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- Ammunét, Tea, et al.
(author)
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Northern geometrids and climate change: from abiotic factors to trophic interactions
- 2015
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In: Climate change and insect pests. - 9781780643786 ; 7, s. 235-247
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Book chapter (peer-reviewed)abstract
- The subarctic mountain birch forests have been periodically disturbed by geometrid moth outbreaks since at least the mid-19th century. The effects of these disturbances can be seen from landscape-level dieback of the birch forest to local-level changes in soil processes. Recent research efforts have demonstrated that the geometrid moth-birch forest system is undergoing changes that could be linked to the ongoing climate warming. Milder winter and spring temperatures influence winter survival and outbreak ranges of the moths, and are also alleviating range expansions and the spread of new species to the area. Moreover, phenology matching with the host plant may be altered. The outcome appears to be intensified outbreaks and a potential for altered species interactions and dynamics with ecosystem-wide consequences.This chapter will first introduce the prevailing dynamics of the mountain birch-geometrid system and the reported ecosystem effects of geometrid outbreaks. Second, the chapter summarizes observations of ongoing abiotic changes in the area and presents the potential known and unknown effects on the study species. Finally, the chapter discusses the future scenarios for this northern ecosystem and the possibility of major ecosystem changes.
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| 2. |
- Björkman, Christer, et al.
(author)
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Effects of new forest management on insect damage risk in a changing climate
- 2015
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In: Climate change and insect pests. - 9781780643786 ; 7, s. 248-266
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Book chapter (peer-reviewed)abstract
- Recent findings suggest that damage by forest insect pests will increase as a consequence of climate warming. Here, we ask whether changes in forest management can alter and possibly mitigate the increased risk of damage and outbreaks. We focus mainly on conditions in northern Europe, particularly Sweden, but conclusions should be valid for northern temperate forests. Three types of insect pests are considered; the regeneration pest,Hylobius abietis(pine weevil), defoliators and the bark beetle,Ips typographus. We compare the expected effect of new management methods with the presently predominant method of even-aged stands, which are thinned two to three times before final harvest by clear-felling. Continuous cover forestry (CCF) is the method most different from the present practice. CCF would lead to a drastic decrease in pine weevils, and also less damage by defoliators, but this latter prediction is uncertain. For the bark beetle, the uncertainty is even greater. In mixed forests, all three insect pest types are expected to become less of a problem. Putative mechanisms involve more abundant and diverse natural enemy fauna, and a more scattered distribution of food resources. A shorter rotation period (including no thinning) is expected to increase the damage by pine weevils, as it will result in more abundant breeding material. For defoliators, it is difficult to foresee the effects. A shorter rotation period will decrease the risk of bark beetle outbreaks, as storm-fellings will be less frequent and young stands more common. The effects of exotic tree species and clonal forestry are complex and will depend on several factors. A general conclusion is that forest management may be used to mitigate the anticipated risk of insect pest damage as a consequence of climate warming, but more research is required to certify these indications
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| 3. |
- Larsson, Stig
(author)
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Climate change and insect pest distribution range
- 2015
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In: Climate change and insect pests. - 9781780643786 ; 7, s. 1-15
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Book chapter (peer-reviewed)abstract
- There is a pressing need to understand better the dynamics of species' distribution, in particular when it comes to predicting the outcomes of climate change-inflicted variations in the range distributions of insect pests. Several insect life history traits, such as survival, growth rate and voltinism, are likely to change in a warmer environment, and it is to be expected that at least some changes will contribute to altered range edges. For many insect taxa, range expansions are not easy to detect, simply because their presence remains undetected in habitats at range edges, where they are likely to occur at low densities. Insect pests are a group for which information on range expansion is beginning to accumulate, for the obvious reason that their effects on managed ecosystems often require action. Thus, increasingly managers of agriculture and forestry are concerned with the predicted range expansions of important insect pests.This chapter offers an update on the range expansions of insect pests in agriculture and forestry, native and alien. We summarize information from the literature where climate change has been interpreted as, or predicted to become, the driver of range expansion. We discuss the type of evidence for the expansion, ongoing or predicted to occur, and aim to classify according to its empirical nature.A critical read of the database of the literature on climate change resulted in surprisingly few documented examples of climate change-induced range expansion. Of course, long-term trends in the distribution and abundance of insect pests are notoriously difficult to document. Thus, it is possible that more insect pests could have responded to climate change, or are likely to do so in the near future, than can be detected in our literature search. It is also possible, however, that biological systems, including insect pests, are less sensitive to direct climate effects than previously thought (due to the buffering effects of trophic interactions). Future research needs to focus more on the mechanisms of responses to changed climate in order to understand better, and predict more accurately, the likelihood that insect pests will expand their outbreak range.
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