Browsing NTNU Open by Author "Hansen, Brage Bremset"

Now showing items 1-20 of 59

    • A new NDVI measure that overcomes data sparsity in cloud-covered regions predicts annual variation in ground-based estimates of high arctic plant productivity 

      Karlsen, Stein Rune; Anderson, Helen B.; van der Wal, René; Hansen, Brage Bremset (Journal article; Peer reviewed, 2018)
      Efforts to estimate plant productivity using satellite data can be frustrated by the presence of cloud cover. We developed a new method to overcome this problem, focussing on the high-arctic archipelago of Svalbard where ...

    • Adaptation to the High-Arctic island environment despite long-term reduced genetic variation in Svalbard reindeer 

      Dussex, Nicolas; Tørresen, Ole Kristian; van der Valk, Tom; Le Moullec, Mathilde; Veiberg, Vebjørn; Tooming-Klunderud, Ave; Skage, Morten; Garmann-Aarhus, Benedicte; Wood, Jonathan; Rasmussen, Jacob Agerbo; Pedersen, Åshild Ønvik; Martin, Sarah Louise; Røed, Knut; Jakobsen, Kjetill Sigurd; Dalén, Love; Hansen, Brage Bremset; Martin, Michael David (Peer reviewed; Journal article, 2023)
      Typically much smaller in number than their mainland counterparts, island populations are ideal systems to investigate genetic threats to small populations. The Svalbard reindeer (Rangifer tarandus platyrhynchus) is an ...

    • Adaptation to the High-Arctic island environment despite long-term reduced genetic variation in Svalbard reindeer 

      Dussex, Nicolas; Tørresen, Ole Kristian; van der Valk, Tom; Le Moullec, Mathilde; Veiberg, Vebjørn; Tooming-Klunderud, Ave; Skage, Morten; Garmann-Aarhus, Benedicte; Wood, Jonathan; Rasmussen, Jacob Agerbo; Pedersen, Åshild Ønvik; Martin, Sarah Louise; Røed, Knut; Jakobsen, Kjetill Sigurd; Dalén, Love; Hansen, Brage Bremset; Martin, Michael David (Peer reviewed; Journal article, 2023)
      Typically much smaller in number than their mainland counterparts, island populations are ideal systems to investigate genetic threats to small populations. The Svalbard reindeer (Rangifer tarandus platyrhynchus) is an ...

    • An integrated population model for a long-lived ungulate: more efficient data use with Bayesian methods 

      Lee, Aline Magdalena; Bjørkvoll, Eirin Marie; Hansen, Brage Bremset; Albon, Steve D.; Stien, Audun; Sæther, Bernt-Erik; Engen, Steinar; Veiberg, Vebjørn; Loe, Leif Egil; Grøtan, Vidar (Journal article, 2015)
      We develop an integrated population model for Svalbard reindeer Rangifer tarandus platyrhynchus, and demonstrate how this type of model can be used to extract more information from the data and separate different sources ...

    • Annual ring growth of a widespread high arctic shrub reflects past fluctuations in community‐level plant biomass 

      Le Moullec, Mathilde; Buchwal, Agata; van der Wal, René; Sandal, Lisa; Hansen, Brage Bremset (Journal article; Peer reviewed, 2018)
      1. Long time series of primary production are rarely available, restricting our mechanistic understanding of vegetation and ecosystem dynamics under climate change. Dendrochronological tools are increasingly used instead, ...

    • Behavioral buffering of extreme weather events in a high-Arctic herbivore 

      Loe, Leif Egil; Hansen, Brage Bremset; Stien, Audun; Albon, Steve D.; Bischof, Richard; Carlsson, Anja M.; Irvine, Justin; Meland, Morten; Rivrud, Inger Maren; Ropstad, Erik; Veiberg, Vebjørn; Mysterud, Atle (Journal article; Peer reviewed, 2016)
      As global warming advances, there is a growing concern about the impact of extreme weather events on ecosystems. In the Arctic, more frequent unseasonal warm spells and rain-on- snow events in winter cause changes in ...

