Change search
Refine search result
1 - 30 of 30
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Rows per page
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sort
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
  • Standard (Relevance)
  • Author A-Ö
  • Author Ö-A
  • Title A-Ö
  • Title Ö-A
  • Publication type A-Ö
  • Publication type Ö-A
  • Issued (Oldest first)
  • Issued (Newest first)
  • Created (Oldest first)
  • Created (Newest first)
  • Last updated (Oldest first)
  • Last updated (Newest first)
  • Disputation date (earliest first)
  • Disputation date (latest first)
Select
The maximal number of hits you can export is 250. When you want to export more records please use the Create feeds function.
  • 1. Anderson, L.G.
    et al.
    Carlsson, K. - Å.
    Hall, P. O. J.
    Holm, E.
    Josefsson, D.
    Olsson, K.
    Persson, B. R. R.
    Persson, T.
    Roos, P.
    Tengberg, A.
    Wedborg, M.
    The effect of the Siberian tundra on the environment of the shelf seas and the Arctic Ocean1999In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 28, no 3, p. 270-280Article in journal (Refereed)
  • 2. Andrews, Christopher
    et al.
    Dick, Jan
    Jonasson, Christer
    Callaghan, Terry
    Assessment of Biological and Environmental Phenology at a Landscape Level from 30 Years of Fixed-Date Repeat Photography in Northern Sweden2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 6, p. 600-609Article in journal (Refereed)
    Abstract [en]

    A 30-year series (1978–2007) of photographic records were analysed to determine changes in lake ice cover, local (low elevation) and montane (high elevation) snow cover and phenological stages of mountain birch (Betula pubescens ssp. czerepanovii) at the Abisko Scientific Research Station, Sweden. In most cases, the photographic-derived data showed no significant difference in phenophase score from manually observed field records from the same period, demonstrating the accuracy and potential of using weekly repeat photography as a quicker, cheaper and more adaptable tool to remotely study phenology in both biological and physical systems. Overall, increases in ambient temperatures coupled with decreases in winter ice and snow cover, and earlier occurrence of birch foliage, signal a reduction in the length of winter, a shift towards earlier springs and an increase in the length of available growing season in the Swedish sub-arctic.

  • 3. Bidleman, Terry
    et al.
    Agosta, Kathleen
    Andersson, Agneta
    Brorström-Lundén, Eva
    Haglund, Peter
    Hansson, Katarina
    Laudon, Hjalmar
    Newton, Seth
    Nygren, Olle
    Ripszam, Matyas
    Tysklind, Mats
    Wiberg, Karin
    Atmospheric pathways of chlorinated pesticides and natural bromoanisoles in the northern Baltic Sea and its catchment2015In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 44, no 3, p. 472-483Article in journal (Refereed)
    Abstract [en]

    Long-range atmospheric transport is a major pathway for delivering persistent organic pollutants to the oceans. Atmospheric deposition and volatilization of chlorinated pesticides and algae-produced bromoanisoles (BAs) were estimated for Bothnian Bay, northern Baltic Sea, based on air and water concentrations measured in 2011–2012. Pesticide fluxes were estimated using monthly air and water temperatures and assuming 4 months ice cover when no exchange occurs. Fluxes were predicted to increase by about 50 % under a 2069–2099 prediction scenario of higher temperatures and no ice. Total atmospheric loadings to Bothnian Bay and its catchment were derived from air–sea gas exchange and “bulk” (precipitation + dry particle) deposition, resulting in net gains of 53 and 46 kg year−1 for endosulfans and hexachlorocyclohexanes, respectively, and net loss of 10 kg year−1 for chlordanes. Volatilization of BAs releases bromine to the atmosphere and may limit their residence time in Bothnian Bay. This initial study provides baseline information for future investigations of climate change on biogeochemical cycles in the northern Baltic Sea and its catchment.

  • 4. Bokhorst, Stef
    et al.
    Bjerke, Jarle W.
    Tømmervik, Hans
    Preece, Catherine
    Phoenix, Gareth K.
    Ecosystem Response to Climatic Change: The Importance of the Cold Season2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 246-255Article in journal (Refereed)
    Abstract [en]

    Winter climate and snow cover are the important drivers of plant community development in polar regions. However, the impacts of changing winter climate and associated changes in snow regime have received much less attention than changes during summer. Here, we synthesize the results from studies on the impacts of extreme winter weather events on polar heathland and lichen communities. Dwarf shrubs, mosses and soil arthropods were negatively impacted by extreme warming events while lichens showed variable responses to changes in extreme winter weather events. Snow mould formation underneath the snow may contribute to spatial heterogeneity in plant growth, arthropod communities and carbon cycling. Winter snow cover and depth will drive the reported impacts of winter climate change and add to spatial patterns in vegetation heterogeneity. The challenges ahead lie in obtaining better predictions on the snow patterns across the landscape and how these will be altered due to winter climate change.

