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  • 151. Ahlmann, H. W:son
    et al.
    Lindblad, T.
    Die Grössenveränderungen des Kårsajökels in Schwedisch-Lappland.1940In: Geografiska Annaler, Vol. 22, no 1-2, p. 80-94Article in journal (Other academic)
  • 152. Ahlmann, H. W:son
    et al.
    Tryselius, O.
    Der Kårsagletscher in Schwedisch Lappland.1929In: Geografiska Annaler, Vol. 11, no 1, p. 1-32Article in journal (Other academic)
  • 153. Ahlström-Bergström, Inger
    The role of the IRF Library in the expanding scientific community in Kiruna - a centre for space research in Sweden1995In: Bi-polar Information Initiatives: the Needs of Polar Research. Proceedings of the 15th Polar Libraries Colloquy, Cambridge, UK: Bluntisham Books , 1995, , p. 12-14Conference paper (Other academic)
  • 154. Akesson, S
    et al.
    Morin, J
    Muheim, R
    Ottosson, U
    Avian orientation at steep angles of inclination: experiments with migratory white-crowned sparrows at the magnetic North Pole2001In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 268, no 1479, p. 1907-1913Article in journal (Refereed)
    Abstract [en]

    The Earth’s magnetic field and celestial cues provide animals with compass information during migration. Inherited magnetic compass courses are selected based on the angle of inclination, making it difficult to orient in the near vertical fields found at high geomagnetic latitudes. Orientation cage experiments were performed at different sites in high Arctic Canada with adult and young white-crowned sparrows (Zonotrichia leucophrys gambelii) in order to investigate birds’ ability to use the Earth’s magnetic field and celestial cues for orientation in naturally,,cry steep magnetic fields at and close to the magnetic North Pole. Experiments were performed during the natural period of migration at night in the local geomagnetic field under natural clear skies and under simulated total overcast conditions. The experimental birds failed to select a meaningful magnetic compass course under overcast conditions at the magnetic North Pole, but could do so in gcomagnetic fields deviating less than 3 degrees from the vertical. Migratory orientation was successful at all sites when celestial cues were available.

  • 155. Alatalo, J.M.
    Climate change: Impacts on structure and biodiversity of subarctic plant communities.1998Student thesis
  • 156.
    Alatalo, J.M.
    Department of Systematic Botany.
    Reproductive biology of Silene acaulis (Caryophyllaceae): Gender expression and potential impact of climate change.1996Student thesis
  • 157. Alatalo, J.M.
    et al.
    Totland, Ø.
    Responses to simulated climatic change in an alpine and subarctic pollen-risk strategist, Silene acaulis.1997In: Global Change Biology, Vol. 3, no Supplement 1, p. 74-79Article in journal (Other academic)
  • 158. Alatalo, Juha M.
    et al.
    Jägerbrand, Annika K.
    Chen, Shengbin
    Molau, Ulf
    Responses of lichen communities to 18 years of natural and experimental warming2017In: Annals of Botany, Vol. 120, no 1, p. 159-170Article in journal (Refereed)
  • 159. Alatalo, Juha M
    et al.
    Jägerbrand, Annika K
    Juhanson, Jaanis
    Michelsen, Anders
    Ľuptáčik, Peter
    Impacts of twenty years of experimental warming on soil carbon, nitrogen, moisture and soil mites across alpine/subarctic tundra communities2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7Article in journal (Refereed)
    Abstract [en]

    High-altitude and alpine areas are predicted to experience rapid and substantial increases in future temperature, which may have serious impacts on soil carbon, nutrient and soil fauna. Here we report the impact of 20 years of experimental warming on soil properties and soil mites in three contrasting plant communities in alpine/subarctic Sweden. Long-term warming decreased juvenile oribatid mite density, but had no effect on adult oribatids density, total mite density, any major mite group or the most common species. Long-term warming also caused loss of nitrogen, carbon and moisture from the mineral soil layer in mesic meadow, but not in wet meadow or heath or from the organic soil layer. There was a significant site effect on the density of one mite species, Oppiella neerlandica, and all soil parameters. A significant plot-scale impact on mites suggests that small-scale heterogeneity may be important for buffering mites from global warming. The results indicated that juvenile mites may be more vulnerable to global warming than adult stages. Importantly, the results also indicated that global warming may cause carbon and nitrogen losses in alpine and tundra mineral soils and that its effects may differ at local scale.

