TY JOUR TI DYNAMICS OF NATURAL SPRUCE AND PINE REGENERATION ON ABANDONED HAYFIELDS KW abandoned hayfields KW regeneration of tree species KW undergrowth structure JO Forestry Engineering Journal AU Ermakova, M.V. PY 2020 IS 10 PB FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov