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The forest must renew itself

The forest must renew itself

03-06-2009
Conifers are on the way out at the Gjorslev estate on the peninsular of Stevns on Sealand. A changing climate will make deciduous forestry a far better business.

Råhoved Forest on scenic Stevns is prime forest. Apart from being at the top of the list for nature lovers, bird watchers and hunters, this forest, characterised by beech trees, is a textbook example of 'natural' or 'close-to-nature' forest management, which allows the forest to regenerate gradually through natural seeding.

The forest belongs to the Gjorslev estate where focus is on deciduous forests managed according to close-to-nature principles. The estate has a total of about 750 hectares of forest. Around 80% is today deciduous forest, most of which is being managed according to close-to-nature principles, and this percentage will increase in the years to come, explains estate owner Peter Henrik Tesdorpf. Climate change means that Norway spruce, the most common tree species in Danish forestry, can no longer be considered a good investment.
"Norway spruce will cope poorly in the climate scenario we are facing. These tees will not be able to yield proper timber in a place like this. So even though it will mean fewer cubic metres of wood, we will be investing in other species that are more suitable for the future climate," says Peter Henrik Tesdorpf.

The conversion at Gjorslev to even more deciduous forest, managed according to close-to-nature principles has taken place gradually over a longer period of time and not only as a response to climate change. The conversion is also good business.
"It is extremely expensive to plant and protect new trees, so it is a real advantage to let the trees regenerate through natural seeding and spend the resources on nurturing the forest instead," explains Peter Henrik Tesdorpf.

Spreading the risk
In close-to-nature forest management, new trees are established through natural seeding under the crowns of the existing trees, and in this way the forest will have a mix of uneven-aged trees. This management method still requires a lot of work. Some of the trees have to be cleared every four years and the forest floor must be harrowed so that new trees can more easily regenerate themselves. However, the method is significantly cheaper than traditional clearcutting, where entire forest areas are planted at once. Furthermore, close-to-nature forests have the advantage of being more robust against expected climate change impacts, says Bo Larsen, professor in silviculture at the University of Copenhagen.

"By mixing different tree species and trees of different ages, you get a forest where you can change the composition of trees over time by choosing the trees to be removed during thinning and the trees to be allowed to regenerate.  In this way foresters can spread their risk and adapt forests to climate change impacts as they become reality," Bo Larsen argues.

He has spoken in favour of introducing close-to-nature forest management in Danish forests since the 1990s. Today, all state forests and some municipal forests are undergoing conversion to close-to-nature forests. However, a great number of privately owned forests are still being managed as monocultures, and Norway spruce is still the most common and widespread species in Danish forestry, Bo Larsen explains.
Norway spruce as well as Sitka spruce, which is also fairly widespread in Denmark, are among the species that will probably be most affected by climate change. 

The direst problems for Danish forestry will probably be more droughts in summer and more frequent and more heavy storms in autumn. Changes that will have a severe impact on both Norway spruce and Sitka spruce. Furthermore, it appears that Norway spruce needs fairly cold winters in order to thrive, which fits badly with the fact that we can expect warmer winters in future. Bo Larsen is however in no way dismissing Norway spruce or conifers as such from Danish forests.
"For example, we're expecting much from North American Douglas fir. And there is nothing to hinder us from having Norway spruce in our forests in future, as long as they are part of a mixed forest," says Bo Larsen.

Waiting for better prices
At the Gjorslev estate, the forestry business is only just making ends meet. The reason the estate's forests on Stevns are not yielding more profits at the moment is mainly because of the many beech forests on the estate today. They may be very pretty, but unfortunately beech wood is not selling well. Beech wood is being rejected to the advantage of lighter species such as ash and maple. However, one must be very patient in forestry. Trees that are planted today, will not be harvested for 50 to 120 years. When beech wood is again selling well, the forests on the Gjorslev estate will be harbouring great value, explains estate owner Peter Henrik Tesdorpf.

In the meantime, one can rejoice over the fact that Råhoved Forest and other close-to-nature forests are good habitats for game and often very beautiful as well.
"The idea is to create forests that are robust and can supply high-quality timber. But they should also have a high degree of biodiversity and offer exciting outdoor recreation. Which is exactly what close-to-nature forests offer," Bo Larsen explains.