• Assessing the effect of predator control on an endangered goose population subjected to predator-mediated food web dynamics 

      Marolla, Filippo; Aarvak, Tomas; Øien, Ingar Jostein; Mellard, Jarad Pope; Henden, John-André; Hamel, Sandra; Stien, Audun; Tveraa, Torkild; Yoccoz, Nigel Gilles; Ims, Rolf Anker (Journal article; Tidsskriftartikkel; Peer reviewed, 2019-01-29)
      <ol> <li>Assessing the effectiveness of conservation actions to halt population declines is challenging when confounded by other factors. We assessed whether culling of red fox, a predator currently increasing in number in the sub‐Arctic, contributed to recent recovery of the critically endangered Fennoscandian population of Lesser White‐fronted Goose <i>Anser erythropus</i>, while controlling for ...
    • Beregning av produksjon og tap i reindriften 

      Tveraa, Torkild; Ballesteros, Manuel; Bårdsen, Bård-Jørgen; Fauchald, Per; Lagergren, Madeleine; Langeland, Knut; Pedersen, Elisabeth; Stien, Audun (Research report; Forskningsrapport, 2013-05)
      En økning i rovdyrbestandene i reinbeiteområdene regnes av næringen som den viktigste enkeltfaktoren som forårsaker lav kalvetilgang, store tap av dyr og derigjennom lav produksjon i tamreinflokkene i Norge. Endringer i reintall og klimatiske forhold er imidlertid også viktige faktorer som påvirker reproduksjon og overlevelse hos rein. Gitt at predasjon har stor innvirkning på reinens demografi ...
    • Berettiget kritikk av NMBU sin reindriftsforskning 

      Stien, Audun; Ims, Rolf Anker; Yoccoz, Nigel; Tveraa, Torkild; Stien, Jennifer (Chronicle; Kronikk, 2021-12-21)
      Det er flere elementer i artikkelen til NMBU-forskerne som fremstår som uforenlig med god vitenskapelig praksis.
    • Biodiversity may wax or wane depending on metrics or taxa 

      Yoccoz, Nigel Gilles; Ellingsen, Kari Elsa; Tveraa, Torkild (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-02-20)
      <i>Introduction</i>: Biodiversity changes have proven surprisingly complex to estimate and understand. While there are negative trends at a global scale such as the substantial losses of vertebrate species (1), changes at local scales may show large variation, with no clear overall trend (2, 3). Because assessing and improving the status of biodiversity are at the core of international agreements ...
    • Demersal fish assemblages in the boreo-Arctic shelf waters around Svalbard during the warm period 2007–2014 

      Bergstad, Odd Aksel; Johannesen, Edda; Høines, Åge Sigurd; Ellingsen, Kari Elsa; Lien, Vidar Surén; Byrkjedal, Ingvar; Yoccoz, Nigel Gilles; Tveraa, Torkild; Wienerroither, Rupert; Langhelle, Gunnar; Wenneck, Thomas de Lange (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-07-17)
      The temporal and spatial resilience of abundance patterns of assemblages of organisms inhabiting transition zones between Arctic and boreal regions is an issue of concern in relation to climate change. The recognition that baseline information spanning such transition zones is required to facilitate future monitoring and assessments of temporal dynamics provided the motivation for the present study. ...
    • Demographic effects of extreme weather events: snow storms, breeding success, and population growth rate in a long-lived Antarctic seabird 

      Descamps, Sebastian; Tarroux, Arnaud; Varpe, Øystein; Yoccoz, Nigel Gilles; Tveraa, Torkild; Lorentsen, Svein-Håkon (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-12-23)
      Weather extremes are one important element of ongoing climate change, but their impacts are poorly understood because they are, by definition, rare events. If the frequency and severity of extreme weather events increase, there is an urgent need to understand and predict the ecological consequences of such events. In this study, we aimed to quantify the effects of snow storms on nest survival ...
    • End-user involvement to improve predictions and management of populations with complex dynamics and multiple drivers 

      Henden, John-André; Ims, Rolf Anker; Yoccoz, Nigel; Asbjørnsen, Einar Johannes; Stien, Audun; Mellard, Jarad Pope; Tveraa, Torkild; Marolla, Filippo; Jepsen, Jane Uhd (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-11)
      Sustainable management of wildlife populations can be aided by building models that both identify current drivers of natural dynamics and provide near-term predictions of future states. We employed a Strategic Foresight Protocol (SFP) involving stakeholders to decide the purpose and structure of a dynamic state-space model for the population dynamics of the Willow Ptarmigan, a popular game species ...
    • Estimating the cumulative impact and zone of influence of anthropogenic features on biodiversity 

