Growth and productivity of energy plantations of poplars in the Right-Bank Forest Steppe conditions

Abstract

Purpose. To determine the features of the growth of an energy plantation of poplar variety ‘Robusta’ on leached chernozems in the conditions of the Central Forest Steppe of Ukraine. Methods. Field, laboratory, statistical. Results. One-year lignified cuttings 25 cm long and 0.8–1.0 cm in diameter were used as planting material. The designed layout of planting places: 2.0x0.8 m (more density version) and 2.0x0.9 m (more sparse version). After the first year of cultivation, the studied plots had the same height (1.6 m). During the second growing season, their growth in height was 2.0±0.05 m in the more sparse version, and 2.1±0.05 m in the thicker version. After the first year, the diameter at a height of 1.3 m was greater in the thicker version (0.5 cm versus 0.3 cm), but already in the next year, the trees of the more sparse stand became 2 mm thicker, and this difference persisted in the third year, when the average diameter of the trees of the denser version was 5.8 cm, and of the sparser — 6.2 cm. As a result of the higher diameter of trees of the more sparse version, they had a higher weight of the average tree, but due to the smaller number of trees, their productivity was lower. So, after three years of growing a poplar plantation created by cuttings, one hectare can yield 11.66–14.58 tons of dry biomass, or 207.5–259.5 GJ of energy. A sharp increase in morphometric indicators during the third year of cultivation indicates the feasibility of using a longer period of cultivation of such plantations to obtain the maximum amount of biomass. Conclusions. The study of a three-year energy plantation of the ‘Robusta’ variety, created by one-year lignified cuttings on the leached soils of the Right Bank Forest Steppe, with the placement of planting sites 2.0 x 0.8 m and 2.0 x 0.8 m, showed that after three years of growing a poplar plantation, one hectare can get 11.66–14.58 tons of dry biomass, or 207.5–259.5 GJ of energy. A significant increase in growth indicators and biomass productivity of poplar plantations during the third year of cultivation indicates the feasibility of using a 4–6-year period of cultivation of such plantations to obtain the maximum amount of biomass.