Components of the Increment Dynamics of Early and Late Wood of Quercus robur Stem in the Upland Oak Forest of the Southern Forest-Steppе

The stem radial increment contains information on the tree growth, development, and condition. The early and late wood increment has essential features. The increment dynamics contains monotonous and cyclic components. Retrospective and predictive assessments of growth and development of a tree and a stand based on the patterns of radial increment are possible. The purpose of the article is to analyze the properties of the components and their contribution to the increment dynamics of oak early and late wood, depending on the favorability of growth period and the crown development. The research object was the artificial upland oak forest of the first quality class (pure in composition). Two periods of growth were considered: 1st – favorable (1968–1996) and 2nd – unfavourable (1997–2014). We studied three groups of oak, each group of 10 trees. The groups were distinguished by the development of crown (original classification) and its dynamics. The stem cores were taken at a height of 1.3 m from the southeast side. Indicators of radial increment were defined in the images of cores scanned at 1200 dpi resolution. Three components of the dynamics were identified: a long-term trend and cyclic components with 12- and 2–5-year cycles. The variability of cyclic components of the dynamics of early wood increment was more than twice lower, than that of the late wood. The contribution of the component with 2–5-year cyclicity to the dynamics of early and late wood increment prevails during the favorable period of growth. The contribution of the component with 12-year cyclicity increases during the unfavorable period and the more, the less developed the crowns. The transition of the radial increment to a lower level occurred during the minimum of the component with 12-year cyclicity. There is no significant correlation between early and late wood increment of the component with 2–5-year cyclicity, which makes the major contribution to their ratio. The correlation between early and late wood increment of other components is closer during the unfavorable period and with a decline in crown development. The correlation between the early and late wood increment of the previous year is closer than that of the same year.