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  • 1.
    Aggemyr, Elsa
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Landscape structure and land use history influence changes in island plant composition after 100 years2012In: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 39, no 9, p. 1645-1656Article in journal (Refereed)
    Abstract [en]

    Aim We investigated how current and historical land use and landscape structure affect species richness and the processes of extinction, immigration and species turnover. Location The northern part of the Stockholm archipelago, Baltic Sea, Sweden. We resurveyed 27 islands ranging from 0.3 to 33 ha in area. Methods We compared current plant survey data, cadastral maps and aerial photographs with records obtained from a survey in 1908, using databases and a digital elevation model to examine changes in plant community dynamics in space and time. We examined the effects of local and landscape structure and land use changes on plant species dynamics by using stepwise regression in relation to eight local and three landscape variables. The eight local variables were area, relative age, shape, soil heterogeneity, bedrock ratio, number of houses, forest cover change, and grazing 100 years ago. The three landscape variables were distance to mainland, distance to closest island with a farm 100 years ago, and structural connectivity. Hanskis connectivity measure was modified to incorporate both connectivity and fragmentation. Results The investigated islands have undergone drastic changes, with increasing forest cover, habitation, and abandonment of grassland management. Although the total species richness increased by 31% and mean island area by 23%, we found no significant increase in species richness per unit area. Local variables explain past species richness (100 years ago), whereas both local and landscape variables explain current species richness, extinctions, immigrations and species turnover. Grazing that occurred 100 years ago still influences species richness, even though grazing management was abandoned several decades ago. The evidence clearly shows an increase in nitrophilous plant species, particularly among immigrant species. Main conclusions This study highlights the importance of including land use history when interpreting current patterns of species richness. Furthermore, local environment and landscape patterns affect important ecological processes such as immigration, extinction and species turnover, and hence should be included when assessing the impact of habitat fragmentation and land use change. We suggest that our modified structural connectivity measure can be applied to other types of landscapes to investigate the effects of fragmentation and habitat loss.

  • 2.
    Aggemyr, Elsa
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology (INK).
    Plant species richness and composition, changes over a 100 year period in the Swedish archipelago - a landscape study2010In: The Future of Biodiversity: Genes, Species, Ecosystems: 40th Anniversary Conference / [ed] Volkmar Wolters, Janine Groh, Franziska Peter, Rainer Waldhardt, Giessen: Justus Liebig University Giessen , 2010, p. 118-118Conference paper (Refereed)
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  • 3.
    Agnesson, Sara
    Linnaeus University, Faculty of Arts and Humanities, Department of Cultural Sciences.
    Biokolsanvändningen i Sverige: Vad krävs för att svenska lantbruk, kommuner och trädgårdsindustrin ska börja använda eller utöka sin användning av biokol?2021Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The amount of carbon dioxide, CO2, in the atmosphere is continuously rising due to human emissions caused by combustion of fossil fuels and changing of land use. In a very short time several measures need to be taken in order to reduce the amount of CO2 in the atmosphere and thereby slowing down climate change as much as possible.

    The land use has changed considerably the last century with the biggest change in recent decades. This has led to that arable land all over the world has been depleted of nutrients with up to 75% in some regions. With a growing population worldwide and increased climate changes that threatens the arable land, something needs to be done to make sure we use the arable land in the most effective way.

    Biochar is one of the solutions to both these problems. By producing char out of biomass in high temperatures with minimized access to oxygen in a pyrolysis process you get biochar. This process releases less CO2 than a normal combustion process and the biochar becomes a carbon sink when it is put in the soil. 

    With its porous structure biochar has a great ability to keep water and nutrients in the soil for a very long time and it also makes the soil porous with a great amount of oxygen, which the roots prefer.

    The purpose of this essay is to find out what the use of biochar looks like in Sweden and how the use could increase within the agriculture, the municipalities and within horticulture.

    With qualitative interviews and a quantitaive and qualitative survey this essay has come to the conclusion that four things are needed to increase the use of biochar in Sweden. First of all, more scientific research is needed on biochar and how this can be used in the best way since it is a new product and there are still much to learn.

    Secondly, an increased production in Sweden is needed since today´s demand is bigger than the supply.

    Thirdly, it is needed to be able to certify ones carbon sink in order to be able to sell carbon-sink-ceritficates to companies who would like to reduce their climate impact. 

    Finally, more information on biochar is needed, in all stages. Producers need information to be able to start producing biochar and consumers need information in order to increase the demand and the interest of biochar.

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  • 4. Ahlkrona, Josefin
    et al.
    Lötstedt, Per
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Zwinger, Thomas
    Dynamically coupling the non-linear Stokes equations with the shallow ice approximation in glaciology: Description and first applications of the ISCAL method2016In: Journal of Computational Physics, ISSN 0021-9991, E-ISSN 1090-2716, Vol. 308, p. 1-19Article in journal (Refereed)
    Abstract [en]

    We propose and implement a new method, called the Ice Sheet Coupled Approximation Levels (ISCAL) method, for simulation of ice sheet flow in large domains during long time-intervals. The method couples the full Stokes (FS) equations with the Shallow Ice Approximation (SIA). The part of the domain where SIA is applied is determined automatically and dynamically based on estimates of the modeling error. For a three dimensional model problem, ISCAL computes the solution substantially faster with a low reduction in accuracy compared to a monolithic FS. Furthermore, ISCAL is shown to be able to detect rapid dynamic changes in the flow. Three different error estimations are applied and compared. Finally, ISCAL is applied to the Greenland Ice Sheet on a quasi-uniform grid, proving ISCAL to be a potential valuable tool for the ice sheet modeling community.

  • 5.
    Akinyemi, Felicia O.
    et al.
    Karlstad University, Faculty of Health, Science and Technology (starting 2013), Department of Environmental and Life Sciences (from 2013). University of Bern, Switzerland.
    Ifejika Speranza, Chinwe
    University of Bern, Switzerland.
    Land transformation across agroecological zones reveals expanding cropland and settlement at the expense of tree-cover and wetland areas in Nigeria2024In: Geo-spatial Information Science, ISSN 1009-5020, E-ISSN 1993-5153Article in journal (Refereed)
    Abstract [en]

    Evaluating how land cover is being transformed is essential to identify patterns necessary to infer the change trajectories and the driving factors. This study considers the case of Nigeria, where various natural ecosystems are being converted and for which a current national scale assessment at high spatial resolution is lacking. Producing 30 m Landsat-based time-series data, we analyze change among land cover types (i.e. tree-covered area, grassland, wetland, waterbody, cropland, artificial surface, and otherland) across seven agroecological zones. The annual change intensity was assessed at multi-levels across two time-intervals (i.e. 2000–2013, 2013–2022). Distinguishing between natural land cover and human activity-related land-use, we estimate the extent of change signifying how humans have appropriated natural land cover. Insights from analysis at the interval level reveal that land transformation accelerated from 3.3% in 2000–2013 to 4.5% during 2013–2022 in all agroecological zones (e.g. rainforest, mangrove), except in Sudan savannah and Sahel savannah where speed was higher in 2000–2013 as grasslands were increasingly cultivated. Cropland expanded almost two-fold (22% to 37%), whereas tree-cover declined from 50% to 31% and wetland from 7% to 3.7% over the 23 years. Much loss of natural land cover (e.g. tree-cover, grassland, and wetland) to cropland occurred in 2000–2013 (22%) when most irrigation schemes in Nigeria were established. In contrast, the loss of natural land cover to settlement (0.9%) during 2000–2013 increased to 2.0% in 2013–2022. Of all agroecological zones, the mangrove zone was most disturbed as its persisting land cover areas reduced from 69% to 5% between 2000–2013 and 2013–2022. The amount of persisting land cover was highest in the Sudan savannah at 44% in 2000–2013 and 49% in 2013–2022. Processes of human-appropriated natural land cover in Nigeria are related to urbanization and cropland expansion into natural areas with some instances of natural regeneration, especially in croplands and abandoned settlement areas.

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  • 6.
    Alavaisha, Edmond
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Agricultural expansion impacts on wetland ecosystem services from Kilombero Valley, Tanzania2020Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Land use change has major impact on the world’s wetland ecosystems and biodiversity. The motivation behind this change has been to increase agricultural production, often resulting in negative effects on water quality and soil fertility. Tanzania has carried out a large expansion and intensification of agriculture under the Kilimo kwanza (First agriculture) initiative which has triggered the need for better knowledge on land use change effects and associated ecosystem functioning. This thesis considers small-scale irrigation schemes to understand the effects of agriculture expansion and farming practices on nutrients, water quality and ecosystem services (ES) in Kilombero Valley, Tanzania. The study approach is multidisciplinary involving interviews, remote sensing, geographical information system techniques, and in-field soil and water ecological sampling. The major land use change in the valley during the last three decades was transformation from forest, bushland and grassland into cultivated land. The rate of change was faster adjacent to irrigation schemes and most changes occurred downstream irrigation canals, close to the floodplain. Irrigation and fertilization contributed to soil carbon and nitrogen accumulation in crop fields, which both declined in concentration with depth into the soil. However, such management practices and agricultural land expansion had impacts on several ES – especially water quality in streams. Streams surrounded mainly by cultivated land, as well as downstream areas, had lower water quality compared to streams with less settlement, more natural vegetation and upstream areas. Furthermore, when evaluated, macroinvertebrates indices were found to be a good indicator of water quality and a complement to chemical and physical water analysis. Irrigation farming produced more food compared to rainfed farming, and also other ES such as flood regulation, erosion control and several cultural services, depending on the river discharge. The thesis shows the importance to use irrigation/fertilization management to enhance soil fertility and preserve soil structure, but also the need for proper irrigation management to prevent flooding and erosion, conserve natural vegetation, and protect water quality. To enhance nature conservation, preserve biodiversity and secure future supply of ES in the valley, investment in irrigation infrastructures should be done at small-scale to mitigate the large-scale exploitation of Kilombero wetland.

