Changing climate and outbreak ranges of forest pest insects in Finland - Observed changes and future projections

Lead Author Seppo, Neuvonen
Institution Contact Natural Resources Institute Finland (Luke), Yliopistokatu 6, FI-80100 Joensuu, Finland
Co-Authors Heli Viiri, Natural Resources Institute Finland (presenter of the paper); Antti Pouttu, Natural Resources Institute Finland
Theme Theme 1: Vulnerability of Arctic Environments
Session Name 1.7 Invasive species in Arctic ecosystems in the changing world: Is it a real threat?
Datetime Wed, Sep 14, 2016 11:35 AM - 02:50 PM
Presentation Type Oral
Abstract text Forest insect outbreaks have been occasional in Finland, but they may increase in a warming climate. Neodiprion sertifer is the main pine defoliator, and outbreaks have been rare in eastern and northern Finland due to cold winters. The outbreak range of species is predicted to expand if winter temperatures increase. No outbreaks of Acantholyda posticalis were known in Finland until ten years ago. In 2006, an outbreak of A. posticalis killed about 20 ha in the western coast of Finland, and currently the outbreak area has expanded to 200 ha. The outbreak was probably triggered by several dry years, but it is difficult to predict future developments.
Outbreaks of Ips typographus and other bark beetles attacking spruce have increased in southern Finland since 2010. More frequent storm damage and warm summers have enabled the development of more sister broods and even a second generation. In a warming climate, the reduction of spruce bark beetle risks with management actions (timely salvage and sanitation cuttings) is urgent to quarantine the sustainability of forestry.
Cyclic outbreaks of defoliating geometrids (Epirrita autumnata, Operophtera brumata) are typical for the mountain birch forests of NW Europe. The intensity of peaks varies a lot, and the largest outbreaks have killed hundreds of square kilometres of birch forest, having devastating effects on ecosystem services and the condition of reindeer pastures. Due to warmer winters (not capable of killing the overwintering eggs), the incidence of outbreaks is predicted to increase in the continental areas of Northern Europe. The number of defoliation years has increased due to outbreaks of these two species following each other, which has detrimental effects for local livelihoods.
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