Invasive species
Invasive exotic insects can cause substantial damage to trees and the environment. The extensive trade with wooden products represents a high risk of transferring forest pests to new territories. In some cases, the damage is greater in the introduced range than in the native range of the pest. Increasing global trade of timber and frequent use of wood packaging materials like pallets, crating, and dunnage, have provided important pathways for the introduction of forest pests worldwide. The increasing import of wood chips for bioenergy production represents a potential introduction pathway for harmful organisms.
Our research is aimed at predicting the effects of forest pest introductions and reducing the risk of spread and establishment of such species. Because direct experiments with introduced species are too dangerous, we most often use a combination of data analysis and modelling. Once alien pest species have become established in their new habitats, they may be extremely difficult to eradicate, and the costs of damages and control programmes may be very high. Thus, it is of particular interest to learn what management efforts are useful for stopping the establishment and spread of new forest pests. Special attention is given to the most damaging taxa that may have biome-wide effects, such as bark beetles and the pinewood nematode.
International publications
Isitt R., Liebhold, A.M., Turner, R.M., Battisti, A., Bertelsmeier, C., Blake, R., Brockerhoff, E.G., Heard, S.B, Krokene, P., Økland, B., Nahrung, H.F., Rassati, D., Roques, A., Yamanaka, T., Pureswaran, D.S. 2024. Assymetrical insect invasions between three world regions. Neobiota 90: 35-51. PDF
Isitt, R. Økland, B., Krokene, P., Sweeney, J., Heard, S.B., Pureswaran, D.S. 2023. Successful colonization of novel spruce hosts by European and North American spruce bark beetles can favor trans-Atlantic range expansion. Forestry 2023, 1-8, https://doi.org/10.1093/forestry/cpad015 PDF
Isitt, R. Økland, B. Krokene, P., Sweeney, J., Heard, S.B., Pureswaran, D.S. 2022. Using semiochemicals to predict biotic resistance and facilitation of introduced species. Biological Invasions.
https://doi.org/10.1007/s10530-022-02925-0. PDF
Økland, B., Flø, D., Schroeder, M., Zach, P., Cocos, D., Martikainen, P., Siitonen, J., Mandelshtam, M.Y., Musolin, D.L., Neuvonen, S, Vakula, J., Nikolov, C., Lindelöw, Å., Voolma, K. 2019. Range shifts of the small spruce bark beetle Ips amitinus – a newcomer in Northern Europe. Agricultural and Forest Entomology https://doi.org/10.1111/afe.12331 PDF
Vettraino, A.M., Santini, A., Nikolov, C., Grégoire, J.-C., Tomov, R., Orlinski, A., Maateng, T., Sverrisson, H., Økland, B., Eschen, R. 2019. A worldwide perspective of the legislation and regulations governing sentinel plants. Biological Invasions. https://doi.org/10.1007/s10530-019-02098-3. PDF
Flø, D., Norli, H.R, Økland, B. and Krokene, P. 2018. Successful reproduction and pheromone production by the spruce bark beetle in evolutionary naïve spruce hosts with familiar terpenoid defenses. Agricultural and Forest Entomology DOI: 10.1111/afe.12280. LINK
Flø, D., Krokene, P., Økland, B. 2015. Invasion potential of Agrilus planipennis and other Agrilus beetles in Europe: import pathways of deciduous wood chips and MaxEnt analyses of potential distribution areas. EPPO Bulletin 45 (2), 259–268. PDF
Flø, D., Krokene, P., Økland, B. 2014. Importing deciduous wood chips from North America to northern Europe – the risk of introducing bark- and wood-boring insects. Scandinavian Journal of Forest Research. 29(1): 77-89. PDF
Økland, B., Haack, R.A. & Wilhelmsen, G. 2012. Detection probability of forest pests in current inspection protocols - A case study of the bronze birch borer. Scandinavian Journal of Forest Research 27: 285-297. PDF