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    Agricultural expansion impacts on wetland ecosystem services from Kilombero Valley, Tanzania
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  • 7.
    Alavaisha, Edmond
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Dar es Salaam, Tanzania.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Smallholder perceptions on ecosystem services generation in irrigated and rainfed farming- Kilombero, TanzaniaManuscript (preprint) (Other academic)
  • 8.
    Alavaisha, Edmond
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Dar es Salaam, Tanzania.
    Mbande, Victor
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Börjeson, Lowe
    Stockholm University, Faculty of Social Sciences, Department of Human Geography.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Effects of land use change related to small-scale irrigation schemes in Kilombero wetland, TanzaniaManuscript (preprint) (Other academic)
  • 9.
    Alavimoghaddam, Mohammadreza
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Assessing the ability of HEC-HMS rainfall-runoff model to simulate stream flow across Sweden2017Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Computer modeling is the powerful tool for simulating nature’s behavior; however, still more efforts are need for reaching perfect simulation with computer models (especially in the hydrological field of study). In this Master’s thesis, the accuracy of the HEC-HMS computer model for long term rainfall-runoff simulation was evaluated across Sweden. Five different catchments from north to south of Sweden were selected and then simulation have done for 34 years of available data. Simulation was conducted using daily, monthly and yearly time scale resolutions. Results from the north to the south of Sweden were completely different. Simulated runoff and observed runoff in northern catchments followed the same pattern over different time scales but in the southern part of Sweden the results had different patterns in space and time. The best results with HEC-HMS were found in the northern catchments with steep main river slopes. In the southern catchments the model could not predict runoff in any realistic manner at any time and space scale. In total the HEC-HMS model cannot simulate the rainfall runoff for long periods of simulation across Sweden. This is especially true in southern parts of the country dominate with low elevation catchments. However, with regards to its ability for event-based simulation HEC-HMS could be a suitable tool to simulate flood event discharges that are needed for road or other hydraulic structures designs. But, this would require significant amounts of calibration and model development.

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  • 10.
    Albjär, Göran
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Physical Geography.
    Sandgrunnorna in Lule Archipelago: Recent Transformation of a Glaciofluvial Deposit in an Environment of Land Uplift1985Licentiate thesis, monograph (Other academic)
    Abstract [en]

    In an area of rapid land uplift the geomorphological evolution of the glaciofluvial island of Sandgrunnorna, 25 km SE Luleå, in the Bothnian Bay, is discussed from old maps, air photographs and field studies. The island were marked on a map for the first time in 1790, but the highest parts can be estimated to have reached the sea surface about 100 years earlier. The areal growth has been reconstructed by map and air photograph studies. A model of the geomorphological evolution based on the interaction between bottom morphology, land uplift and waves is presented.

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    Albjar_1985
  • 11. Albrektson, Eva
    Gör Djurdården till naturreservat1991In: Kulturmiljövård, ISSN 1100-4800, no 1, p. 64-64Article in journal (Other (popular science, discussion, etc.))
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  • 12. Alekseeva, I.
    et al.
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Schrum, C.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Reconstruction of historic changes of the Aral Sea water budget and sea-groundwater interactions by a coupled 3D sea-ice-groundwater model2007In: Geophysical Research Abstracts, Vol. 9, 10629, 2007, 2007Conference paper (Other academic)
    Abstract [en]

    A 3D coupled sea-ice-groundwater model has been developed and applied for an estimation of the water balance and groundwater-seawater interactions in the shrinking Aral Sea. The model developed combines the complete 3D sea-ice hydrodynamics model ECOSMO, including a mass and energy conserving wetting and drying scheme, and a simple groundwater model based on changes in hydraulic gradient in response to the sea surface variability. During the simulation period 1979-1993, the model successfully reproduced the rapid Aral Sea level drop, surface area decrease, coastline position changes and salinization. Model predictions of evaporation and groundwater inflow were also consistent with independent estimations. Model results indicated that within the 15 years period of simulations the net groundwater inflow to the Aral Sea might have increased by 10% or more as a direct effect of the sea level lowering.

    Furthermore, model scenario tests were carried out to examine effects of salinity on sea hydrodynamics and to estimate non-linear feedbacks of the sea thermo- and hydrodynamics, air-sea turbulent fluxes and the sea water balance. It was shown that a neglect of salinity in the sea hydro- and thermo dynamics resulted in considerable differences in the Aral Sea winter thermal conditions, which in turn influenced the air-sea exchange in the following spring and summer. As a result, the zero salinity scenario predicted higher evaporation rates and an considerably accelerated sea level lowering by up to 2 cm/yr, in comparison with the basic model run. An indirect influence of the fresh groundwater inflow in terms of water balance has been identified as less significant, however it was shown that the fresh groundwater input could influence the Aral Sea salinity distribution considerably since 1990’s.

  • 13.
    Algesten, Grete
    Umeå universitet, Ekologi och geovetenskap.
    Regulation of carbon dioxide emission from Swedish boreal lakes and the Gulf of Bothnia2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2.

    This thesis estimates emission of carbon dioxide (CO2) from boreal lakes and factors regulating the CO2 saturation from field measurements of CO2 concentration along with a number of chemical, biological and physical parameters. Concentration of dissolved organic carbon (DOC) was found to be the most important factor for CO2 saturation in lake water, whereas climatic parameters such as precipitation, temperature and global radiation were less influential. All lakes were supersaturated with and, thus, sources of CO2. Sediment incubation experiments indicated that in-lake mineralization processes during summer stratification mainly occurred in the pelagial. Approximately 10% of the CO2 emitted from the lake surface was produced in epilimnetic sediments.

    The mineralization of DOC and emission of CO2 from freshwaters was calculated on a catchment basis for almost 80,000 lakes and 21 major catchments in Sweden, together with rates of sedimentation in lakes and export of organic carbon to the sea. The total export of terrestrial organic carbon to freshwaters could thereby be estimated and consequently also the importance of lakes for the withdrawal of organic carbon export from terrestrial sources to the sea. Lakes removed 30-80% of imported terrestrial organic carbon, and mineralization and CO2 emission were much more important than sedimentation of carbon. The carbon loss was closely related to water retention time, where catchments with short residence times (<1 year) had low carbon retentions, whereas in catchments with long residence times (>3 years) a majority of the imported TOC was removed in the lake systems.

    The Gulf of Bothnia was also studied in this thesis and found to be a net heterotrophic system, emitting large amounts of CO2 to the atmosphere on an annual basis. The rate of CO2 emission was depending on the balance between primary production and bacterial respiration, and the system was oscillating between being a source and a sink of CO2.

  • 14.
    Algesten, Grete
    Umeå University, Faculty of Science and Technology, Ecology and Environmental Science.
    Regulation of carbon dioxide emission from Swedish boreal lakes and the Gulf of Bothnia2005Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The global carbon cycle is subject to intense research, where sources and sinks for greenhouse gases, carbon dioxide in particular, are estimated for various systems and biomes. Lakes have previously been neglected in carbon balance estimations, but have recently been recognized to be significant net sources of CO2.

    This thesis estimates emission of carbon dioxide (CO2) from boreal lakes and factors regulating the CO2 saturation from field measurements of CO2 concentration along with a number of chemical, biological and physical parameters. Concentration of dissolved organic carbon (DOC) was found to be the most important factor for CO2 saturation in lake water, whereas climatic parameters such as precipitation, temperature and global radiation were less influential. All lakes were supersaturated with and, thus, sources of CO2. Sediment incubation experiments indicated that in-lake mineralization processes during summer stratification mainly occurred in the pelagial. Approximately 10% of the CO2 emitted from the lake surface was produced in epilimnetic sediments.

    The mineralization of DOC and emission of CO2 from freshwaters was calculated on a catchment basis for almost 80,000 lakes and 21 major catchments in Sweden, together with rates of sedimentation in lakes and export of organic carbon to the sea. The total export of terrestrial organic carbon to freshwaters could thereby be estimated and consequently also the importance of lakes for the withdrawal of organic carbon export from terrestrial sources to the sea. Lakes removed 30-80% of imported terrestrial organic carbon, and mineralization and CO2 emission were much more important than sedimentation of carbon. The carbon loss was closely related to water retention time, where catchments with short residence times (<1 year) had low carbon retentions, whereas in catchments with long residence times (>3 years) a majority of the imported TOC was removed in the lake systems.

    The Gulf of Bothnia was also studied in this thesis and found to be a net heterotrophic system, emitting large amounts of CO2 to the atmosphere on an annual basis. The rate of CO2 emission was depending on the balance between primary production and bacterial respiration, and the system was oscillating between being a source and a sink of CO2.

