Vorarlberg urges winter action to curb bark beetles

Vorarlberg is urging forest owners to check their trees and remove infested timber over the winter, as damage from bark beetles could emerge next year despite no major outbreaks so far. The state also plans to expand monitoring with additional traps, ORF reported.

The hot summer put considerable strain on the region’s forests. Experience from previous periods of heat and drought suggests that the effects can become apparent only the following year, the state said. Forest owners should use the coming months to take preventive measures, said Christian Gantner, the state councillor responsible for the issue. Attractive timber prices offer an added incentive, he said.

Heat and drought restrict photosynthesis, reduce trees’ ability to build up energy reserves and weaken their defences. They can also damage fine roots and other sensitive tissues. Spruce trees may become more vulnerable to bark beetles even when they still appear healthy.

After the hot summers of 2003, 2015 and 2018, significant beetle damage sometimes appeared the following year, the state warned. Under favourable conditions, bark beetles can multiply rapidly and survive the winter. A small number of infested trees can then develop into larger outbreaks. The state cited severe consequences in East Tyrol as an example.

Forest owners are required under forestry law to remove infested timber promptly. The state said this protects neighbouring forests as well as the owner’s own trees. It recommends regular inspections, quickly clearing infested trees and removing wood that could serve as breeding material.

Autumn, winter and early spring offer an opportunity to reduce the number of beetles before they swarm again. Infested trees containing overwintering beetles, as well as infestations identified during the first spring flight, should be removed from the forest in good time and handled appropriately. Depending on conditions, further measures may be useful and should be discussed with the local forest authority.

Vorarlberg’s state forestry service plans to add pheromone traps to the national bark beetle monitoring network. The traps can indicate when beetles begin flying and how intense that activity is, helping authorities assess the threat and identify when forests need closer inspection.

The state also recommends dealing promptly with trees damaged over winter to prevent surviving beetles from multiplying in spring. Measures can include setting trap trees or leaving suitable bait wood in place, with all infested timber removed in good time.