  • 5. Callaghan, T V
    et al.
    Johansson, M
    Heal, O W
    Saelthun, N R
    Barkved, L J
    Bayfield, N
    Brandt, O
    Brooker, R
    Christiansen, H H
    Forchhammer, M
    Hoye, T T
    Humlum, O
    Jarvinen, A
    Jonasson, C
    Kohler, J
    Magnusson, B
    Meltofte, H
    Mortensen, L
    Neuvonen, S
    Pearce, I
    Rasch, M
    Turner, L
    Hasholt, B
    Huhta, E
    Leskinen, E
    Nielsen, N
    Siikamaki, P
    Environmental changes in the North Atlantic Region: SCANNET as a collaborative approach for documenting, understanding and predicting changes2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, no 13, p. 39-50Article in journal (Refereed)
    Abstract [en]

    The lands surrounding the North Atlantic Region (the SCANNET Region) cover a wide range of climate regimes, physical environments and availability of natural resources. Except in the extreme North, they have supported human populations and various cultures since at least the end of the last ice age. However, the region is also important at a wider geographical scale in that it influences the global climate and supports animals that migrate between the Arctic and all the other continents of the world. Climate, environment and land use in the region are changing rapidly and projections suggest that global warming will be amplified there while increasing land use might dramatically reduce the remaining wilderness areas. Because much of the region is sparsely populated-if populated at all-observational records of past environmental changes and their impacts are both few and of short duration. However, it is becoming very important to record the changes that are now in progress, to understand the drivers of these changes, and to predict future consequences of the changes. To facilitate research into understanding impacts of global change on the lands of the North Atlantic Regions, and also to monitor changes in real time, an EU-funded network of research sites and infrastructures was formed in 2000: this was called SCANNET-SCANdinavian/North European NETwork of Terrestrial Field Bases. SCANNET currently consists of 9 core sites and 5 sites within local networks that together cover the broad range of current climate and predicted change in the region. Climate observations are well replicated across the network, whereas each site has tended to select particular environmental and ecological subjects for intensive observation. This provides diversity of both subject coverage and expertise. In this paper, we summarize the findings of SCANNET to-date and outline its information bases in order to increase awareness of data on environmental change in the North Atlantic Region. We also identify important gaps in our understanding and identify where the roles of existing infrastructures and activities represented by SCANNET can facilitate future research, monitoring and ground-truthing activities.

  • 6. Callaghan, Terry V.
    et al.
    Tweedie, Craig E.
    Webber, Patrick J.
    Multi-decadal Changes in Tundra Environments and Ecosystems: The International Polar Year-Back to the Future Project (IPY-BTF)2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 6, p. 555-557Article in journal (Refereed)
    Abstract [en]

    Polar and alpine environments are changing rapidly due to increases in temperature, which are amplified in the Arctic, as well as changes in many local factors. The impacts on ecosystems and their function have potential consequences for local residents and the global community. Tundra areas are vast and diverse, and the knowledge of geographical variation in environmental and ecosystem change is limited to relatively few locations, or to remote sensing approaches that are limited mostly to the past few decades. The International Polar Year, IPY, provided a context, stimulus and timely opportunities for re-visiting old research sites and data sets to collate data on past changes, to pass knowledge from old to new generations of researchers and to document environmental characteristics of sites to facilitate detection and attribution of future changes. Consequently, the project “Retrospective and Prospective Vegetation Change in the Polar Regions: Back to the Future,” BTF, was proposed and endorsed as an IPY activity (project #512). With national funding support, teams of researchers re-visited former sites and data sets throughout the Arctic and some alpine regions. These efforts have amounted to a gamut of “BTF” studies that are collectively geographically expansive and disciplinary diverse. A selection of these studies are introduced and presented in the current issue together with a brief synthesis of their findings.

