• Alpine garden plants from six continents show high vulnerability to ice encasement 

      Bjerke, Jarle W.; Elvebakk, Arve; Tømmervik, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-10-27)
      Icy surfaces impose challenges for northern societies, wildlife and agriculture. However, there have been relatively few studies of the impacts of anoxic ground ice on non-agricultural plants. During the winter of 2009–2010, an extreme winter warming event led to thick ground-ice layer development in the world’s northernmost botanical garden in Tromsø, in subarctic Norway, due to much rain on ...
    • Arctic greening from warming promotes declines in caribou populations 

      Fauchald, Per; Park, Taejin; Tømmervik, Hans; Myneni, Ranga B.; Hausner, Vera Helene (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-04-26)
      The migratory tundra caribou herds in North America follow decadal population cycles, and browsing from abundant caribou could be expected to counteract the current climate-driven expansion of shrubs in the circumpolar tundra biome. We demonstrate that the sea ice cover in the Arctic Ocean has provided a strong signal for climate-induced changes on the adjacent caribou summer ranges, outperforming ...
    • Changes in Onset of Vegetation Growth on Svalbard, 2000–2020 

      Karlsen, Stein Rune; Elvebakk, Arve; Tømmervik, Hans; Belda, Santiago; Stendardi, Laura (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-12-15)
      The global temperature is increasing, and this is affecting the vegetation phenology in many parts of the world. The most prominent changes occur at northern latitudes such as our study area, which is Svalbard, located between 76300N and 80500N. A cloud-free time series of MODIS-NDVI data was processed. The dataset was interpolated to daily data during the 2000–2020 period with a 231.65 m pixel ...
    • Complexity revealed in the greening of the Arctic 

      Myers-Smith, Isla H.; Kerby, Jeffrey T.; Phoenix, Gareth K.; Bjerke, Jarle W.; Epstein, Howard E.; Assmann, Jakob J.; John, Christian; Andreu-Hayles, Laia; Angers-Blondin, Sandra; Beck, Pieter S. A.; Berner, Logan T.; Bhatt, Uma S.; Bjorkman, Anne D.; Blok, Daan; Bryn, Anders; Christiansen, Casper Tai; Cornelissen, J. Hans C.; Cunliffe, Andrew M.; Elmendorf, Sarah C.; Forbes, Bruce C.; Goetz, Scott J.; Hollister, Robert D.; de Jong, Rogier; Loranty, Michael M.; Macias-Fauria, Marc; Maseyk, Kadmiel; Normand, Signe; Olofsson, Johan; Parker, Thomas C.; Parmentier, Frans-Jan W.; Post, Eric; Schaepman-Strub, Gabriela; Stordal, Frode; Sullivan, Patrick F.; Thomas, Haydn J.D.; Tømmervik, Hans; Treharne, Rachael; Tweedie, Craig E.; Walker, Donald A.; Wilmking, Martin; Wipf, Sonja (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-01-31)
      As the Arctic warms, vegetation is responding, and satellite measures indicate widespread greening at high latitudes. This ‘greening of the Arctic’ is among the world’s most important large-scale ecological responses to global climate change. However, a consensus is emerging that the underlying causes and future dynamics of so-called Arctic greening and browning trends are more complex, variable ...
    • Correction: Anderson, H.B. et al. Using Ordinary Digital Cameras in Place of Near-Infrared Sensors to Derive Vegetation Indices for Phenology Studies of High Arctic Vegetation. Remote Sens. 2016, 8, 847 

      Anderson, Helen; Nilsen, Lennart; Tømmervik, Hans; Karlsen, Stein Rune; Nagai, Shin; Cooper, Elisabeth J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2017-09-28)
      After the publication of the research paper by Anderson et al. [ 1 ], a reanalysis of the data showed that mistakes had been introduced in the calculation of the greenness indices and the filtering for outliers prior to the statistical analysis. The calculation of the 2G_RBi and Channel G% indices were the most affected, while the filtering of the data for outliers had inadvertently removed too ...
    • A distributed time-lapse camera network to track vegetation phenology with high temporal detail and at varying scales 

