Thanks to recent restoration of permanent study plots founded in the 1930s we could repeat the soil scientific investigations and compare the outcomes of soil analysis. Due to precise geodetical positioning, the identical soil pits were sampled and new chemical survey with the same old analytical methods was conducted. Our research includes two natural habitats - pure deciduous forest stand of European beech and mixed forest of with dominating Norway spruce. Both of them are situated in western part of the Ukraine Republic in Carpathian Biosphere National Reserve as relics of last truly virgin forest ecosystem without any direct human impact. Moreover no local sources of air pollution are located in the area. Analysis of seven soil properties were redone: loss on ignition, total nitrogen content, actual and potential soil reaction, base cation content, cation exchange capacity and base saturation. The general trends over time were shown and internal dynamics of forest ecosystem per habitat and growth stage was evaluated. The key role of acidification and its natural and anthropogeneous causes was discussed. The data show significant decreasing of pH-values in all cases. At the same time, an internal dynamics within ecosystem during the forest stand developing was presented.