Browsing by Subject "hakkeen kosteus"

Use of wood as energy source has increased considerably partly due to financial investments made by finnish forestry companies and partly because of political guidance. Especially the use of wood chips made from logging residues and wood trunks increased. With current methods, the harvesting of wood trunks for energy use is problematic due to low productivity and high costs. In this research the light pruning of energy wood trunks was studied and compared with full pruning and whole tree harvesting of energy wood trunks through the whole procurement chain. The research was divided into four phases. In the harvesting phase the productivity of three different ways to prune energy wood trunks was studied. In the forest transportation phase payloads between different pruning ways were studied as well as cargos loading and unloading times. In long distance transportation phase differences between payloads were studied. In the final product phase moisture percentages of wood chips between pruning ways were measured. In the harvesting phase the highest productivity was achieved with whole tree harvesting. When using full pruning the productivity was lowest. The productivity of light pruning took a stand between these two. Highest payload was achieved with light pruned trunks in the forest transportation phase. Second highest payload was measured with full pruned trunks. The payload of whole trees was smallest. On the other hand, whole tree trunks were fastest to load followed by light pruned and full pruned trunks. When unloading, the results were completely opposite. In the long distance transportation the biggest payload was measured with fully pruned trunks. The payload was second biggest with light pruned trunks. Payload of whole trees was measured as smallest. The wood chips made from fully pruned trunks were driest when the moisture percentages of wood chips made from differently pruned trunks were compared. Chips made from light pruned trunks were second driest. The biggest moisture percentage was with chips made from full trees. The whole procurement chain of full trees was the most efficient in terms of economy. On the other hand, the unit costs of light pruned trunks and full pruned trunks were clearly lower than the unit costs of full trees. Based on result of this study it can be said that light pruning is economically and in terms of productivity compet-itive method to prune trees when compared to other methods.