Purpose. To find out quantitative physical and water indicators for which there are significant changes in forest vegetation properties in alluvial sands, as well as to trace their impact on the formation of pine seedling root systems and the accumulation of aboveground phytomass in their plantations. Methodology. The chemical properties of sandy soils were determined taking into account the current requirements of ISO, and their physical and water properties using volumetric cylinders, followed by the calculation of their density, porosity, as well as the coefficients of water content and aeration. The root population of the upper meter layer of sands was determined by the method of monoliths, and plant productivity was assessed by phytomass of medium model trees (7-year-old seedlings, plots 14) and by biometric indicators (22-year-old seedlings, plots 59). Findings. It was found that on alluvial sands with a density of 1.501.66 g × cm-3 in their upper meter thickness, 7-year-old seedlings of Scots pine form a superficial root system (1341.8 g × m-2), which provides accumulation of 2558 kg × ha-1 of aboveground phytomass in seedlings. As the density of sands increases, the production of seedling phytomass decreases. In the case of an increase in density by 14% (1.521.72 g × cm-3), there is a decrease in the mass of roots, in a meter-thick layer of sand (by 53.4%) and aboveground phytomass (by 36%). An increase in the density of sands by 510% with its maximum values (1.741.79 g × cm-3) in a 1030 cm layer causes a decrease in the mass of pine roots by 64.1%. The roots of pine seedlings, for such a density of sand, are not able to inhabit the inter-row space, as indicated by their content in the upper 20-cm layer of sand (2% of the mass of small roots recorded in a one-meter thickness). The phytomass of aboveground organs decreased by 81%, and the seedlings themselves were marked by dwarf growth (were grown by V class of productivity). On sands covered with humus mass of zonal soils, the one meter thickness contained fewer (by 51.4%) pine roots (482.8 g × m-2) than on the control. The share of small roots was smaller (by 61.5%) and that of coarse roots was higher (by 21.5%). Losses of aboveground phytomass per unit area in pine seedlings growing under such conditions can reach 31%, due to the compaction of sands at a depth of 2550 cm (1.671.72 g × cm-3) when they are covered by humus mass and row spacing are overgrown with herbaceous plants (root mass in 60-cm profile 3147 g × m-2) in the phase of their individual growth. Originality. Quantitative indicators of density, porosity and coefficients of water content and aeration of alluvial sands of natural and man-made origin are shown for which the seedlings of Scots pine feature delay in the formation of full-fledged root systems of the surface type, which is reflected in a decrease in the productivity of pine plantations cultivated on the sands, up to the visual manifestation of their dwarf growth. Practical value. The quantitative indicators of their physical and water properties obtained for alluvial sands explain the changes occurring in the structure of the root systems of Scots pine seedlings and the productivity of their aboveground organs. Maintaining the density of sands in the range of 1.501.66 g × cm-3 will allow growing pine seedlings on sands without covering their surface with humus mass, and no-till pre-planting loosening of sands in the rows of future crops allows ensuring the cultivation of multifunctional pine plantations.

The aim of the research was to identify the influence of environmental factors inherent in the alluvial and displaced sands of the study region on the growth of the Jack pine and the prospects for its cultivation. We found that the success of growth of Jack pine seedlings on sandy soils depends on a set of factors, which include the presence or absence, in the rhizosphere of sand, of humus impurities and genetic horizons of zonal soils, silty or loamy layers, soil density and composition of pine stands formed in the cultivation. On alluvial sands, sparse forests of Jack pine and Scots pine with a density of 0.3 units were formed. The yield of seeds from Jack pine cones was 1–2% higher than the normative values, and the mass of 1000 seeds was 50% higher. Jack pine seedlings grow according to I class of productivity on displaced sands, with an admixture of humus mass and remnants of genetic horizons of zonal soils at the root depth. In the rhizosphere of the stand, the roots of Jack pine seedlings occupied 78% of the mass of all roots that inhabited a metre-thick sand. Jack pine seedlings that fall under the canopy of Scots pine fall out of the plantations due to drying, which indicates their demand for light and appropriateness of growing Jack pine in solitary plantings or in mixed low-density plantations with Scots pine.

UDC 630*232 f. Brovko, Dr. Sc. (Agr.), Prof., orcid.org/0000-0001-7498-774x, o. Brovko, Cand. Sc. (Biol.), orcid.org/0000-0003-0969-0194, S. tanchyk, Dr. Sc. (Agr.), Prof., orcid.org/0000-0002-4975-7720, v. yukhnovskyi, Dr. Sc. (Agr.), Prof., orcid.org/0000-0003-3182-4347 oPtIMIzAtIoN of wAteR-PhySICAl PRoPeRtIeS of SANDy SoIlS of NAtuRAl-teChNoGeNIC oRIGIN Purpose. To establish the changes in the waterphysical properties of sandy soils under the influence of different content of forestlike loam, humus mass of sodpodzolic sandy loam and gray loamy soils and to show their influence on the phytomass pro duction of annual seedlings of Scotch pine and common oak.Methodology. Indicators of density, porosity, as well as absolute and relative humidity of sandy soils and their mixtures with different content of loam and humus mass of zonal soils were determined by conventional methods in soil science. The effect of the studied mixtures on the waterphysical properties of the sands was evaluated by the parameters of accumulated absolutely dry phytomass of annual pine seedlings and seedlings of common oak.findings. It is established that with increasing the content of forest loam and humus mass in sandy and sodpodzolic sandy soils from 20 to 80 % in their mixtures there is observed decrease in density (by 3.4-24.8 %), increase in porosity (by 1.1-70.0 %) and humidity -absolute (at 5-560 %) and relative (at 11-442 %). The share of needles in the total phytomass of pine seedlings is in creasing (by 2-8 %), and the share of roots is decreasing (by 2-18 %). Oneyearold pine seedlings accumulated the largest mass (2539 mg) on a mixture with 20 % of humus mass content and 80 % of loam content. With the increase in the sand content of forest loams and humus mass of gray forest loam soils from 20 to 80 % absolute humidity of the mixtures increases by 75.0-870.0 %, and the relative humidity -by 61.0-639.0 %. In the total phytomass of annual oak seedlings, the part of leaves increases (by 11.9-15.8 %), and the proportion of roots decreases (by 13.0-22.8 %). In annual oak seedlings, maximum values of the total mass (10.7 g) were observed on mixtures containing 40 % of humus mass of gray forest soils, 20 % of loess loam and 40 % sand, as well as 80 % of humus mass and 20 % of loam.originality. It is shown that 20-80 % of admixture to the sands of loess loam and humus mass of sodpodzolic sandy soils significantly increases their porosity, their moisture content and has a positive effect on the accumulation of phytomass in annual pine seedlings. The same admixture to the sands of loess loams and humus mass of gray forest loamy soil provides a significant increase in absolute and relative humidity in the studied mixtures and causes oak seedlings to increase the mass of leaves and re duce the mass of roots in annual seedlings.Practical value. The proposed variants of formation of recultivation layer of threecomponent mixtures, which include sand, loess loam and humus mass of zonal soils allow optimizing the waterphysical properties of sandy...