Influence of the afforestation measures in the restoration of forest ecosystems after a fire on the territory of the Territorial Division of State Forestry "Botevgrad"

The purpose of the study is to determine the impact of afforestation measures on the main characteristics of soils, forest litter and grass cover in forest ecosystems after a fire on the territory of the Territorial Division of State Forestry (TD of SF) “Botevgrad” for different recovery periods. Four experimental Objects and four Control variants are selected, spread over brown forest (Cambisols), gray forest (Gray Luvisols) and pseudopodzolic (Planosols) soils to consider the changes that occurred after afforestation. A tendency was confirmed that forest fires lead to an increase in the susceptibility of soils to erosion due to the redistribution of the fractions of the mechanical composition, and to the increase in the amount of sand fraction. Changes in soil acidity have a neutralizing effect on fires, compared to the control option in pseudopodzolic (Planosols) soils. With a longer recovery period after a fire (over 20 years), due to a relative equilibrium reached in the soil, carbon stabilization is observed in brown forest soils (Cambisols), because of its sorption on clay minerals. The predominant part of the soils has a low degree of nitrogen enrichment at C: N>20. Austrian pine crops were found to be characterized by a greater supply of combustible materials in the forest litter. Post-fire period, slope and exposure of the slope, where the Objects are located, determine differences in grass cover mass and stock.