Atmospheric Input to Danish Spruce Forests and Effects on Soil Acidification and Forest Growth Based on 12 Years Measurements

Atmospheric deposition of strong acid and sulphur compounds has been measured at Danish forest sites since 1985. Results from 12 years of measurements are reported from Ulborg experimental forest site situated on the sandy soils of West Jutland. Measurements and model calculated deposition estimates indicate a cumulated acid input from the atmosphere of 40 kmol, during the last 30 years; far more than the forest soils could neutralise by weathering or by base cation exchange. During the period 1985-1997 an increase in soil water concentration of protons (acid) and aluminium were seen and the molar ratio between calcium and aluminium dropped to a minimum of 0.1. A decrease in forest growth and an increase in needle litter fall were seen in the same period.