Comparison of two harvesting systems for the production of forest biomass from the thinning of Picea abies plantations

This study compares two principally different harvesting systems used for the thinning of Norway spruce [Picea abies (L.) Karst.] plantations in the Alps. The first system was whole-tree harvesting (WTH), producing only whole-tree chips for energy purposes. This system minimizes the production costs by simplifying the harvesting process. The other system was cut-to-length (CTL) mechanical harvesting with an excavator-based harvester. This system maximizes value recovery by producing both short sawlogs and quality fuel chips. Trials were conducted on two similar sites in the Dolomites, in northern Italy, and demonstrated that the CTL system resulted in slightly higher harvesting costs, and also higher revenue. The price differences between the different products determine which system offers the best economic results. If the delivered price of sawlogs does not exceed (sic)25 t(-1), WTH and CTL harvesting offer very similar economic performances, and become profitable only if the delivered price of raw chip wood exceeds (sic)40 t(-1). If the delivered price of sawlogs increases to (sic)50 t(-1), the mechanized CTL system always becomes preferable, and it will turn some profits when the price of raw biomass exceeds (sic)35 t(-1). The CTL system is less sensitive to long extraction and transport distances than the WTH system.