Bark beetle problems: An update
The damage caused by the bark beetle to Södra’s forests during the unusually hot, dry summer of 2018 is now estimated at just over a million cubic metres, but Södra is taking action to minimise further losses.
Johannes Bogren, Södra’s Technical Product Director, said that Södra is far from alone in feeling the effects of the beetle which has infested forests across Germany, Austria, The Czech Republic and Switzerland, as well as Sweden.
Södra is very conscious that acting now will help limit further damage in the spring when the beetle begins to breed again. Felling affected trees and removing the logs from the forest is the most effective measure against the bark beetle, which will stay dormant until next spring. It is critical to interrupt their life-cycle so Södra is encouraging its forest owners to fell and remove any infested trees during the winter in case large numbers of the beetle remain in the bark.
“The damaged trees are not suitable for the sawmills but they are our owners’ wood, Bogren says, so we need to find ways to process it, which means sending sawn logs to the pulp mills – they can still make excellent pulp. We are using our harvesting equipment to harvest the dead wood rather than to harvest thinnings, so we are having to adapt our pulp recipes accordingly.”
“The affected wood is spruce which tends to have superior properties to pine,” Bogren explains. “We’ve seen a negligible decrease in tensile strength in Black R from Mörrum, but no effect on production at Värö. Mönsterås is taking measures to limit the damage and we have seen this as an opportunity to change the wood recipes where necessary, with promising results so far.”
Magnus Petersson, Manager of Silviculture Development, adds that the Swedish forest authority has warned that further damage will very much depend on the weather: “If we get a cooler, wetter summer than 2018, we can expect approximately the same volume of dead wood during 2019, but if the summer is warm and dry again, the volume of wood affected could increase fivefold.”
“The measures we’re putting in place could reduce the damage significantly - identifying and removing the trees with dormant beetles from our forests before they start to breed again. We’re also looking at what others are doing in Central Europe, with insecticide-treated nets for example, but we haven’t decided if we will use these methods yet.”
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Subjects: Pulp
