Five Norway spruce stands in the pre-Alpine, Alpine and pre-Dinaric regions of Slovenia were studied. Sample populations included between 200 and 250 trees each, a total of 1200 growing trees on 25 research plots, including trees which had been thinned or self thinned. The study was aimed at analyzing the impact of direct and indirect air pollution on growth trends and
productivity of mature Norway spruce stands by the use of an original quantification method for the evaluation of stand growth losses. The trend of health condition of stands since 1986 was also examined. An attempt was made to comprehensively evaluate the endangerment of physiological functions of forest. The results are presented as a guide to applying the method for an assessment of the endangerment of other forest functions. Some general silvicultural guidelines for florist management in Norway spruce stands endangered on account of air pollution are presented.
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