Ecosystem Impacts of a Range Expanding Forest Defoliator at the Forest-Tundra Ecotone

Jepsen, Jane Uhd; Biuw, Martin; Ims, Rolf A.; Kapari, Lauri; Schott, Tino; Vindstad, Ole Petter Laksforsmo; Hagen, Snorre B.

doi:10.1007/s10021-012-9629-9

Cited by 88 publications

(95 citation statements)

References 47 publications

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“…During these outbreaks, insect deposits (including excreta/frass, cadavers, moults, pupae, greenfall) constitute considerable nutrient fluxes from the canopy to the soil, with the largest single constituent being frass (Hunter 2001;Arnold et al 2016). Understanding how these outbreaks influence element cycling and plant growth is essential for improving predictions of C and N cycling (Throop et al 2004;Metcalfe et al 2016) and plant community composition (Jepsen et al 2013) across the Scandinavian Arctic, particularly as the extent and intensity of outbreaks appear to be increasing due to climate warming (Jepsen et al 2008;Kozlov and Zvereva 2017).…”

Section: Introductionmentioning

confidence: 99%

The biogeochemical consequences of litter transformation by insect herbivory in the Subarctic: a microcosm simulation experiment

2018

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Warming may increase the extent and intensity of insect defoliations within Arctic ecosystems. A thorough understanding of the implications of this for litter decomposition is essential to make predictions of soil-atmosphere carbon (C) feedbacks. Soil nitrogen (N) and C cycles naturally are interlinked, but we lack a detailed understanding of how insect herbivores impact these cycles. In a laboratory microcosm study, we investigated the growth responses of heterotrophic soil fungi and bacteria as well as C and N mineralisation to simulated defoliator outbreaks (frass addition), long-term increased insect herbivory (litter addition at higher background N-level) and non-outbreak conditions (litter addition only) in soils from a Subarctic birch forest. Larger amounts of the added organic matter were mineralised in the outbreak simulations compared to a normal year; yet, the fungal and bacterial growth rates and biomass were not significantly different. In the simulation of long-term increased herbivory, less litter C was respired per unit mineralised N (C:N of mineralisation decreased to 20 ± 1 from 38 ± 3 for pure litter), which suggests a directed microbial mining for N-rich substrates. This was accompanied by higher fungal dominance relative to bacteria and lower total microbial biomass. In conclusion, while a higher fraction of foliar C will be respired by insects and microbes during outbreak years, predicted longterm increases in herbivory linked to climate change may facilitate soil C-accumulation, as less foliar C is respired per unit mineralised N. Further work elucidating animal-plant-soil interactions is needed to improve model predictions of C-sink capacity in high latitude forest ecosystems.

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Section: Introductionmentioning

confidence: 99%

The biogeochemical consequences of litter transformation by insect herbivory in the Subarctic: a microcosm simulation experiment

2018

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“…The economic value of the wood losses due to reduced growth increases exponentially with the extent of defoliation (Reis et al, 2012), and may reach 310 $/ha/year (Lyytikainen-Saarenmaa and Tomppo, 2002). On top of these significant economic losses, regular insect outbreaks may trigger decline chains in the forests resulting in mass tree mortality (McManus and Csóka, 2007;Jepsen et al, 2013).…”

Section: Introductionmentioning

confidence: 99%

Effects of forest heterogeneity on the efficiency of caterpillar control service provided by birds in temperate oak forests

Bereczki

Odór

Csóka

et al. 2014

Forest Ecology and Management

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Controlling herbivore insects by insectivorous birds is a major ecosystem service, nevertheless little is known about how local habitat features and forest management influence the efficiency of this service and about how the pest control service birds provide can be maintained and improved. We conducted an experiment in temperate oak forests in the Mátra Mountains, northern Hungary to measure bird predation rate of artificial caterpillars resembling winter moth (Operophtera brumata L.) larvae, to evaluate the relationships among insectivorous bird communities, caterpillar populations and leaf damage caused by caterpillars and to assess the effect of forest heterogeneity on these processes. We found, that structurally heterogeneous forests maintained a significantly higher abundance of insectivorous birds.Especially the tree size heterogeneity increased bird abundance. The rate of bird predation was positively related to the abundance of insectivorous birds as well as to caterpillar abundance, which indicates that birds were able to respond to caterpillar density. We were not able to demonstrate a direct negative effect of bird predation on caterpillar abundance and a positive effect of caterpillar abundance on leaf damage. Structurally heterogeneous forests, however, suffered from less leaf damage than did homogeneous forests, which result may indicates that the higher activity of insectivorous birds in heterogeneous stands resulted in 3 lower activity of insect herbivores. Thus, we concluded that forest management can contribute to the mitigation of insect damages by maintaining the suitability of forest stands to the insectivorous bird communities through the maintenance of high stand heterogeneity and the presence of some key elements (e.g. retention tree groups, tree diversity, shrub layer).

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“…The largest outbreaks have killed hundreds of square kilometres of birch forest (Seppälä and Rastas 1980). They can have devastating effects on ecosystem services and the condition of reindeer pastures (Biuw et al 2014;Jepsen et al 2013) (Fig. 5.1).…”

Section: Birch Defoliatorsmentioning

confidence: 99%

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

Neuvonen

Viiri

2017

The Interconnected Arctic — UArctic Congress 2016

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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.

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Ecosystem Impacts of a Range Expanding Forest Defoliator at the Forest-Tundra Ecotone

Cited by 88 publications

References 47 publications

The biogeochemical consequences of litter transformation by insect herbivory in the Subarctic: a microcosm simulation experiment

The biogeochemical consequences of litter transformation by insect herbivory in the Subarctic: a microcosm simulation experiment

Effects of forest heterogeneity on the efficiency of caterpillar control service provided by birds in temperate oak forests

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

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