”Continuous-cover silviculture suits self-reliant forest owner”

15.8.2014 / Article

Heikki Kaitila carries on the continuous-cover silviculture started in the family forest by his father. He thinks the method rewards a patient forest owner.

Reportedly, some Finnish forest owners could not find their holdings without outside help. Forestry entrepreneur, Mr. Heikki Kaitila is not one of them. Walking with him in his forests, it feels as if he knows and remembers the history of each individual tree.

We are in the forest belonging to his homestead, which his father bought in 1936. A few years before that, all trees on the holding with the minimum diameter of four or six inches, Kaitila does not remember which, had been felled.

“There are some old photographs that show the forest was quite sparse. My father started developing the estate from there,” Kaitila says. His family has tended the forest according to the principles of continuous-cover silviculture ever since.

Trees felled here and there

Continuous-cover silviculture means that no clear fellings are carried out in the forest. In this way, the forest always contains trees of varying ages and sizes. Trees are felled selectively here and there, to make room for smaller ones to grow.

Small “clear fellings” are possible in continuous-cover silviculture, too. The maximum size of these small-scale fellings is 0.3 hectares. Typically, the size of clear fellings in private Finnish forests is two hectares.

The problem associated with continuous-cover silviculture has been that the number of new seedlings growing underneath the crown cover might be too small. In addition, some suspect that small trees used to shady conditions for years cannot use the advantage of more light and space brought with selective fellings.

Understorey trees catch up

Kaitila’s experience over the years is the opposite: trees in the understorey rally and begin to grow as conditions improve.

”Spruce grows well for its first 150 years. If it has been in the understorey for 70 years, it still has 80 good growth years left,” he explains.

Kaitila says the important thing in continuous-cover silviculture is preserving the existing seedlings. “If the felling is carried out with a harvester, a bigger machine is better. It has the power to guide the falling tree in the right direction,” he says.

He feels that continuous-cover fellings are best carried out with a chainsaw, as a forest worker can guide the tree to fall in any direction. With a harvester the choice is narrower. Therefore the seedlings suffer less if fellings are carried out with a chainsaw.

”Remove no more than 50 cubic metres at a time”

Kaitila’s experience is that in continuous-cover fellings, the maximum volume of timber you should fell at one go is 50 cubic metres. If you take out more, the amount of felling residue, such as tree tops and branches, left in the terrain is so high that it interferes with seedling growth.

”And don’t clear the understorey before the felling, as is done in traditional thinnings. Even small trees can change the direction of a falling tree and protect the trees to be spared. Any damaged trees should be removed last,” he advises.

The problem that prevents continuous-cover silviculture from becoming more common is that few harvester operators know how to carry out selective fellings. Kaitila names the few he says can independently fell an area according to the principles of continuous-cover silviculture.

He himself marks the trees to be spared or removed, whichever is easier, for the harvester operator.

“Never undervalue a tree”

When thinking about where and what to fell, Kaitila considers such things as soil type, terrain contours, the condition of tree roots and the impact of winds. A seedling suitable for growing does not need to be pine, spruce or birch.

Kaitila appreciates alders, aspens, rowans, oaks, whatever grows in the forest. “My father used to say, never undervalue a tree.”

Kaitila’s experience is that monocultures consisting of only one tree species do not stay healthy, and alders, for example, improve the soil as their root nodules release nitrogen. In fact, the predominant periodic-cover silviculture also strives to avoid monocultures.

Clear fellings are carried out in Kaitila’s forests, too. Some of his forest acquisitions have been financed with bank loans, which must be paid back. A clear felling brings in more money than a continuous-cover felling.

Laborious but rewarding

On the other hand, the clear fellings in Kaitila’s forest look more like heavy thinning than what one normally regards as clear felling.

“I feel that you also need to spare big trees in clear fellings. I don’t put price tags on them and I don’t get the point of retention trees with a ten-centimetre diameter. That spruce, for example, is more valuable to me standing than when cut into logs,” he says and points to a huge spruce with a generous cone crop.

Those practicing continuous-cover silviculture reap the rewards over time, he says. After a clear felling, grasses overtake the site and suppress small shrubs with woody stems. This is why clear fellings eventually destroy bilberry and cowberry crops, he says.

Continuous-cover silviculture does not lead to these problems. Also, you will have no regeneration costs caused by soil preparation, seedlings and planting, if regeneration goes as it should. On the other hand, regeneration after a clear felling also fails sometimes.

Kaitila does not rely only on natural regeneration, but plants seedlings, such as lime trees. “Linme tree does well under the shade of birches”, he says and proves it by showing me the planting site.

Continuous growth and contiuous fellings

The usual way to manage a tree stand is to carry out one or two thinnings during its life cycle, ending in clear felling and regeneration. In continuous-cover silviculture felling is also continuous, with trees felled every five years or even every year.

As a forest owner, Kaitila is very much a self-starter. He sells about a thousand cubic metres of timber every year; of this, he himself fells about 500-600 cubic metres.

For a Finnish holding, Kaitila’s estate has a great deal of variation as regards the elevation above sea level. In fact, Kaitila carries out all felling on steep hillsides himself. A harvester then de-branches and cuts the trees into lengths.

The next investment will be a small harvester, Kaitila thinks. It would be useful for first thinnings.

”Method requires know-how”

Kaitila thinks that continuous-cover silviculture suits self-reliant forest owners, but you have to have plenty of know-how and the willingness to take trouble. It is especially suited to small estates and places where the scenery needs to be maintained.

It is very difficult to change an even-aged forest holding into a continuous-cover one, Kaitila thinks. The task is easier with forests left untended for decades.

Kaitila owns a great deal of forest. His custom of leaving some of it untended has caused neighbours to comment that he must be rich to afford it.

”I’m not rich. I fell a few trees a day for sale, that’s my daily wages,” Kaitila says.

It all depends on what you are happy with. “The current mode does not think small is beautiful, everything needs to be on a grand scale,” he says.

Kaitila understands that forest industries rely on efficiency and the use of few tree species. But why it should be this way is something he does not really understand.

Further information:

Finnish forest legislation


Krista Kimmo

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