Bilde av Oksanen, Lauri Kalervo
Bilde av Oksanen, Lauri Kalervo
Institutt for arktisk og marin biologi lauri.k.oksanen@uit.no

Lauri Kalervo Oksanen


Professor Emeritus


  • Gilles Gauthier, Dorothee Ehrich, Maria Belke-Brea, Florent Dominé, Ray Alisauskas, Karin Clark m.fl.:
    Taking the beat of the Arctic: are lemming population cycles changing due to winter climate?
    Proceedings of the Royal Society of London. Biological Sciences 2024 DOI
  • Lauri Oksanen :
    Poroja tarvitaan tunturiluonnon suojelussa
    Helsingin sanomat 25. oktober 2023
  • Lauri Oksanen :
    evalauation of "About the invasions of the Norwegian lemming and other irregular animal migrations, with an overview of small rodent gradations in Finnish Lapland 1900-1948" by Olavi Kalela
    Faculty Opinions 2023 DOI
  • Lauri Oksanen, Katariina Elsa M Vuorinen, Tarja Maarit Oksanen :
    The paradox of searching efficiency or why are violent population cycles so uncommon in terrestrial ecosystem
    Oikos 2023 ARKIV / DOI
  • Katariina Elsa Maria Vuorinen, Tarja Maarit Oksanen, Lauri Oksanen, Timo Vuorisalo, James David Mervyn Speed :
    Why don't all species overexploit?
    Oikos 2021 ARKIV / DOI
  • Lauri Oksanen :
    Oksanen L: Faculty Opinions Recommendation of [Neutel AM et al., Nature 2007 449(7162):599-602
    Faculty Opinions 2021 DOI
  • Lauri Oksanen :
    Oksanen L: Faculty Opinions Recommendation of [Tanhuanpää M et al., J Anim Ecol 1999 68(3):562-570].
    Faculty Opinions 2021 DOI
  • Lauri Oksanen :
    Oksanen L: Faculty Opinions Recommendation of [Tanentzap AJ and Smith BR, Philos Trans R Soc Lond B Biol Sci 2018 373(1761)].
    Faculty Opinions 2021 DOI
  • Lauri Oksanen :
    Oksanen L: Faculty Opinions Recommendation of [Fischer W et al., Biogeosci Discuss 2021 :preprint]. In Faculty Opinions, 12 Oct 2021
    Faculty Opinions 2021 DOI
  • Lauri Oksanen :
    Faculty Opinions Recommendation of [Bråthen KA et al., Front Ecol Environ 2021]. In Faculty Opinions, 14 Oct 2021
    Faculty Opinions 2021 DOI
  • Tarja Maarit Oksanen, Lauri Oksanen, Katariina Vuorinen, Christopher Wolf, Aurelia Mäkynen, Johan Olofsson m.fl.:
    The impact of thermal seasonality on terrestrial endotherm food web dynamics: a revision of the Exploitation Ecosystem Hypothesis
    Ecography 2020 ARKIV / DATA / DOI
  • Dorothee Ehrich, Niels M. Schmidt, Gilles Gauthier, Ray Alisauskas, Anders Angerbjörn, Karin Clark m.fl.:
    Documenting lemming population change in the Arctic: Can we detect trends?
    Ambio 2019 ARKIV / DOI
  • Fidele Bognounou, Philip E. Hulme, Lauri Oksanen, Otso Suominen, Johan Olofsson :
    Role of climate and herbivory on native and alien conifer seedling recruitment at and above the Fennoscandian tree line
    Journal of Vegetation Science (JVS) 2018 DOI
  • Lauri Oksanen, Johan Olofsson :
    Vertebrate Herbivory and Its Ecosystem Consequences
    Encyclopedia of Life Sciences 2018 DOI
  • Maria Wilhelmina Tuomi, Sari Stark, Katrine Skamfer Hoset, Maria Väisänen, Lauri Oksanen, Francisco Javier Ancin Murguzur m.fl.:
    Herbivore Effects on Ecosystem Process Rates in a Low-Productive System
    Ecosystems 2018 FULLTEKST / ARKIV / DOI
  • Henni Ylänne, Johan Olofsson, Lauri Kalervo Oksanen, Sari Stark :
    Consequences of grazer-induced vegetation transitions on ecosystem carbon storage in the tundra
