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  • 1. Abbott, Benjamin W.
    et al.
    Jones, Jeremy B.
    Schuur, Edward A. G.
    Chapin, F. Stuart
    Bowden, William B.
    Bret-Harte, M. Syndonia
    Epstein, Howard E.
    Flannigan, Michael D.
    Harms, Tamara K.
    Hollingsworth, Teresa N.
    Mack, Michelle C.
    McGuire, A. David
    Natali, Susan M.
    Rocha, Adrian V.
    Tank, Suzanne E.
    Turetsky, Merritt R.
    Vonk, Jorien E.
    Wickland, Kimberly P.
    Aiken, George R.
    Alexander, Heather D.
    Amon, Rainer M. W.
    Benscoter, Brian W.
    Bergeron, Yves
    Bishop, Kevin
    Blarquez, Olivier
    Bond-Lamberty, Ben
    Breen, Amy L.
    Buffam, Ishi
    Cai, Yihua
    Carcaillet, Christopher
    Carey, Sean K.
    Chen, Jing M.
    Chen, Han Y. H.
    Christensen, Torben R.
    Cooper, Lee W.
    Cornelissen, J. Hans C.
    de Groot, William J.
    DeLuca, Thomas H.
    Dorrepaal, Ellen
    Fetcher, Ned
    Finlay, Jacques C.
    Forbes, Bruce C.
    French, Nancy H. F.
    Gauthier, Sylvie
    Girardin, Martin P.
    Goetz, Scott J.
    Goldammer, Johann G.
    Gough, Laura
    Grogan, Paul
    Guo, Laodong
    Higuera, Philip E.
    Hinzman, Larry
    Hu, Feng Sheng
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jafarov, Elchin E.
    Jandt, Randi
    Johnstone, Jill F.
    Karlsson, Jan
    Kasischke, Eric S.
    Kattner, Gerhard
    Kelly, Ryan
    Keuper, Frida
    Kling, George W.
    Kortelainen, Pirkko
    Kouki, Jari
    Kuhry, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Laudon, Hjalmar
    Laurion, Isabelle
    Macdonald, Robie W.
    Mann, Paul J.
    Martikainen, Pertti J.
    McClelland, James W.
    Molau, Ulf
    Oberbauer, Steven F.
    Olefeldt, David
    Pare, David
    Parisien, Marc-Andre
    Payette, Serge
    Peng, Changhui
    Pokrovsky, Oleg S.
    Rastetter, Edward B.
    Raymond, Peter A.
    Raynolds, Martha K.
    Rein, Guillermo
    Reynolds, James F.
    Robards, Martin
    Rogers, Brendan M.
    Schaedel, Christina
    Schaefer, Kevin
    Schmidt, Inger K.
    Shvidenko, Anatoly
    Sky, Jasper
    Spencer, Robert G. M.
    Starr, Gregory
    Striegl, Robert G.
    Teisserenc, Roman
    Tranvik, Lars J.
    Virtanen, Tarmo
    Welker, Jeffrey M.
    Zimov, Sergei
    Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment2016In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 11, no 3, article id 034014Article in journal (Refereed)
    Abstract [en]

    As the permafrost region warms, its large organic carbon pool will be increasingly vulnerable to decomposition, combustion, and hydrologic export. Models predict that some portion of this release will be offset by increased production of Arctic and boreal biomass; however, the lack of robust estimates of net carbon balance increases the risk of further overshooting international emissions targets. Precise empirical or model-based assessments of the critical factors driving carbon balance are unlikely in the near future, so to address this gap, we present estimates from 98 permafrost-region experts of the response of biomass, wildfire, and hydrologic carbon flux to climate change. Results suggest that contrary to model projections, total permafrost-region biomass could decrease due to water stress and disturbance, factors that are not adequately incorporated in current models. Assessments indicate that end-of-the-century organic carbon release from Arctic rivers and collapsing coastlines could increase by 75% while carbon loss via burning could increase four-fold. Experts identified water balance, shifts in vegetation community, and permafrost degradation as the key sources of uncertainty in predicting future system response. In combination with previous findings, results suggest the permafrost region will become a carbon source to the atmosphere by 2100 regardless of warming scenario but that 65%-85% of permafrost carbon release can still be avoided if human emissions are actively reduced.

