The forests in the Šalek Valley started to decline after decades of air pollution from the Šoštanj Power Plant (ŠTPP). During this times trees in the forest showed smaller diameter growth and regeneration. The extremely high SO2emissions were reduced by the installation of desulphurisation devices at Unit 4 (1995) and at Unit 5 (2000), but emissions of NOx and CO2 were almost unchanged. In 2004 SO2 emission was reduced to 10% of that in 1991. The main aim of this research was to assess the influence of the reduction of SO2 on condition of forests in the area of influence of ŠTPP, following the same methodology, which was used in the year 1987. Measurements were implemented on16 plots, which lay at the altitude from 310 to 1130 meters and where trees showed 2. and 3. damage class. Geological substratum on panels are tonalite and tuff. They form more acidic soils. Results showed that condition of initial phase was improved after the installation of desulphurisation devices on ŠTPP. Changes had also positive influence on regeneration of deciduous trees, especially beech and chestnut tree, which are very welcome species. General vitality of trees was also improved, what was indicated from last decade diameter growth and from comparison with diameter growth of trees from similar sites from Pohorje and Kaštni vrh. Further orientation of silviculturein this area should be based on irregular shelterwood. Already formed regeneration cones should be extended to enable growth and development of seedlings and saplings.
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