  • 160. Alatalo, Juha M.
    et al.
    Jägerbrand, Annika K.
    Molau, Ulf
    Climate change and climatic events: community-, functional- and species-level responses of bryophytes and lichens to constant, stepwise, and pulse experimental warming in an alpine tundra2014In: Alpine Botany, ISSN 1664-2201, E-ISSN 1664-221X, Vol. 124, no 2, p. 81-91Article in journal (Refereed)
    Abstract [en]

    We experimentally imposed three different kinds of warming scenarios over 3 years on an alpine meadow community to identify the differential effects of climate warming and extreme climatic events on the abundance and biomass of bryophytes and lichens. Treatments consisted of (a) a constant level of warming with open top chambers (an average temperature increase of 1.87 °C), (b) a yearly stepwise increase of warming (average temperature increases of 1.0; 1.87 and 3.54 °C, consecutively), and (c) a pulse warming, i.e., a single first year pulse event of warming (average temperature increase of 3.54 °C only during the first year). To our knowledge, this is the first climate change study that attempts to distinguish between the effects of constant, stepwise and pulse warming on bryophyte and lichen communities. We hypothesised that pulse warming would have a significant short-term effect compared to the other warming treatments, and that stepwise warming would have a significant mid-term effect compared to the other warming treatments. Acrocarpous bryophytes as a group increased in abundance and biomass to the short-term effect of pulse warming. We found no significant effects of mid-term (third-year) stepwise warming. However, one pleurocarpous bryophyte species, Tomentypnum nitens, generally increased in abundance during the warm year 1997 but decreased in control plots and in response to the stepwise warming treatment. Three years of experimental warming (all treatments as a group) did have a significant impact at the community level, yet changes in abundance did not translate into significant changes in the dominance hierarchies at the functional level (for acrocarpous bryophytes, pleurocarpous bryophytes, Sphagnum or lichens), or in significant changes in other bryophyte or lichen species. The results suggest that bryophytes and lichens, both at the functional group and species level, to a large extent are resistant to the different climate change warming simulations that were applied.

  • 161. Alatalo, Juha M
    et al.
    Jägerbrand, Annika K
    Molau, Ulf
    Impacts of different climate change regimes and extreme climatic events on an alpine meadow community2016In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6Article in journal (Refereed)
    Abstract [en]

    Climate variability is expected to increase in future but there exist very few experimental studies that apply different warming regimes on plant communities over several years. We studied an alpine meadow community under three warming regimes over three years. Treatments consisted of (a) a constant level of warming with open-top chambers (ca. 1.9 °C above ambient), (b) yearly stepwise increases in warming (increases of ca. 1.0, 1.9 and 3.5 °C), and (c) pulse warming, a single first-year pulse event of warming (increase of ca. 3.5 °C). Pulse warming and stepwise warming was hypothesised to cause distinct first-year and third-year effects, respectively. We found support for both hypotheses; however, the responses varied among measurement levels (whole community, canopy, bottom layer, and plant functional groups), treatments, and time. Our study revealed complex responses of the alpine plant community to the different experimentally imposed climate warming regimes. Plant cover, height and biomass frequently responded distinctly to the constant level of warming, the stepwise increase in warming and the extreme pulse-warming event. Notably, we found that stepwise warming had an accumulating effect on biomass, the responses to the different warming regimes varied among functional groups, and the short-term perturbations had negative effect on species richness and diversity

  • 162. Alatalo, Juha M.
    et al.
    Jägerbrand, Annika K.
    Molau, Ulf
    Testing reliability of short-term responses to predict longer-term responses of bryophytes and lichens to environmental change2015In: Ecological Indicators, ISSN 1470-160X, E-ISSN 1872-7034, Vol. 58, no Supplement C, p. 77-85Article in journal (Refereed)
    Abstract [en]

    Abstract Environmental changes are predicted to have severe and rapid impacts on polar and alpine regions. At high latitudes/altitudes, cryptogams such as bryophytes and lichens are of great importance in terms of biomass, carbon/nutrient cycling, cover and ecosystem functioning. This seven-year factorial experiment examined the effects of fertilizing and experimental warming on bryophyte and lichen abundance in an alpine meadow and a heath community in subarctic Sweden. The aim was to determine whether short-term responses (five years) are good predictors of longer-term responses (seven years). Fertilizing and warming had significant negative effects on total and relative abundance of bryophytes and lichens, with the largest and most rapid decline caused by fertilizing and combined fertilizing and warming. Bryophytes decreased most in the alpine meadow community, which was bryophyte-dominated, and lichens decreased most in the heath community, which was lichen-dominated. This was surprising, as the most diverse group in each community was expected to be most resistant to perturbation. Warming alone had a delayed negative impact. Of the 16 species included in statistical analyses, seven were significantly negatively affected. Overall, the impacts of simulated warming on bryophytes and lichens as a whole and on individual species differed in time and magnitude between treatments and plant communities (meadow and heath). This will likely cause changes in the dominance structures over time. These results underscore the importance of longer-term studies to improve the quality of data used in climate change models, as models based on short-term data are poor predictors of long-term responses of bryophytes and lichens.