Bergseng, E., Økland, B., Gobakken, T., Magnusson, C., Rafoss, T. and Solberg, B. 2012. Costs of a pest invasion contingency plan – the case of Pine Wood Nematode in Norway. Scandinavian Journal of Forest Research 27: 337-349. PDF
Økland, B., Erbilgin, N., Skarpaas, O. and Christiansen, E. 2011. Inter-species interactions and ecosystem effects of non-indigenous invasive and native tree-killing bark beetles. Biological Invasions. 13(5): 1151-1164. PDF
Økland B, Skarpaas O, Schroeder M, Magnusson C, Lindelöw Å, Thunes K. 2010. Is eradication of the pinewood nematode (Bursaphelenchus xylophilus) likely? An evaluation of current contingency plans. Risk Analysis 30(9): 1424-1439. PDF
Økland, B. Skarpaas, O. & Kausrud, K. 2009. Threshold facilitations of interacting species. Population Ecology 51: 513-523. PDF
Skarpaas, O. & Økland, B. 2009. Timber import and the risk of forest pest introductions. Journal of Applied Ecology 46: 55-63. PDF
Johnson D.M., A.M. Liebhold, K. Kausrud & B. Økland. 2007. The dispersal paradox: Are good dispersers poor invaders? Ecological Society of America Annual Meeting, August 5-10, San Jose, California. LINK
Often, A., Stabbetorp, O. & Økland, B. 2006. The role of imported pulpwood for the influx of invasive plants to Norway. Norwegian Journal of Geography 60(4): 295-302.
Reports and popular scientific publications
Endrestøl, A. & Økland, B. 2019. Fremmede insekter i skog og hage. Naturen 143(6): 257-271. PDF
Økland, B., Børja, I., Solheim, H., Rahlf, J., Fløistad, I. 2019. Risiko for import av fremmede arter og brudd på tømmerforordningen – trendanalyse av importstatistikk for tømmer og treprodukter. Nibio Rapport 5(69). 34s. PDF
Økland, B. 2018. Ips amitinus – en slektning av granbarkbillen på dørterskelen til Norge. In: Timmermann, V. (ed). Skogens helsetilstand i Norge. Resultater fra skogskadeovervåkingen i 2017. NIBIO Rapport 4(102): 49-54.
Flø, D., Thunes, K., Økland, B. 2017. Import av løvtreflis og risiko for innførsel av skadegjørere av biller. In: Timmermann, V. (ed). Skogens helsetilstand i Norge. Resultater fra skogskadeovervåkingen i 2016. NIBIO Rapport 3(107): 43-47.
Sundheim, L., Flø, D., Magnusson, C., Rafoss, T., Solheim, H. & Økland, B. 2013. Import of deciduous wood chips from eastern North America – pathway-initiated risk characterizations of relevant plant pests. Opinion of the Panel on Plant Health of the Norwegian Scientific Committee for Food Safety. PDF
Sundheim, L., Flø, D., Rafoss, T. & Økland, B. 2012. The EPPO PRA for Agrilus anxius: Assessment for Norwegian conditions. Opinion of the Panel on Plant Health of the Norwegian Scientific Committee for Food Safety. PDF
Sundheim, L., Flø, D., Rafoss, T. & Økland, B. 2012. Risikovurdering av planteskadegjøreren Anoplophora chinensis for Norge. Opinion of the Panel on Plant Health of the Norwegian Scientific Committee for Food Safety. [in Norwegian] PDF
Økland, B., Børja, I. and Often, A. 2012. Føre var eller aldri klar. Chronicle in VG, 17 June 2012. PDF
Økland, B., Børja, I., Often, A., Solheim, H. & Flø, D. 2012. Import av tømmer og andre treprodukter som innførselvei for fremmede insekter, sopp og planter - trendanalyse av importstatistikk. Rapport fra Skog og landskap 10/12: 137 s. PDF
Økland, B., Dalen, L.S. and Venn, K. 2011. Risiko for stor skade på skogen. Chronicle in Dagens Næringsliv, 1 February 2011. PDF
Sundheim, L., Økland, B., Magnusson, C., Solberg, B., Rafoss, T. 2010. Pest risk assessment of the Pine Wood Nematode (PWN) Bursaphelenchus xylophilus in Norway – Part 2. Opinion of the Plant Health Panel of the Scientific Committee for Food Safety, 08/906. PDF
Bergseng, E., Økland, B., Gobakken, T., Magnusson, C., Rafoss, T. and Solberg, B. 2010. Report on the economic impacts of the Norwegian contingency plan for Pine Wood Nematode (PWN) Bursaphelenchus xylophilus. Report from VKM to Mattilsynet. PDF
Økland 2009. Tredrepende barkbiller i Europa og Nord-Amerika. Glimt 06/09.