  • 2. Acharya, Kamal Prasad
    et al.
    De Frenne, Pieter
    Brunet, Jörg
    Chabrerie, Olivier
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Diekmann, Martin
    Hermy, Martin
    Kolb, Annette
    Lemke, Isgard
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Verheyen, Kris
    Graae, Bente Jessen
    Latitudinal variation of life-history traits of an exotic and a native impatiens species in Europe2017In: Acta Oecologica, ISSN 1146-609X, E-ISSN 1873-6238, Vol. 81, p. 40-47Article in journal (Refereed)
    Abstract [en]

    Understanding the responses of invasive and native populations to environmental change is crucial for reliable predictions of invasions in the face of global change. While comparisons of responses across invasive species with different life histories have been performed before, comparing functional traits of congeneric native and invasive species may help to reveal driving factors associated with invasion. Here we compared morphological functional trait patterns of an invasive species (Impatiens parviflora) with its congeneric native species (I. noli-tangere) along an approximately 1600 km European latitudinal gradient from France (49 degrees 34'N) to Norway (63 degrees 40'N). Soil nitrogen was recorded during six weeks of the growing season, and light, soil moisture, and nutrient availability were estimated for each sampled population using community weighted means of indicator values for co-occurring species. Temperature data were gathered from nearby weather stations. Both the native and invasive species are taller at higher latitudes and this response is strongest in the invasive species. Seed mass and number of seeds per capsule increase in I. noli-tangere but decrease in I. parviflora towards higher latitudes. Surprisingly, plant height in the invasive I. parviflora decreases with increasing soil nitrogen availability. The latitudinal pattern in seed mass is positively related to temperature in I. noli-tangere and negatively in I. parviflora. Leaf area of both species decreases with increasing Ellenberg indicator values for nitrogen and light but increases with increasing soil moisture. Soil nitrogen concentrations and Ellenberg indicator values for nitrogen have significant positive (I. nolitangere) and negative (I. parviflora) effects on the number of seeds per capsule. Our results show that the native I. noli-tangere has efficient reproduction at its range edge while the invasive I. parviflora shows a marked decrease in seed size and seed number per capsule. These patterns are unrelated to the growth and obtained size of the plants: even low soil nitrogen availability in the north seemed not to limit plant growth and size. Our results suggest that the invasive I. parviflora tends to become more invasive at lower latitudes by producing heavier seeds and more seeds per capsule.

