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  • 1. Björkvoll, Eirin
    et al.
    Pedersen, Bård
    Hytteborn, Håkan
    Department of Biology, Norwegian University of Science and Technology, Trondheim.
    Jónsdóttir, Ingibjörg S.
    Langvatn, Rolf
    Seasonal and inter-annual diet variation during winter in female Svalbard reindeer2009In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 41, no 1, p. 88-96Article in journal (Refereed)
  • 2.
    Geck, JR
    et al.
    U Alaska.
    Hock, R
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Nolan, M
    WERC.
    Geodetic Mass Balance of Glaciers in the Central Brooks Range, Alaska, U.S.A., from 1970 to 20012013In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 45, no 1, p. 29-38Article in journal (Refereed)
    Abstract [en]

    Alaska's arctic glaciers have retreated and thinned during recent decades, and glaciers in the central Brooks Range are no exception. Digital elevation models (DEMs) reconstructed from topographic maps (from 1970 and 1973) were differenced from a 2001 interferometric synthetic aperture radar DEM to calculate the volume and mass changes of 107 glaciers covering 42 km2 (1970/1973) in the central Brooks Range, Alaska, U.S.A. For each glacier the 1970/1973 DEM was 3-D co-registered (horizontal and vertical) to maximize agreement between the non-glacierized terrains of both DEMs. Over the period 1970–2001, total ice volume loss was 0.69 ± 0.06 km3 corresponding to a mean (area-weighted) specific mass balance rate of -0.54 ± 0.05 m w.e. a-1 (± uncertainty). The arithmetic mean of all glaciers' specific mass balance rates was -0.47 ± 0.27 m w.e. a-1 (± 1 std. dev.). A value of -0.52 ± 0.36 m w.e. a-1 (± 1 std. dev.) was found when 3-D coregistration is performed over the entire domain instead of individually for each glacier, indicating the importance of proper co-registration. Glacier area, perimeter, boundary compactness, mean elevation, and mean slope were correlated with specific balance rates, suggesting that large, low-elevation, elongated and shallow sloped glaciers had more negative balance rates than small, high-elevation, circular, and steep glaciers. A subsample of 36 glaciers showed a mean area reduction of 26 ± 16% (±1 std. dev.) over ∼35 years.

  • 3. Ingvander, Susanne
    et al.
    Brown, Ian A.
    Jansson, Peter
    Holmlund, Per
    Johansson, Cecilia
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Rosqvist, Gunhild
    Particle Size Sampling and Object-Oriented Image Analysis for Field Investigations of Snow Particle Size, Shape, and Distribution2013In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 45, no 3, p. 330-341Article in journal (Refereed)
    Abstract [en]

    Snow particle size is an important parameter strongly affecting snow cover broadband albedo from seasonally snow covered areas and ice sheets. It is also important in remote sensing analyses because it influences the reflectance and scattering properties of the snow. We have developed a digital image processing method for the capture and analysis of data of snow particle size and shape. The method is suitable for quick and reliable data capture in the field. Traditional methods based on visual inspection of samples have been used but do not yield quantitative data. Our method provides an alternative to both simpler and more complex methods by providing a tool that limits the subjective effect of the visual analysis and provides a quantitative particle size distribution. The method involves image analysis software and field efficient instrumentation in order to develop a complete process-chain easily implemented under field conditions. The output from the analysis is a two-dimensional analysis of particle size, shape, and distributions for each sample. The results of the segmentation process were validated against manual delineation of snow particles. The developed method improves snow particle analysis because it is quantitative, reproducible, and applicable for different types of field sites.

  • 4. Jansson, Peter
    et al.
    Pettersson, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Spatial and Temporal Characteristics of a Long Mass Balance Record, Storglaciären, Sweden2007In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 39, no 3, p. 432-437Article in journal (Refereed)
    Abstract [en]

    Glacier fluctuations constitute an important indicator for climate change, both current and past. Glacier mass balance measurements are made to correctly reflect the state of the glacier. Very few studies have been made to study the representability of each point measurement to the average mass balance of a particular glacier, an exercise that requires a large number of measurements. Such studies are rare due to the practical constraints and costs involved in collecting data. On Storglaciären, Sweden, a very dense system of measurements of both distributed winter (~100 points km-2) and summer (~15 points km-2) balance allows a spatial analysis of the mass balance components. The results show that local summer balance values are strongly correlated to the average summer balance value of the glacier. Local winter balance values are also generally well correlated to the average winter balance value, but small areas on the glacier exhibit no correlation. These areas correspond to wind-eroded areas of low accumulation on the glacier. The local net balance values are also well correlated to the average net balance value, indicating that the effect of the summer balance is strong and, at least partly, counter-balancing the spatial inhomogeneities in the local spatial winter balance values. These results show that detailed knowledge of both mass balance components and their spatial variability may be necessary to safely use a sparse system of measurements points. On Storglaciären, this is especially true for winter balance measurements since the spatial snow distribution is highly variable and not necessarily representative of the glacier average at each measurement point. The results strictly apply to Storglaciären but similar effects should be present on most glaciers in a similar setting; the results thus serve as an example of conditions that can be expected on a typical mid-latitude to subarctic glacier.