Sundheim, L., Økland, B., Magnusson, C., Solberg, B., Rafoss, T. 2008. Pest risk assessment of the Pine Wood Nematode (PWN) Bursaphelenchus xylophilus in Norway – Part 1. Opinion of the Plant Health Panel of the Scientific Committee for Food Safety, 18.09.08.
Økland, B. & Skarpaas, O. 2008. Draft pest risk assessment report on the small spruce bark beetle, Ips amitinus. Commissioned Report from Norwegian Forest and Landscape Institute 10/08: 20 pp. PDF
Økland, B., Skarpaas, O., Kausrud, K., Stenseth, N.C., Erbilgin, N. 2007. Spatiotemporal dynamics of introduced bark beetles. pp. 89-93 in Evans, H. and Oszako, T. (eds) Alien invasive species and trade. IUFRO Unit 7.03.12 Monograph. PDF
Kausrud, K., Økland, B., Skarpaas, O., Stenseth, N.C. & Erbilgin, N. 2007. Spatiotemporal dynamics of invasive bark beetles - modeling dispersal strategies. USDA Interagency Research Forum USDA General Technical Report-NRS-Proceedings 28: p. 42. PDF
Økland, B & Skarpaas, O. 2006. Risikovurdering av Ips amitinus ved tømmerimport - sannsynlighet for introduksjon og effekt på barkbilleutbrudd. Oppdragsrapport fra Skog og landskap 07/2006 PDF
Økland, B., Kvamme, T. & Wollebæk, G. 2005. Ny barkbilleart funnet overvintrende. Skogeieren 10/2005: 30-31 PDF
Økland, B. (ed.) 2004. Sopp, insekter og karplanter innført til Norge ved tømmerimport fra Russland og Baltikum. Aktuelt fra skogforskningen 5/2004: 1-24. PDF
Økland, B., Kvamme, T. & Thunes, K. 2004. Tømmerimport og innføring av insekter. Glimt fra skogforskningen 2-2004: 1-2. PDF
Kvamme, T., Thunes, K. & Økland, B. 2003. Insekter innført ved tømmerimport. In: Thunes, K. (ed.) Insekter, sopp og karplanter innført til Norge ved tømmerimport fra Russland og Baltikum 2002. Aktuelt fra skogforskningen 4/2003: 1-24.
Økland, B., Kvamme, T. & Thunes, K. 2003. Kan nye insekter introduseres med importtømmer? Aktuelt fra Skogforsk 6/03: 9-10.
Økland, B. 2002 (ed.). Insekter, sopp og karplanter innført til Norge ved tømmerimport fra Russland og Baltikum. Aktuelt fra skogforsk 2/02: 1 – 24.
Biodiversity
Forest management has a strong influence on the biodiversity of invertebrates, and the effects of similar management practice differ significantly for the various invertebrate taxa. There is a taxonomic bias in conservation research making insects, and especially less charismatic insect groups, underrepresented compared to their large species numbers.
Most woodland pastures were abandoned 40-80 years ago, and have been invaded by other trees during secondary succession. A more recent land use, thinning and harvesting of tops and branches for biofuel production, may possibly lead to a new region-wide transformation of qualities in overgrown oak-pasture lands in southern Scandinanvia. The relatively fast changes of the temperate forest landscapes present a challenge to biodiversity management (Götmark et al. 2009). A project leaded from the University of Göteborg examined effects on biodiversity in various organism groups: vascular plants, lichens, bryophytes, fungi, molluscs, saproxylic beetles (Franc et al. 2007), and mycetophilids (Kurina et al. 2005, Økland et al. 2005, 2008).