  • 3.
    Adriansson, Linus
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Stockholm i färger: En kritisk diskursanalys av kulturarvets produktion och legitimering i stadens bebyggelsemiljö2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Avsikten med denna uppsats är att med en kritisk diskursanalys undersöka hur kunskap om kulturarvet och kulturhistoriska värden konstrueras i Stockholms byggda miljö. Akademisk litteratur inom kulturarvsforskningen beskriver en situation där det uppstått ett glapp mellan teori och praktik inom kulturarvssektorn som vidgats sedan postmodernismens och konstruktionismens framväxt i början på 1970-talet. Den utövande kulturarvsvården och värderingsprocessen är i stor utsträckning styrd av värdeorienterade klassificeringssystem där utgångspunkten är att finna och tolka olika värdetyper i ett objekt. Detta traditionella förhållningssätt är en del av ”den auktoriserade kulturarvsdiskursen”; ett begrepp inom kulturarvsforskningen som menar att kulturarvssektorn premierar traditionella värden genom expertutpekanden vilket leder till en reproduktion av kanoniserade objekt med vissa ideologiska förtecken. Sedan år 1974 finns det i Sverige nationella kulturpolitiska mål fastslagna och sedan år 2012 finns det fyra nationella kulturmiljömål som landets kulturmiljövårdande institutioner ska sträva. Målens tankegods förmedlar en ambition om att göra kulturmiljöer och kunskap tillgängligt för att främja demokratisering av kulturarvet. I Stockholms kommun är det Stadsmuseet som ansvarar för utpekandet och klassificeringen av kulturhistoriskt värdefulla byggnader och miljöer. Syftet med undersökningen är att bidra med en djupare förståelse för hur kunskapen om kulturhistoriska värden i Stockholms byggda kulturmiljö produceras och legitimeras. Resultat och analys visar att diskurserna i Stadsmuseets översiktsdokument sedan klassificeringens introduktion under tidigt 1980-tal har förändrats av ideologiska, politiska och ekonomiska element. Museets och kommunens samtida översiktsdokument har en anknytning till kunskapsläget inom kulturarvsforskningen genom att argumentera för relativa, pluralistiska värden. Men den traditionella värdesynen och expertdiskursen i värderingsprocessen har lett till en värdering och klassificering som reproducerar en traditionell förståelse av det byggda kulturarvet. En universell metod i kombination med intern praxis används för att identifiera vilka kulturhistoriska värden som finns, utan att precisera vilka egenskaper som upprätthåller dessa värden. Det ger klassificeringen en svag anknytning till kulturarvsforskning, regeringens kulturpolitiska mål och den egna institutionens värdesyn i samtida översiktsdokument.

  • 4.
    Aggemyr, Elsa
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Auffret, Alistair G.
    Stockholm University, Faculty of Science, Department of Physical Geography. Swedish University of Agricultural Sciences, Sweden.
    Jädergård, Love
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Species richness and composition differ in response to landscape and biogeography2018In: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 33, no 12, p. 2273-2284Article in journal (Refereed)
    Abstract [en]

    Context Understanding how landscape patterns affect species diversity is of great importance in the fields of biogeography, landscape ecology and conservation planning, but despite the rapid advance in biodiversity analysis, investigations of spatial effects on biodiversity are still largely focused on species richness.

    Objectives We wanted to know if and how species richness and species composition are differentially driven by the spatial measures dominating studies in landscape ecology and biogeography. As both measures require the same limited presence/absence information, it is important to choose an appropriate diversity measure, as differing results could have important consequences for interpreting ecological processes.

    Methods We recorded plant occurrences on 112 islands in the Baltic archipelago. Species richness and composition were calculated for each island, and the explanatory power of island area and habitat heterogeneity, distance to mainland and structural connectivity at three different landscape sizes were examined.

    Results A total of 354 different plant species were recorded. The influence of landscape variables differed depending on which diversity measure was used. Island area and structural connectivity determined plant species richness, while species composition revealed a more complex pattern, being influenced by island area, habitat heterogeneity and structural connectivity.

    Conclusions Although both measures require the same basic input data, species composition can reveal more about the ecological processes affecting plant communities in fragmented landscapes than species richness alone. Therefore, we recommend that species community composition should be used as an additional standard measure of diversity for biogeography, landscape ecology and conservation planning.

  • 5. 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.

  • 6. Ahlmer, Anna-Klara
    et al.
    Cavalli, Marco
    Hansson, Klas
    Koutsouris, Alexander J.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Crema, Stefano
    Kalantari, Zahra
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Soil moisture remote-sensing applications for identification of flood-prone areas along transport infrastructure2018In: Environmental Earth Sciences, ISSN 1866-6280, E-ISSN 1866-6299, Vol. 77, no 14, article id 533Article in journal (Refereed)
    Abstract [en]

