Melnyk V. Features of 137Cs migration in Pine Sylvestris L. artificial ecosystems in the unconditional resettlement zone

The thesis is dedicated to the study of features of radionuclide migration in P. sylvestris artificial ecosystems in the unconditional resettlement zone with account taken consequences of the measures termination of the stands tending. In the work the current ecological condition of pine plantations was assessed, methodological approaches to determine the optimal number and depth of soil sampling to assess the vertical migration of 137Cs in soil profile and density of radioactive soil contamination, the regularities of the migration and distribution 137Cs in the components of forest ecosystems were studied. For the first time after a long period after the Chernobyl accident (30 years), the state of artificial pine plantations was studied, where forestry activity was terminated due to significant radioactive contamination. The distributed pine trees, which examined the existing group under growing conditions of intensive radioactive contamination, shows that the proportion of healthy specimens is smaller and that of weakened and very weakened ones is much greater than in control test areas. The productivity of artificial pine sylvestris ecosystems of by indicator technical suitability of wood was assessed and the peculiarities of radial propagula are analyzed in the unconditional resettlement zone. The migration and redistribution radionuclides in different types forest soils of forest growth conditions is studited. As a result, it is found that in fresh subsoils there is a slower 137Cs redistribution between soil layers compared to fresh bors and wet subors. Research results on the study of vertical migration 137Cs by soil profile and density of radioactive soil contamination have allowed to refine methodological questions regarding the required number and the depth of sampling of soil samples. In order to obtain representative results the current 137Cs soil contamination levels, it is necessary to conduct a 10-fold sampling of a 30 cm soil layer. The radionuclides distribution in the main components of forest ecosystems in different types of forest growth conditions is analyzed. It has been found that the bulk of 137Cs is concentrated in forest soil and does not exceed 25 % in forest plants. The current 137Cs content was studied in the above ground phytomass of grass representatives and shrub cover of fresh bors and wet subors. The radionuclides indicators intensity from the soil into the phytomass were calculated. Information on the 137Cs content dynamics in acrocarpous and pleurocarpic mosses was added. It has been found that the radionuclides concentration in mosses as a whole and their individual fractions has decreased over the years.