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  • 1. Abbuehl, Luca M.
    et al.
    Norton, Kevin P.
    Schlunegger, Fritz
    Kracht, Oliver
    Aldahan, Ala
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Possnert, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, För teknisk-naturvetenskapliga fakulteten gemensamma enheter, Tandem Laboratory.
    El Niño forcing on 10Be-based surface denudation rates in the northwestern Peruvian Andes?2010In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 123, no 3-4, 257-268 p.Article in journal (Refereed)
    Abstract [en]

    High magnitude precipitation events provide large contributions to landscape formation and surface denudation in arid environments. Here, we quantify the precipitation-dependent geomorphic processes within the Rio Piura drainage basin located on the Western Escarpment of the northern Peruvian Andes at 5 degrees S latitude. In this region, monsoonal easterly winds bring precipitation to the >3000 m asl high headwaters, from where the annual amount of precipitation decreases downstream toward the Pacific coast. Denudation rates are highest in the knickzones near the headwaters, similar to 200-300 mm ky(-1), and sediment discharge is limited by the transport capacity of the channel network. Every few years, this situation is perturbed by westerly, wind-driven heavy precipitation during El Nino events and results in supply-limited sediment discharge as indicated by bedrock channels. The detailed analysis of the stream-long profiles of two river basins within the Rio Piura catchment reveals a distinct knickzone in the transition zone between the easterly and westerly climatic influences, suggesting an En Nino forcing on the longitudinal channel profiles over at least Holocene timescales. Measured trunk stream catchment-wide denudation rates are up to ca. 300 mm ky(-1) and decrease successively downstream along the river profiles. Denudation rates of tributary rivers are ca. 200 mm ky(-1) near the plateau and show a stronger downstream decreasing trend than trunk stream rates. This suggests that the landscape is in a transient stage of local relief growth, which is driven by fluvial incision. This corroborates the results of paleoclimate studies that point towards higher El Nino frequencies during the past ca. 3000 years, leading to higher runoff and more erosion in the trunk channel compared to the hillslopes and thus growth of local relief. Downstream increases in channel gradient spatially coincide with the reaches of highest precipitation rates during El Nino events, we therefore interpret that Holocene landscape evolution has largely been controlled by climate. The ky-timescale of the Be-10 data together with the transience of the landscape implies that El Nino events in northwestern Peru have occurred since at least the Holocene, and that adjustment to channel incision is still taking place.

  • 2.
    Boelhouwers, Jan
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Holness, Steve
    Sumner, Paul
    The maritime Subantarctic: a distinct periglacial environment2003In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 52, no 1-2, 39-55 p.Article in journal (Refereed)
    Abstract [en]

    Recent research on slope processes and weathering on Marion Island has highlighted distinctive attributes of the maritime Subantarctic periglacial environment, compared to other periglacial environments. This is reflected morphologically by sorted stripe characteristics and stratified solifluction forms, but the wind factor and low diurnal temperature range also results in differences with other diurnal frost environments. Its hyper-maritime setting at low mean annual temperatures results in very high frost cycle frequencies, with associated effectiveness in surface sediment transport and patterned ground development. In addition, a high frequency of wetting and drying cycles is observed in rocks. Small seasonal temperature ranges and steep temperature profiles indicate a high sensitivity to climate change in the Subantarctic, as reflected in a rich relict periglacial record on most islands. This sensitivity appears absent in high tropical environments of low annual temperature range.

  • 3.
    Eriksson, Bert
    et al.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Eldridge, David J.
    Surface destabilisation by the invasive burrowing engineer Mus musculus on a sub-Antarctic island2014In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 223, 61-66 p.Article in journal (Refereed)
    Abstract [en]

    Invasive species are known to have substantial trophic effects on ecosystems and ecosystem processes. The invasion of the house mouse (Mus musculus) onto sub-Antarctic islands has had a devastating effect on plants, invertebrates, and birds with substantial changes in ecosystem functions. Less well understood, however, are the nontrophic, geomorphic effects of mice resulting from their burrowing activities. We examined the extent of burrow construction by M. musculus across an area of about 20 ha on Marion Island and the effects of burrows on water flow and sediment movement. We recorded a density of 0.59 +/- 0.48 (mean +/- SD) burrows m(-2), with more burrows at lower altitudes and shallower slopes, and twice the density in the solifluction risers (0.86 +/- 0.54 m(-2)) than the intervening terraces or treads (0.40 +/- 0.51 m(-2)). Most burrows were dug horizontally into the slope and tended to extend about 20 cm deep before turning. A very conservative estimate of sediment removed from burrows from this depth is 2.4 t ha(-1). However, taking into account more detailed data on burrow morphology based on excavations, actual amounts may be closer to 8.4 t ha(-1). Average soil displacement rate for a single burrow, measured over 5 days, was 0.18 kg burrow(-1) day(-1). Burrows acted as conduits for water and warmer air. Stones at burrow entrances were moved eight times farther by water (10.4 cm) than those not associated with burrows. Similarly, temperatures adjacent to burrow entrances were 4.1 degrees C higher than sites 10 cm away. Together our data indicate that mice are having substantial deleterious and geomorphic effects on sub-Antarctic ecosystems through their burrowing. With lower rates of mouse mortality resulting from warmer climates predicted under global climate models, we can expect an increase in damage resulting from mouse activity. 