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  • 15.
    Alkaradaghi, Karwan
    et al.
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering. Department of Geology, College of Science, Sulaimani University, 460013, Sulaimaniyah, Iraq; Kurdistan Institution for Strategic Studies and Scientific Research, 460013, Sulaimaniyah, Iraq.
    Ali, Salahalddin S.
    Department of Geology, College of Science, Sulaimani University, 460013, Sulaimaniyah, Iraq; Komar University of Science and Technology, 460013, Sulaimaniyah, Iraq.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Laue, Jan
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Landfill Site Selection Using GIS and Multi-criteria Decision-making AHP and SAW Methods: A Case Study in Sulaimaniyah Governorate, Iraq2022In: Research Developments in Geotechnics, Geo-Informatics and Remote Sensing: Proceedings of the 2nd Springer Conference of the Arabian Journal of Geosciences (CAJG-2), Tunisia 2019 / [ed] Hesham El-Askary; Zeynal Abiddin Erguler; Murat Karakus; Helder I. Chaminé, Springer Nature, 2022, p. 289-292Conference paper (Refereed)
    Abstract [en]

    Lack of land for waste disposal is one of the main problems facing urban areas in developing countries. The Sulaimaniyah Governorate, located in Northern Iraq, is one of the main cities of the country in the Kurdistan Region, covering an area of 2400 km2. Currently, there is no landfill site in the study region that meets the scientific and environmental requirements, and the inappropriate dumping of solid waste causes adverse effects to the environment, economic and urban aesthetic. To overcome this phenomenon, it is crucial to suggest a landfill site, even in countries that recycle or burn their waste to protect the environment. Landfill sites should be carefully selected taking into account all regulations and other restrictions. The integration of geographic information systems and the multi-criteria decision analysis were used in this study to select suitable landfill locations in the region. To this end, thirteen layers prepared according to their importance including slope, geology, land use, urban area, villages, rivers, groundwater, slope, elevation, soil, geology, road, oil and gas, land use, archaeology and power lines. Two different methods (simple additive weighting and analytic hierarchy process) were implemented in a geographical information system to obtain the suitability index map for candidate landfill sites, where all these conditions satisfied the scientific and environmental criteria adopted in this study. The comparison of the maps resulting from these two different methods demonstrates that both methods produced consistent results.

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  • 16.
    Alm, Klara
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Inventering av skred genom jämförelse av två generationer LiDAR-genererad höjddata2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Landslides are a natural hazard that is expected to increase in the future, due to climate change. In order to keep risk management plans up to date, an efficient inventory method is needed. In previous studies, multi-temporal high-resolution digital elevation models (DEM) produced with LiDAR technology have been used successfully for landslide inventory and monitoring in different parts of the world. The aim of this study has been to discover an inventory method for landslides in Sweden, using two generations of elevation data produced with LiDAR. The analysis was performed in GIS with the creation of a DEM of difference (DoD) and visual comparison as key components. The sites were also verified using Google Earth satellite imagery and aerial photos. The result of the study shows that a functional, efficient method was developed and several potential landslides were found in the three different study areas. The soil characteristics, slope gradient and distance to areas affected by forestry were recorded for all potential landslide sites. Using multi-temporal DEM for landslide inventory is time- and cost efficient, and the results are more accurate compared to traditional inventory techniques. Hopefully the method developed in this study can be used on a larger scale and lead to updated risk management and prevention plans throughout all risk areas for landslides in Sweden. In future studies field work is recommended to verify the potential landslide sites.

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  • 17.
    Alm, Micael
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Probability Modelling of Alpine Permafrost Distribution in Tarfala Valley, Sweden2017Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    A field data collection has been carried out in Tarfala valley at the turn of March to April 2017. The collection resulted in 36 BTS-measurements (Bottom Temperature of Snow cover) that has been used in combination with data from earlier surveys, to create a model of the occurrence of permafrost around Tarfala. To identify meaningful parameters that permafrost relies on, independent variables were tested against BTS in a stepwise regression. The independent variables elevation, aspect, solar radiation, slope angle and curvature were produced for each investigated BTS-point in a geographic information system.                 The stepwise regression selected elevation as the only significant variable, elevation was applied to a logistic regression to model the permafrost occurrence. The final model showed that the probability of permafrost increases with height. To distinguish between continuous, discontinuous and sporadic permafrost, the model was divided into three zones with intervals of probability. The continuous permafrost is the highest located zone and therefore has the highest likelihood, this zone delimits the discontinuous permafrost at 1523 m a.s.l. The discontinuous permafrost has probabilities between 50-80 % and its lower limit at 1108 m a.s.l. separates the discontinuous zone from the sporadic permafrost. 

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  • 18.
    AL-Rubaye, Safa
    Stockholm University, Faculty of Humanities, Department of Teaching and Learning.
    Frihet eller tvång?: Hur upplevs dagens digitala lärande av lärare och elever i två årskurser i en högstadieskola?2022Independent thesis Advanced level (professional degree), 10 credits / 15 HE creditsStudent thesis
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  • 19.
    Alsafadi, Karam
    et al.
    School of Geographical Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, People's Republic of China.
    Al-Ansari, Nadhir
    Luleå University of Technology, Department of Civil, Environmental and Natural Resources Engineering, Mining and Geotechnical Engineering.
    Mokhtar, Ali
    Department of Agricultural Engineering, Faculty of Agriculture, Cairo University, Giza 12613, Egypt ; State of Key Laboratory of Soil Erosion and Dryland Farming on Loess Plateau, Institute of Soil and Water Conservation, Northwest Agriculture and Forestry University; Institute of Soil and Water Conservation, Chinese Academy of Sciences and Ministry of Water Resources, Yangling 712100, People's Republic of China .
    Mohammed, Safwan
    Institute of Land Use, Technology and Regional Development, University of Debrecen, Debrecen 4032, Hungary.
    Elbeltagi, Ahmed
    Agricultural Engineering Department, Faculty of Agriculture, Mansoura University, Mansoura 35516, Egypt; College of Environmental and Resource Sciences, Zhejiang University, Hangzhou 310058, People's Republic of China .
    Sammen, Saad Sh
    Department of Civil Engineering, College of Engineering, University of Diyala, Diyala Governorate 32001, Iraq .
    Bi, Shuoben
    School of Geographical Sciences, Nanjing University of Information Science and Technology, Nanjing 210044, People's Republic of China .
    An evapotranspiration deficit-based drought index to detect variability of terrestrial carbon productivity in the Middle East2022In: Environmental Research Letters, E-ISSN 1748-9326, Vol. 17, no 1, article id 014051Article in journal (Refereed)
    Abstract [en]

    The primary driver of the land carbon sink is gross primary productivity (GPP), the gross absorption of carbon dioxide (CO2) by plant photosynthesis, which currently accounts for about one-quarter of anthropogenic CO2 emissions per year. This study aimed to detect the variability of carbon productivity using the standardized evapotranspiration deficit index (SEDI). Sixteen countries in the Middle East (ME) were selected to investigate drought. To this end, the yearly GPP dataset for the study area, spanning the 35 years (1982–2017) was used. Additionally, the Global Land Evaporation Amsterdam Model (GLEAM, version 3.3a), which estimates the various components of terrestrial evapotranspiration (annual actual and potential evaporation), was used for the same period. The main findings indicated that productivity in croplands and grasslands was more sensitive to the SEDI in Syria, Iraq, and Turkey by 34%, 30.5%, and 29.6% of cropland area respectively, and 25%, 31.5%, and 30.5% of grass land area. A significant positive correlation against the long-term data of the SEDI was recorded. Notably, the GPP recorded a decline of >60% during the 2008 extreme drought in the north of Iraq and the northeast of Syria, which concentrated within the agrarian ecosystem and reached a total vegetation deficit with 100% negative anomalies. The reductions of the annual GPP and anomalies from 2009 to 2012 might have resulted from the decrease in the annual SEDI at the peak 2008 extreme drought event. Ultimately, this led to a long delay in restoring the ecosystem in terms of its vegetation cover. Thus, the proposed study reported that the SEDI is more capable of capturing the GPP variability and closely linked to drought than commonly used indices. Therefore, understanding the response of ecosystem productivity to drought can facilitate the simulation of ecosystem changes under climate change projections.

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  • 20.
    Altafi, Nasrin
    KTH, School of Engineering Sciences (SCI), Mathematics (Dept.).
    Jordan types with small parts for Artinian Gorenstein algebras of codimension three2022In: Linear Algebra and its Applications, ISSN 0024-3795, E-ISSN 1873-1856, Vol. 646, p. 54-83Article in journal (Refereed)
    Abstract [en]

    We study Jordan types of linear forms for graded Artinian Gorenstein algebras having arbitrary codimension. We introduce rank matrices of linear forms for such algebras that represent the ranks of multiplication maps in various degrees. We show that there is a 1-1 correspondence between rank matrices and Jordan degree types. For Artinian Gorenstein algebras with codimension three we classify all rank matrices that occur for linear forms with vanishing third power. As a consequence, we show for such algebras that the possible Jordan types with parts of length at most four are uniquely determined by at most three parameters.

