Features of the Structure of Blueberry Spruce Forests of Bolshoy Solovetsky Island

The research has been carried out in the most typical and widespread plantations for Bolshoy Solovetsky Island – in blueberry spruce forests. Forest management materials and data obtained from sample plots have been used. In the latter, as well as in their buffer zones, the diameters and heights of 325 registered trees have been measured and samples have been taken to study the age structure of the stands. The presence of all forest-forming species of the island has been established in the composition of blueberry spruce forests. The average breed composition is reflected by the formula: 6S2B1P1As (6 spruce trees, 2 birch trees, 1 pine tree, and 1 aspen tree). The majority (76 %) of stands is of 0.6–0.7 density, but at the same time, low-density stands also make up a significant proportion – 21 %, and high-density stands are almost absent. According to archival data, there have been no clear-cuttings on the Solovetsky Islands, with the exception of individual cuttings in the 1920s and 1930s when the Solovetsky Special Purpose Camp existed there. All this, it would seem, has to contribute to the preservation of old trees. However, the average age of spruce stands is 155 years, and the oldest live up to 250 years. This age can be considered the limit for the conditions of the Solovetsky Archipelago. It has been shown that all the stands are of different ages with a different distribution of trees by age classes. There are blueberry spruce forests with a significant gap between tree generations, as well as with a cyclical appearance of the maximum number of trees in certain periods. The following types of age structure have been identified: absolutely uneven-age, stepwise unevenage and cyclically uneven-age. Spruce trees have been found to grow quite well in diameter, but growth in height is inhibited, resulting in the formation of highly tapering trunks. On average, the trees reach their maximum height of about 20 m with a diameter of 30–40 cm. The relative height averages 0.66 m/cm – this is 67 % of the indicator of the mainland spruce forests. It is inversely related to the diameter: the greater it is, the lower is the relative height.