Comparing model-based approaches with bucking simulation-based approach in the prediction of timber assortment recovery

Summary The aim of the study was to compare model-based approaches in the prediction of timber assortment recovery with bucking simulation based on detailed stem data. A correction function for the total length of saw log fragments and two optional saw log reduction models, that is, the MELA96 version and MELA05 version, were applied. In the bucking simulation, the volumes by timber assortments were calculated using a bucking-to-value simulator. The prediction of saw log recoveries varied between the bucking simulation and different versions of saw log reduction models. The level of the reduction from the MELA96 version was at the same level as from the bucking simulation where defects were taken into account, but the saw log reduction had a very low variance due to a small amount of independent variables. The saw log reduction of the MELA05 version included more variation although the level of the reductions was higher and the variation did not meet with the bucking simulation. As a conclusion, the model-based approaches seem applicable at least for the prediction of saw log recovery in the large area forest inventories where the variance of the standwise timber assortment recoveries need not be predicted.