The effect of harvesting method on biomass retention and operational efficiency in low-value mountain forests

This study determined the biomass retention effects and the technical-financial performance of alternative harvesting practices, applied to mountain sites. The two alternatives were: whole-tree (WT) and tree-length (TL) harvesting. Five cable yarding sites were selected from a larger pool of available sales, and on each site two adjacent and parallel cable corridors were set up, using the same base equipment and crew. For each of the 10 corridors (i.e. 5 sites × 2 corridors), the following data were recorded: biomass retention, product output, time and fuel inputs. Opting for TL harvesting resulted in a large (66 %) and significant increase in biomass retention, which may prove attractive where intensified biomass removal may jeopardize soil fertility and biodiversity. TL harvesting also resulted in a moderate increase (13 %) of total harvesting cost. Furthermore, TL harvesting required 30 % more labour input than WT, which may represent a disadvantage when forest labour is scarce. The increased labour use in TL harvesting occurs mainly at the stump site, where accident risk is highest. For all these reasons, managers should take their decision very carefully and opt out of more efficient WT harvesting only when the risk derived from increased biomass removal is quite severe.