w as studied on the basis of chemical analysis of 3 000 humus samples co llected in a regular grid pattern. In samples with more than 70% organ ic matter the base saturation decreases gradually from 25% in the nort hernmost county Nord-Trondelag to 10% in the Agder counties far south. Base saturation shows a slight increase with increasing organic matte r content in southern and southwestern Norway, but a strong decrease i n more northerly areas. In southeastern Norway there is a regular decr ease in pH and base saturation from north to south, and these differen ces have apparently increased between 1962-64 and 1984, indicating enh anced soil acidification in the south possibly related to acid deposit ion from the atmosphere.