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  • 101. Bayer-Raich, Martí
    et al.
    Jarsjö, Jerker
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi.
    Teutsch, Georg
    Comment on “Analysis of groundwater contamination using concentration-time series recorded during an integral pumping test: Bias introduced by strong concentration gradients within the plume” by Allelign Zeru and Gerhard Schäfer2007Inngår i: Journal of Contaminant Hydrology, ISSN 0169-7722, Vol. 90, nr 3-4, s. 240-251Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We consider the results of a recent paper in this journal [Zeru, A. and Schäfer, G., 2005. Analysis of groundwater contamination using concentration–time series recorded during an integral pumping test: Bias introduced by strong concentration gradients within the plume. Journal of Contaminant Hydrology 81 (2005) 106–124], which addresses the field-scale characterisation of contaminant plumes in groundwater. There, it is concluded that contaminant concentration gradients can bias Integral Pumping Test (IPT) interpretations considerably, in particular if IPTs are conducted in advective fronts of contaminant plumes. We discuss implications of this setting and also argue that the longitudinal and transverse dispersivities used in the examples of Zeru and Schäfer (2005) of up to 30 m and 3 m, respectively, are generally very high for the here relevant capture zone scale (b20 m). However, regardless of both longitudinal and transverse concentration gradients, we further show through a counter-example that IPT results are unbiased as long as the concentration attenuation along the flow direction is linear over the capture zone extent.

  • 102. Beedle, M.
    et al.
    Dyurgerov, Mark
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi.
    Tangborn, W.
    Khalsa, S.J.S.
    Helm, C.
    Raup, Bruce
    Armstrong, R.
    Barry, R.G.
    Improving estimation of glacier volume change: a GLIMS case study of Bering Glacier System, Alaska.2008Inngår i: The Cryosphere, ISSN 1994-0416, Vol. 2, nr 1, s. 33-51Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Global Land Ice Measurements from Space (GLIMS) project has developed tools and methods that can be employed by analysts to create accurate glacier outlines. To illustrate the importance of accurate glacier outlines and the effectiveness of GLIMS standards we conducted a case study on Bering Glacier System (BGS), Alaska. BGS is a complex glacier system aggregated from multiple drainage basins, numerous tributaries, and many accumulation areas. Published measurements of BGS surface area vary from 1740 to 6200 km2, depending on how the boundaries of this system have been defined. Utilizing GLIMS tools and standards we have completed a new outline (3630 km2) and analysis of the area-altitude distribution (hypsometry) of BGS using Landsat images from 2000 and 2001 and a US Geological Survey 15-min digital elevation model. We compared this new hypsometry with three different hypsometries to illustrate the errors that result from the widely varying estimates of BGS extent. The use of different BGS hypsometries results in highly variable measures of volume change and net balance (bn). Applying a simple hypsometry-dependent mass-balance model to different hypsometries results in a bn rate range of −1.0 to −3.1 m a−1 water equivalent (W.E.), a volume change range of −3.8 to −6.7 km3 a−1 W.E., and a near doubling in contributions to sea level equivalent, 0.011 mm a−1 to 0.019 mm a−1. Current inaccuracies in glacier outlines hinder our ability to correctly quantify glacier change. Understanding of glacier extents can become comprehensive and accurate. Such accuracy is possible with the increasing volume of satellite imagery of glacierized regions, recent advances in tools and standards, and dedication to this important task.

  • 103. Beilin, R
    et al.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Biodiversity and Land Abandonment:  Connecting Agriculture, Place and Nature in the Landscape2010Inngår i: Landscape, identities and development / [ed] Roca, Zoran, Springer , 2010Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    This paper considers how cultural and social-centric norms influence the management and the meaning of land abandonment and biodiversity in rural landscapes. We describe historically, geologically, ecologically and socially diverse landscapes in three international case studies.  In Australia, rural land abandonment after only 150 years of European agriculture is associated biophysically with salinity, erosion and acidification.  It triggers a potential loss of place and identity for a nation still imagining a frontier past. Trading water away from the land and deregulation of production regimes due to WTO imperatives may create the opportunity for regeneration of indigenous flora and a new identity associated with conservation values.  In Sweden land abandonment reflects entrenched agricultural landscapes of over 1000 years.  Their landscape biodiversity is considered unique and in need of preservation in the face of aging farmer populations and the realities of food imports making production regimes non-viable. Sustainability appears to be associated with maintaining production regimes strongly linked to local cultural identity and sense of place.  In Portugal agricultural land abandonment in the north seems to offer a chance for oak forest regeneration and improved biodiversity outcomes. Identity here is associated with remembered landscapes prior to EU entry and re-imagining landscape connections built on previous cultural ties. In all three cases we consider what this interplay between natural and cultural landscapes will mean to their local communities; and using the historical and cultural lens, examine the theoretical ecological and sociological platforms surrounding the discourse on land use change.  We consider the benefits from interdisciplinary and international comparative research providing local-global insights that emerge to suggest common larger narratives of place and culture despite divergent histories of settlement and cultivation.

  • 104. Beilin, Ruth
    et al.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Stenseke, Marie
    Pereira, Henrique Miguel
    Llausas, Albert
    Slätmo, Elin
    Cerqueira, Yvonne
    Navarro, Laetitia
    Rodrigues, Patricia
    Reichelt, Nicole
    Munro, Nicola
    Queiroz, Cibele
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen. Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre. Universidade de Lisboa, Portugal.
    Analysing how drivers of agricultural land abandonment affect biodiversity and cultural landscapes using case studies from Scandinavia, Iberia and Oceania2014Inngår i: Land use policy, ISSN 0264-8377, E-ISSN 1873-5754, Vol. 36, s. 60-72Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Agricultural land abandonment (ALA) is widespread in many countries of the global north. It impacts rural communities, traditional landscapes, biodiversity and ecosystem services. It is an opportunity for ecosystem restoration or new landscape functions. We explored ALA in study areas in Australia, Portugal and Sweden. In each, we assessed plant species diversity, historical trajectories of land cover change; and the socioeconomic past, present and future in interviews with farmers. The ALA data was integrated and analysed by identifying the drivers of change. The relative importance of each driver and its scale of action was estimated, both in the past (1950-2010) and in the future (2010-2030). ALA has transformed rural landscapes in the study areas of Portugal and Sweden. It is at a much earlier stage with potential to increase in the Australian case. We identified a set of driving forces, classified into pressures, frictions and attractors that clarify why ALA, noting its temporal and spatial scale, occurs differently in each study area. The effect of the drivers is related to social and historical contexts. Pressures and attractors encouraging agricultural abandonment are strongest in Portugal and Sweden. Generally more (institutionalized) frictions are in place in these European sites, intended to prevent further change, based on the benefits assumed for biodiversity and aesthetics. In Australia, the stimulation of driving forces to promote a well-managed abandonment of some cleared areas could be highly beneficial for biodiversity, minimally disruptive for current dairy farming operations and would bring opportunities for alternative types of rural development.

  • 105.
    Bengtsson, Anneli
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Samråd i miljökonsekvensbeskrivningarför projekt: En studie av dess historiska och nuvarandefunktion samt en inblick i hur dessfunktion skulle kunna se ut i framtiden2014Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Forskare argumenterar för att det krävs mer deliberativa kvaliteter i dagensdemokratiska Sverige för att vi dels ska kunna kallas oss för en fungerande demokratioch dels för att vi ska ha en chans att kunna nå något vi nästan alla strävar efter idag –hållbar utveckling. En lagstadgad och därmed vanlig metod som används idag för attutreda en planerad verksamhets miljökonsekvenser är att upprätta enmiljökonsekvensbeskrivning (MKB). Samrådsprocessen i MKB:s för projekt är ettmedel att göra processen mer demokratisk. Syftet med denna studie är att utvärderadetta demokratiska medel för att kunna dra slutsatser kring om det fyller sin funktionoch hur det skulle gå att förbättra för att generera fler positiva utfall. Syftet harbesvarats med hjälp av två litteraturstudier, sex djupintervjuer och enenkätundersökning som alla har kopplats till studiens teoretiska utgångspunkter. En delav uppsatsens teori är relevant bakgrund (d.v.s. avsnitt Miljökonsekvensbeskrivningar)medan andra delar är vetenskapliga och har som syfte att jämföras med resultaten (d.v.s.avsnitt Samtalsdemokrati).