  • 4.
    Gustavsson, Marcus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    Kolstrup, Else
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    New geomorphological mapping system used at different scales in a Swedish glaciated area2009In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 110, no 1-2, 37-44 p.Article in journal (Refereed)
    Abstract [en]

    A new, detailed geomorphological mapping system is tested at different scales for presentation of landscape configuration and interpretation of landscape development of a formerly glaciated area near Mora in central Sweden. The geomorphological maps are based on fieldwork supported by aerial photographs. The area contains landforms created by mass movement, glacial, glaciofluvial, fluvial, lacustrine, aeolian and anthropogenic processes. In addition, geomorphological effects of isostatic uplift, which has caused a c. 220 m rise of the former Ancylus lake shoreline in the area since the deglaciation, can be seen. The new system is tested at scales 1:5000, 1:25,000 and 1:50,000 using the same legend. At the largest scale information on morphography/morphometry, lithology, and hydrography are included in the map as are details on polygenetic origins of landforms. With each step from the 1:5000 to the 1:50,000 scale some generalisation is needed at the cost of descriptive detail. In turn, with smaller scale, the general overview of the area increases and the impression from the map gradually becomes more dominated by genesis. The emphasis of the map thus changes from a presentation with a high level of descriptive information at the largest scale to a more interpretative overview at smaller scales. The scale transformation shows that the geomorphological presentation of the landscape is a function of both the landscape hierarchy and the geomorphological context within an area. The use of the new geomorphological mapping system at the three scales shows that the tested mapping legend can be used without modification from one scale to another. This is mainly because the geomorphological information parameters are separated in the legend, and that explanatory information is gained from combinations of them. The possibility to apply the same legend at different scales for an area facilitates the choice of an appropriate mapping scale for specific purposes and applications. The new mapping system also has the advantage that the data can be easily transformed into a GIS ESRI geodatabase containing the same "raw-data" as the original map. The differences of information at the different scales illustrate problems that are also relevant for use and presentation of geomorphological data in a GIS and three examples of scale problems in relation to GIS data handling are outlined.

  • 5.
    Gustavsson, Marcus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Environment and Landscape Dynamics.
    Kolstrup, Else
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Environment and Landscape Dynamics.
    Seijmonsbergen, Arie, C.
    A new symbol- and GIS-based detailed geomorphological mapping system: renewal of a scientific discipline for understanding landscape development2006In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 77, no 1-2, 90-111 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents a comprehensive and flexible new geomorphological combination legend that expands the possibilities of current geomorphological mapping concepts. The new legend is presented here at scale of 1:10,000 and it combines symbols for hydrography, morphometry/morphography, lithology and structure with colour variations for process/genesis and geologic age. The piece-by-piece legend forms a “geomorphological alphabet” that offers a high diversity of geomorphological information and a possibility for numerous combinations of information. This results in a scientific map that is rich in data and which is more informative than most previous maps but is based on a simple legend. The system is developed to also be used as a basis for applications in GIS. The symbol-based information in the geomorphological maps can be digitally stored as a powerful database with thematic layers and attribute tables. By combining and further developing aspects of different classical mapping systems and techniques into expanded data combinations, new possibilities of presentation and storage are developed and thus a strong scientific tool is provided for landscape configuration and the reconstruction of its development; in turn the combination paves the way for specific thematic applications. The new system is illustrated for two contrasting landscape types: the first is located on the border of Vorarlberg, western Austria, and Liechtenstein in a glacially influenced, high altitude alpine setting that is strongly modified by various degradation processes; the second area represents a formerly glaciated region in Dalarna, central Sweden near Mora, an area that is characterized by a variety of aeolian, fluvial, glaciofluvial and lacustrine depositional and erosional landforms and also reflects isostatic uplift. The new method functions well for both areas and results in detailed scientific outlines of both landscape types.

  • 6.
    Gustavsson, Marcus
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Environment and Landscape Dynamics.
    Seijmonsbergen, AC
    Kolstrup, Else
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, Environment and Landscape Dynamics.
    Structure and contents of a new geomorphological GIS database linked to a geomorphological map - with an example from Liden, central Sweden2008In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 95, no 3-4, 335-349 p.Article in journal (Refereed)
    Abstract [en]

    This paper presents the structure and contents of a standardised geomorphological GIS database that stores comprehensive scientific geomorphological data and constitutes the basis for processing and extracting spatial thematic data. The geodatabase contains spatial information on morphography/morphometry, hydrography, lithology, genesis, processes and age. A unique characteristic of the GIS geodatabase is that it is constructed in parallel with a new comprehensive geomorphological mapping system designed with GIS applications in mind. This close coupling enables easy digitalisation of the information from the geomorphological map into the GIS database for use in both scientific and practical applications. The selected platform, in which the geomorphological vector, raster and tabular data are stored, is the ESRI Personal geodatabase. Additional data such as an image of the original geomorphological map, DEMs or aerial orthographic images are also included in the database. The structure of the geomorphological database presented in this paper is exemplified for a study site around Liden, central Sweden.

