Radial increment dynamics in Pinus sylvestris stands within the Northern Steppe of Ukraine

The parameters of periodic increment (5-years) and peculiarities of its change depending on age, diameter, height and volume of trunk of Scots pine are determined. The influence of climate conditions (air temperature and precipitation) on the dynamics of radial increment change of Scots pine trees are established. The results of experimental studies, obtained from 20 temporary sample plots of pine stands within the Northern Steppe of Ukraine are presented. We conducted an estimate of radial increment of Scots pine trunks as a basis for development of normative and information support for assessment of biotic productivity of this category of forest. All selected sample trees had different age and biometric parameters. The age of sample trees ranged from 9 to 90 years; diameter at breast height – from 4.0 to 41.7 cm; height – from 4.2 to 30.0 m, trunk volume – from 0.002 to 1.748 m3. It is found that the radial increment of pine stem was significantly dependent on tree age. The highest values of radial increment of Scots pine trees were observed for trees aged up to 20 years. With increasing age, radial increment had a decreasing trend, including 90-year old trees. Regression models of the dependence of radial increment of pine trees on the age and diameter are presented. In the article, the dependence of the values of radial increment of sample trees from types of forest are demonstrated. The highest values of Scots pine radial increment was observed in sugruds and gruds, which were presented in tree samples of 20 years. Comparative analysis of radial increment change in the trees of one age category, which grew in different conditions, was conducted. The older trees had the maximum increment in the conditions of dry sugrud, and the minimum increment in conditions of fresh subor. Also in this article we used generalized chronology of Scots pine radial increment reflecting regional variability of growth in pine trees. The results supplemented the research obtained earlier with new data on the dependence of the pine radial growth rate on forest-biometric parameters. These experimental data, their graph-analytical evaluation yielded an information basis for modeling the radial increment of pine trees, created on the basis of dependence of this parameter on biometric indexes – age and diameter at breast height