  • 5. le Roux, Peter C.
    et al.
    Boelhouwers, Jan
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography. Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Davis, Jacqueline K.
    Haussmann, Natalie S.
    Jantze, Elin J.
    Meiklejohn, K. Ian
    Spatial Association of Lemming Burrows with Landforms in the Swedish Subarctic Mountains: Implications for Periglacial Feature Stability2011In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 43, no 2, p. 223-228Article in journal (Refereed)
    Abstract [en]

    Burrowing mammals often have considerable geomorphological impacts, and their tunneling activities may decrease the stability of landforms. We document the spatial distribution of Norwegian lemming burrows in a subarctic alpine meadow to determine the preferred locations for burrow entrances and to examine the potential for burrowing to decrease the stability of periglacial landforms at the site. Burrow entrances were disproportionately common into the base and sides of landforms (>68% of burrows), probably reflecting the lower energetic cost of moving soil horizontally, rather than vertically, out of burrows. Most burrow entrances (>60%) were also located under large rocks, which probably improve burrow stability by providing a firm ceiling to the entrance. Field observations show that these burrows are relatively stable, as only 3% were associated with any signs of increased erosion or landform instability. Therefore, in contrast to some previous studies, and despite burrowing being concentrated on landforms, we suggest that these rodents have little direct impact on landform integrity at this site.

  • 6.
    Samyn, D.
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Vega, Carmen P.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Motoyama, H.
    Pohjola, Veijo A.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Nitrate and Sulfate Anthropogenic Trends in the 20th Century from Five Svalbard Ice Cores2012In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 44, no 4, p. 490-499Article in journal (Refereed)
    Abstract [en]

    Sulfate and nitrate records from 5 ice cores spread across Svalbard were compared and revealed strong temporal similarities with previously published global estimates of SO2 and NOx anthropogenic emissions during the 20th century. A significant departure from the early century sulfate and nitrate levels was evident at all drilling sites starting from the mid-1940s. A steady increase was observed in both sulfate and nitrate profiles at most sites until the late 1960s, when the annual concentrations started to increase at a higher rate. This peak activity lasted for about a decade, and was observed to decrease steadily from the early 1980s on, when sulfate levels declined significantly and when nitrate levels finally reached sulfate levels for the first time in 20th century. The timing of these trends in Svalbard with global SO2 and NOx concentration profiles was best appraised when considering composite concentration profiles of all Svalbard ice cores for sulfate and nitrate, respectively. Composite profiles were also found to provide a convenient mean for distinguishing between the most important world source regions. Based on correlation analysis, the major pollutant sources appeared to be Western Europe and North America for both sulfate and nitrate, followed by Central Europe and former U.S.S.R. in generally similar proportions.

  • 7. Sjögersten, Sofie
    et al.
    Melander, Erik
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Wookey, Philip A.
    Depth distribution of net methanotrophic activity at a mountain birch forest-tundra heath ecotone, northern Sweden2007In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 39, no 3, p. 477-480Article in journal (Refereed)
    Abstract [en]

    Methanotrophy (the bacterial oxidation of CH4) in soils is the major biological sink for atmospheric CH4. Here we present results from a study designed to quantify the role of the physical diffusion barrier to CH4, through surface soils, as a factor affecting methanotrophy. We used the mountain birch forest-tundra heath ecotone in subarctic northern Sweden as our study system. Our results show that, although CH4 fluxes were generally low (around -20 mu mol m(-2) h(-1); a net flux from atmosphere to soil), the two adjacent communities responded in contrasting ways to in situ experimental reduction of the diffusion barrier (removal of the top 50 mm of soil): Uptake increased by 40% in forest soil in association with the removal, whereas it decreased marginally (by 10%) in tundra heath. Investigations of the depth-distribution of CH4 oxidation in vitro revealed maximum rates at the top of the mineral soil for the forest site, whereas at the tundra heath this was more evenly spread throughout the organic horizon. The contrasting physicochemical properties and methanotroph activity in the organic horizons together explain the contrasting responses to the removal treatment. They also illustrate the potential role of vegetation for methane oxidation around this ecotone, exerted through its influence on the depth and properties of the organic horizons in these subarctic soils.

  • 8. Van Bogaert, Rik
    et al.
    Jonasson, Christer
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Geophysics.
    De Dapper, Morgan
    Callaghan, Terry V.
    Range Expansion of Thermophilic Aspen (Populus tremula L.) in the Swedish Subarctic2010In: Arctic, Antarctic and Alpine research, ISSN 1523-0430, E-ISSN 1938-4246, Vol. 42, no 3, p. 362-375Article in journal (Refereed)
    Abstract [en]

    In subarctic Sweden, recent decadal colonization and expansion of aspen (Populus tremula L.) were recorded. Over the past 100 years, aspen became c. 16 times more abundant, mainly as a result of increased sexual regeneration. Moreover, aspen now reach tree-size (>2 m) at the alpine treeline, an ecotone that has been dominated by mountain birch (Betula pubescens ssp. czerepanovii) for at least the past 4000 years. We found that sexual regeneration in aspen probably occurred seven times or more within the last century. Whereas sexual regeneration occurred during moist years following a year with an exceptionally high June July temperature, asexual regeneration was favored by warm and dry summers. Disturbance to the birch forest by cyclic moth population outbreaks was critical in aspen establishment in the subalpine area. At the treeline, aspen colonization was less determined by these moth outbreaks, and was mainly restricted by summer temperature. If summer warming persists, aspen spread may continue in subarctic Sweden, particularly at the treeline. However, changing disturbance regimes, future herbivore population dynamics and the responses of aspen's competitors birch and pine to a changing climate may result in different outcomes.

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