  • 163. Alatalo, Juha M
    et al.
    Jägerbrand, Annika K
    Čuchta, Peter
    Collembola at three alpine subarctic sites resistant to twenty years of experimental warming2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5Article in journal (Refereed)
    Abstract [en]

    This study examined the effects of micro-scale, site and 19 and 21 years of experimental warming on Collembola in three contrasting alpine subarctic plant communities (poor heath, rich meadow, wet meadow). Unexpectedly, experimental long-term warming had no significant effect on species richness, effective number of species, total abundance or abundance of any Collembola species. There were micro-scale effects on species richness, total abundance, and abundance of 10 of 35 species identified. Site had significant effect on effective number of species, and abundance of six species, with abundance patterns differing between sites. Site and long-term warming gave non-significant trends in species richness. The highest species richness was observed in poor heath, but mean species richness tended to be highest in rich meadow and lowest in wet meadow. Warming showed a tendency for a negative impact on species richness. This long-term warming experiment across three contrasting sites revealed that Collembola is capable of high resistance to climate change. We demonstrated that micro-scale and site effects are the main controlling factors for Collembola abundance in high alpine subarctic environments. Thus local heterogeneity is likely important for soil fauna composition and may play a crucial role in buffering Collembola against future climate change.

  • 164. Alatalo, Juha M.
    et al.
    Little, Chelsea J.
    Simulated global change: contrasting short and medium term growth and reproductive responses of a common alpine/Arctic cushion plant to experimental warming and nutrient enhancement2014In: Springer Series in Chemical Physics, ISSN 0172-6218, E-ISSN 2193-1801, Vol. 3, no 1Article in journal (Refereed)
    Abstract [en]

    Cushion plants are important components of alpine and Arctic plant communities around the world. They fulfill important roles as facilitators, nurse plants and foundation species across trophic levels for vascular plants, arthropods and soil microorganisms, the importance of these functions increasing with the relative severity of the environment. Here we report results from one of the few experimental studies simulating global change impacts on cushion plants; a factorial experiment with warming and nutrient enhancement that was applied to an alpine population of the common nurse plant, Silene acaulis, in sub-arctic Sweden. Experimental perturbations had significant short-term impacts on both stem elongation and leaf length. S. acaulis responded quickly by increasing stem elongation and (to a lesser extent) leaf length in the warming, nutrient, and the combined warming and nutrient enhancements. Cover and biomass also initially increased in response to the perturbations. However, after the initial positive short-term responses, S. acaulis cover declined in the manipulations, with the nutrient and combined warming and nutrient treatments having largest negative impact. No clear patterns were found for fruit production. Our results show that S. acaulis living in harsh environments has potential to react quickly when experiencing years with favorable conditions, and is more responsive to nutrient enhancement than to warming in terms of vegetative growth. While these conditions have an initial positive impact, populations experiencing longer-term increased nutrient levels will likely be negatively affected.

  • 165. Alatalo, Juha M.
    et al.
    Little, Chelsea J.
    Jägerbrand, Annika K.
    Molau, Ulf
    Dominance hierarchies, diversity and species richness of vascular plants in an alpine meadow: contrasting short and medium term responses to simulated global change2014In: PeerJ, ISSN 2167-8359, E-ISSN 2167-8359, Vol. 2Article in journal (Refereed)
    Abstract [en]

    We studied the impact of simulated global change on a high alpine meadow plant community. Specifically, we examined whether short-term (5 years) responses are good predictors for medium-term (7 years) changes in the system by applying a factorial warming and nutrient manipulation to 20 plots in Latnjajaure, subarctic Sweden. Seven years of experimental warming and nutrient enhancement caused dramatic shifts in dominance hierarchies in response to the nutrient and the combined warming and nutrient enhancement treatments. Dominance hierarchies in the meadow moved from a community being dominated by cushion plants, deciduous, and evergreen shrubs to a community being dominated by grasses, sedges, and forbs. Short-term responses were shown to be inconsistent in their ability to predict medium-term responses for most functional groups, however, grasses showed a consistent and very substantial increase in response to nutrient addition over the seven years. The non-linear responses over time point out the importance of longer-term studies with repeated measurements to be able to better predict future changes. Forecasted changes to temperature and nutrient availability have implications for trophic interactions, and may ultimately influence the access to and palatability of the forage for grazers. Depending on what anthropogenic change will be most pronounced in the future (increase in nutrient deposits, warming, or a combination of them both), different shifts in community dominance hierarchies may occur. Generally, this study supports the productivity–diversity relationship found across arctic habitats, with community diversity peaking in mid-productivity systems and degrading as nutrient availability increases further. This is likely due the increasing competition in plant–plant interactions and the shifting dominance structure with grasses taking over the experimental plots, suggesting that global change could have high costs to biodiversity in the Arctic.

