Radial growth of Pinus sylvestris L. under industrial pollution on the Kola Peninsula

Since the beginning of the 21st century in many countries, including Russia (Kola Peninsula), there has been a sharp decrease in the volume of atmospheric emissions from industrial enterprises, which made it possible to trace the reaction of plants to the reduction of aerotechnogenic load. In some regions, very slow recovery of some components of disturbed terrestrial ecosystems has begun; therefore, the urgent task of this study was to reveal the response of radial growth of Scots pine (Pinus sylvestris L.) stem wood to reduced atmospheric emissions of pollutants from the “Severonickel” Combine (Murmansk Region). At the sample plots, established in lichen-green-moss pine forests, 60-65 (background areas), 30 (buffer zone) and 10 (impact zone) km away from the pollution source, stem wood cores (20-50 pieces) were taken from weakened and severely weakened Scots pine trees at a height of 1.3 m from the ground surface using a Pressler drill. At the same time, average samples of the upper organogenic horizon of Al-Fe-humus podzols were taken from each sample plot to assess the level of habitat contamination by heavy metals (Ni, Cu, Co), the content of acid-soluble forms of which was determined by atomic absorption spectrometry. The width of annual rings of each core was measured on a semi-automatic device LINTAB 6, cross-dated and the synchrony index was calculated. It was found that the current level of heavy metal pollution of habitats remains high (buffer zone, the anthropogenic load index varies 7-18 rel. units) and very high (impact zone, the average anthropogenic load index is over 140 rel. units). The most pronounced response of Scots pine radial growth to the reduction of aerotechnogenic load is manifested in the impact zone, where for the period 2000-2019 the width of annual rings increased 2-3 times in relation to the period 1980-1999, and is now comparable or even exceeds the background values. Thus, with further reduction of atmospheric emissions by the “Severonickel” Combine, it is possible to restore the productivity of Scots pine trunk wood in the polluted area.