The coniferous forests constitute a large portion of the northern forest ecosystems and are strongly influenced by management due to their importance for forest economy. In addition to amount of dead wood, the diversity of saproxylic beetles in spruce forests is determined by the spatial distribution of dead wood (Økland et al. 1996), the composition of qualitatively different saproxylic habitats (Økland 1995, Komonen et al. 2004), stand structure (Hågvar & Økland 1997), and canopy cover (Økland 2002). Mycetophilids are in particular species-rich in boreal forests (Økland et al. 2005). These dipteran insects are frequently observed in dark and closed spruce forests, and they are often found in moist holes or under root jars, especially during dry periods. Large-scale logging appears to be unfavourable for mycetophilids (Økland 1994), and their species richness is increasing with the percentage area of oldgrowth forest in the landscape (Økland 1996).
Publications
Hågvar, S., Amundsen, T. & Økland, B. 2014. Mites of the genus Carabodes (Acari, Oribatida) in Norwegian coniferous forests: occurrence in different soils, vegetation types and polypore hosts. Scandinavian Journal of Forest Research 29(7), 629-638. PDF
Götmark, F., Nordén, B., Franc, N., Paltto, H., von Proschwitz, T., Økland, B. & Monrad Jensen, A. 2009. Naturvårdsgallring – vad är det? Biodiverse 1-2009: 20. PDF [in Swedish]
Økland, B., Götmark, F. & Nordén, B. 2008. Oak woodland restoration: testing the effects on biodiversity of mycetophilids in Sweden. Biodiversity & Conservation 17(11): 2599–2616. PDF
Økland, B., Götmark, F., Nordén, B., Franc, N., Kurina, O., Polevoi, A. 2005. Regional diversity of mycetophilids (Diptera: Sciaroidea) in Scandinavian temperate forests. Biological Conservation 121(1): 9-20. PDF
Kurina, O., Polevoi, A., Götmark, F., Økland, B., Frank, N., Norden, B. & Hedmark, K. 2005. Fungus gnats (Diptera: Sciaroidea excl. Sciaridae) in the Swedish boreonemoral forests. - Studia Dipterologica, 11 (2004), Heft 2: 471 - 488.
Franc, N., Götmark, F., Økland, B., Nordén, B. & Paltto, H. 2007. Factors and scales potentially important for saproxylic beetles in temperate mixed oak forest. Biological Conservation 135: 86-98. PDF
Komonen, A, Jonsell, M. & Økland, B. 2004. Insect assemblage associated with the polypore Fomitopsis pinicola: a comparison across Fennoscandia. Ent. Fenn. 15: 102-112.
Økland, B. 2002. Canopy cover favours sporocarp-visiting beetles in spruce forests. Norw. J. Entomol. 49: 29-39. PDF
Økland, B. 2000. Management effects on the decomposer fauna of Diptera in spruce forests. Studia Dipterologica 7(1): 213-223.
Hågvar, S. & Økland, B. 1997. Saproxylic beetle fauna associated with living sporocarps of Fomitopsis pinicola (Fr.) Karst. in four spruce forests with different management histories. Fauna norv. Ser. B 44: 95-105. PDF
Økland, B., Bakke, A., Hågvar, S. and Kvamme, T. 1996. What factors influence the diversity of saproxylic beetles? A multiscaled study from a spruce forest in southern Norway. Biodiversity and Conservation 5: 75-100. PDF
Økland, B. 1996. A comparison of three methods of sampling saproxylic beetles. European Journal of Entomology 93: 195-209.
Økland, B. 1996. Unlogged forests: Important sites for preserving the diversity of mycetophilids (Diptera: Sciaroidea). Biological Conservation 76: 297-310. PDF
Økland, B. 1995. Insect fauna compared between six polypore species in a southern Norwegian spruce forest. Fauna norv. Ser. B. 42: 21-26. PDF
Økland, B. 1994. Mycetophilidae (Diptera), an insect group vulnerable to forestry? A comparison of clearcut, managed and semi-natural spruce forests in southern Norway. Biodiversity and Conservation 3: 68-85. PDF