  • 166. Alatalo, Juha M
    et al.
    Little, Chelsea J
    Jägerbrand, Annika K
    Molau, Ulf
    Vascular plant abundance and diversity in an alpine heath under observed and simulated global change2015In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 5Article in journal (Refereed)
    Abstract [en]

    Global change is predicted to cause shifts in species distributions and biodiversity in arctic tundra. We applied factorial warming and nutrient manipulation to a nutrient and species poor alpine/arctic heath community for seven years. Vascular plant abundance in control plots increased by 31%. There were also notable changes in cover in the nutrient and combined nutrient and warming treatments, with deciduous and evergreen shrubs declining, grasses overgrowing these plots. Sedge abundance initially increased significantly with nutrient amendment and then declined, going below initial values in the combined nutrient and warming treatment. Nutrient addition resulted in a change in dominance hierarchy from deciduous shrubs to grasses. We found significant declines in vascular plant diversity and evenness in the warming treatment and a decline in diversity in the combined warming and nutrient addition treatment, while nutrient addition caused a decline in species richness. The results give some experimental support that species poor plant communities with low diversity may be more vulnerable to loss of species diversity than communities with higher initial diversity. The projected increase in nutrient deposition and warming may therefore have negative impacts on ecosystem processes, functioning and services due to loss of species diversity in an already impoverished environment.

  • 167. Albertson, N.
    Rhytidium rugosum (Hedw. ) i Fennoskandia.1940In: Svensk Botanisk Tidskrift, Vol. 34, no 2, p. 77-100Article in journal (Other academic)
  • 168. Albertson, N.
    Scorpidium turgescens (Th. Jens. ) Moenkem. En senglacial relikt i nordisk alvarvegetation.1940In: Acta Phytogeographica Suecica, Vol. 13, p. 7-26Article in journal (Other academic)
  • 169. Albjär, G.
    et al.
    Rehn, J.
    Strömquist, L.
    Notes on talus formation in different climates.1979In: Geografiska Annaler, Vol. 61A, no 3-4, p. 179-186Article in journal (Other academic)
  • 170. Aldahan, A A
    et al.
    Ning, S
    Possnert, G
    Backman, J
    Bostrom, K
    Be-10 records from sediments of the Arctic Ocean covering the past 350 ka1997In: Marine Geology, ISSN 0025-3227, E-ISSN 1872-6151, Vol. 144, no 1-3, p. 147-162Article in journal (Refereed)
    Abstract [en]

    Records of Be-10, Be-9, mineralogy and grain size were obtained from two cores collected by the Polarstern Expedition 1991 in the southern Nansen Basin (Core 2213-6) and the Yermak Plateau (Core 2208-2). The accumulation of sediments examined started from about 350 ka (BP), and includes relatively well defined trends of Be isotopes coincident with interglacial/glacial climatic cycles. Sediment accumulation rates (g/cm(2) ka) were higher during glacial periods and our estimates of 1.0 and 2.5 cm/ka sedimentation rates during the Holocene agree with other estimates for the southern Nansen Basin and the Yermak Plateau, respectively. The variations in Be-10 concentration (atoms/g) and flux (atoms/cm(2) ka) are inverse to sediment flux, where high Be-10 concentration and flux are associated with generally low sedimentation/accumulation rates during interglacial periods. We hypothesize that climate plays an important role in Be-10 records from the Arctic sediments, reflecting the intensity and distribution of the ice mass on land and the ocean. (C) 1997 Elsevier Science B.V.

  • 171. Aldahan, A. A.
    et al.
    Possnert, G.
    Johnsen, S. J.
    Clausen, H. B.
    Isaksson, E.
    Karlén, W.
    Hansson, M.
    Sixty year long 10Be records from Greenland and Antarctica1998In: Proc. Indian Acad. Sci. (Earth Planet Sc.), Vol. 107, no 2, p. 139 - 147Article in journal (Refereed)
  • 172. Aldahan, A. A.
    et al.
    Possnert, G.
    Shi Ning,
    Backman, J.
    Boström, K.
    Trace element and major-element stratigraphy in Quaternary sediments from Arctic Ocean and implications for glacial termination2000In: Journ. Sed. Res., Vol. 70, p. 1095 - 1106Article in journal (Refereed)
  • 173. Aldahan, A.
    et al.
    Alfimov, V.
    Possnert, G.
    I-129 anthropogenic budget: Major sources and sinks2007In: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 22, no 3, p. 606-618Article in journal (Refereed)
    Abstract [en]

    Data are presented here on the anthropogenic I-129 inventory in regions that have been strongly affected by releases from European reprocessing facilities which, to the authors’ knowledge, presently account for > 90% of the global isotope source in the Earth’s surface environment. The results show that > 90% of the isotope inventory occurs in marine waters with the Nordic Seas and Eurasian basin of the Arctic Ocean containing most of the I-129. Within the terrestrial environment of Europe, soils contain the largest part of the isotope inventory. However, the inventory of the terrestrial system did not provide clues on the most plausible atmospheric source of I-129 to Europe, thus supply from both gaseous and marine releases is proposed. The sum of the total inventory in both the marine and terrestrial environments did not match the estimated releases. This imbalance is likely to relate to unconstrained inventory estimates for marine basins (Irish Sea, English Channel and North Sea) close to the facilities, but also to the occurrence of I-129 in the biosphere, and possible overestimated releases from the nuclear reprocessing facilities. There is no doubt that the available data on I-129 distribution in the environment are far from representative and further research is urgently needed to construct a comprehensive picture. (c) 2006 Elsevier Ltd. All rights reserved.