  • 7.
    Callaghan, Terry V.
    et al.
    Royal Swedish Acad Sci, S-11418 Stockholm, Sweden.;Univ Sheffield, Dept Anim & Plant Sci, Western Bank, Sheffield S10 2TN, S Yorkshire, England..
    Tweedie, Craig E.
    Univ Texas El Paso, Dept Biol, El Paso, TX 79968 USA..
    Åkerman, Jonas
    Andrews, Christopher
    Bergstedt, Johan
    Butler, Malcolm G.
    Christensen, Torben R.
    Cooley, Dorothy
    Dahlberg, Ulrika
    Danby, Ryan K.
    Daniels, Fred J. A.
    de Molenaar, Johannes G.
    Dick, Jan
    Mortensen, Christian Ebbe
    Ebert-May, Diane
    Emanuelsson, Urban
    Eriksson, Hakan
    Hedenas, Henrik
    Henry, Greg. H. R.
    Hik, David S.
    Hobbie, John E.
    Jantze, Elin J.
    Jaspers, Cornelia
    Johansson, Cecilia
    Johansson, Margareta
    Johnson, David R.
    Johnstone, Jill F.
    Jonasson, Christer
    Kennedy, Catherine
    Kenney, Alice J.
    Keuper, Frida
    Koh, Saewan
    Krebs, Charles J.
    Lantuit, Hugues
    Lara, Mark J.
    Lin, David
    Lougheed, Vanessa L.
    Madsen, Jesper
    Matveyeva, Nadya
    McEwen, Daniel C.
    Myers-Smith, Isla H.
    Narozhniy, Yuriy K.
    Olsson, Hakan
    Pohjola, Veijo A.
    Price, Larry W.
    Riget, Frank
    Rundqvist, Sara
    Sandstroem, Anneli
    Tamstorf, Mikkel
    Van Bogaert, Rik
    Villarreal, Sandra
    Webber, Patrick J.
    Zemtsov, Valeriy A.
    Multi-Decadal Changes in Tundra Environments and Ecosystems: Synthesis of the International Polar Year-Back to the Future Project (IPY-BTF)2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 6, p. 705-716Article in journal (Refereed)
    Abstract [en]

    Understanding the responses of tundra systems to global change has global implications. Most tundra regions lack sustained environmental monitoring and one of the only ways to document multi-decadal change is to resample historic research sites. The International Polar Year (IPY) provided a unique opportunity for such research through the Back to the Future (BTF) project (IPY project #512). This article synthesizes the results from 13 papers within this Ambio Special Issue. Abiotic changes include glacial recession in the Altai Mountains, Russia; increased snow depth and hardness, permafrost warming, and increased growing season length in sub-arctic Sweden; drying of ponds in Greenland; increased nutrient availability in Alaskan tundra ponds, and warming at most locations studied. Biotic changes ranged from relatively minor plant community change at two sites in Greenland to moderate change in the Yukon, and to dramatic increases in shrub and tree density on Herschel Island, and in sub-arctic Sweden. The population of geese tripled at one site in northeast Greenland where biomass in non-grazed plots doubled. A model parameterized using results from a BTF study forecasts substantial declines in all snowbeds and increases in shrub tundra on Niwot Ridge, Colorado over the next century. In general, results support and provide improved capacities for validating experimental manipulation, remote sensing, and modeling studies.

  • 8. Chapin, F S
    et al.
    Peterson, G
    Berkes, F
    Callaghan, T V
    Angelstam, P
    Apps, M
    Beier, C
    Bergeron, Y
    Crepin, A S
    Danell, K
    Elmqvist, T
    Folke, C
    Forbes, B
    Fresco, N
    Juday, G
    Niemela, J
    Shvidenko, A
    Whiteman, G
    Resilience and vulnerability of northern regions to social and environmental change2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 33, no 6, p. 344-349Article in journal (Refereed)
    Abstract [en]

    The arctic tundra and boreal forest were once considered the last frontiers on earth because of their vast expanses remote from agricultural land-use change and industrial development. These regions are now, however, experiencing environmental and social changes that are as rapid as those occurring anywhere on earth. This paper summarizes the role of northern regions in the global system and provides a blueprint for assessing the factors that govern their sensitivity to social and environmental change.

  • 9. Christensen, Torben R.
    et al.
    Jackowicz-Korczy´nski, Marcin
    Aurela, Mika
    Crill, Patrick
    Heliasz, Michal
    Mastepanov, Mikhail
    Friborg, Thomas
    Monitoring the Multi-Year Carbon Balance of a Subarctic Palsa Mire with Micrometeorological Techniques2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 207-217Article in journal (Refereed)
    Abstract [en]

    This article reports a dataset on 8 years of monitoring carbon fluxes in a subarctic palsa mire based on micrometeorological eddy covariance measurements. The mire is a complex with wet minerotrophic areas and elevated dry palsa as well as intermediate sub-ecosystems. The measurements document primarily the emission originating from the wet parts of the mire dominated by a rather homogenous cover of Eriophorum angustifolium. The CO2/CH4 flux measurements performed during the years 2001–2008 showed that the areas represented in the measurements were a relatively stable sink of carbon with an average annual rate of uptake amounting to on average −46 g C m−2 y−1 including an equally stable loss through CH4 emissions (18–22 g CH4–C m−2 y−1). This consistent carbon sink combined with substantial CH4 emissions is most likely what is to be expected as the permafrost under palsa mires degrades in response to climate warming.

