Sawlog Recovery in Birch, Black Alder, and Aspen Stands of Hemiboreal Forests in Latvia

Abstract

In any forest stand, the theoretically modelled output of sawlogs (the most valuable roundwood assortments) will differ from what is actually obtained. The aim of this study was to assess whether it is possible to characterise this difference by site properties or forest inventory parameters for birch, black alder, and aspen. We compared theoretically modelled sawlog recovery with actual recovery according to harvester data from final fellings. The difference between the theoretically modelled and actually recovered sawlog outcomes varied from −24.32 to −60.96 percentage points, with overestimations reaching up to three times for aspen. The differences in yield of sawlogs varied among soil types and increased with age and the average diameter of a tree. The sawlog recovery was underestimated up to the mean diameter at breast height of 16 cm and age of 20 years while being overestimated for larger and older trees. The results highlight the necessity to consider decreasing wood quality with increasing age to account for decay, such as stem rot, in assortment tables.