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 ... -
Biodiversity dynamics in urban areas under changing land-uses
Petersen, Tanja Kofod (Doctoral theses at NTNU;2021:107, Doctoral thesis, 2021)Ecology goes to town Urbanisation is increasing worldwide, but as urban expansion inevitably happens at the cost of other ecosystems, understanding how this will affect biodiversity is crucial. Especially if we wish to ... -
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 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, ... -
Competitors and ruderals go to town: plant community composition and function along an urbanisation gradient
Petersen, Tanja Kofod; Speed, James David Mervyn; Grøtan, Vidar; Austrheim, Gunnar (Journal article; Peer reviewed, 2021)Urbanisation is expected to function as a filter for plant species by changing the physiochemical environment, causing species turnover along an urbanisation gradient. Analyses of the functional traits of species characteristic ... -
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 density, species interactions, and environmental stochasticity on the dynamics of British bird communities
Sandal, Lisa; Grøtan, Vidar; Sæther, Bernt-Erik; Freckleton, Robert P.; Noble, David G.; Ovaskainen, Otso (Journal article; Peer reviewed, 2022)Our knowledge of the factors affecting species abundances is mainly based on time-series analyses of a few well-studied species at single or few localities, but we know little about whether results from such analyses can ... -
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 ... -
An evolutionary and ecological community model for distribution of phenotypes and abundances among competing species
Engen, Steinar; Grøtan, Vidar; Sæther, Bernt-Erik; Coste, Christophe (Peer reviewed; Journal article, 2021) -
Extreme events, trophic chain reactions, and shifts in phenotypic selection
Layton-Matthews, Kate; Vriend, Stefan J.G.; Grøtan, Vidar; Loonen, Maarten J. J. E.; Sæther, Bernt-Erik; Fuglei, Eva; Hansen, Brage Bremset (Peer reviewed; Journal article, 2023)Demographic consequences of rapid environmental change and extreme climatic events (ECEs) can cascade across trophic levels with evolutionary implications that have rarely been explored. Here, we show how an ECE in high ... -
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 ...