  • 174. Aldahan, Ala
    et al.
    Possnert, Göran
    Alfimov, Vassilii
    Radioactive 129 I and 10 Be in the Nordic seas2006In: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , p. 106 - 108Chapter in book (Other academic)
  • 175. Aldenius, J.
    et al.
    Carlsson, B.
    Karlsson, S.
    Effects of insect trapping on growth and nutrient content of Pinguicula vulgaris L. in relation to the nutrient content of the substrate.1983In: New Phytologist, Vol. 93, p. 53-59Article in journal (Other academic)
  • 176. Alerstam, T
    et al.
    Gudmundsson, G A
    Bird orientation at high latitudes: flight routes between Siberia and North America across the Arctic Ocean1999In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 266, no 1437, p. 2499-2505Article in journal (Refereed)
    Abstract [en]

    Bird migration and orientation at high latitudes are of special interest because of the difficulties associated with different compass systems in polar areas and because of the considerable differences between flight routes conforming to loxodromes (rhumblines) or orthodromes (great circle routes). Regular and widespread east-north-east migration of birds from the northern tundra of Siberia towards North America across the Arctic Ocean (without landmark influences) were recorded by ship-based tracking radar studies in July and August. Field observations indicated that waders, including species such as Phalaropus fulicarius and Calidris melanotos, dominated, but also terns and skuas may have been involved. Analysis of flight directions in relation to the wind showed that these movements are not caused by wind drift. Assuming possible orientation principles based on celestial or geomagnetic cues, different flight trajectories across the Arctic Ocean were calculated: geographical loxodromes, sun compass routes, magnetic loxodromes and magnetoclinic routes. The probabilities of these four alternatives are evaluated on the basis of both the availability of required orientation cues and the predicted flight paths. This evaluation supports orientation along sun compass routes. Because of the longitudinal time displacement sun compass routes show gradually changing compass courses in close agreement with orthodromes. It is suggested that an important migration link between Siberia and North American stopover sites 1000-2500 km apart across the Arctic Ocean has evolved based on sun compass orientation along orthodrome-like routes.

  • 177. Alerstam, T
    et al.
    Gudmundsson, G A
    Migration patterns of tundra birds: Tracking radar observations along the northeast passage1999In: Arctic, ISSN 0004-0843, E-ISSN 1923-1245, Vol. 52, no 4, p. 346-371Article in journal (Refereed)
    Abstract [en]

    Bird migration was recorded by tracking radar and visual observations at 15 study sites, situated between 50 degrees E and 170 degrees E along the Northeast Passage, during a ship-based expedition in July and August 1994. A total of 1087 radar tracks (average duration 220 s) of bird flocks on postbreeding migration were recorded. Migration was dominated by waders and to a certain degree also skuas (especially pomarine skua Stercorarius pomarinus). Terns, gulls, ducks, and geese were also among the migrants tracked by radar. The radar data revealed a major migratory divide at about 100 degrees E (Taymyr Peninsula), with mainly eastbound migration to the east of this divide, and mainly westbound migration to the west of it. The main stream of eastbound migration was directed toward the sector 90-120 degrees and that of westbound migration toward the sector 240-270 degrees; these directions are broadly in parallel with the coasts of the Arctic Ocean east and west of the Taymyr Peninsula, respectively. There was also important ENE migration, which provided strong indications of long-distance flights along orthodrome-like routes directly between Siberia and North America, across vast expanses of the Arctic Ocean pack ice. Analysis of flight directions in relation to wind indicated complete compensation for wind drift. Mean flight altitude was 1.3 km, and the birds regularly travelled at high altitudes above 3 km (9% of the tracks) up to a maximum height of 4.8 km. They preferred to migrate on occasions and at altitudes with following winds; such conditions provided an average gain in speed of 4.6 m/s. There were also recurrent cases of birds migrating in tailwinds of gale force, between 18 and 24 m/s. The birds' airspeed varied between 8 and 22 m/s, with a mean of 14 m/s. Airspeed was significantly correlated with altitude, wind, and vertical speed and seemed to be intermediate between the speeds for minimum power and maximum range predicted by aerodynamic theory.

  • 178. Alerstam, Thomas
    Bird migration and species diversity under polar conditions: the Siberian - American migration systems2006In: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , p. 116 - 120Chapter in book (Other academic)
  • 179. Alerstam, Thomas
    Conflicting evidence about long-distance animal navigation2006In: Science, Vol. 313, p. 791-793Article in journal (Refereed)
  • 180. Alerstam, Thomas
    Radar studies of bird migration in the Arctic Ocean1999In: Polarforskningssekretariatets årsbok 1998 / [ed] Grönlund, Eva red, Stockholm: Swedish Polar Research , 1999, , p. 59 - 61Chapter in book (Other academic)
  • 181. Alerstam, Thomas
    et al.
    Bäckman, Johan
    Gudmundsson, Gudmundur A.
    Hedenström, Anders
    Henningsson, Sara S.
    Karlsson, Håkan
    Rosen, Mikael
    Strandberg, Roine
    A polar system of intercontinental bird migration2007In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 274, no 1625, p. 2523-2530Article in journal (Refereed)
    Abstract [en]

