Bedernichek T. Transformation of Soil Organic Matter under various cutting systems in hornbeam-oak forests of the Upper Dniester basin

The environmental impact of deforestation on soil organic matter (SOM) was studied in this thesis. The reliable indicators of SOM transformation in forest ecosystems under various forest management scenarios were described. The influence of different cutting felling systems in old growth oak-hornbeam forest and agricultural use of adjacent deforested ecosystems on soil organic carbon reservoir were explored. It was found that the top 50-cm soil layer contains up to 95 t/ha of soil organic carbon. This indicates a significant carbon sequestration and a high energy potential of the above layer. The analysis showed that deforestation leads to a decrease in SOM content, especially in its labile (water-soluble and easily oxidized) fractions, which was accompanied by a significant decrease in C-mineralization potential and environmental protection capacity of SOM. Experimentally-simulated global warming showed that emission rates of CO2 from soils decrease with the increase in anthropogenic pressure. Deforestation-associated reduction in temperature tolerance (Q10) of forest soils indicates the existence of compensatory mechanisms that maintain the balance of carbon in soil-plant-atmosphere system, according to the principle of negative feedback. The most prominent changes in response to various anthropogenic influences were observed in the top 5-cm soil layer. This thin soil layer has been proposed to be recognized as a soil stress-sensitive zone.