      Parmentier, Frans-Jan W.; Nilsen, Lennart; Tømmervik, Hans; Cooper, Elisabeth J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-07-29)
      Near-surface remote sensing techniques are essential monitoring tools to provide spatial and temporal resolutions beyond the capabilities of orbital methods. This high level of detail is especially helpful to monitor specific plant communities and to accurately time the phenological stages of vegetation – which satellites can miss by days or weeks in frequently clouded areas such as the Arctic. In ...
    • Feasibility of active handheld NDVI sensors for monitoring of lichen ground cover 

      Erlandsson, Rasmus; Arneberg, Marit Klemetsen; Tømmervik, Hans; Finne, Eirik Aasmo; Nilsen, Lennart; Bjerke, Jarle W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-03-04)
      Vegetation indices are corner stones in vegetation monitoring. However, previous field studies on lichens and NDVI have been based on passive sensors. Active handheld sensors, with their own light sources, enables high- precision monitoring under variable ambient conditions. We investigated the use of handheld sensor NDVI for monitoring pale lichen cover across three study sites from boreal heathlands ...
    • Five decades of terrestrial and freshwater research at Ny-Ålesund, Svalbard 

      Pedersen, Åshild Ønvik; Convey, P.; Newsham, Kevin K.; Mosbacher, Jesper Bruun; Fuglei, Eva; Ravolainen, Virve; Hansen, Brage Bremset; Jensen, Thomas Correll; Augusti, A.; Biersma, Elisabeth Mackteld; Cooper, Elisabeth J.; Coulson, S.J.; Gabrielsen, Geir W.; Gallet, Jean-Charles; Karsten, U.; Kristiansen, Silje Marie; Svenning, Mette Marianne; Tveit, Alexander; Uchida, M.; Baneschi, I.; Calizza, E.; Cannone, N.; de Goede, E.M.; Doveri, M.; Elster, J.; Giamberini, M.S.; Hayashi, K.; Lang, Simone; Lee, Y.K.; Nakatsubo, T.; Pasquali, V.; Paulsen, I.M.G.; Pedersen, Christina Alsvik; Peng, F.; Provenzale, A.; Pushkareva, E.; Sandström, C.A.M.; Sklet, Vera; Stach, A.; Tojo, M.; Tytgat, B.; Tømmervik, Hans; Velazquez, D.; Verleyen, E.; Welker, J.M.; Yao, Y.-F.; Loonen, M.J.J.E. (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-19)
      For more than five decades, research has been conducted at Ny-Ålesund, in Svalbard, Norway, to understand the structure and functioning of High-Arctic ecosystems and the profound impacts on them of environmental change. Terrestrial, freshwater, glacial and marine ecosystems are accessible year-round from Ny-Ålesund, providing unique opportunities for interdisciplinary observational and experimental ...
    • Global economic drivers in the development of different industrial hubs in the European Arctic 

      Suopajärvi, Leena; Nygaard, Vigdis; Edvardsdóttir, AG; Iversen, Audun; Kyllönen, Katri-Maaria; Lesser, Pamela; Lindestav, Gun; Moioli, Sara; Nojonen, Matti; Olafsdottir, Ragnheidur; Bergström, D; Bjerke, Jarle W.; Bogadóttir, Rangheiour; Elomina, Jerbelle; Engen, Sigrid; Koivurova, Timo; Leppiaho, Toumas; Lynge-Pedersen, K; Rantala, Outi; Siikavuopio, Sten Ivar; Skum, Marja-Kristin; Tuulentie, Seija; Tømmervik, Hans (Research report; Forskningsrapport, 2022-03)
      This project report discusses global drivers affecting the development of key industries in the European Arctic (EA). Aquaculture is important for littoral states in the North, forestry and mining for northern Scandinavia, and tourism throughout the northern regions in the EA, and all are affected by globalization. Globalization is not a homogeneous, uniform phenomenon, but consists of various global ...
    • High seasonal overlap in habitat suitability in a nonmigratory High Arctic ungulate 

      Pedersen, Åshild Ønvik; Soininen, Eeva M; Hansen, Brage Bremset; Le Moullec, Mathilde; Loe, Leif Egil; Paulsen, I.M.G.; Eischeid, Isabell; Karlsen, Stein Rune; Ropstad, Erik; Stien, Audun; Tarroux, Arnaud; Tømmervik, Hans; Ravolainen, Virve (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-05-26)
      Understanding drivers of space use and habitat selection is essential for management and conservation, especially under rapid environmental change. Here, we develop summer and winter habitat suitability models for the endemic wild Svalbard reindeer (Rangifer tarandus platyrhynchus). The High Arctic Svalbard tundra is currently subject to the fastest temperature increases on Earth, and reindeer ...
    • High tolerance of a high-arctic willow and graminoid to simulated ice encasement 

