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.
Vegetation growing on the slopes counteracts the development of erosion processes, directly affects the improvement of soil properties, which are largely determined by the morphological structure of the root system. We studied the development and distribution of the root systems of trees and shrubs on the slopes with different steepness in a forest park in the northern environs of Kyiv (Ukraine). The method of complete excavation of plants growing under the conditions of composite topography, in the park stands employed near ravines, where the plants were exposed due to erosion, was chosen for the research. The samples of root systems of 15 trees and 5 shrubs selected from different locations of growth places were examined: under the canopy, in canopy windows, in the open space, and at the slopes of different expositions with steepness from 6° to 39°. The plants aged up to 13 years, up to 3.5 m high, with crown diameter up to 130 cm and root neck thickness up to 80 mm were selected from undergrowth and understory. The depth of penetration of the root systems into the soil and the order of their branching were measured for further studying the anti-erosion properties of root systems. The area of horizontal projection of the root system to the crown diameter ratio, the soil saturation with roots and the intensity of root system branching were determined. Numerical indicators of the spatial structure of root systems are extremely important when assessing the studied trees and shrubs. Key words: park planting, undergrowth, understore, soil saturation with roots, depth of soil penetration, branching intensity
The effective performance of ameliorative functions by water protection plantations is largely determined by the development of the forest litter, its structure, capacity, quality composition, and degree of mineralization. Therefore, the aim of the study was to identify the features of the formation of the forest litter of pine plantations of the Ukrainian interfluves of the Dnipro and Desna. The study of forest litter was carried out on the accounting sites in all age groups of plantations, in which 22 test plots were laid. Litter samples were taken in between rows and directly in rows of forest plantations. During the analysis of the qualitative composition of the forest litter of young plantations, the dominance of the upper horizon of the inactive fraction, which consisted mainly of needles and branches, was revealed. Here, the share of inactive litter in the conditions of moist poor pine site and moist relatively poor pine site was 8.13 t/ha or 85.1% and 12.54 t/ha or 92.1%, respectively. A large amount of dust, which forms the active fraction, was recorded in the lower horizon. Its stocks were 5.3-5.6 times higher than the reserves of inactive litter. In general, in young pine forests in the conditions of moist poor pine site, the stock of inactive litter is 15.10 t/ha (28.1%), while its presence in of moist poor pine site is 17.91 t/ha, 36.5%. In middle-aged pine forests, the share of the active litter fraction increases, which is a consequence of the active action of its decomposition processes. The share of active litter is 79.3% or 155.29 t/ha in mature stands of the conditions of moist poor pine site. This is evidence of the intensification of the processes of mineralization and activation of the circulation of substances. Three horizons are clearly distinguished in the litter of plantations of older age groups, with a strong connection between them. The lower layer of the forest litter of water conservation plantations is permeated with physiologically active roots, which forms its dense type of structure. Under such conditions, during the separation of the lower layer of litter from the upper one, it does not fall apart and its structure remains dense. The presence of strongly intertwined physiologically active roots in the third horizon of the litter is evidence of the activation of microbiological processes, which are also accelerated by the interception of moisture and the accumulation of humus particles of the soil by the lower layers of the forest litter. To prevent the development of flood processes, the effective performance of water regulation and water purification functions, it is recommended to create water conservation plantations with the formation of the identified type of forest litter
During land unsoldering in Ukraine, so-called “self-seeded forests” appeared on lands that had not been used for agriculture for a long time. The purpose of the research is to find out the erosion control properties of self-seeded forests. Twelve locations of natural regeneration of various types of woody plants on the ravine-gully system of Cherkasy region were chosen as research sites. Self-seeded woods have a structure of different ages from 8 to 25 years. Most of them are represented by mixed stands, which increase their biological stability. They are better adapted to the current climate change. The formation of uneven-aged stands of natural regeneration with high resistance and erosion control properties was noted. According to the qualitative indicator of productivity, the natural regeneration turned out to be different, which was primarily caused by forest sites conditions, in particular, the steepness, the position on the slope, and the thickness of the humus horizon of the soil. The hardness of the soil was determined in the range from 17.1 to 19.0 kg/cm2, which corresponds to an average loose state. The hardness of the soil in the control was 23.9 kg/cm2, which corresponds to its compacted state. The water permeability of the soil under the studied stands was 11.1–27.3 (control – 8.9) mm/min, which characterizes it from the best to chasm. The obtained soil water permeability data confirm the rapid transfer of surface runoff to subsoil, which prevents the development of erosion processes. Natural regeneration on the slopes of the ravine-gully system is determined to be successful, although it requires considerable time for the formation of full-fledged 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.
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