  • 21.
    Amora-Nogueira, Leonardo
    et al.
    Biomass & Water Management Res Ctr NAB UFF, Brazil; Fluminense Fed Univ UFF, Brazil; Fluminense Fed Univ, Brazil.
    Sanders, Christian J.
    Southern Cross Univ, Australia.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Univ Fed Rio de Janeiro, Brazil.
    Monteiro Sanders, Luciana Silva
    Biomass & Water Management Res Ctr NAB UFF, Brazil; Fluminense Fed Univ UFF, Brazil; Fluminense Fed Univ, Brazil; Southern Cross Univ, Australia.
    Abuchacra, Rodrigo Coutinho
    Biomass & Water Management Res Ctr NAB UFF, Brazil; State Univ Rio de Janeiro UERJ FFP, Brazil.
    Moreira-Turcq, Patricia F.
    Inst Rech Dev IRD, France.
    Cordeiro, Renato Campello
    Fluminense Fed Univ, Brazil.
    Gauci, Vincent
    Univ Birmingham, England; Univ Birmingham, England.
    Moreira, Luciane Silva
    Fluminense Fed Univ, Brazil.
    Machado-Silva, Fausto
    Univ Toledo, OH 43606 USA; Univ Fed Rio de Janeiro, Brazil.
    Libonati, Renata
    Univ Fed Rio de Janeiro, Brazil; Univ Lisbon, Portugal; Univ Lisbon, Portugal.
    Fonseca, Thairiny
    Biomass & Water Management Res Ctr NAB UFF, Brazil; Fluminense Fed Univ UFF, Brazil; Fluminense Fed Univ, Brazil.
    Francisco, Cristiane Nunes
    Fluminense Fed Univ, Brazil.
    Marotta, Humberto
    Biomass & Water Management Res Ctr NAB UFF, Brazil; Fluminense Fed Univ UFF, Brazil; Fluminense Fed Univ, Brazil.
    Tropical forests as drivers of lake carbon burial2022In: Nature Communications, E-ISSN 2041-1723, Vol. 13, no 1, article id 4051Article in journal (Refereed)
    Abstract [en]

    A significant proportion of carbon (C) captured by terrestrial primary production is buried in lacustrine ecosystems, which have been substantially affected by anthropogenic activities globally. However, there is a scarcity of sedimentary organic carbon (OC) accumulation information for lakes surrounded by highly productive rainforests at warm tropical latitudes, or in response to land cover and climate change. Here, we combine new data from intensive campaigns spanning 13 lakes across remote Amazonian regions with a broad literature compilation, to produce the first spatially-weighted global analysis of recent OC burial in lakes (over ~50-100-years) that integrates both biome type and forest cover. We find that humid tropical forest lake sediments are a disproportionately important global OC sink of 7.4 Tg C yr−1 with implications for climate change. Further, we demonstrate that temperature and forest conservation are key factors in maintaining massive organic carbon pools in tropical lacustrine sediments.

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  • 22.
    Ampel, Linda
    et al.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Kylander, Malin E.
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Steinthorsdottir, Margret
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Wohlfarth, Barbara
    Stockholm University, Faculty of Science, Department of Geological Sciences.
    Abrupt climate change and early lake development - the Lateglacial diatom flora at Hasseldala Port, southeastern Sweden2015In: Boreas, ISSN 0300-9483, E-ISSN 1502-3885, Vol. 44, no 1, p. 94-102Article in journal (Refereed)
    Abstract [en]

    The fossil diatom record from the Hasseldala Port palaeolake, southeastern Sweden, offers an excellent opportunity to investigate how past climatic shifts influenced catchment conditions and early lake development. The record, dating to between 13900 and 11200 cal. a BP, covers a climatically dynamic period, starting with deglaciation followed by oscillations between warmer and colder climate states. The stratigraphical changes in the fossil diatom assemblages show a trend of less open-water taxa and a successively more complex periphytic community as the lake shallows and the aquatic habitat structure develops. A diatom-based reconstruction of lake water pH indicates a natural acidification trend early in the record from 13900 to 12500 cal. a BP. From 12500 cal. a BP, coincident with the start of climate cooling, to 11300 cal. a BP this trend is disrupted and lake waters become more alkaline. A cooler and drier climate most likely resulted in reduced soil organic matter build-up as well as more frozen ground that impeded hydrological flow and decreased the input of dissolved organic matter and organic acids into the lake system. This study demonstrates the importance of the hydrological system as a link between terrestrial and aquatic ecosystems during early lake ontogeny.

  • 23.
    Andersson, Camilla
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences.
    The influence of wind-induced resuspension on sediment accumulation rates: A study of archipelago and offshore areas in the NW Baltic proper2000Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The processes of sedimentation such as erosion, resuspension, transportation and accumulation are of major importance when handling environmental problems such as pollutants and eutrophication. Redistribution of sediment can induce transport of pollutants, why a greater knowledge of the sediment processes and the factors giving rise to sediment transport is desirable. There are a multiple of factors that could affect sediment processes, such as currents, waves, wind and sea level changes. Wind conditions are one of the major factors influencing oceanographic conditions, why focus in this study is set on the relationship between wind frequencies and sedimentation processes.

    The aim of this study is to investigate gross accumulation rates (accumulation of dry substance), foremost in archipelago areas of the NW Baltic Proper, and to some extent an offshore area in the NW Baltic Proper. The thesis suggests time trends in gross accumulation rates to be affected by wind conditions.

    Former analyses of water content, Cesium-137, carbon and nitrogen in combination with dating from lamina counting resulted in data on dry substance deposition data from six enclosed bays in the archipelago of the NW Baltic Proper. In order to receive new materiel from an offshore area, field work were performed during the summer of 1999. Analyses were performed in the same way as above. The gross accumulation rates could be calculated and dated in a satisfactory way in the accumulation areas. The offshore area proved to be difficult to interpret, why no conclusions could be made concerning accumulation in deep offshore areas (180-203 m).

    Data on wind force and durability from SMHI together with accurate described annual gross accumulation rates allowed plotting the time trends of the two parameters. It proved that a good correlation was seen in wind speed ≥7-9 m/s (r2=0.5) when using annual core mean values. Former investigations has showed a good correlation at higher wind speeds, ≥14 m/s. It is suggested that in small enclosed bays, fetch are the limiting factor which does not allow wind speeds exceeding ≥7-9 m/s to lower the critical depth at which erosion/resuspension occur. Since great similarities were found between the inner and outer Stockholm archipelago and the archipelago of Södermanland it is indicated that the results are valid for a large part of the NW Baltic Proper archipelago area, provided that the predictions are based on a sufficient number of bays and cores.

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  • 24.
    Andersson, Ingela
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Implementing the European Water Framework Directive at local to regional level -Case Study Northern Baltic Sea River Basin District, Sweden2011Licentiate thesis, comprehensive summary (Other academic)
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    sammanfattning
  • 25.
    Andersson, Ingela
    et al.
    Södertörn University, School of Life Sciences, Environmental science. Södertörn University, School of Life Sciences, Geography. Stockholm University, Department of Physical Geography and Quarternary Geology.
    Petersson, Mona
    Södertörn University, School of Life Sciences, Environmental science. Södertörn University, School of Life Sciences, Geography.
    Jarsjö, Jerker
    Stockholm University, Department of Physical Geography and Quarternary Geology.
    Impact of the European Water Framework Directive on local-level water management: Case study Oxunda Catchment, Sweden2012In: Land use policy, ISSN 0264-8377, E-ISSN 1873-5754, Vol. 29, no 1, p. 73-82Article in journal (Refereed)
    Abstract [en]

    The Water Framework Directive (WFD) of the European Union provides a common framework for water policy that focuses on holistic and integrated water management in river basins. In many member states, implementation of the WFD has shifted the main responsibility for local water issues from the municipal level to the regional or supra-regional levels. In this study, we investigated how the implementation of the WFD has influenced local-level water management including the interpretation of the new environmental quality standards. Specifically, we considered Sweden, which has traditionally had relatively strong governance at the municipal level. Because a sufficient amount of time has now passed for evaluation of WFD-related effects on operational water handling, we interviewed individuals directly involved in water planning and land use planning at the municipal level in one sub catchment in the Northern Baltic Sea River Basin District of Sweden, as well as representatives for superior levels and associations. Despite divergent views regarding the priority of water issues in physical planning among the local-level planners interviewed, they had all participated in successful inter-municipal pre-WFD collaboration projects. Although such collaborations could help increase the understanding and acceptance of WFD-related goals and costs, as well as facilitate conflict solving, as shown in the Oxunda Catchment, they have not gained much attention in the WFD implementation process. Additionally, physical planners have generally been reluctant to accept new environmental quality standards resulting from WFD implementation, in part because they lack precise definitions, but also because they could challenge the municipal routine of weighing various objectives against each other. Furthermore, despite WFD-related increases in ambition levels, lack of resource improvements at the municipal level were identified as potential problems by local environmental planners.

  • 26.
    Andersson, Ingela
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Petersson, Mona
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Impact of the European Water Framework Directive on local-level water management: Case study Oxunda Catchment, Sweden2012In: Land use policy, ISSN 0264-8377, E-ISSN 1873-5754, Vol. 29, no 1, p. 73-82Article in journal (Refereed)
    Abstract [en]

    The Water Framework Directive (WFD) of the European Union provides a common framework for waterpolicy that focuses on holistic and integrated water management in river basins. In many member states,implementation of the WFD has shifted the main responsibility for local water issues from the municipallevel to the regional or supra-regional levels. In this study, we investigated how the implementation of theWFD has influenced local-level water management including the interpretation of the new environmentalquality standards. Specifically, we considered Sweden, which has traditionally had relatively stronggovernance at the municipal level. Because a sufficient amount of time has now passed for evaluationof WFD-related effects on operational water handling, we interviewed individuals directly involved inwater planning and land use planning at the municipal level in one sub catchment in the Northern BalticSea River Basin District of Sweden, as well as representatives for superior levels and associations. Despitedivergent views regarding the priority of water issues in physical planning among the local-level plannersinterviewed, they had all participated in successful inter-municipal pre-WFD collaboration projects.Although such collaborations could help increase the understanding and acceptance of WFD-related goalsand costs, as well as facilitate conflict solving, as shown in the Oxunda Catchment, they have not gainedmuch attention in the WFD implementation process. Additionally, physical planners have generally beenreluctant to accept new environmental quality standards resulting from WFD implementation, in partbecause they lack precise definitions, but also because they could challenge the municipal routine ofweighing various objectives against each other. Furthermore, despite WFD-related increases in ambitionlevels, lack of resource improvements at the municipal level were identified as potential problems by local environmental planners.

