Changing Climate and Outbreaks of Forest Pest Insects in a Cold Northern Country, Finland

Abstract

Pest insect population dynamics are species specific and complex due to nonlinearities and interactions among different trophic levels. Consequently, the impacts of climate change on pests are also species specific and they are often difficult to predict. However, there are some clear examples of increasing forest pest risks due to a warming climate. The damage caused by the Eurasian spruce bark beetle has recently increased in Finland as a consequence of more frequent storm damage and longer growing seasons. In a warming climate, timely salvage and sanitation cuttings will be needed to guarantee the sustainability of the forestry. Several defoliating pests overwinter in the egg stage. Warmer winters may not kill the eggs and, therefore, the incidence of outbreaks is predicted to increase in the northern and continental areas. The most important societal implications will be due to Geometrids attacking subarctic mountain birch forests. Together with heavy reindeer grazing, Geometrids reduce the resilience of the ecosystem and they are threatening the sustainability of local livelihoods.

Can novel pest outbreaks drive ecosystem transitions in northern‐boreal birch forest?

“…These regenerative mechanisms are not always effective, as stands that have been killed by more small‐scale outbreaks in the past have sometimes failed to recover, and undergone a transition to secondary tundra. Reindeer browsing on birch recruits has traditionally been invoked to explain these regenerative failures (Käyhkö & Horstkotte, ; Neuvonen & Viiri, ). Browsing undoubtedly has negative effects on birch sprouts and saplings (Biuw et al, ; den Herder & Niemela, ; Kumpula et al, ), but our current results suggest that dead stands may also struggle to recover due to the loss of internal positive feedbacks between birch recruits and mature conspecifics.…”

“…The most notable example stems from the Utsjoki municipality in northern Finland, where an autumnal moth outbreak during the 1960s caused extensive mortality of MBF over an area of more than 100,000 ha (Kallio & Lehtonen, ). Forest recovery after this outbreak has been poor, and much of the area has now devolved to treeless secondary tundra (Neuvonen & Viiri, ). Such regenerative failures have usually been attributed to browsing by semi‐domestic reindeer ( Rangifer tarandus L.; Käyhkö & Horstkotte, ), which are abundant in northern Fennoscandia, and have negative impacts on the growth and survival of birch sprouts and saplings (Biuw et al, ; den Herder & Niemela, ; Kumpula, Stark, & Holand, ).…”

Forest health monitoring in transition: Evaluating insect-induced disturbances in forested landscapes at varying spatial scales

“…In comparison, cool and moist summers and cold winters can mitigate populations considerably. Milder winters may also promote success of insect pests (Neuvonen and Viiri 2017). Increased minimum winter temperatures are associated with reduced bark beetle mortality (Benz et al 2010).…”

Динаміка Популяцій Короїдів У Соснових Лісах Житомирської Області

“…Водночас, зміна клімату сприяла прискоренню розвитку комах, зокрема короїдів (Neuvonen & Viiri, 2017;Shvidenko et al, 2017;Оkland et al, 2019), і переваги в заселенні дерев отримали види, спроможні розвиватися у декількох поколіннях на рік . Ці види можуть заселяти дерева впродовж майже всього вегетаційного періоду, а також ослабляти їх під час до-даткового живлення та внаслідок перенесення фітопатогенних організмів (Davydenko et al, 2017;Meshkova, 2017Meshkova, , 2019.…”