    Det viktigaste resultatet från de två litteraturstudierna var att kapitlet om MKB imiljöbalken inte har genomgått någon större förändring från det att det skapades tillsidag och att det behövs andra metoder (ex. intervjuer och observationer) för att kunnaavgöra om det som kommer fram på samrådet tas hänsyn till i MKB:n. Det mestframträdande resultatet från intervjuer och enkätundersökning var dels att denvanligaste formen på samråd är antingen skriftligt eller ett stormöte och dels attupplägget på stormöten ofta inleds med att verksamhetsutövaren håller en långpresentation och i slutet blir det en kort frågestund. Resultatet visar också att det verkarvara form och upplägg på samrådsprocessen som skapar de största problemen för att videls ska få ut de kvaliteter som konsulter och verksamhetsutövare själva anser ärviktigast, nämligen synpunkter och dels för att kunna säkra att detta verktyg för att ökademokratin, som samråd just är, inte bara gör det i teorin utan också i praktiken. Det ärkring detta som diskussionen till största del har kretsat och det är detta som äruppsatsens viktigaste slutsats. Resultatet visar också att konsulter ochverksamhetsutövare är medvetna om att de vanligaste formerna för samråd inte äroptimala för att leverera de synpunkter de så gärna vill ha, ändå finns en motvilja till attändra och utveckla formen. Ett förslag för vidare utredning är att gå djupare in på vaddetta beror på för att på sikt kanske finna nyckeln till hur man kan ändra på dennamotvilja att utveckla form och upplägg på samrådsförfarandet.

  • 106. Benjaminsen, Tor Arvid
    et al.
    Bryceson, Ian
    Dahlberg, Annika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Stockholms universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Holmgren, Karin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Johansson, Lars
    Widgren, Mats
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Östberg, Wille
    Svenskt bistånd ska rädda miljöfarligt etanolprojekt2009Inngår i: Dagens NyheterArtikkel i tidsskrift (Annet (populærvitenskap, debatt, mm))
  • 107. Bennett, Elena M.
    et al.
    Peterson, Garry D.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Stockholms universitet, Stockholm Resilience Centre. McGill University, Canada.
    Gordon, Line J.
    Stockholms universitet, Stockholm Resilience Centre.
    Understanding relationships among multiple ecosystem services.2009Inngår i: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 12, nr 12, s. 1394-1404Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ecosystem management that attempts to maximize the production of one ecosystem service often results in substantial declines in the provision of other ecosystem services. For this reason, recent studies have called for increased attention to development of a theoretical understanding behind the relationships among ecosystem services. Here, we review the literature on ecosystem services and propose a typology of relationships between ecosystem services based on the role of drivers and the interactions between services. We use this typology to develop three propositions to help drive ecological science towards a better understanding of the relationships among multiple ecosystem services. Research which aims to understand the relationships among multiple ecosystem services and the mechanisms behind these relationships will improve our ability to sustainably manage landscapes to provide multiple ecosystem services.

  • 108. Berggren, A. -M
    et al.
    Aldahan, A.
    Possnert, G.
    Hansson, Margareta
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Steen-Larsen, H. C.
    Storm, A. Sturevik
    Mörth, Carl-Magnus
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    Murad, A.
    Variability of Be-10 and delta O-18 in snow pits from Greenland and a surface traverse from Antarctica2013Inngår i: Nuclear Instruments and Methods in Physics Research Section B: Beam Interactions with Materials and Atoms, ISSN 0168-583X, E-ISSN 1872-9584, Vol. 294, s. 568-572Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    To examine temporal variability of Be-10 in glacial ice, we sampled snow to a depth of 160 cm at the NEEM (North Greenland Eemian Ice Drilling) drilling site in Greenland. The samples span three years between the summers of 2006 and 2009. At the same time, spatial variability of Be-10 in glacial ice was explored through collection of the upper similar to 5 cm of surface snow in Antarctica during part of the Swedish-Japanese traverse from Svea to Syowa station during the austral summer in 2007-2008. The results of the Greenlandic 1 Be snow suggested variable concentrations that apparently do not clearly reflect the seasonal change as indicated by the delta O-18 data. The Be-10 concentration variability most likely reflects also effects of aerosol loading and deposition pathways, possibly in combination with post-depositional processes. The Antarctic traverse data expose a negative correlation between Be-10 and delta O-18, while there are weaker but still significant correlations to altitude and distance to the coast (approximated by the distance to the 70th latitude). These relationships indicate that geographical factors, mainly the proximity to the coast, may strongly affect 1 Be concentrations in snow in Queen Maud Land, Antarctica.

  • 109. Bergström, J.
    et al.
    Lundqvist, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Maurits Lindström2009Annet (Annet (populærvitenskap, debatt, mm))
  • 110.
    Berkström, Charlotte
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Gullström, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Stockholms universitet, Stockholm Resilience Centre.
    Mwandya, Augustine W.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Yahya, Saleh A. S.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Kautsky, Nils
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Nyström, Magnus
    Stockholms universitet, Stockholm Resilience Centre.
    Exploring 'knowns' and 'unknowns' in tropical seascape connectivity with insights from East African coral reefs2012Inngår i: Estuarine, Coastal and Shelf Science, ISSN 0272-7714, E-ISSN 1096-0015, Vol. 107, s. 1-21Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Applying a broader landscape perspective to understand spatio-temporal changes in local populations and communities has been increasingly used in terrestrial systems to study effects of human impact and land use change. With today’s major declines in fishery stocks and rapid degradation of natural coastal habitats, the understanding of habitat configuration and connectivity over relevant temporal and spatial scales is critical for conservation and fisheries management of the seascape. Coral reefs, seagrass beds and mangroves are key-components of the tropical seascape. The spatial distribution of these habitat-types may have strong influences on cross-habitat migration and connectivity patterns among organisms. However, the consequences of seascape fragmentation and ecological connectivity are largely unknown. Here, we review the literature to provide an overview of current knowledge with regards to connectivity and food-web interactions within the tropical seascape. We show that information on fish acting as mobile links and being part of nutrient transfer and trophic interactions is scarce. We continue by making an in-depth analysis of the seascape around Zanzibar (Eastern Africa) to fill some of the knowledge gaps identified by the literature survey. Our analysis shows that (i) fifty percent of all fish species found within the Zanzibar seascape use two or multiple habitat-types, (ii) eighteen percent of all coral reef-associated fish species use mangrove and seagrass beds as juvenile habitat, and (iii) macrocarnivores and herbivores are highly represented among those coral reef fish species that use mangrove and seagrass beds as juvenile habitat. We argue that understanding the inter-linkages within and between habitat-types is essential for successful management of the tropical seascape.

  • 111.
    Berkström, Charlotte
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Thyresson, Matilda
    Stockholms universitet, Naturvetenskapliga fakulteten, Stockholm Resilience Centre.
    Gullström, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och botanik.
    Assessing connectivity in a tropical embayment: Fish migrations and seascape ecology2013Inngår i: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 166, s. 43-53Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seascape connectivity and configuration of multiple habitats are important features to include in marine spatial planning, and protecting seascapes with high connectivity is recommended. The present study examines the potential connectivity of reef fish assemblages in a shallow-water conservation area in Zanzibar (Tanzania) by analysing relationships between a set of habitat variables and fish diversity and density for different functional groups (based on diet) and life stages of fish using PLS-analysis. We combined spatial pattern metrics (habitat type, patch size, distance to patch) and dispersal abilities of a number of fish species using buffer radius to answer the questions; (i) do coral reefs with high connectivity to seagrass habitats have higher abundances and higher species richness of fish that undertake routine migrations during their life-history? and (ii) do coral reefs closer to mangrove forest support higher abundances of nursery species (i.e., fish species that use mangrove and seagrass beds as juvenile habitat)? Habitat mosaics surrounding fish survey sites and within-patch measurements inside fish survey sites were quantified at multiple scales (meters to kilometers) using aerial photography and scuba. Fish data was collected using a standardized point census method. We found that both fine- and broad-scale variables were important in structuring fish communities and connectivity with surrounding habitats, where predominantly seagrass beds within a 750 m radius had a positive influence on fish abundances of invertebrate feeders/piscivores (especially for lutjanids and lethrinids). Additionally, fine-scale seagrass cover had a positive influence on nursery species. Depth also had a positive influence on total species richness and the abundance of invertebrate feeders/piscivores. This study highlights the importance of combining connectivity and habitat configuration at different scales to fully understand and manage the tropical seascape.

  • 112.
    Berkström, Charlotte
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Thyresson, Matilda
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Gullström, Martin
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Seascape configuration influences connectivity of reef fish assemblagesManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    Shallow-water habitats within tropical seascapes are intimately connected through ontogenetic and/or feeding migrations of fish. Knowledge on connectivity in the Indo-Pacific region is however sparse. Landscape ecology has been suggested as a useful approach when studying seascape connectivity. In this study, we examine the influence of habitat connectivity on reef fish assemblages in shallow-water habitats surrounding Zanzibar (Tanzania), using a seascape approach. We tested the relationships between a set of landscape and habitat variables and fish diversity and density for different functional groups and life stages. Habitat data was collected at scales ranging from 1m to >2km using aerial photography and ground-truthing. Fish data was collected using a standardised point census method. Furthermore, semi-structured interviews with 127 fishers in the bay were conducted to account for different fishing activity. We show that coral reefs in a complex seascape of Zanzibar are connected to seagrass beds through migration of fish. Habitat connectivity of seagrass and seagrass/coral mix within a 750m radius of coral reefs had a positive influence on fish abundances in the functional group of invertebrate feeders/piscivores, especially within the family Lutjanidae and Lethrinidae. Within-patch seagrass cover had a positive influence on nursery species. Depth also had a positive influence on fish assemblages, highlighting the importance of considering a third dimension, not accounted for in terrestrial studies. Generally, fishing activity between sites did neither influence species richness nor abundance, except for the abundance of juvenile parrotfish. We demonstrate that a landscape ecology approach, combining connectivity and habitat variables, is important for understanding and managing the tropical seascape, although it must be applied at relevant scales, habitat metrics and seascape configurations to fully capture ecological connectivity.