      Niebuhr, Bernardo Brandão; Van Moorter, Bram; Stien, Audun; Tveraa, Torkild; Strand, Olav; Langeland, Knut; Sandstrom, Per; Alam, Moudud; Skarin, Anna; Panzacchi, Manuela (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-06-02)
      1. The concept of cumulative impacts is widespread in policy documents, regu-lations and ecological studies, but quantification methods are still evolving. Infrastructure development usually takes place in landscapes with preexist-ing anthropogenic features. Typically, their impact is determined by computing the distance to the nearest feature only, thus ignoring the potential cumulative impacts of ...
    • The ghost of development past : the impact of economic security policies on Saami pastoral ecosystems 

      Hausner, Vera Helene; Fauchald, Per; Tveraa, Torkild; Pedersen, Elisabeth; Jernsletten, Johnny-Leo L.; Ulvevadet, Birgitte; Ims, Rolf Anker; Yoccoz, Nigel; Bråthen, Kari Anne (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      To ensure economic viability over time, any efforts to meet the Millennium Development Goals need to reconcile conservation with development interventions. Particularly, in marginal and risk prone areas erosion of resilience could make production systems more susceptible to environmental risks that compromise the economic security. By longitudinal analyses of long-term data records we investigated the ...
    • Long-term environmental monitoring for assessment of change: measurement inconsistencies over time and potential solutions 

      Ellingsen, Kari Elsa; Yoccoz, Nigel Gilles; Tveraa, Torkild; Hewitt, Judi E.; Thrush, Simon F. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-30)
      The importance of long-term environmental monitoring and research for detecting and understanding changes in ecosystems and human impacts on natural systems is widely acknowledged. Over the last decades, a number of critical components for successful long-term monitoring have been identified. One basic component is quality assurance/quality control protocols to ensure consistency and comparability ...
    • The neglected season: Warmer autumns counteract harsher winters and promote population growth in Arctic reindeer 

      Loe, Leif Egil; Liston, Glen E.; Pigeon, Gabriel; Barker, Kristin; Horvitz, Nir; Stien, Audun; Forchhammer, Mads C.; Getz, Wayne M.; Irvine, Robert Justin; Lee, Aline Magdalena; Movik, Lars K.; Mysterud, Atle; Pedersen, Åshild Ønvik; Reinking, Adele K.; Ropstad, Erik; Trondrud, Liv Monica; Tveraa, Torkild; Veiberg, Vebjørn; Hansen, Brage Bremset; Albon, Steve D. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-24)
      Arctic ungulates are experiencing the most rapid climate warming on Earth. While concerns have been raised that more frequent icing events may cause die‐offs, and earlier springs may generate a trophic mismatch in phenology, the effects of warming autumns have been largely neglected. We used 25 years of individual‐based data from a growing population of wild Svalbard reindeer, to test how warmer ...
    • Pastoral herding strategies and governmental management objectives: predation compensation as a risk buffering strategy in the Saami reindeer husbandry 

      Næss, Marius Warg; Bårdsen, Bård-Jørgen; Pedersen, Elisabeth; Tveraa, Torkild (Journal article; Tidsskriftartikkel; Peer reviewed, 2011-05-12)
      Previously it has been found that an important risk buffering strategy in the Saami reindeer husbandry in Norway is the accumulation of large herds of reindeer as this increases long-term household viability. Nevertheless, few studies have investigated how official policies, such as economic compensation for livestock losses, can influence pastoral strategies. This study investigated the effect of ...
    • Plastic reproductive allocation as a buffer against environmental stochasticity : linking life history and population dynamics to climate 

      Bårdsen, Bård-Jørgen; Henden, John-André; Fauchald, Per; Tveraa, Torkild; Stien, Audun (Journal article; Tidsskriftartikkel; Peer reviewed, 2011)
      Empirical work suggest that long-lived organisms have adopted risk sensitive reproductive strategies where individuals trade the amount of resources spent on reproduction versus survival according to expected future environmental conditions. Earlier studies also suggest that climate affects population dynamics both directly by affecting population vital rates and indirectly through long-term changes ...
    • Rangifer management controls a climate-sensitive tundra state transition 