  • 10. Gwynn-Jones, Dylan
    et al.
    Jones, Alan G.
    Waterhouse, Alice
    Winters, Ana
    Comont, David
    Scullion, John
    Gardias, Rosie
    Graee, Bente J.
    Lee, John A.
    Callaghan, Terry V.
    Enhanced UV-B and Elevated CO2 Impacts Sub-Arctic Shrub Berry Abundance, Quality and Seed Germination2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 256-268Article in journal (Refereed)
    Abstract [en]

    This study investigated the effects of long-term-enhanced UV-B, and combined UV-B with elevated CO2 on dwarf shrub berry characteristics in a sub-arctic heath community. Germination of Vaccinium myrtillus was enhanced in seeds produced at elevated UV-B, but seed numbers and berry size were unaffected. Elevated UV-B and CO2 stimulated the abundance of V. myrtillus berries, whilst UV-B alone stimulated the berry abundance of V. vitis-idaea and Empetrum hermaphroditum. Enhanced UV-B reduced concentrations of several polyphenolics in V. myrtillus berries, whilst elevated CO2 increased quercetin glycosides in V. myrtillus, and syringetin glycosides and anthocyanins in E. hermaphroditum berries. UV-B × CO2 interactions were found for total anthocyanins, delphinidin-3-hexoside and peonidin-3-pentosidein in V. myrtillus berries but not E. hermaphroditum. Results suggest positive impacts of UV-B on the germination of V. myrtillus and species-specific impacts of UV-B × elevated CO2 on berry abundance and quality. The findings have relevance and implications for human and animal consumers plus seed dispersal and seedling establishment.

  • 11. Hedenås, Henrik
    et al.
    Carlsson, Bengt Å.
    Emanuelsson, Urban
    Headley, Alistair D.
    Jonasson, Christer
    Svensson, Brita M.
    Callaghan, Terry V.
    Changes Versus Homeostasis in Alpine and Sub-Alpine Vegetation Over Three Decades in the Sub-Arctic2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 187-196Article in journal (Refereed)
    Abstract [en]

    Plant species distributions are expected to shift and diversity is expected to decline as a result of global climate change, particularly in the Arctic where climate warming is amplified. We have recorded the changes in richness and abundance of vascular plants at Abisko, sub-Arctic Sweden, by re-sampling five studies consisting of seven datasets; one in the mountain birch forest and six at open sites. The oldest study was initiated in 1977–1979 and the latest in 1992. Total species number increased at all sites except for the birch forest site where richness decreased. We found no general pattern in how composition of vascular plants has changed over time. Three species, Calamagrostis lapponica, Carex vaginata and Salix reticulata, showed an overall increase in cover/frequency, while two Equisetum taxa decreased. Instead, we showed that the magnitude and direction of changes in species richness and composition differ among sites.

  • 12. Hedenås, Henrik
    et al.
    Olsson, Håkan
    Jonasson, Christer
    Bergstedt, Johan
    Dahlberg, Ulrika
    Callaghan, Terry V.
    Changes in Tree Growth, Biomass and Vegetation Over a 13-Year Period in the Swedish Sub-Arctic2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 6, p. 672-682Article in journal (Refereed)
    Abstract [en]

    This study was conducted in the Swedish sub-Arctic, near Abisko, in order to assess the direction and scale of possible vegetation changes in the alpine–birch forest ecotone. We have re-surveyed shrub, tree and vegetation data at 549 plots grouped into 61 clusters. The plots were originally surveyed in 1997 and re-surveyed in 2010. Our study is unique for the area as we have quantitatively estimated a 19% increase in tree biomass mainly within the existing birch forest. We also found significant increases in the cover of two vegetation types—“birch forest-heath with mosses” and “meadow with low herbs”, while the cover of snowbed vegetation decreased significantly. The vegetation changes might be caused by climate, herbivory and past human impact but irrespective of the causes, the observed transition of the vegetation will have substantial effects on the mountain ecosystems.

  • 13. Hein, Catherine L.
    et al.
    Öhlund, Gunnar
    Englund, Göran
    Future Distribution of Arctic Char Salvelinus alpinus in Sweden under Climate Change: Effects of Temperature, Lake Size and Species Interactions2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 303-312Article in journal (Refereed)
    Abstract [en]

    Novel communities will be formed as species with a variety of dispersal abilities and environmental tolerances respond individually to climate change. Thus, models projecting future species distributions must account for species interactions and differential dispersal abilities. We developed a species distribution model for Arctic char Salvelinus alpinus, a freshwater fish that is sensitive both to warm temperatures and to species interactions. A logistic regression model using lake area, mean annual air temperature (1961–1990), pike Esox lucius and brown trout Salmo trutta occurrence correctly classified 95 % of 467 Swedish lakes. We predicted that Arctic char will lose 73 % of its range in Sweden by 2100. Predicted extinctions could be attributed both to simulated temperature increases and to projected pike invasions. The Swedish mountains will continue to provide refugia for Arctic char in the future and should be the focus of conservation efforts for this highly valued fish.