    Functional Ecology 2017 DOI
  • Katariina Vuorinen, Lauri Kalervo Oksanen, Tarja Maarit Oksanen, Anni Pyykönen, Johan Olofsson, Risto Virtanen :
    Open tundra persist, but arctic features decline - vegetation changes in the warming Fennoscandian tundra
    Global Change Biology 2017 DOI
  • Tim Horstkotte, Tove Aagnes Utsi, Åsa Larsson-Blind, Peter Burgess, Bernt Johansen, Jukka Kayhko m.fl.:
    Human-animal agency in reindeer management: Sami herders perspectives on vegetation dynamics under climate change
    Ecosphere 2017 ARKIV / DOI
  • Katrine S. Hoset, Lise Ruffino, Maria Wilhelmina Tuomi, Tarja Maarit Oksanen, Lauri Kalervo Oksanen, Aurelia Mäkynen m.fl.:
    Changes in the spatial configuration and strength of trophic control across a productivity gradient during a massive rodent outbreak
    Ecosystems 2017 DOI
  • Risto Virtanen, Lauri Kalervo Oksanen, Tarja Maarit Oksanen, Juval Cohen, Bruce C. Forbes, Bernt Johansen m.fl.:
    Where do the treeless tundra areas of northern highlands fit in the global biome system: toward an ecologically natural subdivision of the tundra biome
    Ecology and Evolution 2016 ARKIV / DOI
  • Lise Ruffino, Tarja Maarit Oksanen, Katrine S. Hoset, Maria Tuomi, Lauri Kalervo Oksanen, Erkki Korpimäki m.fl.:
    Predator–rodent–plant interactions along a coast–inland gradient in Fennoscandian tundra
    Ecography 2016 ARKIV / DOI
  • Katrine S. Hoset, Kukka Kyrö, Tarja Oksanen, Lauri Kalervo Oksanen , Johan Olofsson :
    Spatial variation in vegetation damage relative to primary productivity, small rodent abundance and predation
    Ecography 2014 DOI
  • Johan Olofsson, Lauri Kalervo Oksanen , Tarja Maarit Oksanen, Maria Wilhelmina Tuomi, Katrine S. Hoset, Risto Virtanen m.fl.:
    Long-Term Experiments Reveal Strong Interactions Between Lemmings and Plants in the Fennoscandian Highland Tundra
    Ecosystems 2014 DOI
  • Mari Lyly, Tero Klemola, Elina Koivisto, Otso Huitu, Lauri Kalervo Oksanen , Erkki Korpimäki :
    Varying impacts of cervid, hare and vole browsing on growth and survival of boreal tree seedlings
    Oecologia 2014 DOI
  • Juval Cohen, Jouni Pulliainen, Cecile B Menard, Bernt Johansen, Lauri Kalervo Oksanen , Kari Luojus m.fl.:
    Effect of reindeer grazing on snowmelt, albedo and energy balance based on satellite data analyses
    Remote Sensing of Environment 2013 DOI
  • Tarja Oksanen, Lauri Kalervo Oksanen , Gunnar Johannes Søderbacka , Katrine S. Hoset, Lise Ruffino, Maria Tuomi :
    Impact of marine-subsidized predators on lemming-plant oscillations
    Evolutionary Ecology Research 2013
  • Risto Virtanen, John Arvid Grytnes, Jonathan Lenoir, Miska Luoto, Jari Oksanen, Lauri Kalervo Oksanen m.fl.:
    Productivity-diversity patterns in arctic tundra vegetation
    Ecography 2013 DOI
  • Jonathan Lenoir, Risto Virtanen, Jari Oksanen, Lauri Kalervo Oksanen , Miska Luoto, John Arvid Grytnes m.fl.:
    Dispersal ability links to cross-scale species diversity patterns across the Eurasian Arctic tundra
    Global Ecology and Biogeography 2012 DOI
  • James A. Estes, John Terborgh, Justin S. Brashares, Mary E. Power, Joel Berger, William J. Bond m.fl.:
    Trophic Downgrading of Planet Earth
    Science 2011 DOI
  • Lauri Oksanen :
    Tunturit ovat poronhoidon kulttuurimaisemaa
    Poromies 04. desember 2023