      Bjerke, Jarle W.; Elverland, Ellen; Jaakola, Laura; Lund, Leidulf; Zagajewski, Bogdan; Bochenek, Zbigniew; Kłos, Andrzej; Tømmervik, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-12-17)
      Climate change-induced snow thaw and subsequent accumulation of ice on the ground is a potential, major threat to snow-dominated ecosystems. While impacts of ground-ice on arctic wildlife are well explored, the impacts on tundra vegetation is far from understood. We therefore tested the vulnerability of two high-arctic plants, the prostrate shrub <i>Salix polaris</i> and the graminoid <i>Luzula ...
    • Impact of Multiple Ecological Stressors on a Sub-Arctic Ecosystem: No Interaction Between Extreme Winter Warming Events, Nitrogen Addition and Grazing 

      Bokhorst, Stef; Berg, Matty P.; Edvinsen, Guro Kristine; Ellers, Jacintha; Heitman, Amber; Jaakola, Laura; Mæhre, Hanne K; Phoenix, Gareth K.; Tømmervik, Hans; Bjerke, Jarle W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-11-30)
      Climate change is one of many ongoing human-induced environmental changes, but few studies consider interactive effects between multiple anthropogenic disturbances. In coastal sub-arctic heathland, we quantified the impact of a factorial design simulating extreme winter warming (WW) events (7 days at 6–7∘C) combined with episodic summer nitrogen (+N) depositions (5 kg N ha-1) on plant winter physiology, ...
    • Local land use associated with socio-economic development in six arctic regions 

      Ehrich, Dorothee; Thuestad, Alma Elizabeth; Tømmervik, Hans; Fauchald, Per; Hausner, Vera Helene (Journal article; Tidsskriftartikkel; Peer reviewed, 2018-09-04)
      The socioeconomic causes of land use change are complex. They are highly context dependent, but most often studied through case studies. Here, we use a quasi-experimental paired block design to investigate whether better access to wage income leads to more visible land use around 28 settlements in six regions of the circumpolar Arctic. We mapped visible land use on high-resolution satellite images ...
    • Multi-Sensor Analysis of Snow Seasonality and a Preliminary Assessment of SAR Backscatter Sensitivity to Arctic Vegetation: Limits and Capabilities 

      Stendardi, Laura; Karlsen, Stein Rune; Malnes, Eirik; Nilsen, Lennart; Tømmervik, Hans; Cooper, Elisabeth J.; Notarnicola, Claudia (Journal article; Tidsskriftartikkel; Peer reviewed, 2022-04-13)
      Snow melt timing and the last day of snow cover have a significant impact on vegetation phenology in the Svalbard archipelago. The aim of this study is to assess the seasonal variations of the snow using a multi-sensor approach and to analyze the sensitivity of the Synthetic Aperture Radar (SAR) backscatter to vegetation growth and soil moisture in an arctic environment. A combined approach using ...
    • The northernmost hyperspectral FLoX sensor dataset for monitoring of high-Arctic tundra vegetation phenology and Sun-Induced Fluorescence (SIF) 

      Tømmervik, Hans; Julitta, Tommaso; Nilsen, Lennart; Park, Taejin; Burkart, Andreas; Ostapowicz, Katarzyna Anna; Karlsen, Stein Rune; Parmentier, Frans-Jan W.; Pirk, Norbert; Bjerke, Jarle W. (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-09-16)
      A hyperspectral field sensor (FloX) was installed in Adventdalen (Svalbard, Norway) in 2019 as part of the Svalbard Integrated Arctic Earth Observing System (SIOS) for monitoring vegetation phenology and Sun-Induced Chlorophyll Fluorescence (SIF) of high-Arctic tundra. This northernmost hyperspectral sensor is located within the footprint of a tower for long-term eddy covariance flux measurements ...
    • SIOS’s Earth Observation (EO), Remote Sensing (RS), and operational activities in response to COVID-19 