  • 14. Hell, Benjamin
    et al.
    Broman, Barry
    Jakobsson, Lars
    Jakobsson, Martin
    Magnusson, Ake
    Wiberg, Patrik
    The Use of Bathymetric Data in Society and Science: A Review from the Baltic Sea2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 2, p. 138-150Article in journal (Refereed)
    Abstract [en]

    Bathymetry, the underwater topography, is a fundamental property of oceans, seas, and lakes. As such it is important for a wide range of applications, like physical oceanography, marine geology, geophysics and biology or the administration of marine resources. The exact requirements users may have regarding bathymetric data are, however, unclear. Here, the results of a questionnaire survey and a literature review are presented, concerning the use of Baltic Sea bathymetric data in research and for societal needs. It is demonstrated that there is a great need for detailed bathymetric data. Despite the abundance of high-quality bathymetric data that are produced for safety of navigation purposes, the digital bathymetric models publicly available to date cannot satisfy this need. Our study shows that DBMs based on data collected for safety of navigation could substantially improve the base data for administrative decision making as well as the possibilities for marine research in the Baltic Sea.

  • 15. Huntington, H
    et al.
    Callaghan, T
    Fox, S
    Krupnik, I
    Matching traditional and scientific observations to detect environmental change: A discussion on Arctic terrestrial ecosystems2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, no 13, p. 18-23Article in journal (Refereed)
    Abstract [en]

    Recent environmental changes are having, and are expected to continue to have, significant impacts in the Arctic as elsewhere in the world. Detecting those changes and determining the mechanisms that cause them are far from trivial problems. The use of multiple methods of observation can increase confidence in individual observations, broaden the scope of information available about environmental change, and contribute to insights concerning mechanisms of change. In this paper, we examine the ways that using traditional ecological knowledge (TEK) together with scientific observations can achieve these objectives. A review of TEK observations in comparison with scientific observations demonstrates the promise of this approach, while also revealing several challenges to putting it into practice on a large scale. Further efforts are suggested, particularly in undertaking collaborative projects designed to produce parallel observations that can be readily compared and analyzed in greater detail than is possible in an opportunistic sample.

  • 16.
    Johansson, Cecilia
    et al.
    Uppsala Univ, Dept Earth Sci, S-75236 Uppsala, Sweden..
    Pohjola, Veijo A.
    Uppsala Univ, Dept Earth Sci, S-75236 Uppsala, Sweden..
    Jonasson, Christer
    Swedish Polar Res Secretariat, Abisko Sci Res Stn, S-98107 Abisko, Sweden..
    Callaghan, Terry V.
    Royal Swedish Acad Sci, S-10405 Stockholm, Sweden.;Univ Sheffield, Dept Plant & Anim Sci, Sheffield Ctr Arctic Ecol, Sheffield S10 5BR, S Yorkshire, England..
    Multi-Decadal Changes in Snow Characteristics in Sub-Arctic Sweden2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 6, p. 566-574Article in journal (Refereed)
    Abstract [en]

    A unique long term, 49-year record (divided into three time periods 1961-1976, 1977-1992, and 1993-2009) of snow profile stratigraphy from the Swedish sub Arctic, was analyzed with a focus on changes in snow characteristics. The data set contained grain size, snow layer hardness, grain compactness, and snow layer dryness, observed every second week during the winter season. The results showed an increase in very hard snow layers, with harder snow in early winter and more moist snow during spring. There was a striking increase in the number of observations with very hard snow at ground level over time. More than twice as many occasions with hard snow at ground level were observed between 1993 and 2009 compared to previous years, which may have a significant effect on plants and animals. The changes in snow characteristics are most likely a result of the increasing temperatures during the start and the end of the snow season.

  • 17. Johansson, Margareta
    et al.
    Christensen, Torben R.
    Akerman, H. Jonas
    Callaghan, Terry V.
    What determines the current presence or absence of permafrost in the Tornetrask region, a sub-arctic landscape in Northern Sweden?2006In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 35, no 4, p. 190-197Article in journal (Refereed)
    Abstract [en]