      Bråthen, Kari Anne; Ravolainen, Virve Tuulia; Stien, Audun; Tveraa, Torkild; Ims, Rolf Anker (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-04)
      Rangifer (caribou/reindeer) management has been suggested to mitigate the temperature- driven transition of Arctic tundra into a shrubland state, yet how this happens is uncertain. Here we study this much focused ecosystem state transition in riparian areas, where palatable willows (Salix) are dominant tall shrubs and highly responsive to climate change. For the state transition to take place, ...
    • Reindeer behavioural ecology and use of pastures in pastoral livelihoods 

      Skarin, Anna; Kumpula, Jouko; Tveraa, Torkild; Åhman, Birgitta (Chapter; Bokkapittel, 2022)
      Reindeer pastoralists have, for centuries, followed free-roaming animals throughout the Eurasian Arctic. The closing of national borders about a century ago forced the reindeer pastoralists to adapt to new conditions. Today, environmental conditions are changing rapidly with climate and land use change. Local history, migration and pasture use strategies of reindeer herding, and also the biogeography ...
    • Resource‐driven colonization by cod in a high Arctic food web 

      Johannesen, Edda; Yoccoz, Nigel; Tveraa, Torkild; Schackell, Nancy L.; Ellingsen, Kari; Dolgov, Andrey V.; Frank, Kenneth T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-11-23)
      <ol> <li>Climate change is commonly associated with many species redistributions and the influence of other factors may be marginalized, especially in the rapidly warming Arctic.</li> <li>The Barents Sea, a high latitude large marine ecosystem in the Northeast Atlantic has experienced above‐average temperatures since the mid‐2000s with divergent bottom temperature trends at subregional ...
    • The rise of a marine generalist predator and the fall of beta diversity 

      Ellingsen, Kari; Yoccoz, Nigel; Tveraa, Torkild; Frank, Kenneth T.; Johannesen, Edda; Anderson, Marti J.; Dolgov, Andrey V.; Shackell, Nancy L. (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-03-17)
      Determining the importance of physical and biological drivers in shaping biodiversity in diverse ecosystems remains a global challenge. Advancements have been made towards this end in large marine ecosystems with several studies suggesting environmental forcing as the primary driver. However, both empirical and theoretical studies point to additional drivers of changes in diversity involving trophic ...
    • The role of a dominant predator in shaping biodiversity over space and time in a marine ecosystem 

      Ellingsen, Kari Elsa; Anderson, Marti J.; Shackell, Nancy L.; Tveraa, Torkild; Yoccoz, Nigel Gilles; Frank, Kenneth T. (Journal article; Tidsskriftartikkel; Peer reviewed, 2015-06-24)
      Exploitation of living marine resources has resulted in major changes to populations of targeted species and functional groups of large-bodied species in the ocean. However, the effects of overfishing and collapse of large top predators on the broad-scale biodiversity of oceanic ecosystems remain largely unexplored. Populations of the Atlantic cod (Gadus morhua) were overfished and several collapsed ...
    • The role of predation and food limitation on claims for compensation, reindeer demography and population dynamics 

      Tveraa, Torkild; Stien, Audun; Brøseth, Henrik; Yoccoz, Nigel Gilles (Journal article; Tidsskriftartikkel; Peer reviewed, 2014-10)
      1.A major challenge in biodiversity conservation is to facilitate viable populations of large apex predators in ecosystems where they were recently driven to ecological extinction due to resource conflict with humans. 2. Monetary compensation for losses of livestock due to predation is currently a key instrument to encourage human–carnivore coexistence. However, a lack of quantitative estimates ...
    • SEAPOP studies in the Barents and Norwegian Seas in 2007 

      Anker-Nilssen, Tycho; Barrett, Robert T.; Bustnes, J.O.; Christensen-Dalsgaard, Signe; Erikstad, K.E.; Fauchald, Per; Lorentsen, Svein-Håkon; Steen, Harald; Strøm, H.; Systad, Geir Helge; Tveraa, Torkild (Research report; Forskningsrapport, 2008-04)
      This is the third annual report of the SEAPOP programme, which was initiated in 2005. In 2007, the work continued at full scale in the Lofoten-Barents Sea area, and similar studies were initiated in the southern part of the Norwegian Sea. The report is divided into three sections. The first is an executive summary, the second presents five selected highlights from the studies in 2007, whereas the ...