A 17-year-old Norway-spruce stand at Mt. Kleiner Feldberg (Taunus) was investigated. The mineral soil was found to be in the aluminum buffer range (pH H2O = 3.5) but the fine and very fine roots of injured and uninjured trees were sufficiently supplied with Ca and Mg. Mg-deficiency, however, was observed in current-year needles where the contents were 30 % and 45 % below standard values in uninjured and injured trees, respectively. In injured trees the severe Mg-losses of current-year needles coincided with a 20 to 60 % loss of the activities of a number of enzymes involved in the carbohydrate metabolism and a significant reduction of the growth of current-year twigs.