Debarking In Whole-Tree Cable Yarding Operations As A Measure For Bark Beetle Management

Bark beetle calamities, which are mainly triggered by climatic impacts such as storms, temperature stress or even snow breakage, are increasingly affecting the roundwood supply in mountainous regions. This leads to unscheduled volumes and oversupply which challenges the responsible participants along the supply chain. Transportation and storage capacities of processed logs reach their limits. Interim storage facilities can support the supply chain and ease the tense market situation. However, storage of roundwood close to or in the forest must meet phytosanitary requirements. For this reason, immediate debarking at the forest road during processing can serve as a technical measure to effectively reduce the breeding potential for bark beetles to reduce the risk of mass propagations and could have a positive effect on the wood quality development after harvest. The aim of this contribution is to present the results of an ongoing research project that aims to evaluate integrated processor debarking at the forest road during whole tree cable yarding operations. During field experiments the truck mounted tower yarder Konrad Mounty 5000 was equipped with a Konrad Woody H60 processing unit. The processor was equipped with special designed feed-rollers combined with adapted pressure-settings of the delimbing knives. The observed harvesting operations took place in spruce dominated stands, each covering cable lines with and without integrated debarking as treatment- and control groups. The harvesting operations were recorded by two video cameras. Tree data and terrain information were linked to the video data during post-processing. Using structure from motion technique, debarking-quality was examined on the basis of remaining bark surface on 24 randomly selected logs per variant. Subsequently, the breeding-potential of the remaining bark strips was evaluated. Therefore the logs were stored near a wood yard and analyzed weekly regarding wood- and bark breeding insects. Additionally, probes were taken weekly from the same logs to monitor the development of blue-stain in the sapwood, caused by fungi. The results to present will focus on the additional effort for integrated debarking during processing. Furthermore, the debarking quality will be assessed with regards to a phytosanitary effect and a positive effect on wood quality development after harvest.