PRINCIPAL GEOGRAPHIC-VARIATION IN THE ACIDIFICATION OF SWEDISH FOREST SOILS

The principal geographic variation in acid-base status of 25 deep soil profiles (maximum 2.6 m deep) was investigated along three transects across Sweden. The transects represent gradients in the atmospheric deposition of acidifying compounds. A latent variable describing the acidity of the profile was extracted by Principal Component Analysis (PCA) and found to contain information that could be geographically interpreted. The variable was correlated more strongly with the atmospheric deposition of S (r = -0.86) than with groundwater recharge (r = -0.30) or base mineral index (r = 0.45). It was concluded that variation in the deposition of S, in the form of H2SO4, is the main factor responsible for the large geographical differences in acidity in forest soils along transects from west to east in southern and middle parts of Sweden.