    • Body mass growth in nestlings of Svalbard snow buntings (Plectrophenax nivalis) in response to seasonal variation in arthropod biomass 

      Hilmarsen, Kjerstin Bakken (Master thesis, 2020)
      Hekkende fugler står overfor et utall avveininger i løpet av deres livssyklus for å maksimere overlevelse og reproduksjon som fører til høy levedyktighet. For trekkfugler inkluderer en av disse avveiningene når de skal ...

    • Changes in greening in the High Arctic - insights from a 30-year AVHRR max NDVI dataset for Svalbard 

      Vickers, Hannah; Høgda, Kjell Arild; Solbø, Stian; Karlsen, Stein Rune; Tømmervik, Hans; Aanes, Ronny; Hansen, Brage Bremset (Journal article; Peer reviewed, 2016)
      Satellite-aided studies ofvegetation cover, biomass and productivity are becoming increasingly important for monitoring the effects ofa changing climate on the biosphere. With their large spatial coverage and good temporal ...

    • Climate and density-dependence cause changes in adult sex ratio in a large Arctic herbivore 

      Peeters, Bart; Veiberg, Vebjørn; Pedersen, Åshild Ønvik; Stien, Audun; Irvine, Robert Justin; Aanes, Ronny; Sæther, Bernt-Erik; Strand, Olav; Hansen, Brage Bremset (Journal article; Peer reviewed, 2017)
      Variation in adult sex ratio (ASR) affects population demography and dynamics of large mammals. The mechanisms behind this variation are largely unclear, but may be partly related to climatic drivers and density dependence ...

    • Climate change influences reproduction in Arctic breeding geese through altered predator-prey interactions 

      Sætre, Mikael Andreas (Master thesis, 2022)
      Klimaendringer påvirker Arktiske herbivorer både direkte og indirekte gjennom endringer i tilgang på ressurser. I senere tid er det også funnet bevis som indikerer at effektene av klimaendringer også kan forekomme gjennom ...

    • Climate Events Synchronize the Dynamics of a Resident Vertebrate Community in the High Arctic 

      Hansen, Brage Bremset; Grøtan, Vidar; Aanes, Ronny; Sæther, Bernt-Erik; Stien, Audun; Fuglei, Eva; Ims, Rolf Anker; Yoccoz, Nigel; Pedersen, Åshild Ønvik (Journal article; Peer reviewed, 2013)
      Recently accumulated evidence has documented a climate impact on the demography and dynamics of single species, yet the impact at the community level is poorly understood. Here, we show that in Svalbard in the high Arctic, ...

    • Contrasting consequences of climate change for migratory geese: Predation, density dependence and carryover effects offset benefits of high‐arctic warming 

      Layton-Matthews, Kate; Hansen, Brage Bremset; Grøtan, Vidar; Fuglei, Eva; Loonen, Maarten J.J.E. (Journal article; Peer reviewed, 2019)
      Climate change is most rapid in the Arctic, posing both benefits and challenges for migratory herbivores. However, population‐dynamic responses to climate change are generally difficult to predict, due to concurrent changes ...

    • Contrasting effects of summer and winter warming onbody mass explain population dynamics in a food-limitedArctic herbivore 

      Albon, Steve D.; Irvine, R. Justin; Halvorsen, Odd; Langvatn, Rolf; Loe, Leif Egil; Ropstad, Erik; Veiberg, Vebjørn; van der Wal, René; Bjørkvoll, Eirin Marie; Duff, Elizabeth I.; Hansen, Brage Bremset; Lee, Aline Magdalena; Tveraa, Torkild; Stien, Audun (Journal article; Peer reviewed, 2016)
      The cumulative effects of climate warming on herbivore vital rates and population dynamics are hard to predict, given that the expected effects differ between seasons. In the Arctic, warmer summers enhance plant growth ...

    • Contrasting genomic consequences of anthropogenic reintroduction and natural recolonization in high-arctic wild reindeer 

      Burnett, Hamish Andrew; Bieker, Vanessa Carina; Le Moullec, Mathilde; Peeters, Bart; Rosvold, Jørgen; Pedersen, Åshild Ønvik; Dalén, Love; Loe, Leif Egil; Jensen, Henrik; Hansen, Brage Bremset; Martin, Michael David (Peer reviewed; Journal article, 2023)
      Anthropogenic reintroduction can supplement natural recolonization in reestablishing a species' distribution and abundance. However, both reintroductions and recolonizations can give rise to founder effects that reduce ...

