There have been a huge number of insect infestations on trees this year. Insect infestations that occur in the summer are often only detected in trees at the end of the year, when the trees brown and dry out.
The number of insect sightings has increased in south-east Finland. The Southeast Finland Forestry Council finds the rate of change alarming.
Last year, a total of 260 hectares of forests in South-East Finland were reported to have been felled due to insect damage.
Around half of the year’s felling is usually recorded towards the end of the year.
The warm weather of the past summer has promoted the growth of insect pests. There have now been at least two dry and hot summers in a row in the southeast.
However, the amount of damage is still small in relation to the number of forests, the Forest Council of Southeast Finland informs.
Spruce trees in particular are worth watching
This autumn, it is worth monitoring the condition of the forests and especially the spruce trees closely. Damage caused in the summer is often not noticed until the end of the year, when the trees turn brown and dry up – even though the damage itself has already been caused in the summer.
Individual dead trees often indicate bark beetles. In grown-up firs, the cause of destruction is usually the letterpress.
In practice, the destruction of trees is due to the fact that the pests live under the tree bark during the summer and eat the nila of the tree from under the bark. This cuts off the wood’s liquid flow.
The canopy can remain green until autumn and winter, but then the tree will inevitably dry out, turn brown and eventually shed its needles. The bark of the tree comes off because the base of the bark has been eaten away. For these reasons, damage is often noticed late.
Dry wood is only good for energy
Good forest management is the best prevention against destruction, thinks Väkäva. The tree should be kept as vibrant as possible. The dry summers have particularly burdened the spruces that were already in a dry growing area.
If the insects have already managed to attack the tree, it is necessary to actively monitor the spread of the insects further, from dead to living trees.
– If this happens, you have to quickly start prevention measures, that is, in practice, logging. If the wood has dried out, it is practically no longer suitable for energy use, says Jouni Väkevä of the Finnish Forestry Center.
The Forest Council of Southeastern Finland consists of various forest sector operators, public administration, non-governmental organizations and stakeholders. It is one of Finland’s fourteen provincial councils.