Over half of Sweden’s total land surface is productive forest land. Forests are affected by climate change and there are expected to be marked changes in the climate over time.
Effects of climate change
In the future, the growth period may be extended by 1-2 months and the annual rate of forest growth may therefore increase by up to 30% over current figures. However, the negative effects of climate change are likely to hit forests very hard.
A warmer climate means increased risk of drought in the summer. When trees are affected by drought stress, they do not develop a full root system, which increases the risk of storm damage even if it is not expected that storms will become more frequent in the future.
It is likely that the extended growth period will increase the potential for wood-rotting fungi to spread. Trees affected by drought stress may be at increased risk of infestation by both established and new species of insect, which will also find it easier to spread in a warmer climate.
A decrease in the length of periods when the ground is frozen and increased rainfall in autumn and winter will probably result in greater damage by vehicles, as the stability and accessibility of roads are reduced. This may in turn have a harmful effect on biodiversity as sediment, mercury, organic material and large volumes of nutrients are carried out into water courses and lakes.
Adaptation results in resilient forests
Häradsmarken is a forest management company that looks after 12 areas of ‘common land’ in Östergötland and Jönköping counties. The common land is land that is jointly owned by several people. The profits from forestry, agriculture and concessions belong to the taxable properties and their owners in the jurisdictional district. Häradsmarken is undertaking work on climate change adaptation in line with Swedish Forest Agency recommendations.
In order to adapt to an increased incidence of windthrow, Häradsmarken now thins its trees earlier than it did previously. This is done so that the trees get used to wind at an earlier stage and become hardened to it.
Another important area that Häradsmarken is working hard on is water management. Since summer 2014 they have been making use of a mapping function that shows the ground conditions, surface structure, slope and ground moisture levels of the terrain. The tool is used for advance planning of felling and extraction. It makes it easy to see where tree branches should be laid down to protect the ground or where a bridge should be built so as avoid driving on ground where there is a considerable risk of damage to a watercourse. The water map also means that people can see where they should establish new wetlands or clear out old ditches. This enables forest management to adjust to current and future ground conditions.
To spread the risk of pest damage, Häradsmarken also now plants a wider variety of tree species than before. From having almost never worked with foreign tree species at all, they are now planting species such as hybrid larch, Douglas fir and lodgepole pine.
In forestry, the climate change adaptation process differs from that in other industries as it operates on longer time scales.The greatest challenge, therefore, is putting measures in place to deal with situations a long way in the future. Some of the actions now being taken for the purpose of climate change adaptation have high initial costs but in the long run they will generate greater dividends for the owners and a better adapted forest.
The whole estate was laser-scanned in 2008 with the aim of mapping the forest. At the same time, a terrain model was created with new calculation matrices, and this has now been used to create the water map showing wet areas with poor bearing capacity. The cost of this computation was a few Swedish kronor per hectare, and it has provided a map that is used to plan access so as to avoid damage from vehicles.
More examples of climate adaptation
This is one of many examples of climate adaptation. There are more in the collection of ideas being built up by the Swedish National Knowledge Centre for Climate Change Adaptation at the Swedish Meteorological and Hydrological Institute (SMHI). The collection of examples has the aim of sharing experiences and providing ideas to everyone who works with climate adaptation. Examples describe concrete measures and challenges in several subject areas. They show how different actors have worked to adapt their activities to the climate changes that are already being noticed today and those that we cannot prevent in the future.