    • Cratering behaviour and faecal C:N ratio in relation to seasonal snow-pack characteristics in a High-Arctic ungulate 

      Beumer, Larissa Teresa; Varpe, Øystein; Hansen, Brage Bremset (Journal article; Peer reviewed, 2017)
      Snow and ice determine winter forage availability for Arctic herbivores. Winter precipitation is anticipated to increase, and icing following warm spells and rain-on-snow (ROS) are likely to become more frequent. While ...

    • Demographic buffering of life histories? Implications of the choice of measurement scale 

      Bjørkvoll, Eirin Marie; Lee, Aline Magdalena; Grøtan, Vidar; Sæther, Bernt-Erik; Stien, Audun; Engen, Steinar; Albon, Steve D.; Loe, Leif Egil; Hansen, Brage Bremset (Journal article; Peer reviewed, 2016)
      Life-history theory predicts that the vital rates that influence population growth the most should be buffered against environmental fluctuations due to selection for reduced variation. However, it remains unclear whether ...

    • Density‐dependent population dynamics of a high Arctic capital breeder, the barnacle goose 

      Layton-Matthews, Kate; Loonen, M. J. J. E; Hansen, Brage Bremset; Coste, Christophe Francois Daniel; Sæther, Bernt-Erik; Grøtan, Vidar (Journal article; Peer reviewed, 2019)
      Density regulation of the population growth rate occurs through negative feedbacks on underlying vital rates, in response to increasing population size. Here, we examine in a capital breeder how vital rates of different ...

    • Developing common protocols to measure tundra herbivory across spatial scales 

      Barrio, Isabel C.; Ehrich, Dorothee; Soininen, Eeva M; Ravolainen, Virve; Bueno, C. G.; Gilg, Olivier; Koltz, Amanda; Speed, James David Mervyn; Hik, David S.; Mörsdorf, M.; Alatalo, Juha M.; Angerbjørn, A.; Bêty, Joël; Bollache, L.; Boulanger-Lapointe, N.; Brown, G. S.; Eischeid, Isabell; Giroux, M. A.; Hajek, T.; Hansen, Brage Bremset; Hofhius, S. P.; Lamarre, J.-F.; Lang, J.; Latty, C.; Lecomte, N.; Macek, P.; McKinnon, L.; Myers-Smith, I. H.; Pedersen, Åshild Ønvik; Prevey, J. S.; Roth, J. D.; Saalfeld, S. T.; Schmidt, N. M.; Smith, P.; Sokolov, A.; Sokolova, N.; Stolz, C.; van Bemmelen, R.; Varpe, Øystein; Woodard, P. F.; Jonsdottir, I. S. (Peer reviewed; Journal article, 2021)
      Understanding and predicting large-scale ecological responses to global environmental change requires comparative studies across geographic scales with coordinated efforts and standardized methodologies. We designed, ...

    • Don't go chasing the ghosts of the past: habitat selection and site fidelity during calving in an Arctic ungulate 

      Paulsen, Ingrid M.; Soininen, Eeva M; Ravolainen, Virve; Loe, Leif Egil; Hansen, Brage Bremset; Irvine, Justin R; Stien, Audun; Ropstad, Erik; Veiberg, Vebjørn; Fuglei, Eva; Pedersen, Åshild Ønvik (Peer reviewed; Journal article, 2021)
      Predator avoidance and food availability are both factors known to influence habitat selection and site fidelity around calving in caribou and reindeer. Here, we assess habitat selection and site fidelity during the calving ...

    • Effects of arthropod abundance on reproductive success in Svalbard snow bunting (Plectrophenax nivalis) 

      Gravelsæther, Maria Angelil (Master thesis, 2021)
      Arktisk oppvarming fører til store miljøforandringer og biologiske forandringer, samt påvirker trofiske interaksjoner. Effekter av klimaforandringer har allerede blitt observert hos flere arktis-hekkende trekkfugler, med ...