The contorta pine is a newcomer to Swedish forests. Planting began almost 40 years ago, and the new source of timber is now coming into use in the production.
With several advantages over its Swedish counterparts, the Canadian contorta pine is growing fast in Swedish forests.
SCA was one of the pioneers and began growing contorta on a large scale in the early 1970s. The seeds were carefully selected to fit the Swedish climate.
“The plantation was most extensive from the late 1970s to the mid-1980s,” says Åke Westberg, project director at SCA Forest Products. “Then the trend eased up a bit, but SCA has continued to plant it every year, and we will continue to do so in the future.”
The contorta pine has already provided, and will keep providing, major increases in production. It grows 40 percent faster than Swedish pine, and it has been shown to withstand damage from moose and fungus attacks.
Thinning has already started and that provides a signify cant source of new timber, something that would have taken at least another 20 years if ordinary pine had been planted. In about 30 years the oldest plantings will be ready for harvesting.
“About 200,000 cubic meters of contorta timber are now coming out each year from thinning in our forests,” Westberg says. “And the figure will rise toward a half million within a decade.”
"On our own land the target is to have 20 percent of the surface we harvest each year replanted with contorta."
Up to now, contorta timber has largely been used for the manufacture of CTMP, or chemo-thermomechanical pulp, the basis of liquidboard material.
“That’s where contorta has unique properties,” Westberg says. “The board gets bulky, which means you can reduce the weight and keep the thickness. This has been used for things like milk cartons, where you want a lot of flexible rigidity so that the packages keep their shape even when they are stacked on top of one another. At the same time, you want the weight as low as possible.”
He explains how the unique properties of contorta are due to the fibers looking different than in Swedish pine. The advantages have also been made apparent in plant tests with bleached sulfate pulp, which is used for producing tissue for paper towels, toilet paper and the like. The contorta fiber provides a high degree of strength even when there is little energy used in paper production, which contributes to its useful product qualities.
Contorta also shows great properties as raw material for sawn timber. But the trees that are currently harvested at thinning are not big enough for sawing, and consequently need to grow still some years before we will see solid-wood products made of contorta.
Today SCA has about 280,000 hectares of contorta planted, which is almost half the total area of contorta in Sweden.
“On our own land the target is to have 20 percent of the surface we harvest each year replanted with contorta,” Westberg says.
Rewrite from SCA’s corporate magazine SHAPE 2/2008