Paal Krokene
Research Professor
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Min CVBiography
I study plant-insect interactions, and particularly how conifers defend themselves against bark beetles and fungi. The work is highly interdisciplinary and I collaborate with chemists, molecular biologists and ecologists at NIBIO and abroad. The methods we use span from field experiments to chemical ecology and molecular biology. I have worked at NIBIO since 1992. I studied at the University of Oslo, where I graduated as Master of Science in ecology / entomology in 1992 and Dr. Scient. (PhD) in forest entomology in 1996. Since 2004, I have been an adjunct professor at the Norwegian University of Life Sciences (NMBU), where I teach forest entomology. Since 2018, I am also a member of the Plant Health Panel of the Norwegian Scientific Committee for Food and Environment (VKM).
Authors
Tao Zhao Suresh Ganji Christian Schiebe Björn Bohman Philip Weinstein Paal Krokene Anna-Karin Borg-Karlson C. Rikard UneliusAbstract
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Abstract
submittedVersion
Abstract
The purpose of this study is to increase the basic understanding of outbreak dynamics in order to improve the management of bark beetle outbreaks. The spruce bark beetle Ips typographus is a major disturbance agent of European forests and is the continent’s most economically and environmentally damaging bark beetle. Outbreaks of the spruce bark beetle are often triggered by large windfall episodes, and we have utilized a unique opportunity to study a Slovakian outbreak where little salvage logging was performed in some areas after a 2.5 million m3 storm-felling in 2004. Our analyses focused on the first five years after the windfall, and we used a combination of empirical data and simulation models to understand the spatial patterns of beetle-killed forest patches developing during the outbreak. The univoltine beetle population used an increasing proportion of the windfelled trees during the two first seasons after the storm, but from the third season onwards our comparisons of inter-patch distance distributions indicated a transition from beetle production largely in windfall areas to a self-sustaining outbreak with infestation patches developing independently of the windthrows. The size of new infestation patches formed after this transition was modeled as a function of beetle pressure, estimated by the proportion of a circle area surrounding new patches that was covered by infestation patches the previous year. Our model results of patch size distribution did not correspond well with the empirical data if patch formation was modeled as a pure dispersal–diffusion process. However, beetle aggregation on individual trees appears to be important for patch development, since good correspondence with empirical data was found when beetle aggregation was incorporated in the modeled dispersal process. The strength of correspondence between the beetle aggregation model and the empirical data varied with the density of aggregation trees in the modeled landscape, and reached a maximum of 83% for a density of three aggregation trees per infestation patch. Our results suggest that efficient removal of windfelled trees up until the start of the second summer after a major windfall is important to avoid a transition into a patch-driven bark beetle outbreak that is very difficult to manage. Our results also indicate that the outcome of a patch-driven outbreak is difficult to predict, since the development of new infestation patches is not a simple function of beetle pressure but is also affected by beetle behavior and local forest conditions.
Authors
Paal KrokeneAbstract
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Authors
Daniel Flø Johan A. Stenberg Kjetil Klaveness Melby Selamawit Tekle Gobena Beatrix Alsanius Jorunn Børve Paal Krokene Christer Magnusson Mogens Nicolaisen Line Nybakken May-Guri Sæthre Iben M. Thomsen Sandra WrightAbstract
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Authors
Paal KrokeneAbstract
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