  • 27.
    Andersson, Kjell
    et al.
    School for Forest Management, Faculty of Forest Sciences, Swedish University of Agriculture.
    Angelstam, Per
    School for Forest Management, Faculty of Forest Sciences, Swedish University of Agriculture / Department of Forestry and Wildlife Management, Inland Norway University of Applied Sciences.
    Brandt, S. Anders
    University of Gävle, Faculty of Engineering and Sustainable Development, Department of Computer and Geospatial Sciences, Geospatial Sciences.
    Axelsson, Robert
    County Administrative Board Västmanland.
    Bax, Gerhard
    Limited GIS skills hamper spatial planning for green infrastructures in Sweden2022In: Geografiska Notiser, ISSN 0016-724X, Vol. 80, no 1, p. 16-35Article in journal (Other academic)
    Abstract [en]

    The term green infrastructure captures the need to conserve biodiversity and to sustain landscapes’ different ecosystem services. Maintaining green infrastructures through protected areas, management and landscape restoration requires knowledge in geography, spatial data about biophysical, anthropogenic and immaterial values, spatial comprehensive planning, and thus geographical information systems (GIS). To understand land use planning practices and planning education regarding GIS in Sweden we interviewed 43 planners and reviewed 20 planning education programmes. All planners used GIS to look at data but did not carry out spatial analyses of land covers. BSc programmes included more GIS than MSc programmes but very few taught analyses for spatial planning. As key spatial planning actors, municipalities’ barriers and bridges for improved GIS use for collaborative learning about green infrastructures are discussed. A concluding section presents examples of how GIS can support spatial planning for green infrastructures.

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  • 28.
    Andersson, Kristin E. W.
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Human Geography.
    Skydda Falun från översvämning!: Platser som kan minska översvämningsrisken från Vällansjöarna2023Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Sydväst om Falu centrum är Vällansjöarna belägna. Sjöarna utsätter tätorten för översvämningsrisk på grund av utdikningar och korrigeringar i vattendrag uppströms sjöarna som genomfördes då Falu Koppargruva var aktiv. Idag utgör dessa avledningar av vatten ett problem för centrala Falun med risk för översvämning vid höga vattenflöden. Syftet med denna studie är att presentera en alternativ lösning för att minska den totala översvämningsrisken i Falu centrum med fokus på Vällansjöarna. De lösningar som diskuteras i denna studie kopplas till möjligheter att tillfälligt dämma upp vatten och undersökning av lämpliga platser med våtmarker som översvämningshantering. Genom att applicera en GIS-baserad metod har kartor framställts över utvalda områden som varit särskilt intressanta för att uppnå syftet. Resultaten visar att de utvalda områdena rymmer 3 gånger så mycket vatten relativt vad som tillrinner och avvattnar Vällansjöarna under ett dygn vid ett högsta beräknat flöde med 50 års återkomsttid. Därmed har områdena även god potential att ta vara på vattnen vid ett normalflöde. Slutsatsen är att samtliga områden i analysen är lämpade för tillfällig uppdämning av vatten vid höga flöden samt att våtmarker är en potentiell lösning för att minska översvämningsrisken i Falun.

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  • 29.
    Andersson, Linda
    et al.
    Karlstad University, Division for Environmental Sciences.
    Höiseth Borg, Veronica
    Karlstad University, Division for Environmental Sciences.
    Regnoväder och erosion: Ravinskadorna efter oväderstillfället i Hagfors kommun 4-5 augusti 20042008Independent thesis Basic level (degree of Bachelor), 10 points / 15 hpStudent thesis
    Abstract [en]

    Abstract

    Global changes in the climate during the last decade is frequently debated in today`s society. It is established that the climate is getting warmer. The consequences are already noticeable because of the warmer temperature. Since the earth temperature is increasing the weather systems around the world changes. The question is if the increasing temperature has something to do with both frequency and the extent of natural disasters. This question is very important and therefore research must continue to find new and improved facts.

    The 4-5 of August in 2004 an area in Hagfors municipality was strike by a serious rain and thunder storm. The following consequences were severe and the road around Rådasjön was totally destroyed in several places. This study is connected to the storm in Hagfors and the current climate changes. The present question is if the storm and its consequences are caused by a warmer climate. Following this study also discusses causes of this storm and its consequences.

    The area where this study was performed is tremendously sensitive to water erosion. The latest ice age has affected this area and therefore consists of material from till. Above this Rådasjön is situated in a broken valley that makes the lake very deep and steep sided. During the storm in 2004 there were at lot of material that strived down the steep sides to the lake. This affected not only the roads, but also the people who lived there during the time.

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  • 30.
    Andersson, Malin
    et al.
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    Erikson, Erica
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    The Ability of Regional Climate Models to Simulate Weather Conditions on Nordenskiöldbreen, Svalbard2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this project, we analyse the ability of two regional climate models to simulate meteorological conditions on Nordenskiöldbreen, a glacier in Svalbard. To do so, regional climate model output is compared with in situ measurements from an automatic weather station. Detailed information about the weather conditions on Nordenskiöldbreen is important for simulating the glacial mass balance in a changing climate. The parameters analysed were the following: temperature, air pressure, relative humidity, precipitation, cloud cover, wind speed and wind direction. The weather station did not measure all parameters, cloud cover was instead estimated through the incoming longwave radiation and temperature, while precipitation was calculated from snow depth. The results show that the models represent certain parameters better than others. Temperature, air pressure and wind speed and direction are found to be simulated with high precision. Poorest agreement is found for precipitation, which appears to be both difficult to simulate and observe. Relative humidity and cloud cover show average agreement with the station.

    The conclusion of the project is that the estimation of some of the parameters is satisfactory, while others are lacking. None of the models can be determined to have performed significantly better than the other.

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    The Ability of Regional Climate Models to Simulate Weather Conditions on Nordenskiöldbreen, Svalbard
  • 31.
    Andersson, Tord
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Mercury and radiocesium in Swedish lakes1993Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    Two large, nationwide monitoring data sets were compiled and statistically treated in order to create a national picture of the problems with high contents of mercury (Hg) and radiocesium (137Cs) in fish. Beside these two data sets, 75 lakes in four counties (Västernorrland, Gävleborg, Örebro and Kronoberg) were studied in connection to an evaluation of different measures to decrease the content of Hg and 137Cs in fish. An important objective was to investigate and determine the relationship between the content in fish and the load of the elements and how this relationship was affected by different abiotic lake characteristics. Several alternatives to measure the lake doses of Hg and 137Cs were evaluated (concentration in different fractions in lake water, in settling particles, and in surface sediments).

    About 10000 Swedish lakes were calculated to have a mean Hg content in 1-kg pike (FHg) above 1 mg kg-1 (wet weight) in the end of 1980’s, that is a 5-fold increase compared to the calculated preindustrial mean value. The cumulated domestic Hg- sources of emission make the largest contribution to the presently high mercury levels in pike and particularly so in central and northern Sweden.The second most important cause is acidification and thirdly Hg emissions from European sources. The content of 137Cs in fish normalized to 100 g perch (FCs) was above the limit for commercial sale, 1500 Bq kg-k in about 14000 Swedish lakes during autumn of 1987.

    An empirical model including Chernobyl fallout, hydraulic residence time and ionic strength explained almost 60 % of the inter-lake variation in FCs. At the same level of fallout, this difference in lake sensitivity, gave a tenfold difference in the initial transfer from fallout to small perch. A significant relationship was demonstrated between the lake dose of 137Cs and the content in fish. No such clear relationship existed for Hg due to the much more complex chemical and biological behaviour of Hg, where especially factors affecting méhylation and food web structure seems crucial. Lakes with a low relative sedimentation of Hg did also have a low relative sedimentation of 137Cs due to differences in particle sedimentation rates between the lakes. The sedimentation rate of radiocesium was well correlated to the natural concentration of major base cations and intercorrelated parameters such as pH, alkalinity and conductivity. The higher scavenging capacity in lakes with higher concentration of major base cations was due to higher particle sedimentation rates and higher K<i values in these lakes. However, the water chemistry was probably not causal in this respect, despite the high correlation, the distribution and sedimentation coefficients for radiocesium was not notably affected of the increased mean concentration of major base cations after liming and potash addition. It is suggested that a likely causal factor rather would be the amount and nature of scavenging agents (possibly clay minerals), which in these lakes was indicated by the natural concentration of base cations in the water.

    In general, the remedial measures gave the intended water chemical response with substantially increased mean values of alkalinity, hardness and pH. Two years after the start of the remedies, the Hg concentration in small perch (Hg-pe) was reduced by about 30% on average. The sedimentation rate of Hg decreased during 1988 and 1989 (i.e. after remedial measures) in contrast to the mean concentration of total Hg in water, thus, the retention decreased. None of the methods applied gave any rapid and clear reduction in the concentrations of 137Cs in fish, in comparison with lakes where the water chemical or biological conditions not were changed.