  • 113.
    Berntsson, Annika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Reconstruction of centennial scale climate change in NW Sweden, using Chironomids and high resolution XRF-data2010Inngår i: ESF TOPO-EUROPE Workshop and PhD Summer School on Detecting Landscape Change / [ed] Achim A. Beylich and Katja Laute, Trondheim: Norsk Geologisk Forening (NGF) , 2010, s. 75-77Konferansepaper (Annet vitenskapelig)
  • 114.
    Berntsson, Annika
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    The sensitivity of Swedish alpine lakes to hydro-climatic changes during the Late Holocene2014Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The thesis objective is to use lake sediments to investigate the relationships between chironomids, as proxy for temperature, and δ18O and minerogenic in-wash, as precipitation proxies, in northern Sweden during the Late Holocene. Three lakes along a N–S transect in the Scandes were studied using biological, geochemical and physical sediment properties, together with numerical methods. Emphasis was put on changes in hydrological and erosional regimes and the configurations of lake catchments in an attempt to avoid misinterpretation of the climate signals. Mean July air temperatures were inferred from the chironomid composition in sediment records covering the last 5000 yrs in Vindelfjällen Mountains in Mid Lapland and the last 1000 yrs in Jämtland. The temperature reconstructions underwent significance tests, suggesting reliable results for the Vindelfjällen reconstruction but not the Jämtland reconstruction. Data from XRF core scanning and grain size variations, interpreted together with catchment geomorphology, suggested periods with increased fluvial erosion. A major flood event occurred at the Vindelfjällen site c. 2800 cal. yr BP. Furthermore, this record indicates stream flow and wetland surface erosion during the last 1200 yrs. Seasonal variations in the amount of precipitation, reflecting changes in atmospheric circulation during the last 1000 yrs, were reconstructed based on δ18O in diatoms from one lake in Jämtland and one in northern Lapland. Relatively higher summer precipitation was inferred between AD 1000 and 1080, AD 1300 and 1440, and during the early 19th century as a result of a positive Arctic Oscillation mode. Changes in chironomid composition in the Jämtland lake were concurrent with shifts in δ18Odiatom suggesting indirect responses to circulation changes. Changes in precipitation are suggested to be an important factor that may cause the spatially variable results among chironomid-based July air temperature reconstructions in Scandinavia.

  • 115.
    Berntsson, Annika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Jansson, Krister
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Kylander, Malin E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologiska vetenskaper.
    De Vleeschouwer, François
    CNRS, EcoLab, Castanet Tolosan, France.
    Bertrand, Sebastien
    Ghent University.
    Late Holocene high precipitation events recorded in lake sediments and catchment geomorphology, Lake Vuoksjávrátje, NW SwedenManuskript (preprint) (Annet vitenskapelig)
    Abstract [en]

    In this paper, we highlight the importance of combining multi-proxy analysis of lake sediments with associated catchment geomorphology to better understand the late Holocene palaeoenvironmental evolution in a high latitude Alpine lake in N Sweden. Previous studies have suggested that such lakes may be highly sensitive to variations in catchment erosion and variations in precipitation, and that this sensitivity may influence ecologically-based reconstructions of past temperature changes. Here we have analysed lake sediments covering the last 5100 years from Lake Vuoksjávrátje in NW Sweden to identify different erosional regimes in the lake catchment and to identify sediment sources and lake sedimentary processes, which ultimately affect the palaeoecological record. Methods that were used include XRF core scanning, grain size analysis and geomorphological mapping, supported by previously published chironomid, total organic carbon and carbon/nitrogen data. From the integrated results we identify time intervals when increased amounts/intensity of precipitation altered sedimentation and lake catchment erosional processes. The most prominent event in our record occurred between 3090 and 2750 cal. a BP and is interpreted to be the result of excessive precipitation in relation to the 2.8 ka event. By combining the multi-proxy analysis of a lake sediment core with a detailed catchment characterisation it is possible to reach a better understanding of the processes active within the lake catchment, the factors governing the erosional regimes and the way these are recorded in lake sediments. For future palaeoclimatological research based on lake sediments we recommend increasing the integration of catchment geomorphology, sedimentology and palaeoecology.

  • 116.
    Berntsson, Annika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Kaislahti Tillman, Päivi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Ling, Johan
    Risberg, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Shore displacement in the world heritage area Tanum on the Swedish west coast2007Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 117.
    Berntsson, Annika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Kaislahti Tillman, Päivi
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Risberg, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Bilaga 18. Miljöförändringar kring Gamla Älvsborgs fästning baserade på diatoméstratigrafi, samt analyser av svavel och organiskt kol, i sediment avsatta i vallgraven2011Inngår i: Gamla Älvsborg i nytt ljus: Arkeologiska undersökningar 2004-2006 / [ed] Ulf Ragnesten, Mölnlycke: Elanders , 2011Kapittel i bok, del av antologi (Annet vitenskapelig)
  • 118.
    Berntsson, Annika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Rosqvist, Gunhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Reconstructing environmental and climate changes in Vindelfjällen, using lake sediments.2008Konferansepaper (Annet (populærvitenskap, debatt, mm))
  • 119.
    Berntsson, Annika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Rosqvist, Gunhild C.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Velle, Gaute
    Late-Holocene temperature and precipitation changes in Vindelfjallen, mid-western Swedish Lapland, inferred from chironomid and geochemical data2014Inngår i: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 24, nr 1, s. 78-92Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, we present results from a palaeolimnological study from Lake Vuoksjavratje in the mountain tundra region in the Vindelfjallen Mountains, northwest Sweden. We suggest that the influence of precipitation may be one of the factors causing discrepancies between chironomid-based late-Holocene July temperature (JulyT) reconstructions from Fennoscandia. We combine quantitative temperature reconstruction using chironomids for the last 5100 years with qualitative analysis of chironomid composition and geochemical analyses, such as x-ray fluorescence (XRF), total organic carbon (TOC) and C/N analysis. The studied sequence is dated by Pb-210, Cs-137 and 11 C-14 datings from terrestrial macrofossils. The aim of the study was to use chironomids to reconstruct late-Holocene summer temperature variation on a multi-centennial to centennial timescale and to use geochemical data to identify periods during which the changes in chironomid composition might have been forced by environmental variables other than temperature, such as within lake processes or precipitation. Based on ordination techniques, and a comparison between chironomid-inferred JulyTs and changes in minerogenic sedimentation with regional temperature and wetness records, it is concluded that the JulyT signal was modulated by precipitation. The proxies indicate that both JulyT and annual precipitation have influenced the chironomid communities in Lake Vuoksjavratje, and that catchment-related processes caused by enhanced precipitation have overridden the summer temperature signal between 3000 and 2200 cal. yr BP, and between 1050 and 100 cal. yr BP.

  • 120.
    Berntsson, Annika
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Velle, Gaute
    University of Bergen.
    Rosqvist, Gunhild
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Bergman, Jonas
    Holzkämper, Steffen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Eriksson, Lars
    Sveriges Landbruksuniversitet.
    An evaluation of a chironomid-based summer temperature reconstruction from west 1 central Sweden covering the last millenniumManuskript (preprint) (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Here we present a lake sediment study from west central Sweden that covers the last thousand years. The study site Lake Spåime is a shallow, hydrologically open lake situated above the present tree line. We applied chironomid analysis with the aim to reconstruct mean July air temperature at a high temporal resolution and we evaluated our reconstruction with significance tests and comparison with observed meteorological data. We examined the relationship between changes in chironomid-inferred July temperature, isotope hydrology and minerogenic detrital input. We also assessed the influence of running water and semi-terrestrial/terrestrial chironomids. The inferred July air temperatures ranged from 8.5˚C to 11.6˚C (mean 9.6˚C) over the past millennium. The temperatures inferred with running water- and terrestrial taxa removed was similar, but with a 0.6 ˚C higher amplitude. The results of significance testing were inconclusive. Comparison with meteorological data showed that the chironomid-based July air temperatures were similar during the last 110 years. Individual years when chironomid-inferred July air temperatures were lower than the instrumental data were characterized by low June air temperatures and high amounts of winter precipitation. From this, we assume that late snowmelt led to cool melt water input in July which in turn caused a decoupling between water and air temperatures causing too low inferred temperatures. Inferred July temperatures show similarities and discrepancies with reconstructions derived from other proxies in the region, such as tree-ring and sea surface temperature records, and fail to reconstruct the cold summer conditions characteristic of the years between AD 1650 and 1750. We conclude that the Spåime July temperature reconstruction was partly biased, possibly because of major changes in the Spåime catchment system that influenced the chironomids. For example, changes in hydrology caused by shifts in seasonality and amount of precipitation may have triggered changes in sediment erosion and deposition rates, affecting the chironomid composition to a larger extent than mean July air temperatures. Future challenges include examination of the temperature sensitivity of chironomid taxa and continued critical assessment of individual chironomid inferred temperature reconstructions, not only against other temperature proxies but also against proxies for variations in hydrology.

