The growth dynamics of paulownia trees cultivated as energy plantations in the forest-steppe zone of ukraine

The main objective of this study was to establish the impact of varietal characteristics of Paulownia trees on growth and productivity depending on the density of planting in the forest-steppe zone of Ukraine. The greatest increasing of Paulownia Clone 112 trees height -425 cm was fixed in the first year of vegetation at a density of 625 plants/ha. The same tendency observed in the fourth year. The highest height of Paulownia Clone 112 during the vegetation season was observed in June (170 cm), Paulownia tomentosa -140 cm. The smallest increase in height was achieved in October, 40 cm and 35 cm, and in April, 15 cm and 10 cm, respectively. A first year trunk of a Paulownia tree reaches a diameter of 4-6 cm, a second year trunk -7-10 cm, a three-year trunk -11-16 cm, a four-year trunk -15-23 cm. A linear relationship between the height and diameter of Paulownia trees was established. It is enough to measure one leaf dimension (length or width) to determine the area of the leaf surface.