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  • 32.
    Andreas C., Bryhn
    Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences. Uppsala University, Teknisk-naturvetenskapliga vetenskapsområdet, Earth Sciences, Department of Earth Sciences, Air and Water Science. LUVA.
    Improving the management of aquatic ecosystems through modelling.2005Licentiate thesis, monograph (Other scientific)
  • 33.
    Andréen, Sigrid
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The development of landscape structures affecting biodiversity in the Hanveden and Tyresta green wedges2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The green wedges of Stockholm are meant to support a high level of biodiversity as well as cultural and recreational services but evaluating the spatial development of the wedges is difficult because their delineation has changed since they were first used in a regional development plan. This study examines a part of the Hanveden and Tyresta wedges in southern Stockholm, with the goal to use robust ecological theory to evaluate the development of the wedges from 1992 until today with focus on conserving a high level of biodiversity. Using an already existing GIS-based method of identifying connectivity weaknesses in the wedges, more weaknesses were found in 2010 than in 1992 although the total area of the wedges had only declined 3.3%. The shape of the wedges had also changed, with more narrow parts in 2010 than in 1992. To more effectively compare the development of factors in the landscape that are relevant for biodiversity, this study proposes a new method using the common shrew and hazel grouse as surrogate species. The total area loss for the common shrew was 2.96% from 1991 to 2013 and 2.23% for the hazel grouse. Fragmentation increased for both species. A large part of the greenspaces relevant to the surrogate species are covered by the green wedges, meaning that important cultural and recreational values identified by the county council are also present in areas relevant to the surrogate species. Using surrogate species to delineate and monitor the green wedges could enhance the cultural and recreational qualities of the wedges, emphasize the need for connectivity planning, identify ecologically important parts of the greenspaces as well as provide a tool for following up the development of the urban greenspaces of Stockholm. However, formulating goals relevant to biodiversity is important to fully evaluate development and municipal cooperation is needed.

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  • 34.
    Andrén, Hans
    Linnaeus University, Faculty of Arts and Humanities, Department of Cultural Sciences.
    Betraktelser från Aktse: Hans Andréns berättar2020In: Naturskyddsföreningen i Aktse: 75 år / [ed] Marcus Lidström, Södra Sunderbyn: Naturskyddsföreningen i Norrbottens län , 2020, p. 53-56Chapter in book (Other (popular science, discussion, etc.))
  • 35.
    Andwinge, Maria
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Reading Pollen Records at Peloponnese, Greece2014Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The eastern Mediterranean area is a region of high archaeological importance, it is also a region where climate has been a force interacting with humans in shaping the landscape and vegetation history. Variations in pollen content and composition in various climate archives (e.g. lake sediments and peat sections) are widely used to reconstruct vegetation changes and human impact in the Quaternary environments. Pollen sampling has been conducted throughout the Peloponnese peninsula but there is a lack of regional synthesis of these locally based studies. The aims of the thesis are partly to show how pollen data may be used in a regional analysis on Late Pleistocene and Holocene vegetation changes, partly to assemble all published pollen data from Peloponnese peninsula in a database. The question formulations are; i) how may a database with pollen dataserve as a basis for interpretations of regional vegetation changes on Peloponnese?, ii) what are the possibilities of using classification of pollen and distinguish between driving factors behind the historic vegetation changes? The constructed database facilitates further research regarding pollen records at Peloponnese. Pollen recordsmay show important patterns in landscape changes during Late Pleistocene and Holocene but using pollen records at a regional scale need comparisons between coring sites which may be troublesome due to different approaches, different species investigated and varied calculation of pollen sum. In order to distinguish between driving forces and actors affecting the vegetation, pollen data may be used both in detail but also in using groups and classifications of the pollen included.

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  • 36.
    Angelstam, Per
    et al.
    Swedish Univ Agr Sci SLU, Sweden.
    Manton, Michael
    Vytautas Magnus Univ, Lithuania.
    Yamelynets, Taras
    Ivan Franko Natl Univ, Ukraine.
    Fedoriak, Mariia
    Chernivtsi Natl Univ, Ukraine.
    Albulescu, Andra-Cosmina
    Alexandru Ioan Cuza Univ, Romania.
    Bravo, Felipe
    Univ Valladolid, Spain.
    Cruz, Fatima
    Univ Valladolid, Spain.
    Jaroszewicz, Bogdan
    Univ Warsaw, Poland.
    Kavtarishvili, Marika
    LLM European & Int Law Sch, Georgia.
    Munoz-Rojas, Jose
    Univ Evora, Portugal.
    Sijtsma, Frans
    Univ Groningen, Netherlands.
    Washbourne, Carla-Leanne
    UCL, England.
    Agnoletti, Mauro
    Univ Firenze, Italy.
    Dobrynin, Denis
    Univ Eastern Finland, Finland.
    Izakovicova, Zita
    Slovak Acad Sci, Slovakia.
    Jansson, Niklas
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Kanka, Robert
    Slovak Acad Sci, Slovakia.
    Kopperoinen, Leena
    Finnish Environm Inst SYKE, Finland.
    Lazdinis, Marius
    European Commiss, Belgium.
    Metzger, Marc
    Univ Edinburgh, Scotland.
    van der Moolen, Bert
    Bosgrp Noord Oost Nederland, Netherlands.
    Ozut, Deniz
    Nat Conservat Ctr, Turkey.
    Gjorgieska, Dori Pavloska
    Secretariat Reg Rural Dev Standing Working Grp SW, North Macedonia.
    Stryamets, Natalie
    Nat Reserve Rortochya, Ukraine.
    Tolunay, Ahmet
    Isparta Univ Appl Sci, Turkey.
    Turkoglu, Turkay
    Mugla Sitki Kocman Univ, Turkey.
    Zagidullina, Asiya
    St Petersburg State Univ, Russia.
    Maintaining natural and traditional cultural green infrastructures across Europe: learning from historic and current landscape transformations2021In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 36, no 2, p. 637-663Article in journal (Refereed)
    Abstract [en]

    Context Maintaining functional green infrastructures (GIs) require evidence-based knowledge about historic and current states and trends of representative land cover types. Objectives We address: (1) the long-term loss and transformation of potential natural forest vegetation; (2) the effects of site productivity on permanent forest loss and emergence of traditional cultural landscapes; (3) the current management intensity; and (4) the social-ecological contexts conducive to GI maintenance . Methods We selected 16 case study regions, each with a local hotspot landscape, ranging from intact forest landscapes, via contiguous and fragmented forest covers, to severe forest loss. Quantitative open access data were used to estimate (i) the historic change and (ii) transformation of land covers, and (iii) compare the forest canopy loss from 2000 to 2018. Qualitative narratives about each hotspot landscape were analysed for similarities (iv). Results While the potential natural forest vegetation cover in the 16 case study regions had a mean of 86%, historically it has been reduced to 34%. Higher site productivity coincided with transformation to non-forest land covers. The mean annual forest canopy loss for 2000-2018 ranged from 0.01 to 1.08%. The 16 case studies represented five distinct social-ecological contexts (1) radical transformation of landscapes, (2) abuse of protected area concepts, (3) ancient cultural landscapes (4) multi-functional forests, and (5) intensive even-aged forest management, of which 1 and 4 was most common. Conclusions GIs encompass both forest naturalness and traditional cultural landscapes. Our review of Pan-European regions and landscapes revealed similarities in seemingly different contexts, which can support knowledge production and learning about how to sustain GIs.

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  • 37.
    Angergård, Tilda
    Uppsala University, Disciplinary Domain of Science and Technology, Earth Sciences, Department of Earth Sciences, LUVAL.
    The Bed Topography ofthe Reidda Glaciers2024Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    There are around 250 glaciers in Sweden, all of which are constantly changing. Knowledge about the bottom topography of glaciers can be used in many different fields and is therefore important to develop.Through ground-penetrating radar data it is possible to calculate ice thicknesses on glaciers, a method that has been used for a long time but is inefficient. At Uppsala University, the glaciology researchgroup is working on developing a new inverse method to find ice thicknesses and bottom topographyon glaciers more easily and less costly. They are testing their method on the Unna and Stour Reiddaglaciers, located in the Kebnekaise masiff just outside Kiruna. The Kebnekaise masiff are part of the Seves Nappes, which was created during the collision of the Laurentia and Baltica continents. The bedrock consists mostly of mafic rocks, but there are parts with varying resistance. This may influence the varying ice thickness. Evidence for overdeepenings in the area is believed to exist, where the glaciers themselves have created bowl-shaped depressions in the bedrock that affect how thick the ice canbecome. Lateral moraines also affect how quickly some parts of the glacier melt. To validate an inverse model method, a map based on radar measurements is needed to compare results. During the survey done in March 2024, radar measurements from the glacier was also taken.These measurements were processed by dewow filtering, normal moveout correction, depth calculations and glacier bottom marking. Based on an interpolation of the processed radar data, a map of the ice thickness of the two glaciers was made. The thickness of Unna Reidda varies from 0 to 123 meters depth and for Stour Reidda from 0 to 147 meters depth. The thickness of the glacier ice was then subtracted from the topography of the mountain to produce the bottom topographic map of the Reidda glaciers. 

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  • 38.
    Antikainen, Catarina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Formation and Retention of Soil Organic Matter (SOM) in the Taygetos Mountains (Greece): Influence of Soil Properties and Wildfire2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Deforestation and soil degradation is a worldwide problem, and especially so in the Greek Taygetos mountains. With wildfires affecting thousands of square kilometers of land, soil quality assessments are important in order to choose the right land management measures in the process of landscape restoration. Soil organic matter (SOM) is a good indicator of soil quality, but its response to wildfires and dependence on other soil properties is not well known in the Taygetos area. This study attempts to investigate the influence of topographic aspect and slope inclination on SOM formation and retention in fire damaged forests. Results are put into context with other soil properties such as pH and water content as well as the influence of wildfires. The study found unexpectedly high amounts of SOM in all sampled slopes, which was attributed to the incorporation of charcoal from burnt litter produced during low intense fires. No correlation was detected between SOM and aspect, and only a weak negative correlation between SOM and slope inclination. However, the study found a strong correlation between SOM amounts and water content, which suggests that water is one of the main limiting factors of SOM in the Taygetos mountains.