    In a warming climate, permafrost is likely to be significantly reduced and eventually disappear from the sub-Arctic region. This will affect people at a range of scales, from locally by slumping of buildings and roads to globally as melting of permafrost will most likely increase the emissions of the powerful greenhouse gas methane, which will further enhance global warming. In order to predict future changes in permafrost, it is crucial to understand what determines the presence or absence of permafrost under current climate conditions, to assess where permafrost is particularly vulnerable to climate change, and to identify where changes are already occurring. The Tornetrask region of northern sub-Arctic Sweden is one area where changes in permafrost have been recorded and where permafrost could be particularly vulnerable to any future climate changes. This paper therefore reviews the various physical, biological, and anthropogenic parameters that determine the presence or absence of permafrost in the Tornetrask region under current climate conditions, so that we can gain an understanding of its current vulnerability and potential future responses to climate change. A patchy permafrost distribution as found in the Tornetrask region is not random, but a consequence of site-specific factors that control the microclimate and hence the surface and subsurface temperature. It is also a product of past as well as current processes. In sub-Arctic areas such as northern Sweden, it is mainly the physical parameters, e.g., topography, soil type, and climate (in particular snow depth), that determine permafrost distribution. Even though humans have been present in the study area for centuries, their impacts on permafrost distribution can more or less be neglected at the catchment level. Because ongoing climate warming is projected to continue and lead to an increased snow cover, the permafrost in the region will most likely disappear within decades, at least at lower elevations.

  • 18. Johansson, Margareta
    et al.
    Jonasson, Christer
    Sonesson, Mats
    Christensen, Torben R.
    The Man, the Myth, the Legend: Professor Terry V. Callaghan and His 3M Concept2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 175-177Article in journal (Refereed)
    Abstract [en]

    During almost half a century, Professor Terry V. Callaghan has been active in polar research focusing on Arctic environment and the ecology of Arctic plants, animals, and ecosystem processes, including ecological responses to changes in climate, atmospheric CO2 concentrations, and UV-B radiation. Professor Callaghan is an excellent scientist who has carried out outstanding research and he is also a role model for colleagues and young scientists, and an excellent friend. Through his hard work he has made himself a strong and positive reputation within the polar community and beyond.

    Professor Callaghan has contributed to and led numerous international scientific synthesizing processes. He was a member of the United Nations Environment Programme’s expert panel on Stratospheric Ozone Depletion Effects for many years (Zepp et al. 1998, 2003), he was a lead author of the Intergovernmental Panel on Climate Change Polar and Ecosystems Chapters (Anisimov et al. 2007) as well as...

  • 19. Johansson, Margareta
    et al.
    Åkerman, Jonas
    Keuper, Frida
    Christensen, Torben R.
    Lantuit, Hugues
    Callaghan, Terry V.
    Past and Present Permafrost Temperatures in the Abisko Area: Redrilling of Boreholes2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 6, p. 558-565Article in journal (Refereed)
    Abstract [en]

    Monitoring of permafrost has been ongoing since 1978 in the Abisko area, northernmost Sweden, when measurements of active layer thickness started. In 1980, boreholes were drilled in three mires in the area to record permafrost temperatures. Recordings were made twice per year, and the last data were obtained in 2002. During the International Polar Year (2007–2008), new boreholes were drilled within the ‘Back to the Future’ (BTF) and ‘Thermal State of Permafrost’ (TSP) projects that enabled year-round temperature monitoring. Mean annual ground temperatures (MAGT) in the mires are close to 0°C, ranging from −0.16 to −0.47°C at 5 m depth. Data from the boreholes show increasing ground temperatures in the upper and lower part by 0.4 to 1°C between 1980 and 2002. At one mire, permafrost thickness has decreased from 15 m in 1980 to ca. 9 m in 2009, with an accelerating thawing trend during the last decade.

  • 20. Jonasson, C.
    et al.
    Johansson, M.
    Christensen, T. R.
    Special Report: Festschrift in honor of Terry V. Callaghan.2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Ambio, Vol. 41, no Suppl. 3, p. 175-313Article in journal (Refereed)
    Abstract [en]

                                                Professor Terry V. Callaghan has been active in polar research focusing on Arctic environment and the ecology of Arctic plants, animals and ecosystems processes, including ecological responses to changes in climate, atmospheric CO2 concentrations and UV-B radiation. This special issue contains 12 papers inspired by this scientist's works focusing in the subarctic and Arctic zones.

  • 21. Jonasson, Christer
    et al.
    Sonesson, Mats
    Christensen, Torben R.
    Callaghan, Terry V.
    Environmental Monitoring and Research in the Abisko Area—An Overview2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 178-186Article in journal (Refereed)
    Abstract [en]

    This article gives an overview of the studies on the environment surrounding the Abisko Scientific Research Station in Swedish Lapland. The long-term monitoring of the Station on processes related to the climate, and to the physical, biotic, and chemical environmental conditions is particularly addressed. Some variables are recorded since more than 100 years. The obtained data in combination with results from short-term studies and manipulation experiments are important to understand past and future conditions of the ecosystems. This has practical applications for the planning of tourism, transports, reindeer herding, and for societal purposes.

