11 June 2018

FINLAND: CONTINUOUS-COVER SILVICULTURE PRODUCES TOP QUALITY PINE – PROFITABILITY REQUIRES MORE STUDY

The quality of the best Scots pine butt logs from continuous-cover forests is so high that market demand for it may be non-existent. Evaluating the profitability of growing them is difficult, as this would require information about the market, which does not exist for this grade of wood. Sufficient data on tree growth is also lacking. In any case, Mr Sauli Valkonen, Senior Scientist at Natural Resources Institute Finland, recommends caution: ”This is an example of extreme results. We have carried out sawing tests in an 180-year-old Scots pine stand in Evo, southern Finland, where the wood quality is practically as high as it can get. Our message is that this is something that can be reached, but probably not always,” says Valkonen.
In addition to an overstorey, the stand contained an advanced understorey, where the breast-height diameter of the trees could be even 30 centimeters.

Seedling felling is a good way to start
The continuous-cover management of Scots pine differs from that of spruce, which is managed by selective fellings or small-diameter clearcuttings. Still, according to Valkonen, it is not difficult. The change from clearcut-based management of pine to continuous-cover management does not require a transition period. The first step could be a normal seedling felling, where all trees are felled, leaving only large mother trees to provide seeds for the new forest. ”You also have to prepare the soil to some extent to ensure a good start for the new seedlings,” says Valkonen. Normally the mother trees that are good stout timber are logged as soon as the new stand has got off to a good start. ”However, in this case you should have the patience to leave them standing for a bit longer,” says Valkonen. The next operation in the forest is thinning, which could take place in 20 years after the start of the new stand. ”At this point you could harvest some of the mother trees left over from the previous overstorey,” says Valkonen. The harvesting operation must be carried out carefully so as not to damage the young trees. ”But it isn’t much more difficult than normal thinning,” says Mrs Riikka Piispanen, Senior Research Scientist at Natural Resources Institute Finland. Small-scale clearcutting, which is a good method for managing spruce under continuous cover, does not function for pine. ”It leads to similar results as the method we suggest, but it takes more time and is more difficult,” says Valkonen.

The result is very strong wood
Unlike with spruce, the wood produced by the continuous-cover management of Scots pine is very homogeneous in quality. In addition, the butt logs have no knots even in their outer parts up to a height of 15 metres. There are fewer knots even in the other parts of the wood, and they are smaller than in pines cultivated by traditional methods. According to Mrs Riikka Piispanen, this is because of the characteristics of Scots pine. ”Scots pine needs plenty of light. Its branches are situated in whorls, and between the whorls there are no branches. All branches growing in shadow will fall off, so there are branches only towards the top of the trunk,” says Piispanen. ”It is essential to create growth conditions where the annual rings of the inner parts of the log are narrow and there is little poor-quality wood close to the pith;” says Piispanen.

For more information contact Mr Anders Portin, Managing Director:

Finnish Forest Association
Salomonkatu 17-A
FI-00100 Helsinki / Finland
Ph. +358 40 5866179
E-mail: info@smy.fi