The goal of the study was to compare the dynamic changes in individual biometric indices of Scots pine in different natural zones of Ukraine, Polissya and Steppe. Scots pine stands were mainly concentrated in the Polissya zone, and their area was 3.6 times larger than that of forests in the Steppe zone, and the total wood stock by 4.6 times. The regression equations for biometric indices of artificial modal stands were developed. A comparison of the average height, diameter, and wood stock for pine stands of site index І^а, I, and II growing in Polissya and Steppe was made. It was found that the average differences in the average height (from 1.9 to 2.6 m) are observed at the age of 15–20 years. For the average diameter, the difference increases with age and the growth of the site index. The difference in the average stock is constantly increasing with age. At the age of 20 years this difference is 20–30 m³, and at the age of 120 years from 100 to 120 m³ depending on the site index. The developed growth models can be used in planning and prioritizing appropriate forestry activities for pine stands growing in specific regional conditions.

Lovynska V., Sytnyk S., Gritsan Y. (2018): Energy potential of main forest-forming species of stands in the Northern Steppe, Ukraine. J. For. Sci., 64: 25-32.The study evaluated the energy potential of Scots pine and black locust stands within the Northern Steppe of Ukraine, in forest plantations subordinated to the State Agency of Forest Resources (Ukraine). This study defined general values of aboveground biomass components per age-class structure in the forest stands. Allocated carbon was calculated using the biomass components by age groups as follows: stem, branches and leaves (needles). Contribution of different age groups to carbon allocation was investigated. A key role of stem wood in the process of carbon allocation in the forest stands was shown. It was found that the maximum carbon budget was accumulated in stands of both forest-forming species aged 41-60 years. The models are made on a dependence of carbon allocation in the different components of aboveground biomass by age. Results of energy content in the aboveground biomass were presented in Scots pine and black locust stands within the surveyed area. The study has shown that the energy potential of carbon accumulated in the biomass of Scots pine stands amounted to 40.31 PJ, and that of black locust stands was 32.04 PJ. Development of forest ecosystems in the Steppe zone of Ukraine can result in the optimization of abiotic conditions on a local level under the influence of the global climate changes.