The main purpose of this work is to define the biological and economic features of various phenological forms of aspen. The research objectives were to visualize the early budbreaking (E), the late budbreaking (L) and the intermediate budbreaking (I) aspen phenological forms and to study the differences in prevalence of heart rot attack, productivity and quality of wood stock, and timber density. The research methodology included stationary and route observations. Stationary surveys were conducted on 4 pairs of trial areas in the C2 and D3 forest types. It is observed 620 allotments (total area 823.1 ha). It was found that budbreaking of the E-forms began in for 7-14 days earlier than of the L-forms. The prevalence of heart rot attack among the L-forms was by 30-40 % less, than among the E-forms. The stem quality of the L-forms was higher by 14-50 %. The timber density of the L-forms is reliability higher than of the E-forms.