Protsenko I. Meliorative Properties of Protective Forest Plantations on Recultivated Dumps of Yurkiv Brown Coal Quarry

The thesis is devoted to the study of reclamation properties, sanitary condition, productivity and ameliorative efficiency of protective plantations on reclaimed dumps of Yurkiv brown coal quarry. A comprehensive study of the impact of forest reclamation plantations of different species composition on forest site conditions, the sanitary status, growth and productivity of plantations on reclaimed lands were determined. The depth of the humus layer of soil under the canopy of plantations on recultivated dumps varies from 5 to 30 cm. Low-thickness 5 cm humus horizon is typical of places where pure plantations of Scots pine and mixed with birch aged 37–40 years are grown. In terms of humus content, the highest values are inherent in mixed pine-birch, black locust and birch plantations. Soil hardness of reclaimed dumps in pine, oak and black locust plantations was respectively 6.7 kg∙(cm^2)^-1, 4.6 and 3.7 kg∙(cm^2)^-1. In terms of humus content, the highest values are characteristic of mixed pine-birch, black locust and birch plantations, which are close in value to the indicators for soil samples taken under the canopy of plantations on intact soils. The thickness of the humus layer and the humus content has the highest values in the lower part of the slope, where the fertile soil layer is alluvial. The ratio of active and conductive roots of Scots pine is 1:3.4, which indicates low physiological activity of the underground part of the trees and thus the weakening of the stands. At the same time, the ratio of active and conductive roots in common oak and red oak, which is in the range of 1:2.4 and 1:2.3, respectively, indicates the activation of physiological processes, intensive root growth, development of lower horizons, which ultimately enriches the soil and promotes the growth of these recultivation plantations on reclaimed lands. Analysis of the sanitary condition index showed that pine stands are highly weakened. Weakened pine trees account for 44.7 %, and the sanitary index varies between 3.01–3.41. It is established that the most influential factors of significant deterioration of the sanitary condition of pine plantations on the recultivation lands are root sponge damage and drying of trees due to reduced nutrition of plants that have reached the disturbed maternal horizon at depths over 40–50 cm.