Scots pine (Pinus sylvestris L.) seasonal growth at different stages of ontogenesis in Taiga zone (Karelia)

Abstract

The studies were conducted in 2014–2015 in southern Karelia (middle taiga subzone). The aim of the research was to study the seasonal growth of shoots, needles and trunks in young (22 years old), middle-aged (55 years old) and ripening (86 years old) stands of Pinetum vacciniosum. The study found that the dynamics of the seasonal growth of vegetative organs in trees during ontogenesis varies somewhat. The beginning of the growth of shoots, needles and trunks does not depend on the age of the tree. The formation of wood cells in the lower part of the trunk in relatively young trees begins on days 8–12 earlier. The end of the growth of shoots and needles in trees of different ages is observed at the same time. The formation of trunks in relatively young stands lasts for 18–25 days longer. The growth rate of the trunks decreases with the age of the tree, the needles — increase, and in shoots it reaches its greatest value in middle age. On average, the annual growth of trunks in young, middle-aged and ripening stands is 2,54, 2,11 and 1,06 mm, respectively, needles — 11,3, 15,5 and 18,8 mg, shoots — 35,1, 38,4 and 34,4 cm. Differences in annual growth of shoots and needles are associated exclusively with the change the intensity of their growth, and the trunks, in addition, and with a difference in the duration of their formation. The features of the curves reflecting the dynamics of growth of vegetative organs in stands of different ages generally remain unchanged, the culmination of their growth being observed almost simultaneously.