Aim of the work – to analyze the regularities of quality rates variation and to make the evaluation models of birch assortment structure, concerted with Europe Union standard’s requirements. Object of the work – semi mature and mature birch forests. During research there were used measurement data of birch stems quality rates (diameter, bark thickness at full stem length) and round wood defects. Methodology of the research – there were measured pruned birch stems, filled in the model wood card, indicating the forest and the model wood characteristics. After this empirical database was structured and normatives were made, which allow to evaluate the volume of timbers of various diameter and high trees A, B, C and D quality classes, paper wood, firewood and waste wood. Results of the research – birch - grove felling sorting – grading structure prognosis method was prepared. Sorting – grading tables in MS “Excel” computer program make its essence.

Amounts of pine sawlogs, pine pulpwood as well as spruce pulpwod can be estimated rather precisely. The accuracy of the prognosis is as high as 90%. The amount of spruce sawlogs can be prognosed with less accuracy (75%). The biggest errors are obtained by prognosis of smal dimensions softwood and hardwood as well as of birch pulpwood. Prognosis of birch pulpwood differs from actuall volume 3.7 times. When prognosed income is being compared with the actual one, very small discrepancies are found, though the assorment composition is different. The difference between actual and theoretical income were 2.4% and -0.5% respectively for 2004 and 2005.