  • 22. Keuper, Frida
    et al.
    Parmentier, Frans-Jan W.
    Blok, Daan
    van Bodegom, Peter M.
    Dorrepaal, Ellen
    van Hal, Jurgen R.
    van Logtestijn, Richard S. P.
    Aerts, Rien
    Tundra in the Rain: Differential Vegetation Responses to Three Years of Experimentally Doubled Summer Precipitation in Siberian Shrub and Swedish Bog Tundra2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 269-280Article in journal (Refereed)
    Abstract [en]

    Precipitation amounts and patterns at high latitude sites have been predicted to change as a result of global climatic changes. We addressed vegetation responses to three years of experimentally increased summer precipitation in two previously unaddressed tundra types: Betula nana-dominated shrub tundra (northeast Siberia) and a dry Sphagnum fuscum-dominated bog (northern Sweden). Positive responses to approximately doubled ambient precipitation (an increase of 200 mm year−1) were observed at the Siberian site, for B. nana (30 % larger length increments), Salix pulchra (leaf size and length increments) and Arctagrostis latifolia (leaf size and specific leaf area), but none were observed at the Swedish site. Total biomass production did not increase at either of the study sites. This study corroborates studies in other tundra vegetation types and shows that despite regional differences at the plant level, total tundra plant productivity is, at least at the short or medium term, largely irresponsive to experimentally increased summer precipitation.

  • 23. Korner, C
    Mountain biodiversity, its causes and function2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, no 13, p. 11-17Article in journal (Refereed)
    Abstract [en]

    The personal safety and well-being of one fifth, and water supply for almost half of all people depend directly or indirectly on the functional integrity of mountain ecosystems, the key component of which is a robust vegetation cover. The green ‘coat’ of the world’s mountains is composed of specialized plants, animals and microbes, all nested in a great variety of microhabitats. Because a single mountain may host a series of climatically different life zones over short elevational distances, mountains are hot spots of biodiversity and priority regions for conservation. With their diverse root systems, plants anchor soils on slopes and prevent erosion. Both landuse and atmospheric changes such as elevated CO2 and climatic warming affect mountain biodiversity. Sustained catchment value depends on sustained soil integrity, which in turn depends on a diverse plant cover. Whether landuse in mountains is sustainable is a question of its consequences for water yield and biodiversity. Given their dependence on mountains, lowlanders should show concern for the highlands beyond their recreational value.

  • 24. Körner, Christian
    Treelines Will be Understood Once the Functional Difference Between a Tree and a Shrub Is2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 197-206Article in journal (Refereed)
    Abstract [en]

    Trees are taller than shrubs, grasses, and herbs. What is the disadvantage of being tall so that trees are restricted to warmer regions than low stature life forms? This article offers a brief review of the current state of biological treeline theory, and then explores the significance of tallness from a carbon balance, freezing resistance, and microclimatological perspective. It will be argued that having of a woody stem is neither a burden to the carbon balance nor does it add to the risk of freezing damage. The physiological means of trees to thrive in cold climates are similar to small stature plants, but due to their size, and, thus, closer aerodynamic coupling to air circulation, trees experience critically low temperatures at lower elevation and latitude than smaller plants. Hence, trees reach a limit at treeline for physical reasons related to their stature.

  • 25.
    Lindeberg, Carola
    et al.
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Bindler, Richard
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Bigler, Christian
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Rosen, P
    Renberg, Ingemar
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Mercury pollution trends in subarctic lakes in the northern Swedish mountains2007In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 36, no 5, p. 401-405Article in journal (Refereed)
  • 26. Michelsen, Anders
    et al.
    Rinnan, Riikka
    Jonasson, Sven
    Two Decades of Experimental Manipulations of Heaths and Forest Understory in the Subarctic2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 218-230Article in journal (Refereed)
    Abstract [en]

    Current atmospheric warming due to increase of greenhouse gases will have severe consequences for the structure and functioning of arctic ecosystems with changes that, in turn, may feed back on the global-scale composition of the atmosphere. During more than two decades, environmental controls on biological and biogeochemical processes and possible atmospheric feedbacks have been intensely investigated at Abisko, Sweden, by long-term ecosystem manipulations. The research has addressed questions like environmental regulation of plant and microbial community structure and biomass, carbon and nutrient pools and element cycling, including exchange of greenhouse gases and volatile organic compounds, with focus on fundamental processes in the interface between plants, soil and root-associated and free-living soil microorganisms. The ultimate goal has been to infer from these multi-decadal experiments how subarctic and arctic ecosystems will respond to likely environmental changes in the future. Here we give an overview of some of the experiments and main results.