  • Lauri Oksanen :
    Tunturit ovat poronhoidon kulttuurimaisemaa
    Helsingin sanomat 01. oktober 2023
  • Lauri Oksanen :
    Oksanen L: Faculty Opinions Recommendation of [Biuw M et al., Ecosystems 2022 17(5:890-905)]
    Svart á hvítu 2022 DOI
  • Lauri Oksanen :
    Oksanen L: Faculty Opinions Recommendation of [Lagerholm VK et al., Mol Ecol 2022 23(8:2060-2071)]. In Faculty Opinions, 24 Aug 2022;
    Faculty Opinions 2022 DOI
  • Lauri Oksanen :
    Oksanen L: Faculty Opinions Recommendation of [Holt RD, Theor Popul Biol 2022 12(2:197-129)]. In Faculty Opinions, 09 Nov 2022;
    Faculty Opinions 2022 DOI
  • Katariina Elsa Maria Vuorinen, Tarja Maarit Oksanen, Lauri Oksanen, James David Mervyn Speed, Timo Vuorisalo :
    Erratum to: Why don't all species overexploit (Oikos, (2021), 130, 11, (1835-1848), 10.1111/oik.08358)
    Oikos 2021 DOI
  • Dorothee Ehrich, Niels M. Schmidt, Gilles Gauthier, Ray Alisauskas, Anders Angerbjörn, Karin Clark m.fl.:
    Correction to: Documenting lemming population change in the Arctic: Can we detect trends?
    Ambio 2020 DOI
  • Lauri Oksanen :
    Correction: Exploitation Ecosystems in Gradients of Primary Productivity (American Naturalist 118: 240–261)
    The American Naturalist 2020 DOI
  • Lauri Oksanen :
    Poro tunturiluonnossa: ongelma vai ratkaisu?
    2019
  • Lauri Oksanen :
    Poro tunturiluonnossa: ongelma vai ratkaisu?
    2019
  • Lauri Oksanen :
    Kesälaidunnus ei ole ylilaidunnusta
    Poromies 2019 ARKIV
  • Lauri Oksanen :
    Tunturit, laidunnus ja kukat: näköaloja Jotunheimilta Pohjoiskalotille
    Poromies 2019 ARKIV
  • Lauri Kalervo Oksanen, Johan Olofsson :
    Renbetet inte skadligt för sällsynta fjällväxter
    Hufvudstadsbladet 30. oktober 2016 FULLTEKST
  • Lauri Kalervo Oksanen, Bruce C. Forbes, Jouko Kumpula, Timo kumpula, Jukka Käyhkö, Sari Stark :
    Laidunnus ei ole juuri lisännyt eroosiota (Beite har neppe skapt erosjon)
    Helsingin sanomat 29. september 2016 FULLTEKST
  • Bruce C. Forbes, Tim Horstkotte, Tove Aagnes Utsi, Åsa Larsson-Blind, Philip Burgess, Jukka Käyhkö m.fl.:
    Human-animal agency in reindeer management: Sami herders’ perspectives on Fennoscandian tundra vegetation dynamics under climate change
    2016 DATA
  • Lauri Kalervo Oksanen :
    Reindeer and tundra in a changing world: threats and opportunities (språk: engelsk og samisk)
    2015 ARKIV
  • J. Käyhkö, Tim Horstkotte, Sonja Kivinen, Jarmo Vehmas, Lauri Kalervo Oksanen, Bruce C. Forbes m.fl.:
    Warming Climate and Changing Societies - a Challenge or an Opportunity for Reindeer Herding
  • Jukka Käyhkö, Tim Horstkotte, Sonja Kivinen, Jarmo Vehmas, Lauri Oksanen, Bernt Johansen m.fl.:
    Warming Climate and Changing Societies – a Challenge or an Opportunity for Reindeer Herding?
    2015
  • J. Käyhkö, Lauri Kalervo Oksanen , Tim Horstkotte, Sonja Kivinen, Tarja Oksanen, Pekka Niemelä m.fl.:
    Can reindeer grazing stop expansion of woody vegetation in the warming tundra?
    2014 FULLTEKST / DATA
  • Käyhkö Jukka, Lauri Kalervo Oksanen , Lars Ericson, Bruce C. Forbes, Tim Horstkotte, Rolf Anker Ims m.fl.:
    How to preserve the tundra in a warming climate?
    2013 DATA
  • Tove Aagnes Utsi , Lauri Kalervo Oksanen , Rune Muladal :
    Hvordan bevare tundraen i et varmere klima?
    01. mai 2013 DATA / FULLTEKST

  • De 50 siste resultatene fra Cristin vises på siden. Se alle arbeider i Cristin her →


    Forskningsinteresser

    Research perspectives

    The backbone of my research is the Exploitation Ecosystem’s Hypothesis (EEH, Oksanen et al. 1981, Am. Nat. 118: 240-261) which states that, everything else being equal, the strong interaction will inevitably shift from the predator-herbivore interface to the herbivore-plant interface, as there must be a productivity threshold where the herbivore density required for zero population growth by predators exceeds the density that the slowly growing vegetation can sustain. During the past decade, my research team has shown that this “everything else being equal” clause holds for the productivity gradients of northernmost Norway, where the critical threshold corresponds to the transition from low arctic shrublands to the tundra proper (see publications in Cristin). The success of EEH in organizing our ideas on food web dynamics has also been confirmed by its inclusion in the new edition of “Foundations of Ecology”.

    In spite of its successes, EEH also has serious shortcomings, which I am now inspecting and remedying in collaboration with my colleague-wife Tarja Oksanen. In the 1981 paper, the “everything else being equal” clause was presented as if it were a fact, which is not true. In our recent paper (Oksanen, T., Oksanen, L., Vuorinen, K.E.M., Ripple, W.J., Wolf, C. Virtanen, R. Mäkynen, A., Olofsson, J., and Utsi, T. Aa. 2020. The impact of thermal seasonality on terrestrial endotherm food web dynamics: a revision of the Exploitation Ecosystem Hypothesis. – Ecography 43: 1859-1877) we explored the impact of thermal seasonality, which turned out to have a profound impact on the location of the critical productivity threshold. Without megaherbivores, the existence of wide areas where the strong interaction is between herbivores and plants requires genuine winters, when much of the energy fixed by plants is locked in the frozen soil and thus unavailable for herbivores.

    With megaherbivores present, the situation changes radically, even if they were not absolutely invulnerable (there were megapredators, too). High size diversity of herbivores implies that only a small fraction of the total herbivore stock is within the size interval that a given predator is adapted to exploit. The community level predator-herbivore equilibrium is therefore reached at essentially higher over-all herbivore density than in ecosystems with lower size diversity among herbivores. We are currently working on this issue.

    Moreover, EEH is no panacea for solving all ecological problems. When working with Norwegian lemmings and when discussing with our North American colleagues, we have become convinced that all lemmings are not born equal. There are essential dynamical and behavioral differences between the Norwegian lemming of Fennoscandia and its congeners. Behind the unique traits and dynamics of the Norwegian lemming lies a unique evolutionary history: its survival in a tiny set of refugia in the Andøya-Vesterålen region during the last glacial maximum (Lagerholm, V. K. et al. 2014. On the origin of the Norwegian lemming. – Molecular Ecology 23, 2060–2071). Moreover, modeling studies show that population cycles driven by the herbivore-plant interaction have two alternative stable states: one where herbivore peaks are extremely sharp and short-lived, being timed to the end of the growing season, and one where high densities are obtained in spring, making the area attractive for avian predators. We argue that the Norwegian lemming of Fennoscandia is locked in dynamics of the former type, while the latter type prevails elsewhere on the circumpolar tundra. The MS dealing with this issue is almost ready for submission.

    Terrestrial food web dynamics have also been studied by applying the ECOPATH method, based on energetic calculus and originally designed for studies on pelagic food webs. By comparing the results of ECOPATH to experimental evidence, we show that its applicability to terrestrial food web dynamics is limited. Strong herbivore-plant interactions can be accompanied by modest (less than 0.1) consumption to primary production ratios. A MS on this topic will get ready within a few months.

    At my age, an important task of a researcher is to ensure that the empirical studies conducted or initiated in the past will be useful for younger generations. This is especially important in the arctic where climate is changing rapidly. In 1976, I conducted a nested vegetation transect study on four different mountains, ranging from the continental inland of Finnish Lapland to the coastal mountains of Lyngen, Norway. One of these transect studies was repeated by two of my students, Katariina Vuorinen and Anne Pyykönen, in collaboration with some senior team members. The results were quite unexpected and extremely interesting (Vuorinen, K.E.M., et al. 2017. Open tundra persists, but arctic features decline: vegetation changes in the warming Fennoscandian tundra. – Global Change Biol. 23: 3794-3807). The other transect sites have now been marked in terrain and with GPS. Visual inspection indicated that the results will be equally exciting. (For instance, on the mountains at Kilpisjärvi, the formerly abundant arctic dwarf shrub Cassiope tetragona has been largely replaced by the wood rush Juncus trifidus, typical for South Scandinavian mountains.) These studies will be repeated as soon as possible.

    Another gift for the next generation is the EU-financed study “DART” (Dynamic response of the forest-tundra ecotone to environmental change 1998-2000), where the core idea was to seed and to plant treeline forming Eurasian trees – mountain birches, Norway spruces, Siberian larches and Scots pines – in sites at the current treeline, with and without pivotal herbivores. In the seeding study, conducted at Joatka tundra lodge, small and large herbivores were excluded using fences with different mesh sizes. In the planting study on the shores and islands of Iešjávri, a 68 km2 lake just at the treeline, water barriers were used for the same effect. The fences were repaired by me and Katariina Vuorinen last summer. The planted trees were individually marked and the GPS bearings of the planting lines were taken 2014. Survival and geowth of planted trees has been studied recurrwntly. Many planted trees and some of the sown ones are now getting tall enough to have their leader shoots rising above the snow surface (or trying to do so and getting killed). The study is now ready for inerested young ecologists to harvest the results. An unexpeted result was that the in the conditions of interior Finnmark, the currently domianting mountain birch performed worst: it germinated poorly, it has grown poorly even when planted, it has survivived poorly and it has been sensitive to herbivory. Pines initially grew and survived well (see Bognounou F. et al. 2018, J. Veget. Sci. 29: 573-584), but many have died in recent years. Acccording to my visual impressions, larches and spruces, which do not naturally occur in the area, have performed best, especially at Iešjávri.


    Medlem i forskningsgruppe