  • 39.
    Applegate, Patrick J.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Kirchner, Nina
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Stone, E. J.
    Keller, K.
    Greve, R.
    An assessment of key model parametric uncertainties in projections of Greenland ice sheet behavior2012In: The Cryosphere, ISSN 1994-0416, E-ISSN 1994-0424, Vol. 6, no 3, p. 589-606Article in journal (Refereed)
    Abstract [en]

    Lack of knowledge about the values of ice sheet model input parameters introduces substantial uncertainty into projections of Greenland Ice Sheet contributions to future sea level rise. Computer models of ice sheet behavior provide one of several means of estimating future sea level rise due to mass loss from ice sheets. Such models have many input parameters whose values are not well known. Recent studies have investigated the effects of these parameters on model output, but the range of potential future sea level increases due to model parametric uncertainty has not been characterized. Here, we demonstrate that this range is large, using a 100-member perturbed-physics ensemble with the SICOPOLIS ice sheet model. Each model run is spun up over 125 000 yr using geological forcings and subsequently driven into the future using an asymptotically increasing air temperature anomaly curve. All modeled ice sheets lose mass after 2005 AD. Parameters controlling surface melt dominate the model response to temperature change. After culling the ensemble to include only members that give reasonable ice volumes in 2005 AD, the range of projected sea level rise values in 2100 AD is similar to 40 % or more of the median. Data on past ice sheet behavior can help reduce this uncertainty, but none of our ensemble members produces a reasonable ice volume change during the mid-Holocene, relative to the present. This problem suggests that the model's exponential relation between temperature and precipitation does not hold during the Holocene, or that the central-Greenland temperature forcing curve used to drive the model is not representative of conditions around the ice margin at this time (among other possibilities). Our simulations also lack certain observed physical processes that may tend to enhance the real ice sheet's response. Regardless, this work has implications for other studies that use ice sheet models to project or hindcast the behavior of the Greenland Ice Sheet.

  • 40.
    Archila Bustos, Maria Francisca
    et al.
    Lund University, Department of Human Geography, Sölvegatan 10, Lund, 223 62, Sweden.
    Hall, Ola
    Lund University, Department of Human Geography, Sölvegatan 10, Lund, 223 62, Sweden.
    Niedomysl, Thomas
    Department of Analysis and Coordination, Region Halland, Halmstad, Sweden; Stockholm University, Department of Human Geography, Stockholm, Sweden .
    Ernstson, Ulf
    University West, Department of Engineering Science, Division of Mathematics, Computer and Surveying Engineering.
    A pixel level evaluation of five multitemporal global gridded population datasets: a case study in Sweden, 1990-20152020In: Population and environment, ISSN 0199-0039, E-ISSN 1573-7810, Vol. 42, p. 255-277Article in journal (Refereed)
    Abstract [en]

    Human activity is a major driver of change and has contributed to many of the challenges we face today. Detailed information about human population distribution is fundamental and use of freely available, high-resolution, gridded datasets on global population as a source of such information is increasing. However, there is little research to guide users in dataset choice. This study evaluates five of the most commonly used global gridded population datasets against a high-resolution Swedish population dataset on a pixel level. We show that datasets which employ more complex modeling techniques exhibit lower errors overall but no one dataset performs best under all situations. Furthermore, differences exist in how unpopulated areas are identified and changes in algorithms over time affect accuracy. Our results provide guidance in navigating the differences between the most commonly used gridded population datasets and will help researchers and policy makers identify the most suitable datasets under varying conditions. © 2020, The Author(s).

  • 41.
    Ardung, Ola
    Uppsala University, Disciplinary Domain of Humanities and Social Sciences, Faculty of Social Sciences, Department of Social and Economic Geography.
    Aspektorienterade vittringsprocesser: En studie i ett nordiskt klimat2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Weathering on rocks is an important component of the world’s geomorphology. One way to measure weathering on rocks is to analyse rock hardness. This is a study conducted in the northern hemisphere on granite rocks in Uppsala, Sweden. A Schmidt hammer is used to create a correlation analysis between the aspects on three glacial erratic boulders and rock weathering. Statistics from the Schmidt hammer were then collected and analysed. The results showed a difference between the aspects of the rocks. Although only small differences between the rocks were found, the south and south-east aspects of the rocks were softer and suffered from a more dynamic rock weathering than the north aspects of the rocks. The reason to the more dynamic weathering on the south facing aspects is suggested to be because of a more dynamic thermal stress weathering. The same reason caused the north aspect to have a steeper slope and a more dense lichen cover. 

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  • 42.
    Aringo, Deborah
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Climate-resilient cities: A comparative study of climate adaptationstrategies in Botkyrka and Ekerö municipalities2018Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    This thesis research investigates and contributes to increased knowledge on municipalities’ approaches to climate adaptation and associated challenges that slow down or hinder climate adaptation approaches in cities. The Stockholm region has experienced climate change and impacts of severe floods, heat waves, storms, sea level rise, forest-fire outbreaks, erosion and landslides. To control the frequency and magnitude of these impacts, local authorities and administrations need to integrate mitigation and adaptation management strategies into physical plans of towns and cities.

    Surveys carried out in 2016 and 2017 consecutively, evaluate municipalities’ efforts in climate adaptation in different counties in Sweden. The survey report in 2017 reveals that not all municipalities are equally implementing climate adaptation in Stockholm county; and yet the impacts of climate change are to affect all municipalities regardless of size and geographical location.

    Therefore, to understand the state of climate change adaptation in the municipalities, the author interviewed municipal planners, engineers, environmental investigators, and climate group in Botkyrka, to collect qualitative data for analysis. Data was also gathered through qualitative document analysis to compare drivers of municipality approaches to climate adaptation in Botkyrka and Ekerö municipality. The study results show that there is a gap between Botkyrka and Ekerö municipalities’ climate adaptation work. However, much as these two municipalities are sustainably eveloping, they face a number of challenges that hamper their ability to integrate climate adaptation measure in urban physical plans in order to reduce urban vulnerabilities, and thus build sustainable and climate-resilient cities.

  • 43.
    Arleskär, Staffan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Bostadsrätt, gräsmark eller skog?: Hur har exploatering för bostadsbyggande år 2000-2015 påverkat Järvakilens funktion som spridningsväg?2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Urbanization is a key driver of habitat loss, ecosystem degradation and has a great impact on biodiversity. Exploitation of buffer zones surrounding conservation areas and green structures in urban environment can affect biodiversity through reduced total area of habitat, increased edge effects and lost connectivity on a landscape level. The previous regional development plans for the Stockholm region, had the purpose of leaving large green structures undeveloped to secure core areas of great biological value by focusing on a dense city core. However, the latest regional development strategy puts stress on the green wedges by shifting the focal areas of the development into suburban regional city centers, in many cases close to the green wedges. The purpose of this study was to map habitat loss and changes in the total area of the Järva green wedge, west of Stockholm, caused by development of housing areas in previously sparsley exploited buffer zones, during the period 2000 – 2015. The study uses theories of landscape ecology, remote sensing and GIS to map and quantify habitat loss between 2000 and 2015. Two different birds were used as surrogate species, one grassland habitat specialist – Corncrake (Crex crex) and one forest habitat generalist – Eurasian jay (Garrulus glandarius). The two different surrogate species were used to identify how loss of two nature types could influence biodiversity and connectivity for a group of species. Documents and development plans on regional and local scale were also used to map and predict further habitat loss and exploitation of the green wedge until 2030. The result of the study shows that grassland habitat lost nearly twice the area than forest habitat due to development of housing areas during the period 2000 to 2015. A total of 1.3 km² of grassland and 0.7 km² forest habitat were replaced by housing areas during the fifteen years covered in the study, and the Järva green wedge will have lost a total of 3.84 km² buffer zones by the year 2030. The Corncrake and other grassland specialist species is likely to get most affected when grassland suffered the greatest habitat loss in the area. Even though the Eurasian jay has a key ecological function for the Oak forest in the Järva green wedge and relies on forest habitat for successful breeding, the loss of forest habitat will probably not affect the habitat generalist species in the same way. On a regional scale, the study suggests that habitat loss and fragmentation may affect grassland specialist species more than forest generalist species. The overall connectivity in the Järva green wedge is likely to get affected by a shrinking total area caused by narrowing of the green wedge until 2030. The function of the Järva green wedge as a dispersal corridor for biodiversity in the Stockholm region will most certainly get affected by further loss of buffer zones caused by exploitation of land for housing areas.

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  • 44.
    Arra, Venni
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Storm Frequency in the Northern Baltic Sea Region and its Association to the North Atlantic Oscillation2018Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Storms can be both destructive and valuable at the same time. They expose coastal areas to various risks but can also enhance the supply of wind energy and provide marine ecosystems with oxygen rich water. As the North Atlantic Oscillation (NAO) is known to have a significant impact on the wind climate in Europe, investigating its interconnection to storm frequency and intensity under global warming circumstances in the Northern Baltic Sea region was of interest in this study. Wind speed data series of annual storm counts were obtained from five meteorological stations along with PC-based NAO values over the period 1960-2017. The data series were analysed in Microsoft Excel and modelled using a Poisson regression or negative binomial regression model in SPSS Statistics. The results display an unsystematic spatial pattern both in the association to the NAO as well as in the overall storm frequency. However, storm (≥ 21 m s-1) frequency has generally been decreasing, whereas the proportion of severe storms (≥ 24 m s-1) has slightly been increasing, suggesting a tendency toward stronger but fewer storms. Even though only certain data series display statistically significant findings (p ≤ .05), a majority of the winter storms and severe winter storms display a positive association, indicating that a higher NAOI is related to a greater number of winter storms. The spatial and temporal variability in the obtained results can partially be explained by storm tracks and prevalent wind directions. Nevertheless, inhomogeneities do presumably affect the wind speed observations through internal and external influences and changes related to the meteorological stations. Future research should, therefore, also consider integrating other storm related parameters, such as direct air pressure measurements, wave heights and storm surges, as well as implement different data homogenization methods and techniques.