      Jawak, Shridhar D.; Andersen, Bo N.; Pohjola, Veijo; Godøy, Øystein; Hübner, Christiane E.; Jennings, Inger; Ignatiuk, Dariusz; Holmen, Kim; Sivertsen, Agnar; Hann, Richard; Tømmervik, Hans; Kääb, Andreas; Błaszczyk, Małgorzata; Salzano, Roberto; Luks, Bartłomiej; Høgda, Kjell Arild; Storvold, Rune; Nilsen, Lennart; Salvatori, Rosamaria; Krishnan, Kottekkatu Padinchati; Chatterjee, Sourav; Lorentzen, Dag Arne; Erlandsson, Rasmus; Lauknes, Tom Rune; Malnes, Eirik; Karlsen, Stein Rune; Enomoto, Hiroyuki; Fjæraa, Ann Mari; Zhang, Jie; Marty, Sabine; Nygård, Knut Ove; Lihavainen, Heikki (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-02-15)
      Svalbard Integrated Arctic Earth Observing System (SIOS) is an international partnership of research institutions studying the environment and climate in and around Svalbard. SIOS is developing an efficient observing system, where researchers share technology, experience, and data, work together to close knowledge gaps, and decrease the environmental footprint of science. SIOS maintains and facilitates ...
    • Snefjord Vindpark. Vurdering av konsekvenser for landskap, flora, fauna, friluftsliv, kulturminner og reindriftsnæring 

      Tombre, Ingunn; Andersen, Oddgeir; Barlindhaug, Stine; Bjerke, Jarle W.; Erikstad, Lars; Frivoll, Vigdis Irene; Johnsen, Trond Vidar; Sloreid, Svein Erik; Strann, Karl Birger; Svestad, Asgeir; Tømmervik, Hans (Research report; Forskningsrapport, 2005-02)
      This report summarises consequences of a planned wind park at the Sneqord peninsula, Måsøy municipality. Impact assessments are conducted for landscape perspectives, flora, fauna, outdoor recreation, cultural heritage and reindeer herding. The whole peninsula, 150 km2. is evaluated, with the main focus on higher parts where the potential wind turbines will be located. For the landscape, a wind park ...
    • Spreading or Gathering? Can Traditional Knowledge be a Resource to Tackle Reindeer Diseases Associated with Climate Change? 

      Riseth, Jan Åge; Tømmervik, Hans; Tryland, Morten (Journal article; Tidsskriftartikkel; Peer reviewed, 2020-08-18)
      This paper inquires whether reindeer herders’ traditional knowledge (TK) provides a reservoir of precaution and adaptation possibilities that may be relevant to counteract climate change. As our core example, we used the milking of reindeer—which, in some areas, was practiced up until the 1950s–1960s—and the risk of getting foot rot disease (digital necrobacillosis; slubbo in North Sámi), caused by ...
    • Sub-arctic mosses and lichens show idiosyncratic responses to combinations of winter heatwaves, freezing and nitrogen deposition 

      Bokhorst, Stef; Bjerke, Jarle W.; Phoenix, Gareth K.; Jaakola, Laura; Mæhre, Hanne; Tømmervik, Hans (Journal article; Tidsskriftartikkel; Peer reviewed, 2023-02-25)
      Arctic ecosystems are increasingly exposed to extreme climatic events throughout the year, which can affect species performance. Cryptogams (bryophytes and lichens) provide important ecosystem services in polar ecosystems but may be physiologically affected or killed by extreme events. Through field and laboratory manipulations, we compared physiological responses of seven dominant sub-Arctic ...
    • Time-series of cloud-free sentinel-2 ndvi data used in mapping the onset of growth of central Spitsbergen, Svalbard 

      Karlsen, Stein Rune; Stendardi, Laura; Tømmervik, Hans; Nilsen, Lennart; Arntzen, Ingar; Cooper, Elisabeth J. (Journal article; Tidsskriftartikkel; Peer reviewed, 2021-08-02)
      The Arctic is a region that is expected to experience a high increase in temperature. Changes in the timing of phenological phases, such as the onset of growth (as observed by remote sensing), is a sensitive bio-indicator of climate change. In this paper, the study area was the central part of Spitsbergen, Svalbard, located between 77.28°N and 78.44°N. The goals of this study were: (1) to prepare, ...