  • 121. Bigg, Grant R.
    et al.
    Levine, Richard C.
    Clark, Chris D.
    Greenwood, Sarah L.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Haflidason, Haflidi
    Hughes, Anna L. C.
    Nygard, Atle
    Sejrup, Hans Petter
    Last glacial ice-rafted debris off southwestern Europe: the role of the British-Irish Ice Sheet2010Inngår i: Journal of Quaternary Science, ISSN 0267-8179, E-ISSN 1099-1417, Vol. 25, nr 5, s. 689-699Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Ice-rafted debris (IRD) seeded into the ocean from Northern Hemisphere ice sheets is found in ocean cores along the southwestern European margin through the last glacial period. It is known that the origin of this IRD, especially off Iberia, can vary between North America and western Europe during short-lived episodes of greatly enhanced iceberg flux, known as Heinrich events, although in most Heinrich events the IRD has a North American source. During the longer times of much lower IRD fluxes between Heinrich events, use of an intermediate complexity climate model, coupled to an iceberg dynamic and thermodynamic model, shows that background levels of IRD most likely originate from western Europe, particularly the British Irish Ice Sheet. Combining modelling with palaeoceanographic evidence supports reconstructions of a short-lived, but substantial, Celtic and Irish Sea Ice Stream around 23 ka.

  • 122. Bishop, K.
    et al.
    Goedkoop, W.
    Johnson, R.
    Löfgren, S.
    Wallin, M.
    Kreuger, J.
    Kyllmar, K.
    Tranvik, L.
    Laudon, H.
    Destouni, G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Tranvik, L.
    Halldin, S.
    Skilj inte på vatten och vatten!2010Annet (Annet (populærvitenskap, debatt, mm))
  • 123. Bishop, K.
    et al.
    Seibert, J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Nyberg, L.
    Rodhe, A.
    Water storage in a till catchment. II: Implications of transmissivity feedback for flow paths and turnover times2011Inngår i: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 25, nr 25, s. 3950-3959Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper explores the flow paths and turnover times within a catchment characterized by the transmissivity feedback mechanism where there is a strong increase in the saturated hydraulic conductivity towards the soil surface and precipitation inputs saturate progressively more superficial layers of the soil profile. The analysis is facilitated by the correlation between catchment water storage and groundwater levels, which made it possible to model the daily spatial distribution of water storage, both vertically in different soil horizons and horizontally across a 6300-m2 till catchment. Soil properties and episodic precipitation input dynamics, combined with the influence of topographic features, concentrate flow in the horizontal, vertical, and temporal dimensions. Within the soil profile, there was a vertical concentration of lateral flow to superficial soil horizons (upper 30?cm of the soil), where much of the annual flow occurred during runoff episodes. Overland flow from a limited portion of the catchment can contribute to peak flows but is not a necessary condition for runoff episodes. The spatial concentration of flow, and the episodic nature of runoff events, resulted in a strong and spatially structured differentiation of local flow velocities within the catchment. There were large differences in the time spent by the laterally flowing water at different depths, with turnover times of lateral flow across a 1-m-wide soil pedon ranging from under 1?h at 10- to 20-cm depth to a month at 70- to 80-cm depth. In many regards, the hydrology of this catchment appears typical of the hydrology in till soils, which are widespread in Fenno-Scandia. Copyright (c) 2011 John Wiley & Sons, Ltd.

  • 124. Bishop, Kevin
    et al.
    Beven, Keith
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Abrahamsson, Katarina
    Andersson, Lotta
    Johnson, Richard
    Rodhe, Johan
    Hjerdt, Niclas
    Nature as the “natural” goal for water management: A Conversation2009Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 38, nr 4, s. 209-214Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The goals for water-quality and ecosystem integrity are often defined relative to “natural” reference conditions in many water-management systems, including the European Union Water Framework Directive. This paper examines the difficulties created for water management by using “natural” as the goal. These difficulties are articulated from different perspectives in an informal (fictional) conversation that takes place after a workshop on reference conditions in water-resources management. The difficulties include defining the natural state and modeling how a system might be progressed toward the natural, as well as the feasibility and desirability of restoring a natural state. The paper also considers the appropriateness for developing countries to adopt the use of natural as the goal for water management. We conclude that failure to critically examine the complexities of having “natural” as the goal will compromise the ability to manage the issues that arise in real basins by not making the ambiguities associated with this “natural” goal explicit. This is unfortunate both for the western world that has embraced this model of “natural as the goal” and for the developing world in so far as they are encouraged to adopt this model.

  • 125.
    Bishop, Kevin
    et al.
    SLU-Ultuna.
    Lyon, Steve
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Dahlke, Helen
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    The relationship between land use and water2012Inngår i: EOS: Transactions, ISSN 0096-3941, E-ISSN 2324-9250, Vol. 93, nr 28, s. 259-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Water As the Mirror of Landscapes: How Useful a Hypothesis for Resource Management?; Uppsala, Sweden, 28–29 March 2012 The question posed in the title of this workshop formed its focus as an international group of more than 50 researchers and managers gathered to discuss our current level of understanding of land-water interactions and the potential impacts this has for resource management. Special emphasis was placed on the Ethiopian highlands, which deliver more than 85% of the flow in the Nile in Egypt. The 2-day workshop, held at the Swedish University of Agricultural Sciences in Uppsala, was cosponsored by the Swedish Ministry for Foreign Affairs as part of its special allocation for global food security and by the International Union of Forest Research Organizations' Unit 3.05, Forest Operations Ecology.

  • 126. Bishop, Paul
    et al.
    Jansen, John
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Castillo, Miguel
    Reinhardt, Liam
    Whitbread, Katie
    Kim, Jong-Yong
    Fabel, Derek
    Hoey, Trevor
    ‘Bottom-up’ bedrock river response to rock uplift: Unravelling the controls of landscape responses to transience.2010Inngår i: British Society for Geomorphology Programme & Abstracts. London, England, Aug 2010., 2010Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Bedrock rivers set the boundary conditions for landscape evolution. Most recent bedrock river research has been in steady-state settings in which rock uplift is matched by landscape lowering driven by bedrock river incision and slope lowering, but more attention is now being paid to bedrock rivers is transient settings (where transience in the fluvial system is triggered by changes in the rate of rock uplift and/or by climatic oscillations).  Transient responses in bedrock rivers close to base-level are dominated by ‘bottom-up’ processes.  Those processes remain less well understood than the ‘top-down’ processes that are thought to be characteristic of steady state landscapes and are driven by discharges of water and sediment. Key issues in understanding rates of landscape-wide response to transience are (i) rates of knickpoint retreat to transmit a base-level fall signal through the drainage net, and (ii) rates of hillslope response once that base-level fall has passed the foot of a hillslope.  Terrestrial cosmogenic nuclide (TCN) data from a transient landscape in southern Spain point to the latter being the rate-limiting control (“fast rivers, slow hillslopes”).  In terms of the former, morphometric and TCN data from coastal rivers in Scotland confirm knickpoint retreat in response to glacio-isostatic rebound, whereas TCN data from higher up these rivers, above the reach affected by glacio-isostatic base-level fall, point to more diffusive bedrock channel incision, without knickpoint retreat.  Determining why diffusive incision is initiated at a particular locality in those settings is difficult but in at least one case the incision is probably ‘pinned’ on resistant lithologies.  A wider and more taxing issue is the relationship between ‘bottom-up’ and ‘top-down’ incisional processes and whether the former must precede, and can evolve into, the latter.

     

  • 127.
    Bjursäter, Stefan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Borrning efter interstadiala sediment vid Ultevisplatån, Norrbotten2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    The purpose of this study is to find datable interstadial sediments in the core area of the LateWeicheslian ice sheet extent. Based on geomorphological evidence, three coring sites wereidentified close to the Ultevis plateau in Norrbotten, northern Sweden. Sediment coring wascarried out in two pre-Late Weichselian stream channels and in a sediment basin. Stratigraphyfrom one of the sites, a 100 meter wide meltwater channel, was chosen for further analysis. Thestudied core was 5,93 m long and ended in a lower till unit. The core contained silt and sandbelow an upper till unit, indicating presence of interstadial sediments in the stratigraphy. Thecore was subsampled for luminescence dating. Two samples from above the upper till unit andtwo samples from below this unit were chosen for initial luminescence measurements onfeldspar. These preliminary measurements indicate a significant difference in paleodosebetween the upper samples and the lower. The upper samples displayed relatively highpaleodoses, possibly representing pre-Late Weichselian ages. This could imply presence of twointerstadials in the stratigraphy. The lower samples exhibited significantly higher paleodosesthan the upper ones, possibly indicating early-Weichselian or even Saalian ages for the lowersamples.

  • 128.
    Bjärås, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Studie i materialrörelser orsakade av fartygsvågor2014Independent thesis Advanced level (degree of Master (One Year)), 20 poäng / 30 hpOppgave
    Abstract [sv]

    Examensarbetets målsättning var att studera de materialrörelser som uppkommer i direkt anslutning till stranden genom påverkan av fartygsvågor. Intressant var just att studera sådant material som Daleke et al (1989) finner en överensstämmelse med – mellan sina iakttagelser och en felaktig version av Hjulströmskurvan – men även annat material skulle studeras. Arbetet utfördes i Furusundsleden och i farleden vid Lidingö där trafiken av Finlandsfärjor är tät.I farleder som till vattenvolym är begränsade uppstår kraftiga vattenrörelser, sugeffekter förutom de vanliga svallvågor som bryter mot stranden. Dessa båda typer av vattenrörelser påverkar materialet längs stränderna.

  • 129. Björck, S
    et al.
    Backman, Jan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologi och geokemi.
    Bengtsson, S
    Destouni, Georgia
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Rodhe, Henning
    Stockholms universitet, Naturvetenskapliga fakulteten, Meteorologiska institutionen (MISU).
    Uttalande från klimatgruppen inom akademiens klass för geovetenskaper angående Climate Change 2007: The Physical Science Basis2007Annet (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    Björck S., Backman J., Bengtsson S., Destouni G., Rodhe H., Uttalande från klimatgruppen inom akademiens klass för geovetenskaper angående Climate Change 2007: The Physical Science Basis (Statement on Climate Change 2007: The Physical Science Basis; in Swedish), Climate Group of the Class of Geosciences at the Royal Swedish Academy of Sciences, 5 June, 2007.

  • 130.
    Björck, Svante
    et al.
    Inst. för geo- och ekosystemvetenskaper Enheten för geologi, Lunds universitet.
    Moberg, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Historiska varningssignaler2010Inngår i: Sverige i nytt klimat - våtvarm utmaning / [ed] Birgitta Johansson, Stockholm: Forskningsrådet Formas , 2010, s. 71-86Kapittel i bok, del av antologi (Annet (populærvitenskap, debatt, mm))
    Abstract [sv]

    De senaste tjugo årens klimat i Stockholmstrakten är troligen det varmaste under den senaste femhudraårsperioden. Människans utsläpp av växthusgaser har bidragit, men även naturliga faktorer. Av historien kan vi lära oss att klimatet plötsligt kan slå om till att fungera på ett helt nytt sätt - en förändring som kan bli en obehaglig överraskning för människans samhälle och dess känsliga infrastruktur. Därför bör vi vara lyhörda för varningssignaler från jordens klimatsystem. Varningssignaler är den geologiska historien full av, skriver Svante Björck och Anders Moberg.

  • 131. Björklund, J. A.
    et al.
    Gunnarson, Björn E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Seftigen, K.
    Esper, J.
    Linderholm, H. W.
    Blue intensity and density from northern Fennoscandian tree rings, exploring the potential to improve summer temperature reconstructions with earlywood information2014Inngår i: Climate of the Past, ISSN 1814-9324, E-ISSN 1814-9332, Vol. 10, nr 2, s. 877-885Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Here we explore two new tree-ring parameters, derived from measurements of wood density and blue intensity (BI). The new proxies show an increase in the inter-annual summer temperature signal compared to established proxies, and present the potential to improve long-term performance. At high latitudes, where tree growth is mainly limited by low temperatures, radiodensitometric measurements of wood density, specifically maximum latewood density (MXD), provides a temperature proxy that is superior to that of tree-ring widths. The high cost of developing MXD has led to experimentation with a less expensive method using optical flatbed scanners to produce a new proxy, herein referred to as maximum latewood blue absorption intensity (abbreviated MXBI). MXBI is shown to be very similar to MXD on annual timescales but less accurate on centennial timescales. This is due to the fact that extractives, such as resin, stain the wood differentially from tree to tree and from heartwood to sapwood. To overcome this problem, and to address similar potential problems in radiodensitometric measurements, the new parameters Delta blue intensity (Delta BI) and Delta density are designed by subtracting the ambient BI/ density in the earlywood, as a background value, from the latewood measurements. As a case-study, based on Scots pine trees from Northern Sweden, we show that Delta density can be used as a quality control of MXD values and that the reconstructive performance of warm-season mean temperatures is more focused towards the summer months (JJA - June, July, August), with an increase by roughly 20% when also utilising the interannual information from the earlywood. How-ever, even though the new parameter Delta BI experiences an improvement as well, there are still puzzling dissimilarities between Delta density and Delta BI on multicentennial timescales. As a consequence, temperature reconstructions based on Delta BI will presently only be able to resolve information on decadal-to- centennial timescales. The possibility of trying to calibrate BI into a measure of lignin content or density, similarly to how radiographic measurements are calibrated into density, could be a solution. If this works, only then can Delta BI be used as a reliable proxy in multicentennial-scale climate reconstructions.

  • 132. Björklund, Jesper A.
    et al.
    Gunnarson, Björn E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Swedish University of Agricultural Sciences, Sweden.
    Krusic, Paul J.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Grudd, Håkan
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Josefsson, Torbjörn
    Östlund, Lars
    Linderholm, Hans W.
    Advances towards improved low-frequency tree-ring reconstructions, using an updated Pinus sylvestris L. MXD network from the Scandinavian Mountains2013Inngår i: Journal of Theoretical and Applied Climatology, ISSN 0177-798X, E-ISSN 1434-4483, Vol. 113, nr 3-4, s. 697-710Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dendrochronological use of the parameter maximum density (MXD) in Pinus Sylvestris L., at high latitudes, has provided valuable insights into past summer temperature variations. Few long MXD chronologies, from climatically coherent regions, exist today, with the exception being in northern Europe. Five, 500-year-long, Fennoscandian, MXD chronologies were compared with regard to their common variability and climate sensitivity. They were used to test Signal-free standardization techniques, to improve inferences of low-frequency temperature variations. Climate analysis showed that, in accordance with previous studies on MXD in Fennoscandia, the summer temperature signal is robust (R (2) > 50 %) and reliable over this climatically coherent region. A combination of Individual standardization and regional curve standardization is recommended to refine long-term variability from these MXD chronologies and relieve problems arising from low replication and standardization end-effects.

  • 133. Björklund, Jesper
    et al.
    Gunnarson, Björn E.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Seftigen, Kristina
    Zhang, Peng
    Linderholm, Hans W.
    Using adjusted Blue Intensity data to attain high-quality summer temperature information: A case study from Central Scandinavia2015Inngår i: The Holocene, ISSN 0959-6836, E-ISSN 1477-0911, Vol. 25, nr 3, s. 547-556Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The inexpensive Blue Intensity proxy has been considered a complement or surrogate to maximum latewood density (MXD), but is associated with biases from differential staining between sapwood and heartwood and also between deadwood samples and living-wood samples that compromise centennial-scale information. Here, we show that, with some minor adjustments, Blue Intensity (BI) is comparable with MXD or Density (=the difference or contrast between latewood and earlywood density) in dendroclimatological reconstructions of summer temperatures in the Central Scandinavian region, using Pinus sylvestris L. (Scots pine), on annual and multi-centennial timescales. By using BI, this bias is significantly reduced, but the contrast between earlywood and latewood in BI is altered with degree of staining, while for density it is not. Darker deadwood samples have a reduced contrast compared with the lighter living-wood samples that make BI and Density chronologies diverge. Here, we quantify this behaviour in BI and offer an adjustment that can reduce this bias. The adjustment can be derived on independent samples, so in future work on BI, parallel density measurements are not necessary. We apply this methodology to two Central Scandinavian Scots pine chronologies that averaged into a composite is able to reconstruct summer temperatures with an explained variance in excess of 60% in each verification period using a split sample calibration verification procedure. Although the amount of data used to derive this contrast adjustment produces desirable results, more tests are needed to confirm its performance, and we suggest that future work on the BI proxy should aim for a small subset of parallel BI and density measurements while the bulk of the data is only measured with the BI technique. This is to ensure that the adjustment is continuously updated with new data and that the conclusions derived here are robust.

  • 134. Björkman, L.
    et al.
    Feurdean, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Cinthio, K.
    Wohlfarth, B.
    Possnert, G.
    Lateglacial and early Holocene vegetation development in the Gutaiului Mountains, NW Romania2002Inngår i: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 21, nr 8-9, s. 1039-1059Artikkel i tidsskrift (Fagfellevurdert)
  • 135. Björkman, L.
    et al.
    Feurdean, A.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Wohlfarth, B.
    Late-Glacial and Holocene forest dynamics at Steregoiu in the Gutaiului Mountains, Northwest Romania2003Inngår i: Review of Palaeobotany and Palynology, ISSN 0034-6667, E-ISSN 1879-0615, Vol. 124, nr 1-2, s. 79-111Artikkel i tidsskrift (Fagfellevurdert)
  • 136. Blaauw, M.
    et al.
    Wohlfarth, B.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologi och geokemi.
    Preusser, F.
    Veres, Daniel
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Ampel, Linda
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hughen, K.
    Reimer, P.
    Bayesian testing for synchrony of events in glacial proxy archives2007Inngår i: European Geosciences Union, 2007, 2007, s. 00301-Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    Often chronological uncertainties are ignored in multi-site comparisons, resulting in

    potentially wrong assumptions concerning (a)synchrony of events between archives.

    We explore this problem in a Bayesian framework, constructing millions of plausible

    wiggle-match age-models in order to quantify the chronological uncertainties within

    and between proxy archives. Using these data we can now calculate the statistical

    probability that events indeed coincided. The method is applied to a high-resolution

    14C and OSL dated lake core from south-eastern France which largely predates the

    IntCal04 14C calibration curve. Depending on the applied comparison curve, events

    in this core appear synchronous or asynchronous with events in the NGRIP ice core.

  • 137.
    Blomdin, Robin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Deglaciationsförloppet och Isdämda sjöar i Vindelälvens källområde2009Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [sv]

    En detaljerad landformkartering av ett högfjällsområde i Vindelälvens källområde har utförts med syfte att öka kunskapen om inlandsisens dynamik och karaktär (iskantens reträtt, isens aktivitet och rörelseriktningar och isens basala temperatur) under deglaciationen i denna del av den Svenska fjällkedjan.

    Undersökningsområdet antas ha varit beläget inom det, för inlandsisen, bottenfrusna kärnområde som karaktäriserade det senaste istidsmaximat (LGM). Trots avsaknaden av subglacial smältning under de kallbottnade subglaciala temperaturförhållandena fanns det tillgång på smältvatten. Spår efter forna issjöar och det glacifluviala landformsystemet är därför de enda data som finns för att rekonstruera isens reträttmönster där den varit kallbottnad eller där det är brist på andra landformer.

    Den flygbildstolkning som genomfördes fokuserade på glaciolakustrina, glaciofluviala och subglaciala landformer. Rekonstruktionen av isreträttmönstet bygger på fördelningen av glacialmorfologin, de dämda issjöarna och den iskant som krävdes för att en dämning av dessa issjöar skulle uppstå. En teoretisk modell för beräkning av isprofilen användes för att öka detaljgraden i rekonstruktionen av isavsmältningen och som kontroll av den landformbaserade rekonstruktionen. Karterade landformer formade basen för issjörekonstruktionen som genomfördes i ett GIS. Som topografiskt underlag användes Lantmäteriets höjddatabas.

    Iskantlägen rekonstruerade utifrån den teoretiska modellen visade god överensstämmelse med karterade landformer. Åtta issjöar kunde identifieras under arbetets gång. Två av dessa, Vindelälvens issjö och Båssjuosjávrrie – Gávásjávrries issjö, existerade med stor säkerhet och var ett dominerande inslag i landskapsbilden under deglaciationen. De dämdes i nordväst respektive västerut mellan blottade passpunkter i terrängen och den retirerande isen.

    Dämningen av större smältvattenmassor visar att inlandsisen, i undersökningsområdet, var aktiv under hela deglaciationen och retirerade generellt mot sydost. Deglaciationsmodellen indikerade nordvästliga och västliga isrörelseriktningar, i ett tidigt skede av deglaciationen, och västliga i ett sent skede. Den sista isrörelseriktningen i undersökningsområdet var mot väst och härrörde förmodligen från den sista isdelaren vid lågfjället Kráhpiesvarrie. Den basala temperaturfördelningen i undersökningsområdet får dock ses som oklar pga. tvetydiga bevis.

  • 138.
    Blomdin, Robin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Purdue University, USA.
    Heyman, Jakob
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Stroeven, Arjen P.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Hättestrand, Clas
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Harbor, Jonathan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK). Purdue University, USA.
    Gribenski, Natacha
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Jansson, Krister N.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Petrakov, Dmitry A.
    Ivanov, Mikhail N.
    Alexander, Orkhonselenge
    Rudoy, Alexei N.
    Walther, Michael
    Glacial geomorphology of the Altai and Western Sayan Mountains, Central Asia2016Inngår i: Journal of Maps, ISSN 1744-5647, E-ISSN 1744-5647, Vol. 12, nr 1, s. 123-136Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this article, we present a map of the glacial geomorphology of the Altai andWestern Sayan Mountains, covering an area of almost 600,000 km2. Although numerous studies provide evidence for restricted Pleistocene glaciations in this area, others have hypothesized the past existence of an extensive ice sheet. To provide a framework for accurate glacial reconstructions of the Altai and Western Sayan Mountains, we present a map at a scale of 1:1,000,000 based on a mapping from 30 m resolution ASTER DEM and 15 m/30 mresolution Landsat ETM+ satellite imagery. Four landform classes have been mapped: marginal moraines, glacial lineations, hummocky terrain, and glacial valleys. Our mapping reveals an abundance of glacial erosional and depositional landforms. The distribution of these glacial landforms indicates that the Altai and Western Sayan Mountains have experienced predominantly alpine-style glaciations, with some small ice caps centred on the higher mountain peaks. Large marginal moraine complexes mark glacial advances in intermontane basins. By tracing the outer limits of present-day glaciers, glacial valleys, and moraines, we estimate that the past glacier coverage have totalled to 65,000 km2 (10.9% of the mapped area), whereas present-day glacier coverage totals only 1300 km2 (0.2% of the mapped area). This demonstrates the usefulness of remote sensing techniques for mapping the glacial geomorphology in remote mountain areas and for quantifying the past glacier dimensions. The glacial geomorphological map presented here will be used for further detailed reconstructions of the paleoglaciology and paleoclimate of the region.

  • 139.
    Blomdin, Robin
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Murray, Andrew
    Thomsen, Kristina J.
    Buylaert, Jan-Pieter
    Sohbati, Reza
    Jansson, Krister N.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Alexanderson, Helena
    Timing of the deglaciation in Southern Patagonia: testing the applicability of k feldspar irsl2012Inngår i: Quaternary Geochronology, ISSN 1871-1014, E-ISSN 1878-0350, Vol. 10, s. 264-272Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The timing of the ice margin retreat of the Late Glacial Patagonian Ice Sheet (PIS) in southern Patagonia has been the object of discussion for many years. In order to resolve questions about the complex response of the PIS to past climate change, any geological interpretation and data modelling need evaluation against an absolute chronology. The aim of this project is to investigate the applicability of OSL dating to sediments from southern Patagonia; in particular, we examine the dating potential of K-feldspar IRSL signals. Samples were collected from landforms interpreted as being deposited during deglaciation of the PIS, with an expected age range of 17 and 22 ka, and from recently deposited sediment. We measure small aliquots and single grain distributions using an IR50 SAR protocol with IRSL stimulation at 50 degrees C following a preheat at 250 degrees C (held for 60 s). Uncertainties are assigned to our individual dose estimates based on the over-dispersion (OD) observed in laboratory gamma dose recovery experiments (22% for small aliquots and 18% for single grains). Then the possible effects of incomplete bleaching and differential fading are examined. For our natural samples we observe environmental ODs between 30 and 130% and mean residual doses between similar to 30 and 80 Gy. Minimum age models are used to identify the part of the dose population that is most likely to have been well-bleached and results from these models are compared. The models give ages that are consistent with each other; this may imply that they successfully identified the fully-bleached grains in the distributions, although there are some discrepancies between our small aliquot and single grain data. We observe large fading rates (on average 7.9 +/- 0.6%/decade for large aliquots) but nevertheless a comparison of our fading corrected ages with the expected age range shows that 2 out of 3 ages are consistent with geological interpretation and an established radiocarbon and cosmogenic nuclide chronology. We conclude that these investigations suggest that fading corrections can be based on laboratory average small aliquot/single grain fading rates. The third age is supported by an alternative geological interpretation, and the two ages consistent with the existing chronology imply that in the Strait of the Magellan the hills of the Brunswick peninsula (>70 m.a.s.l) were deglaciated at around 22 ka.