    Studies of birdmigration in the Beringia region of Alaska and eastern Siberia are of special interest for revealing the importance of bird migration between Eurasia and North America, for evaluating orientation principles used by the birds at polar latitudes and for understanding the evolutionary implications of intercontinental migratory connectivity among birds as well as their parasites. We used tracking radar placed onboard the ice-breaker Oden to register bird migratory flights from 30 July to 19 August 2005 and we encountered extensive birdmigration in the whole Beringia range from latitude 64 degrees N in Bering Strait up to latitude 75 degrees N far north of Wrangel Island, with eastward flights making up 79% of all track directions. The results from Beringia were used in combination with radar studies from the Arctic Ocean north of Siberia and in the Beaufort Sea to make a reconstruction of a major Siberian-American birdmigration system in a wide Arctic sector between longitudes 1108 E and 130 degrees W, spanning one-third of the entire circumpolar circle. This system was estimated to involve more than 2 million birds, mainly shorebirds, terns and skuas, flying across the Arctic Ocean at mean altitudes exceeding 1 km (maximum altitudes 3-5 km). Great circle orientation provided a significantly better fit with observed flight directions at 20 different sites and areas than constant geographical compass orientation. The long flights over the sea spanned 40-80 degrees of longitude, corresponding to distances and durations of 1400-2600 km and 26-48 hours, respectively. The birds continued from this eastward migration system over the Arctic Ocean into several different flyway systems at the American continents and the Pacific Ocean. Minimization of distances between tundra breeding sectors and northerly stopover sites, in combination with the Beringia glacial refugium and colonization history, seemed to be important for the evolution of this major polar bird migration system.

  • 182.
    Alerstam, Thomas
    et al.
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Bäckman, Johan
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Strandberg, Roine
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Gudmundsson, Gudmundur A.
    Iceland Inst Nat Hist, IS-125 Reykjavik, Iceland..
    Hedenström, Anders
    Lund Univ, Dept Theoret Ecol, SE-22362 Lund, Sweden..
    Henningsson, Sara S.
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Karlsson, Håkan
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Rosen, Mikael
    Lund Univ, Dept Anim Ecol, SE-22362 Lund, Sweden..
    Great-circle migration of arctic passerines2008In: The AUK: A Quarterly Journal of Ornithology, ISSN 0004-8038, E-ISSN 1938-4254, Vol. 125, no 4, p. 831-838Article in journal (Refereed)
    Abstract [en]

    Birds can save distance and time on their migratory journeys by following great circles rather than rhumblines, but great-circle routes require more complex orientation with changing courses. Flight directions at different places along the route and in relation to the destination can be used to test whether birds migrate along great circles or rhumblines. Such data have indicated great-circle migration among shorebirds at high latitudes, but no critical tests have been made for passerines. Using tracking radar on board the icebreaker Oden in August 2005, we recorded westerly flight directions of passerine migrants over the Chukchi Sea. The main sector of migratory directions was 237-311 degrees centered oil a mean heading direction of 274 degrees. The most likely species to participate in this westward trans-Beringia migration, mainly departing from Alaska, were Eastern Yellow Wagtail (Motacilla Ischutschensis), Arctic Warbler (Phylloscopus borealis kennicotti), Northern Wheatear (Oenanthe oenanthe), and Bluethroat (Luscinia svecica); all except the Bluethroat were recorded from the ship. Observed flight directions agreed with predicted great-circle courses but not with rhumbline courses for three of these four species with winter quarters in Southeast Asia; no definite conclusion could be drawn for the Northern Wheatear (wintering in East Africa). These results support great-circle migration among passerines traveling between Alaska and Old World winter quarters, though the long-distance precision and orientation mechanisms are Still unknown. The relative importance of different evolutionary causes-such as circumvention of geographic barriers, retracing of ancient colonization ways, or distance reduction by great-circle migration-to complex bird migration routes with changing courses remains to be understood. Received 24 August 2007, accepted 6 March 2008.

  • 183. Alerstam, Thomas
    et al.
    Gudmundsson, Gudmundur A.
    Larsson, Bertil
    Flight tracks and speeds of Antarctic and Atlantic seabirds: radar and optical measurements1993In: Phil. Trans. R. Soc. Lond. B, no 340, p. 55-67Article in journal (Refereed)
  • 184. Alerstam, Thomas
    et al.
    Gudmundsson, Gudmundur A.
    Larsson, Bertil
    Migration patterns and flight routes of tundra birds1995In: Swedish-Russian Tundra Ecology-expedition-94. Tundra Ecology-94. A Cruise Report, Stockholm: Swedish Polar Research Secretariat , 1995, , p. 252-263Chapter in book (Other academic)
  • 185. Alerstam, Thomas
    et al.
    Gudmundsson, Gudmundur
    Green, Martin
    Hedenström, Anders
    Migration along orthodromic sun compass routes by Arctic birds2001In: Science, Vol. 291, p. 300-303Article in journal (Refereed)
    Abstract [en]