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  • 45.
    Arrhenius, M.
    et al.
    Stockholms universitet.
    Lundholm, C.
    Stockholms universitet.
    Bladh, Gabriel
    Karlstad University, Faculty of Arts and Social Sciences (starting 2013), Centre for the Studies of Social Sciences Didactics (from 2013).
    Swedish 12–13-year-old students’ conceptions of the causes and processes forming eskers and erratics2020In: Journal of Geoscience education, ISSN 1089-9995, E-ISSN 2158-1428, Vol. 69, no 1, p. 43-54Article in journal (Refereed)
    Abstract [en]

    This study investigates students’ conceptions of the causes and processes that form eskers and erratics, types of glacial and glaciofluvial landforms which to date have been little researched in geoscience education. The data collected for the study included 134 responses to an assignment completed by 12- to 13-year-old students in the Swedish national geography test in 2013. The responses were sampled and analyzed using qualitative content analysis. The findings show that many of the students held alternative conceptions regarding the causes of these landforms, which included landslides, meteor impacts and human activity. Although some students were able to give a scientific explanation that considered the possible causes and relevant processes involved in the formation of erratics, many students did not give a full account of these processes. Furthermore, only a few students were able to describe the relevant processes involved in the formation of eskers and were more likely to discuss alternative or glacial processes rather than glaciofluvial processes. Given the lack of research on students’ understanding of glacial processes and landforms in geoscience and geography education, this study contributes with new knowledge of students’ conceptions of eskers and erratics and makes a theoretical contribution to research on students’ alternative conceptions and understanding of sequential and emergent processes in geoscience. The findings provide specific insights for teachers and are useful in the design of classroom practices that can change alternative conceptions and strengthen scientific conceptions.

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  • 46.
    Ask, Jenny
    Umeå University, Faculty of Science and Technology, Department of Ecology and Environmental Sciences.
    Carbon metabolism in clear-water and brown-water lakes2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The trophic state of lakes is commonly defined by the concentration of nutrients in the water column. High nutrient concentrations generate high phytoplankton production, and lakes with low nutrient concentrations are considered low-productive. This simplified view of lake productivity ignores the fact that benthic primary producers and heterotrophic bacteria can be important basal producers in lake ecosystems.

    In this thesis I have studied clear-water and brown-water lakes with respect to primary production, respiration and bacterial production based on allochthonous organic carbon. These processes were quantified in pelagic and benthic habitats on temporal and spatial scales. I also calculated the net ecosystem production of the lakes, defined as the difference between gross primary production (GPP) and respiration (R). The net ecosystem production indicates whether a lake is net heterotrophic (GPP < R), net autotrophic (GPP > R) or in metabolic balance (GPP = R). Net heterotrophic lakes are sources of carbon dioxide (CO2) to the atmosphere since respiration in these lakes, by definition, is subsidized by an external organic carbon source. External organic carbon is transported to lakes from the terrestrial environment via inlets, and can serve as a carbon source for bacteria but it also limits light availability for primary producers by absorbing light.

    On a seasonal scale, four of the clear-water lakes studied in this thesis were dominated by primary production in the soft-bottom benthic habitat and by respiration in the pelagic habitat. Concentrations of dissolved organic carbon (DOC) were low in the lakes, but still high enough to cause the lakes to be net heterotrophic. However, the lakes were not low-productive due to the high production in the benthic habitat. One of the clear-water lakes was studied also during the winter and much of the respiration under ice was supported by the benthic primary production from the previous summer. This is in contrast to brown-water lakes where winter respiration is suggested to be supported by allochthonous organic carbon.

    By studying lakes in a DOC gradient (i.e. from clear-water to brown-water lakes) I could draw two major conclusions. The lakes became less productive since benthic primary production decreased with increasing light extinction, and the lakes became larger sources of CO2 to the atmosphere since pelagic respiration was subsidized by allochthonous organic carbon. Thus, lake carbon metabolism can have an important role in the global carbon cycle due to their processing of terrestrial organic carbon and to their possible feedback effects on the climate system.

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  • 47.
    Ask, Jenny
    Umeå universitet, Institutionen för ekologi, miljö och geovetenskap.
    Carbon metabolism in clear-water and brown-water lakes2010Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The trophic state of lakes is commonly defined by the concentration of nutrients in the water column. High nutrient concentrations generate high phytoplankton production, and lakes with low nutrient concentrations are considered low-productive. This simplified view of lake productivity ignores the fact that benthic primary producers and heterotrophic bacteria can be important basal producers in lake ecosystems.

    In this thesis I have studied clear-water and brown-water lakes with respect to primary production, respiration and bacterial production based on allochthonous organic carbon. These processes were quantified in pelagic and benthic habitats on temporal and spatial scales. I also calculated the net ecosystem production of the lakes, defined as the difference between gross primary production (GPP) and respiration (R). The net ecosystem production indicates whether a lake is net heterotrophic (GPP < R), net autotrophic (GPP > R) or in metabolic balance (GPP = R). Net heterotrophic lakes are sources of carbon dioxide (CO2) to the atmosphere since respiration in these lakes, by definition, is subsidized by an external organic carbon source. External organic carbon is transported to lakes from the terrestrial environment via inlets, and can serve as a carbon source for bacteria but it also limits light availability for primary producers by absorbing light.

    On a seasonal scale, four of the clear-water lakes studied in this thesis were dominated by primary production in the soft-bottom benthic habitat and by respiration in the pelagic habitat. Concentrations of dissolved organic carbon (DOC) were low in the lakes, but still high enough to cause the lakes to be net heterotrophic. However, the lakes were not low-productive due to the high production in the benthic habitat. One of the clear-water lakes was studied also during the winter and much of the respiration under ice was supported by the benthic primary production from the previous summer. This is in contrast to brown-water lakes where winter respiration is suggested to be supported by allochthonous organic carbon.

    By studying lakes in a DOC gradient (i.e. from clear-water to brown-water lakes) I could draw two major conclusions. The lakes became less productive since benthic primary production decreased with increasing light extinction, and the lakes became larger sources of CO2 to the atmosphere since pelagic respiration was subsidized by allochthonous organic carbon. Thus, lake carbon metabolism can have an important role in the global carbon cycle due to their processing of terrestrial organic carbon and to their possible feedback effects on the climate system.

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  • 48.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Appendix to Paper V: Climate model performance versus basin-scalehydro-climatic dataManuscript (preprint) (Other academic)
  • 49.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Irrigation effects on hydro-climatic change: Basin-wise water balance-constrained quantification and cross-regional comparison2014In: Surveys in geophysics, ISSN 0169-3298, E-ISSN 1573-0956, Vol. 35, no 3, p. 879-895Article, review/survey (Refereed)
    Abstract [en]

    Hydro-climatic changes driven by human land and water use, including water use for irrigation, may be difficult to distinguish fromthe effects of global, natural and anthropogenic climate change. This paper quantifies and compares the hydro-climatic change effects ofirrigation using a data-driven, basin-wise quantification approach in two different irrigated world regions: the Aral Sea drainage basinin Central Asia, and the Indian Mahanadi River Basin draining into the Bay of Bengal. Results show that irrigation-driven changesin evapotranspiration and latent heat fluxes and associated temperature changes at the land surface may be greater in regions withsmall relative irrigation impacts on water availability in the landscape (here represented by the MRB) than in regions with severe suchimpacts (here represented by the Aral region). Different perspectives on the continental part of Earth’s hydrological cycle may thus implydifferent importance assessment of various drivers and impacts of hydro-climatic change. Regardless of perspective, however, actualbasin-wise water balance constraints should be accounted to realistically understand and accurately quantify continental water change.

  • 50.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography and Quaternary Geology.
    Dutta, Dushmanta
    Analysis of water resources in the Mahanadi River Basin, India under projected climate conditions2008In: Hydrological Processes, ISSN 0885-6087, E-ISSN 1099-1085, Vol. 22, no 18, p. 3589-3603Article in journal (Refereed)
    Abstract [en]

    The paper presents the outcomes of a study conducted to analyse water resources availability and demand in the Mahanadi River Basin in India under climate change conditions. Climate change impact analysis was carried out for the years 2000, 2025, 2050, 2075 and 2100, for the months of September and April (representing wet and dry months), at a sub-catchment level. A physically based distributed hydrologic model (DHM) was used for estimation of the present water availability. For future scenarios under climate change conditions, precipitation output of Canadian Centre for Climate Modelling and Analysis General Circulation Model (CGCM2) was used as the input data for the DHM. The model results show that the highest increase in peak runoff (38%) in the Mahanadi River outlet will occur during September, for the period 2075-2100 and the maximum decrease in average runoff (32·5%) will be in April, for the period 2050-2075. The outcomes indicate that the Mahanadi River Basin is expected to experience progressively increasing intensities of flood in September and drought in April over the considered years. The sectors of domestic, irrigation and industry were considered for water demand estimation. The outcomes of the analysis on present water use indicated a high water abstraction by the irrigation sector. Future water demand shows an increasing trend until 2050, beyond which the demand will decrease owing to the assumed regulation of population explosion. From the simulated future water availability and projected water demand, water stress was computed. Among the six sub-catchments, the sub-catchment six shows the peak water demand. This study hence emphasizes on the need for re-defining water management policies, by incorporating hydrological response of the basin to the long-term climate change, which will help in developing appropriate flood and drought mitigation measures at the basin level.

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