  • 140.
    Bognäs, Désirée
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    To save water or not?: A study of water scarcity at multiple levels, and people's attitudestowards it in Bangalore, India2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In a situation where population growth and development is to be sustained throughnaturally limited water resources, something needs to be done to either render waterusage more effective or make more water available. This is the situation in Bangalore Urban District (BUD), an ever growing city lying far from perennial water sources. This thesis presents the water situation in BUD, and aims to analyze the current status of water resources on multiple levels in BUD. Further the aim is to look at people‘s attitudes towards water scarcity. The methods used are literature studies and semistructured interviews. The study shows that there is a lack of water in relation to the population on basin level, creating the perquisites for water scarcity. Even so, the water stress on city level does not seem to be a direct effect off the water scarcity on basin level, but rather a result of inefficient governance and inadequate infrastructure. This means that to solve the issue, the governing entities in BUD must firstly look at improving the situation on city level rather than focusing on Water Supply Managementon basin level. The perception of this problem varies among people in BUD, and the perception of water stress in relation to the most favorable incentives to care which are a combination of personal and common good incentives, can affect household‘s water behavior. The significance of these results is that people‘s attitudes towards water resources will affect how they handle and use water. Through further research this knowledge can be vital to understanding how to achieve behavioral changes that can lover usage in a growing city like Bangalore.

  • 141. Bommarco, Riccardo
    et al.
    Lindborg, Regina
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Marini, Lorenzo
    Öckinger, Erik
    Extinction debt for plants and flower-visiting insects in landscapes with contrasting land use history2014Inngår i: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 20, nr 5, s. 591-599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim Species are lost world-wide because of habitat destruction and fragmentation. Impacted communities can exhibit transient dynamics in response to such environmental changes, where slow extinctions and immigration delay the arrival to a new equilibrium. Life history traits such as generation time, resource use and dispersal capacity, as well as landscape history can be expected to affect possible extinction debt, but few have examined this for multiple taxa in the same study and particularly so for arthropods. The aim was to assess under which current and historical land use circumstances an extinction debt occurs for vascular plants and three insect taxa. Location South-eastern Sweden. Method We sampled current species richness of habitat specialist and generalist butterflies, bees, hoverflies, and vascular plants in 45 dry to mesic semi-natural grassland fragments of various size and degree of connectivity, and situated in landscapes with contrasting land use conversion history. Habitat loss was estimated in each landscape by comparing modern maps to ~45year old digitized aerial photographs. An extinction debt can be assumed if historical habitat size and connectivity better explain current species distribution than current habitat variables do. Results Bees responded rapidly to habitat loss possibly as a result of their primary nesting resource being destroyed. Interestingly, species richness of specialist plants was best explained by historical habitat connectivity, richness of hoverflies by historical habitat area, and richness of butterflies by both historical habitat area and connectivity, indicating extinction debt for these taxa. Habitat generalist butterflies and hoverflies, but not plants and bees, exhibited extinction debt mainly in relation to habitat area. No effect of landscape type was found on the observed extinction debt. Main conclusions Slow extinctions of persistent and long-lived plants might explain extinction debt for both plants and herbivorous insects linked to these plants.

  • 142.
    Bonow, Johan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Palaeosurfaces and palaeovalleys on North Atlantic previously glaciated passive margins: reference forms for conclusions on uplift and erosion2004Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Palaeosurfaces and palaeovalleys are landforms under destruction in the present climate and/or tectonic regime, and thus mainly reflect processes not active today. Uplifted palaeosurfaces exist along the formerly glaciated passive continental margins around the North Atlantic. Large-scale landform development has recently become a matter of interest also for geologists and geophysicists as the result of an increasing awareness that a thorough knowledge of uplift, erosion, deposition and development of landforms along continental margins can only be accomplished by combined studies using independent data from different scientific disciplines. The present study focuses on one of these above data sets; the landform record. Two uplifted areas, southern Norway and central West Greenland, were selected for landform analysis of high resolution digital elevation models, aerial photographs, relation between landforms in basement and cover rocks, offshore seismic lines and X-ray diffraction of clay minerals in saprolites.

    In southern Norway, analysis of slope angles within the range of pediment slopes was combined with analysis of main valley incision. This resulted in the identification of three main planation surfaces in a stepped sequence formed along the main valleys as a consequence of tectonic uplift events, maybe in the Palaeogene, (in total >1000 m). Two phases of late uplift (~900 m), probably in the Neogene, triggered incision of deep fluvial valleys, later reshaped by glacial erosion (up to 300 m).

    In central West Greenland palaeosurfaces were analysed in relation to cover rock of different age. An exhumed etch surface, characterized by a typical hilly relief, occurs on Disko and south of Disko Bugt, and are by the presence of cover rocks shown to be sub-Palaeocene in origin. To the north, a post-Eocene erosion surface on Nuussuaq, cuts across basement and basalt and was probably formed close to sea level. Uplift in two phases elevated this surface up to 2000 m above present sea level and broke it in differently tilted tectonic blocks. South of Disko Bugt, a planation surface, of probably the same age as the one on Nuussuaq, cuts the tilted etch surface, and also cuts across different bedrock types. The planation surface rises towards the south and splits in two surfaces, separated in altitude up to 300 m, within two highly elevated areas. The separation into two surfaces indicate two uplift events: A first minor event of a few hundred metres in the uplift centres resulted in incision of the lower planation surface. This event was later followed by a major uplift event amounting to >1000 m. Correlation with the offshore sedimentary record suggests that both uplift events occurred in the Neogene. The erosion pattern calculated from one reconstructed palaeosurface to present topography shows large spatial variations. This is interpreted as an effect of differential bedrock resistance and local variations of glacial erosion (400–1300 m in low areas).

    The results presented in this thesis demonstrate the usefulness of palaeosurfaces and palaeovalleys as tools for deciphering magnitude of uplift events, establishing relative event chronologies and for calculation of erosion. Moreover integrated studies of palaeolandforms, offshore geology and thermal chronologies, are shown to be invaluable when used to solve the spatial and temporal patterns of uplift, erosion and deposition.

  • 143.
    Bonow, Johan M.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Re-exposed basement landforms in the Disko region, West Greenland: disregarded data for estimation of glacial erosion and uplift modelling2005Inngår i: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 74, nr 1-4, s. 106-127Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Classifications of large-scale landscapes in Greenland have traditionally been based on type and intensity of glacial erosion, with the general idea that present landforms are mainly the result of erosion from ice sheets and glaciers. However, on southern Disko and in areas offshore in Disko Bugt, a basement surface has preserved remnants of weathered gneiss and pre-Paleocene landforms, recently exhumed from Paleocene basalt. Isolated hills and lineaments have been mapped in a digital terrain model and aerial photographs. Offshore have hills been mapped from seismic lines. The medium size bedrock forms on southern Disko as tors, clefts and roche moutonées have been studied in the field. Remnant saprolites were inventoried, sampled and analysed according to grain size and clay mineralogy. The basement surface retains saprolites up to 8 m thick in close relation to the cover rocks. The landforms in the basement rocks belong essentially to an etched surface only slightly remodelled by glacial erosion and, below the highest coastline, also by wave action. The outline of hills is governed by two lineament directions, ENE–WSW representing the schistocity of the gneiss and NW–SE fracture zones. These structures are thus interpreted to have been exploited by the deep weathering while the frequent N–S lineaments have not and thus might be younger. Main ice-flow has been from the NE and has resulted in plucking of SW facing lee sides, however the resulting bedrock forms are mainly controlled by structures and orientation of joints. The identification of re-exposed sub-Paleocene etch forms on Disko and the hills of similar size offshore, forming a hilly relief, have implications for identification of a hilly relief south of Disko Bugt, its relation to younger planation surfaces as well as for conclusions of uplift events.

  • 144. Bonow, Johan M.
    et al.
    Japsen, Peter
    Green, Paul F.
    Wilson, Robert W.
    Chalmers, James A.
    Klint, Knud Erik S.
    Gool, Jeroen A.M.
    Lidmar-Bergström, Karna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi.
    Pedersen, Asger Ken
    A multi-disciplinary study of Phanerozoic landscape development in West Greenland2007Inngår i: Geological Survey of Denmark and Greenland Bulletin: Review of Survey activities 2006, ISSN 1604-8156, nr 13, s. 33-36Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The western margin of the Greenland craton has been much

    less stable in the Phanerozoic than previously thought. This

    new insight has come from close integration of independent

    data sets: geomorphological analysis of large-scale landscapes,

    apatite fission track analysis (AFTA), onshore and offshore

    stratigraphy and analysis of onshore fault and fracture sys -

    tems. Each data set records specific and unique parts of the

    event chronology and is equally important to establish a con-

    sistent model. A key area for understanding the Mesozoic-

    Cenozoic landscape evolution and into the present is the

    uplifted part of the Nuussuaq Basin, where remnants of pla-

    nation surfaces cut across the Cretaceous to Eocene sedimen-

    tary and volcanic rocks. Our integrated analysis concluded

    that the West Greenland mountains were formed by late

    Neogene tectonic uplift (Fig. 1) and also provided new

    insight into early Phanerozoic development. To understand

    our model, we present the different methods and the results

    that can be deduced from them.