    Flight directions of birds migrating at high geographic and magnetic latitudes can be used to test bird orientation by celestial or geomagnetic compass systems under polar conditions. Migration patterns ofarctic shorebirds, revealed by tracking radar studies during an icebreaker expedition along the Northwest Passage in 1999, support predicted sun compass trajectories but cannot be reconciled with orientation along either geographic or magnetic loxodromes (rhumb Lines). Sun compass routes are similar to orthodromes (great circle routes) at high latitudes, showing changing geographic courses as the birds traverse longitudes and their internal clock gets out of phase with Local time. These routesbring the shorebirds from high arctic Canada to the east coast of North America, from which they make transoceanic flights to South America. The observations are also consistent with a migration Link between Siberia and the Beaufort Sea region by way of sun compass routes across the Arctic Ocean.

  • 186. Alerstam, Thomas
    et al.
    Gudmundsson, Gudmundur
    Green, Martin
    Hedenström, Anders
    Larsson, Bertil
    Bird migration at polar latitudes: radar studies of routes, orientation, process and pattern?2000In: Polarforskningssekretariatets årsbok 1999 / [ed] Grönlund, Eva, Stockholm: Swedish Polar Research Secretariat , 2000, , p. 122 - 126Chapter in book (Other academic)
  • 187. Alerstam, Thomas
    et al.
    Jönsson, Paul Eric
    Ecology of tundra birds: patterns of distribution, breeding and migration along the Northeast passage1999Chapter in book (Other academic)
    Abstract [en]

    Several different aspects of the geographical ecology of tundra birds were investigated during theSwedish-Russian Tundra Ecology -94 expedition along the Northeast Passage in 1994. Quantitative censuses of breeding bird communities and populations were made at the temporary field sites, supplemented by surveys from helicopter over wider tundra areas. The occurrence of avian predatory species-skuas, snowy owl and rough-legged buzzard-was analyzed with respect to interspecific relationships as well as to the abundance of their main prey, the lemmings. Geographical variation in color phases among skuas and of genetics in dunlins (based on mitochondrial DNA) were examined, as well as the social organization in different wader species and moult strategies among populations ofdunlins;Bird migration was recorded by a tracking radar placed on the expedition ship, and by complementary visual observations. These studies demonstrated the patterns of flight directions, altitudes, speeds (also measured by optical instruments) and migratory routes of the tundra birds. Ringing results contributed to put these results into a global migratory perspective. Two important aspects of the energetics of arctic birds were investigated during the expedition: the basal metabolic rates of waders when departing on migration, and the fuel loads deposited by the migrating waders.The effect of longitudinal displacement on the migratory orientation of a long-distance passerine migrant, the wheatear, was tested by repeated orientation experiments at a number of test sites alongthe Northeast Passage.

  • 188. Alerstam, Thomas
    et al.
    Pettersson, Sve-Göran
    Orientation along great circles by migrating birds using a sun compass1991In: J. Theor. Biol., Vol. 152, p. 191 - 202Article in journal (Refereed)
  • 189. Alerstam, Thomas
    et al.
    Rosén, Mikael
    Bäckman, Johan
    Ericson, Per G. P.
    Hellgren, Olof
    Flight speeds among bird species: allometric and phylogenetic effects2007In: PLoS biology, ISSN 1544-9173, E-ISSN 1545-7885Article in journal (Refereed)
  • 190. Aletsee, L.
    Einige rezente Pollenspektren aus Schwedisch-Lappland.1957Report (Other academic)
  • 191. Aletsee, L.
    Über den Besuch eines Palsmoores und seine pflanzengeographische Stellung.1955Report (Other academic)
  • 192. Alexanderson, Helena
    Glacial geology and palaeo-ice dynamics of two ice-sheet margins, Taymyr Peninsula, Siberia and Jameson Land, East Greenland2002Doctoral thesis, monograph (Other academic)
  • 193. Alexanderson, Helena
    Landsat mapping of ice-marginal features on the Taymyr Peninsula, Siberia - image interpretation versus geological reality2000In: Geological Quarterly, Vol. 44, no 1, p. 15-25Article in journal (Refereed)
  • 194. Alexanderson, Helena
    et al.
    Adrielsson, Lena
    Hjort, Christian
    Möller, Per
    Antonov, Oleg
    Eriksson, Saskia
    Pavlov, Maksim
    Depositional history of the North Taymyr ice-marginal zone, Siberia - landsystem approach2002In: Journal of Quaternary Science, Vol. 17, no 4, p. 361-382Article in journal (Refereed)
  • 195. Alexanderson, Helena
    et al.
    Backman, Jan
    Cronin, Thomas M.
    Funder, Svend
    Ingolfsson, Olafur
    Jakobsson, Martin
    Landvik, Jon Y.
    Lowemark, Ludvig
    Mangerud, Jan
    Maerz, Christian
    Moller, Per
    O’Regan, Matt
    Spielhagen, Robert F.
    An Arctic perspective on dating Mid-Late Pleistocene environmental history2014In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 92, no SI, p. 9-31Article in journal (Refereed)
    Abstract [en]

    To better understand Pleistocene climatic changes in the Arctic, integrated palaeoenvironmental and palaeoclimatic signals from a variety of marine and terrestrial geological records as well as geochronologic age control are required, not least for correlation to extra-Arctic records. In this paper we discuss, from an Arctic perspective, methods and correlation tools that are commonly used to date Arctic Pleistocene marine and terrestrial events. We review the state of the art of Arctic geochronology, with focus on factors that affect the possibility and quality of dating, and support this overview by examples of application of modern dating methods to Arctic terrestrial and marine sequences. Event stratigraphy and numerical ages are important tools used in the Arctic to correlate fragmented terrestrial records and to establish regional stratigraphic schemes. Age control is commonly provided by radiocarbon, luminescence or cosmogenic exposure ages. Arctic Ocean deep-sea sediment successions can be correlated over large distances based on geochemical and physical property proxies for sediment composition, patterns in palaeomagnetic records and, increasingly, biostratigraphic data. Many of these proxies reveal cyclical patterns that provide a basis for astronomical tuning. Recent advances in dating technology, calibration and age modelling allow for measuring smaller quantities of material and to more precisely date previously undatable material (i.e. foraminifera for C-14, and single-grain luminescence). However, for much of the Pleistocene there are still limits to the resolution of most dating methods. Consequently improving the accuracy and precision (analytical and geological uncertainty) of dating methods through technological advances and better understanding of processes are important tasks for the future. Another challenge is to better integrate marine and terrestrial records, which could be aided by targeting continental shelf and lake records, exploring proxies that occur in both settings, and by creating joint research networks that promote collaboration between marine and terrestrial geologists and modellers. (C) 2013 Elsevier Ltd. All rights reserved.

  • 196. Alexanderson, Helena
    et al.
    Hakansson, Lena
    Coastal glaciers advanced onto Jameson Land, East Greenland during the late glacial-early Holocene Milne Land Stade2014In: Polar Research, ISSN 0800-0395, E-ISSN 1751-8369, Vol. 33, article id 20313Article in journal (Refereed)
    Abstract [en]

    We report on Be-10 and optically stimulated luminescence ages from moraines and glaciolacustrine sediments on eastern Jameson Land, East Greenland. Sampled landforms and sediment are associated with advances of outlet glaciers from the local Liverpool Land ice cap situated in the coastal Scoresby Sund region. Previous studies have tentatively correlated these advances with the Milne Land Stade moraines, which are prominent moraine sets deposited by mountain glaciers in the inner Scoresby Sund region. Recent constraints on the formation of the outer and inner of these moraines have suggested two advances of local glaciers, one prior to or during the Younger Dryas and another during the Preboreal. In this paper, we test the correlation of the Liverpool Land glacial advance with the Milne Land Stade. Our results show that outlet glaciers from the Liverpool Land ice cap reached ice-marginal positions marked by moraines in east-facing valleys on Jameson Land sometime during late glacial-early Holocene time (ca. 13-11 Kya). This confirms the correlation of these moraines with the Milne Land Stade moraines described elsewhere in the Scoresby Sund region.

  • 197. Alexanderson, Helena
    et al.
    Hjort, Christian
    Möller, Per
    Antonov, Oleg
    Pavlov, Maksim
    The North Taymyr ice-marginal zone, Arctic Siberia - a preliminary overview and dating2001Other (Other (popular science, discussion, etc.))
  • 198. Alexanderson, Helena
    et al.
    Håkansson, Lena
    Did ice-free areas exist on East Greenland during the peak of the last ice age2006In: Polarforskningssekretariatets årsbok 2005, Stockholm: Swedish Polar Research Secretariat , 2006, , p. 70 - 73Chapter in book (Other academic)
  • 199. Alexandersson, H.
    et al.
    Holmgren, B.
    Climatological extremes in the mountains. Physical background, geomorphological and ecological consequences.1987Report (Other academic)
  • 200. Alfimov, V
    et al.
    Aldahan, A
    Possnert, G
    Tracing water masses with I-129 in the western Nordic Seas in early spring 20022004In: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 31, no 19Article in journal (Refereed)
    Abstract [en]

    The distribution of I-129 was utilized for labeling water masses in three sections of the western Nordic Seas. An increase of the tracer in Polar Waters of the East Greenland Current was observed between the Fram Strait and 72degreesN section and attributed to either unaccounted Polar Waters and/or recirculation of cold and fresh Atlantic Waters from the West Spitzbergen Current. Recent convection homogenized I-129 in upper 1000 m of the Greenland Sea, and similar concentrations were observed in dense waters of the Denmark Strait. The densest outflow waters were not found in either the Greenland Sea or the East Greenland Current at 72degreesN.

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