  • 27. Molau, U
    Mountain biodiversity patterns at low and high latitudes2004In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, no 13, p. 24-28Article in journal (Refereed)
    Abstract [en]

    This paper presents an overview of mountain biodiversity at a multitude of scales in space, time, and function. Even though species richness is usually the focal component in nature conservation, genetic diversity within species is equally important. The small-scale distribution of species in the tropical Andes, as exemplified by the plant genera Calceolaria and Bartsia, contrasts against the situation in high-latitude mountains, e.g., the Scandes, where species have wide ranges and many are circumpolar. Recent studies on alpine plants based on molecular methods show that the intraspecific genetic diversity tends to increase with latitude, a situation brought about by the glaciation history with repeated contraction-expansion episodes of species’ distributions. In tropical mountains, species distributions are geographically much narrower, often as a result of relatively recent, local speciation. Thus, whereas species richness in mountains decreases from the Equator towards the poles, genetic diversity shows the opposite trend. Finally, a comparison of ecosystem diversity in low- and high-latitude mountain ranges (tropical Andes vs. Scandes) shows that the landscapes differ profoundly with regard to timberline ecotones, snow distribution, and climate variables, and are subject to widely different impacts of global change.

  • 28. Rundqvist, Sara
    et al.
    Hedenås, Henrik
    Sandström, Anneli
    Emanuelsson, Urban
    Eriksson, Håkan
    Jonasson, Christer
    Callaghan, Terry V.
    Tree and Shrub Expansion Over the Past 34 Years at the Tree-Line Near Abisko, Sweden2011In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 40, no 6Article in journal (Refereed)
    Abstract [en]

    Shrubs and trees are expected to expand in the sub-Arctic due to global warming. Our study was conducted in Abisko, sub-arctic Sweden. We recorded the change in coverage of shrub and tree species over a 32– to 34-year period, in three 50 × 50 m plots; in the alpine-tree-line ecotone. The cover of shrubs and trees (<3.5 cm diameter at breast height) were estimated during 2009–2010 and compared with historical documentation from 1976 to 1977. Similarly, all tree stems (≥3.5 cm) were noted and positions determined. There has been a substantial increase of cover of shrubs and trees, particularly dwarf birch (Betula nana), and mountain birch (Betula pubescens ssp. czerepanovii), and an establishment of aspen (Populus tremula). The other species willows (Salix spp.), juniper (Juniperus communis), and rowan (Sorbus aucuparia) revealed inconsistent changes among the plots. Although this study was unable to identify the causes for the change in shrubs and small trees, they are consistent with anticipated changes due to climate change and reduced herbivory.

  • 29. Teterukovskiy, A
    et al.
    Edenius, L
    Effective field sampling for predicting the spatial distribution of reindeer (Rangifer tarandus) with help of the Gibbs sampler2003In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 32, no 8, p. 568-572Article in journal (Refereed)
    Abstract [en]

    We describe an approach to estimation of the spatial distribution of reindeer (Rangifer tarandus). Spatial auto-correlation, inherent to the data describing the distribution of wildlife species, contains information that can be utilized to improve the effciency of field inventories. Our data included reindeer fecal pellet counts, satellite imagery and a digital terrain model. We applied ordinary logistic regression, autologistic regression, and the Gibbs sampler to predict spatial distribution of reindeer based on the combined data. A training set was used to compare the outcome for different field sampling designs for each method. Results suggested the possibility to reduce the number of plots by up to 75% with a 15% reduction in prediction accuracy (quality). We also showed that the Gibbs sampler outperformed, in terms of accuracy, the logistic regression. The outcome however, was dependent on the spectral homogeneity of the area and on the relative position of the sampling design to the elevation curves. Our results justify the incorporation of spatial information when modeling the distribution of reindeer at finer scales (< 1 km).

  • 30. Yang, Zhenlin
    et al.
    Sykes, Martin T.
    Hanna, Edward
    Callaghan, Terry V.
    Linking Fine-Scale Sub-Arctic Vegetation Distribution in Complex Topography with Surface-Air-Temperature Modelled at 50-m Resolution2012In: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 41, no 3, p. 292-302Article in journal (Refereed)
    Abstract [en]

    Recent studies have shown that the complexities of the surface features in mountainous terrain require a re-assessment of climate impacts at the local level. We explored the importance of surface-air-temperature based on a recently published 50-m-gridded dataset, versus soil variables for explaining vegetation distribution in Swedish Lapland using generalised linear models (GLMs). The results demonstrated that the current distribution of the birch forest and snowbed community strongly relied on the surface-air-temperature. However, temperature alone is a poor predictor of many plant communities (wetland, meadow). Because of diminishing sample representation with increasing altitude, the snowbed community was under-sampled at higher altitudes. This results in underestimation of the current distribution of the snowbed community around the mountain summits. The analysis suggests that caution is warranted when applying GLMs at the local level.

1 - 30 of 30
CiteExportLink to result list
Permanent link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf