Blar i NTNU Open på forfatter "Grøtan, Vidar"
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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 ... -
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 ... -
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 ... -
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 ... -
Demographic routes to variability and regulation in bird populations
Sæther, Bernt-Erik; Grøtan, Vidar; Engen, Steinar; Coulson, Tim; Grant, Peter R.; Visser, Marcel E.; Brommer, Jon E.; Grant, B. Rosemary; Gustafsson, Lars; Hatchwell, Ben J.; Jerstad, Kurt; Karell, Patrik; Pietiäinen, Hannu; Roulin, Alexandre; Røstad, Ole Wiggo; Weimerskirch, Henri (Journal article; Peer reviewed, 2016)There is large interspecific variation in the magnitude of population fluctuations, even among closely related species. The factors generating this variation are not well understood, primarily because of the challenges ... -
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 ... -
Effects of Experimental Icing and Summer Warming on the Polar Willow Salix polaris on Svalbard
Grotheim, Marta Dahl (Master thesis, 2017)The effects of climate change are particularly strong in the Arctic, where temperatures are increasing rapidly. While a clear trend of a more productive and greener Arctic in response to summer warming has been confirmed ... -
Effects of experimental winter icing and summer warming on high Arctic tundra vascular plants: a comparison of growth forms
Haraldsen, Hanne Kristin (Master thesis, 2017)No other place has experienced such pronounced changes in temperature and precipitation due to climate change, as the terrestrial Arctic. Ecological responses to warmer summers are already well documented, yet the responses ... -
Elgen i Norge sett med jegerøyne. En analyse av jaktmaterialet fra overvå-kingsprogrammet for elg og det samlede sett elg-materialet for perioden 1966-2004
Solberg, Erling Johan; Rolandsen, Christer Moe; Heim, Morten; Grøtan, Vidar; Garel, Mathieu; Sæther, Bernt-Erik; Nilsen, Erlend Birkeland; Austrheim, Gunnar; Herfindal, Ivar (NINA rapport;125, Research report, 2006)Elgen er en viktig utmarksressurs i Norge. Som et ledd i overvåkingen av denne ressursen be-nyttes elgjegere til å samle inn forskjellig type data fra observerte og felte elg under jakta hvert år. Dette materialet er i ... -
Environmental correlates of variation in a holistic analysis of annual offspring production in the high Arctic songbird snow bunting (Plectrophenax nivalis) on Spitsbergen
Egil Lillehaug (Master thesis, 2019)Klima og vær er viktige abiotiske faktorer som påvirker organismer, spesielt i områder med store værforskjeller, som Arktis. Hvordan været påvirker reproduksjonssuksessen til en fugl som hekker der er spesielt interessant ... -
Family planning in the high Arctic: earlier spring onset advances age at first successful reproduction in barnacle geese
Fjelldal, Mari Aas (Master thesis, 2018)I en verden under oppvarming der arter møter nye miljøforandringer er evalueringen av klimaeffekter på individnivå gjennom livshistorie egenskaper viktig for å forstå langtids- utsiktene til naturlige populasjoner. ... -
Fragmented tropical forests lose mutualistic plant–animal interactions
Marjakangas, Emma-Liina; Abrego, Nerea; Grøtan, Vidar; de Lima, Renato A.F.; Bello, Caroline; Bovendorp, Ricardo S; Laurence, Culot; Hasui, Érica; Lima, Fernando; Muylaert, Renata Lara; Niebuhr, Bernardo Brandão; Oliveira, Alexandre A.; Pereira, Lucas Augusto; Prado, Paulo I.; Stevens, Richard D.; Vancine, Maurício Humberto; Ribeiro, Milton Cezar; Galetti, Mauro; Ovaskainen, Otso (Journal article; Peer reviewed, 2019)Aim Forest fragmentation is among the principal causes of global biodiversity loss, yet how it affects mutualistic interactions between plants and animals at large spatial scale is poorly understood. In particular, ... -
Habitat characteristics and small-scale variation in life history traits of a large herbivore
Langen, Siri Hånes (Master thesis, 2018)Identification of habitat characteristics shaping small-scale variation in life history traits is important for our understanding of the magnitude of small-scale resource utilisation for different life history traits. Based ... -
Interactions between demography and environmental effects are important determinants of population dynamics
Gamelon, Marlène; Grøtan, Vidar; Nilsson, Anna L. K.; Engen, Steinar; Hurrell, James W.; Jerstad, Kurt; Phillips, Adam S.; Røstad, Ole Wiggo; Slagsvold, Tore; Walseng, Bjørn; Stenseth, Nils Christian; Sæther, Bernt-Erik (Journal article; Peer reviewed, 2017)Climate change will affect the population dynamics of many species, yet the consequences for the long-term persistence of populations are poorly understood. A major reason for this is that density-dependent feedback effects ... -
Interactions between demography and environmental effects are important determinants of population dynamics
Gamelon, Marlène; Grøtan, Vidar; Nilsson, Anna; Engen, Steinar; Hurrell, James W.; Jerstad, Kurt; Phillips, Adam S.; Røstad, Ole Wiggo; Slagsvold, Tore; Walseng, Bjørn; Stenseth, Nils Christian; Sæther, Bernt-Erik (Journal article; Peer reviewed, 2017)Climate change will affect the population dynamics of many species, yet the consequences for the long-term persistence of populations are poorly understood. A major reason for this is that density-dependent feedback effects ... -
More frequent extreme climate events stabilize reindeer population dynamics
Hansen, Brage Bremset; Gamelon, Marlène; Albon, Steve D.; Lee, Aline Magdalena; Stien, Audun; Irvine, Robert Justin; Sæther, Bernt-Erik; Loe, Leif Egil; Ropstad, Erik; Veiberg, Vebjørn; Grøtan, Vidar (Journal article; Peer reviewed, 2019)Extreme climate events often cause population crashes but are difficult to account for in population-dynamic studies. Especially in long-lived animals, density dependence and demography may induce lagged impacts of ... -
Spatial heterogeneity in climate change effects decouples the long‐term dynamics of wild reindeer populations in the high Arctic
Hansen, Brage Bremset; Pedersen, Åshild Ønvik; Peeters, Bart; Le Moullec, Mathilde; Albon, Steve D.; Herfindal, Ivar; Sæther, Bernt-Erik; Grøtan, Vidar; Aanes, Ronny (Journal article; Peer reviewed, 2019)The ‘Moran effect’ predicts that dynamics of populations of a species are synchronized over similar distances as their environmental drivers. Strong population synchrony reduces species viability, but spatial heterogeneity ... -
Spatiotemporal patterns of plant growth in a warming high Arctic: insights from dendrochronology of Salix polaris
Sandal, Lisa (Master thesis, 2017)Climate change is most pronounced at high latitudes, where plant and animal populations are often strongly regulated by environmental drivers. Theory suggests that if these environmental drivers are synchronized over large ... -
Stochastic rain events increase NDVI through moss water content: a High-Arctic field experiment
Valøen, Kristine (Master thesis, 2019)Målinger av ”Normalized Difference Vegetation Index” (NDVI) gjennom fjernmålinger blir brukt til å indikere produktiviteten til vegetasjonen i Høyarktis, og hvordan den påvirkes av klimaendringer. Tolkningen av observerte ...