  • 7.
    Haussmann, Natalie
    et al.
    Department of Conservation Ecology and Entomology, Stellenbosch University, South Africa.
    McGeoch, Melodie
    DST-NRF Centre for Invasion Biology and Cape Research Centre, South African National Parks.
    Boelhouwers, Jan
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Interactions between a cushion plant (Azorella selago) and surface sediment transport on sub-Antarctic Marion Island2009In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 107, no 3-4, 139-148 p.Article in journal (Refereed)
    Abstract [en]

    On sub-Antarctic Marion Island cushions of the dominant vascular plant species, Azorella selago, interact with the geomorphology of fellfield landscapes by affecting sediment distribution and ultimately terrace formation. Here, to understand the consequences of Azorella cushions for substrate movement and sorting, we quantified the size and shape of Azorella cushions and the grain size distribution of sediment surrounding these cushions, using a combination of image analysis approaches. Results show that as cushions become larger, they tend to become more elongated and grow more perpendicular to the slope. Mean and variance of grain size were greater upslope of Azorella cushions, while the number of particles was higher downslope of cushions, although these differences were not significant at all sites studied. Differences between upslope and downslope particle sizes were, however, not related to cushion elongation or growth angle as had been expected. The observed sediment partitioning is likely caused by a combination of frost-related sediment transport and Azorella cushions acting as sediment obstructions. Understanding these interactions between Azorella cushions and the landscape is especially important in the light of recent warming and drying on the island, as particle size affects soil properties such as water-holding capacity and frost susceptibility.

  • 8.
    Kolstrup, Else
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Thyrsted, Tage
    Stone heave field experiment in clayey silt2010In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 117, no 1-2, 90-105 p.Article in journal (Refereed)
    Abstract [en]

    We recorded movements of 24 cm large globes and cuboids made of granite, concrete and wood buried at three different depths in silty soil, in a cool temperate environment during four and a half years. We also monitored 4-hourly soil moisture and air and ground temperature. All objects heaved during freezing and fell back during thawing, and some sank during the summers. Freeze thaw in a very shallow surface layer may result in heave of objects due partly to sediment infill in unfrozen soils beneath the objects. The net result was sinking of some of the granite and concrete objects and rise of wooden ones. The recorded object movements, in relation to the thermal properties and specific gravity of the objects and the embedding soil, show that an (almost) isodiametric object tends to sink or remain in place if its thermal conductivity and density exceed those of the surrounding soil, and to rise if the reverse is the case. (C) 2009 Elsevier B.V. All rights reserved.

  • 9.
    Kolstrup, Else
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Thyrsted, Tage
    Stone heave field experiment in sand2011In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 129, no 3-4, 361-375 p.Article in journal (Refereed)
    Abstract [en]

    Movements of 24 cm large globes and cuboids of granite, concrete and wood were recorded during four and a half years. The objects were buried at three different depths in well-sorted sand in a natural cool temperate environment. All objects moved during the experiment and at the end most wood objects, which had a relatively low thermal conductivity had moved up, and the granite and concrete objects with higher thermal conductivities had sunk a little or remained almost in place. Also the soil surface moved and its final height was up to 1 cm above that at the start. The movements of the objects started within a few hours after temperature shifts around 0 degrees C with the granite reacting more readily than the wood. It is hypothesized that the movements are related to the thermal properties of the objects and the soil. The experiment was done in parallel with an experiment in clayey silt and the net results in sand show clear parallels to the movements of similar objects in the silt. It is concluded that the material and shape of the object are more important to movements than whether they are embedded in sand or silty clay. (C) 2011 Elsevier B.V. All rights reserved.

  • 10.
    Lindbäck, Katrin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Pettersson, Rickard
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Spectral roughness and glacial erosion of a land-terminating section of the Greenland Ice Sheet2015In: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 238, 149-159 p.Article in journal (Refereed)
    Abstract [en]

    Spectral roughness offers a significant potential for understanding the evolution of glaciated landscapes. Here, we present the first roughness study combining a high-resolution (250 to 500 m) DEM of a large land-terminating section (12,000 km2) of the Greenland Ice Sheet with the topography of the proglacial area. Subglacial roughness shows a directional dependence with consistently lower values in the ice flow direction compared to the across–flow direction. We find a correlation between low basal roughness, fast ice flow, and subglacial troughs. The northern part of the subglacial study area has an undulating topography with variable roughness, resembling the landscape in the proglacial area. In this area, there is a glacially eroded, overdeepened trough with bed elevations 510 m below sea level, consistent with warm ice and a well-lubricated bed. The southern part of the subglacial study area has higher bed elevations and higher roughness than the northern part, possibly because the bedrock consists of hard granitic gneiss as in the adjacent proglacial area. The subglacial troughs, which have been eroded to various extents, are aligned with geological weakness zones suggesting a preglacial origin. In general, there is a major geological control on the distribution of bed variability.

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