TY CONF TI STUDY OF GROUP (INTERFAMILY) VARIABILITY OF PRODUCTIVITY TRAITS IN BIRCH HYBRIDS KW productivity KW hybridization KW correlation coefficient JO BIOLOGICAL AND FORESTRY AND ENVIRONMENTAL FUNDAMENTALS OF SUSTAINABILITY OF NATURAL AND ARTIFICIAL PHYTOCENOSES AU Isakov, I.Y. AU Koltunova, L.I. PY 2025 PB FSBE Institution of Higher Education Voronezh State University of Forestry and Technologies named after G.F. Morozov