The condition of tree stands in middle taiga Piceetum myrtillosum on automorphic soils in the plots affecting by aerotechnogenic pollution from the timber industry complex (the Komi Republic)

The authors accessed the effect of aerotechnogenic emissions from the pulp-and-paper plant of the Syktyvkar timber industry complex on the condition of spruce stands. Carbon monoxide, nitrogen dioxide, inorganic dust, hydrogen sulfide, sulfur dioxide and mercaptans are the main pollutants. By the radial growth dynamics of spruce stem wood we identified the development trend of forest stands affected by the long-term technogenic impact. The old-growth blueberry spruce forests located at distances of 4, 5, 11, 24, 50 km from the emission source in the direction of prevailing winds were studied. The vitality of spruce forest stands has been analyzed via visual evaluation of tree crowns at the sample plots. The studied spruce stands are ‘healthy’ with initial weakening signs which slightly intensify towards the discharge chimneys of the enterprise. the impact of aerotechnogenic emissions from pulp-and-paper production on the radial increment of spruce stem wood was assessed by the tree-ring indication methods. The study by this methods has utilized wood samples (cores) taken from trunks of old-growth spruce trees within sample plots. Finally, we have identified the increased radial growth of spruce in the impact zone. At distances longer than 11 km from the air pollution source, the radial growth of spruce stem wood resists relatively stable from the very beginning of the timber industry enterprise (from 1969 to the present). The increase in radial growth of spruce trees is associated to the time when the enterprise attained its installed capacity in the late 1980s. This was followed by a long-time decrease in radial growth of trees. This period is characterized by a production decline due to the deterioration of the financial situation in Russia during the 1990s and production modernization from 2008 to 2018 which reduced gas and dust emissions of the enterprise.