Forest17.01.2011

Koskitukki harvests the whole length of a tree

Loading full-lenght loggs to sorting line at Koskisen yard in Järvelä.

Loading full-lenght loggs to sorting line at Koskisen yard in Järvelä.

Koskisen Group’s wood procurement company Koskitukki Oy is the only operator in the Nordic Countries using the full-length logging method, where only the pulp wood section is cut off in the forest and the 12–20-metre sawlog is brought to the sawmill full length.

According to Koskinen’s Chief Forester Jussi Joensuu, the full-length method is particularly well suited for softwood-dominated regeneration fellings where the local conditions, including the forest roads, allow transportation of full-length logs.

“The method benefits forest owners by guaranteeing maximum utilisation of the sawlog portion, as the whole length fit for sawmilling is carefully harvested as dictated by the dimensional and quality requirements. Full-length logging allows cutting off freely at any length from 12 to 20 metres, ensuring an optimal yield of the sawlog portion. The canopy often hides some of the defects in forest trees, so after making three 5-metre logs, one may discover a defect at 17 metres that makes the rest of the trunk unusable as a sawlog. The only choice then is to cut a 3-metre length of pulpwood. The full-length method gives a maximal yield from the entire sawlog portion up to the defect,” explains Joensuu.

Full-length logging is only suitable for regeneration harvests and some seed-tree cuts, however.

Sought-after timber

Logs harvested with the full-length method are highly sought after at the Koskisen sawmill, as they make fast and flexible deliveries of sawn timber possible. Thus it is the preferred method in all cuts where the harvesting and transportation conditions allow it. Difficult sites always require the standard cut-to-length (CLT) method, where the trunk is cut into various timber assortments already at the stump. Birches and aspens, as well as pines and spruces with excessive defects are normally cut into sawlogs and pulpwood.

“The trunks are measured with the measuring system of the harvester, similar to other timber grades. In a standing sale, where the seller takes care of the felling, the trunks are measured at the mill’s trunk measuring facility,” says Joensuu.

Haulage with specialised equipment

Full-length logs are transported to Koskisen on a tailor-made timber truck suited for normal road conditions. The actual vehicle is a regular timber truck. According to Joensuu, it is possible to manoeuvre long logs even from difficult locations without damaging the roads.

“The full-length method is highly functional for the harvesting contractor as well because full-length logs can be cut very quickly in an optimal location and bigger loads are possible when hauling the logs in the forest. Planning and co-operation between the harvesting and transportation contractors must be seamless, however. The company has 12 years of experience using the full-length method, and some of the contractors and employees have participated in the operations since day one. Forest owners have also become wise to the benefits of full-length logging, and for many it has been the preferred method for several years,” Joensuu concludes.