  • 145.
    Bonow, Johan M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Japsen, Peter
    Lidmar-Bergström, Karna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Chalmers, James A.
    Pedersen, Asger Ken
    Cenozoic uplift of Nuussuaq and Disko, West Greenland: elevated erosion surfaces as uplift markers of a passive margin2006Inngår i: Geomorphology, ISSN 0169-555X, E-ISSN 1872-695X, Vol. 80, nr 3-4, s. 325-337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Remnants of a high plateau have been identified on Nuussuaq and Disko, central West Greenland. We interpret the plateau as an erosion surface (the summit erosion surface) formed mainly by a fluvial system and graded close to its former base level and subsequently uplifted to its present elevation. It extends over 150 km east–west, being of low relative relief, broken along faults, tilted westwards in the west and eastwards in the east, and having a maximum elevation of ca. 2 km in central Nuussuaq and Disko. The summit erosion surface cuts across Precambrian basement rocks and Paleocene–Eocene lavas, constraining its age to being substantially younger than the last rift event in the Nuussuaq Basin, which took place during the late Maastrichtian and Danian. The geological record shows that the Nuussuaq Basin was subjected to subsidence of several kilometres during Paleocene–Eocene volcanism and was transgressed by the sea later during the Eocene. By comparing with results from apatite fission track analysis and vitrinite reflectance maturity data, it is suggested that formation of the erosion surface was probably triggered by an uplift and erosion event starting between 40 and 30 Ma. Surface formation was completed prior to an uplift event that started between 11 and 10 Ma and caused valley incision. This generation of valleys graded to the new base level and formed a lower erosion surface, at most 1 km below the summit erosion surface, thus indicating the magnitude of its uplift. Formation of this generation of valleys was interrupted by a third uplift event also with a magnitude of 1 km that lifted the landscape to near its present position. Correlation with the fission-track record suggests that this uplift event started between 7 and 2 Ma. Uplift must have been caused initially by tectonism. Isostatic compensation due to erosion and loading and unloading of ice sheets has added to the magnitude of uplift but have not significantly altered the configuration of the surface. It is concluded that the elevations of palaeosurfaces (surfaces not in accordance with present climate or tectonic conditions) on West Greenland's passive margin can be used to define the magnitude and lateral variations of Neogene uplift events. The striking similarity between the landforms in West Greenland and those on many other passive margins is also noted.

  • 146.
    Bonow, Johan M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Lidmar-Bergström, Karna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Japsen, Peter
    Palaeosurfaces in central West Greenland as reference for identification of tectonic movements and estimations of glacial erosion2006Inngår i: Global and Planetary Change, ISSN 0921-8181, E-ISSN 1872-6364, Vol. 50, nr 3-4, s. 161-183Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Landform analysis of basement rocks has been undertaken with the aid of digital elevation data, aerial photographs and field observations in central West Greenland (69°15′N–66°00′N). Palaeosurfaces have been identified, dated relatively to each other, used to quantify uplift and fault movements and also used to estimate differential erosion. Two types of palaeosurfaces were mapped across the Precambrian basement: a surface at low elevation with distinct hills (hilly relief), and two planation surfaces formed across different types of basement rocks. The hilly relief surface emerges as an inclined surface from Cretaceous cover rocks in Disko Bugt and is interpreted as a stripped late Mesozoic etch surface. This surface is cut off towards the south by a less inclined planation surface, which is younger and thus of Cenozoic age. It is similar to the post-Eocene (Miocene?) planation surfaces identified on Disko and Nuussuaq in other studies. The planation surface splits in two southwards towards high areas around Nordre Isortoq and Sukkertoppen Ice Cap. The upper planation surface forms near-summit areas of tectonic blocks dipping in different directions and with different tilts. The uplift centres define the crests of two mega blocks, separated by the ‘Sisimiut Line’ which coincides with the Precambrian Ikertôq thrust zone. A partially developed lower planation surface indicates a first uplift of maximum 500 m followed by a second uplift of maximum 1000 m. We infer that these uplift events occurred during the late Neogene based on correlation with similar surfaces on Nuussuaq and the timing of exhumational events estimated from apatite fission track analyses of samples from a deep borehole on Nuussuaq (reported elsewhere). The difference between a reconstruction of the upper planation surface across the entire area and the present topography was used as an estimate of erosion of basement rock since the formation of the upper planation surface. The erosion is unevenly distributed and varies from almost none on the well-preserved planation surfaces to 800–1300 m along valleys, and even more in the fjords. Erosion is less within areas of gneiss in granulite facies, than in areas of gneiss in amphibolite facies.

  • 147.
    Bonow, Johan M.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för geologi och geokemi.
    Lidmar-Bergström, Karna
    Institutionen för naturgeografi och kvartärgeologi.
    Japsen, Peter
    Chalmers, James A.
    Green, Paul F.
    Elevated erosion surfaces in central West Greenland and southern Norway: their significance in integrated studies of passive margin development2007Inngår i: Norwegian Journal of Geology, ISSN 0029-196X, Vol. 87, s. 197-206Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Elevated erosion surfaces were used as an independant data set in an integrated study of the landscape development in central West Greenland. The study resulted in a time-constrained model describing multiple episodes of post-rift uplift, erosion and burial on a passive margin. The model is based on full integration of three data sets: analysis of large-scale landforms, apatite fission track analysis (AFTA) of samples from outcrops and deep boreholes, and the geological record. These data are equally important as they record specific an unique parts of the landscape history. The relative chronology obtained from the landform record is constrained by geology, which gives the maximum age of an erosin surface, and AFTA that records the cooling history of the subsurface rock. This combined approach validates the interpretation of erosion surface as having been goverened by different base levels in the past, and shows that erosion surfaces can be used to reconstruct tectonic events. Geomorphological key observations for the landscapes of southern Norway are presented and the similarities with landscapes in central West Greenland emphasised, especially the elevated plateaux and the Mesozoic etch surfaces. This similarity suggests that it may be possible to construct a time-constrained model for the landscape development of southern Norway based on our West Greenland approach.

  • 148.
    Bonow, Johan Mauritz
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Lidmar-Bergström, Karna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Näslund, Jens-Ove
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Palaeosurfaces and major valleys in the area of Kjølen Mountains, southern Norway: consequences of uplift and climatic change2003Inngår i: Norsk Geografisk Tidsskrift, ISSN 0029-1951, E-ISSN 1502-5292, Vol. 57, nr 2, s. 83-101Artikkel i tidsskrift (Fagfellevurdert)
  • 149. Booth, Adam D.
    et al.
    Mercer, Andrew
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Clark, Roger
    Murray, Tavi
    Jansson, Peter
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Axtell, Charlotte
    A comparison of seismic and radar methods to establish the thickness and density of glacier snow cover2013Inngår i: Annals of Glaciology, ISSN 0260-3055, E-ISSN 1727-5644, Vol. 54, nr 64, s. 73-82Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We show that geophysical methods offer an effective means of quantifying snow thickness and density. Opportunistic (efficient but non-optimized) seismic refraction and ground-penetrating radar (GPR) surveys were performed on Storglaciaren, Sweden, co-located with a snow pit that shows the snowpack to be 1.73 m thick, with density increasing from similar to 120 to similar to 500 kg m(-3) (with a +50 kg m(-3) anomaly between 0.73 and 0.83 m depth). Depths estimated for two detectable GPR reflectors, 0.76 +/- 0.02 and 1.71 +/- 0.03 m, correlate extremely well with ground-truth observations. Refraction seismic predicts an interface at 1.90 +/- 0.31 m depth, with a refraction velocity (3730 +/- 190 m s(-1)) indicative of underlying glacier ice. For density estimates, several standard velocity-density relationships are trialled. In the best case, GPR delivers an excellent density estimate for the upper snow layer (observed = 321 +/- 74 kg m(-3), estimated = 319 +/- 10 kg m(-3)) but overestimates the density of the lower layer by 20%. Refraction seismic delivers a bulk density of 404 +/- 22 kg m(-3) compared with a ground-truth average of 356 +/- 22 kg m(-3). We suggest that geophysical surveys are an effective complement to mass-balance measurements (particularly for controlling estimates of snow thickness between pits) but should always be validated against ground-truth observations.

  • 150.
    Borgmark, Anders
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Holocene climate variability and periodicities in south-central Sweden, as interpreted from peat humification analysis2005Inngår i: The Holocene, ISSN 0959-6836, Vol. 15, nr 3, s. 387-395Artikkel i tidsskrift (Fagfellevurdert)
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