    The expected increase in precipitation and temperature in Scandinavia, and especially short-time heavy precipitation, will increase the frequency of flooding. Urban areas are the most vulnerable, and specifically, the road infrastructure. The accumulation of large volumes of water and sediments on road-stream intersections gets severe consequences for the road drainage structures. This study integrates the spatial and temporal soil moisture properties into the research about flood prediction methods by a case study of two areas in Sweden, Vastra Gotaland and Varmland, which was affected by severe flooding in August 2014. Soil moisture data are derived from remote-sensing techniques, with a focus on the soil moisture-specific satellites ASCAT and SMOS. Furthermore, several physical catchments descriptors (PCDs) are analyzed and the result shows that larger slopes and drainage density, in general, mean a higher risk of flooding. The precipitation is the same; however, it can be concluded that more precipitation in most cases gives higher soil moisture values. The lack, or the dimensioning, of road drainage structures seems to have a large impact on the flood risk as more sediment and water can be accumulated at the road-stream intersection. The results show that the method implementing soil moisture satellite data is promising for improving the reliability of flooding.

  • 7. Ahlström, A. P.
    et al.
    Anderson, B.
    Arenillas, M.
    Bajracharya, S.
    Baroni, C.
    Bidlake, W. R.
    Braun, L. N.
    Caceres, B.
    Casassa, G.
    Ceballos, J. L.
    Cobos, G.
    Davila, L. R.
    Delgado Granados, H.
    Demberel, O.
    Demuth, M. N.
    Espizua, L.
    Fischer, A.
    Fujita, K.
    Gadek, B.
    Ghazanfar, A.
    Hagen, J. O.
    Hoelzle, M.
    Holmlund, Per
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Karimi, N.
    Li, Z.
    Martinez De Pison, E.
    Pelto, M.
    Pitte, P.
    Popovnin, V. V.
    Portocarrero, C. A.
    Prinz, R.
    Ramirez, J.
    Rudell, A.
    Sangewar, C.
    Severskiy, I
    Sigurdsson, O.
    Soruco, A.
    Tielidze, L.
    Usubaliev, R.
    Van Ommen, T.
    Vincent, C.
    Yakovlev, A.
    Historically unprecedented global glacier decline in the early 21st century2015In: Journal of Glaciology, ISSN 0022-1430, E-ISSN 1727-5652, Vol. 61, no 228, p. 745-+Article in journal (Refereed)
    Abstract [en]

    Observations show that glaciers around the world are in retreat and losing mass. Internationally coordinated for over a century, glacier monitoring activities provide an unprecedented dataset of glacier observations from ground, air and space. Glacier studies generally select specific parts of these datasets to obtain optimal assessments of the mass-balance data relating to the impact that glaciers exercise on global sea-level fluctuations or on regional runoff. In this study we provide an overview and analysis of the main observational datasets compiled by the World Glacier Monitoring Service (WGMS). The dataset on glacier front variations (similar to 42 000 since 1600) delivers clear evidence that centennial glacier retreat is a global phenomenon. Intermittent readvance periods at regional and decadal scale are normally restricted to a subsample of glaciers and have not come close to achieving the maximum positions of the Little Ice Age (or Holocene). Glaciological and geodetic observations (similar to 5200 since 1850) show that the rates of early 21st-century mass loss are without precedent on a global scale, at least for the time period observed and probably also for recorded history, as indicated also in reconstructions from written and illustrated documents. This strong imbalance implies that glaciers in many regions will very likely suffer further ice loss, even if climate remains stable.

  • 8. Akselsson, Cecilia
    et al.
    Belyazid, Salim
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Critical biomass harvesting - Applying a new concept for Swedish forest soils2018In: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 409, p. 67-73Article in journal (Refereed)
    Abstract [en]

    The contribution of forest harvesting to base cation losses and soil acidification has increased in recent years in Sweden, as the demand for bioenergy has increased and the sulphur deposition has decreased. Thus, new policy tools are required to evaluate the progress of the recovery from acidification, and as a basis for forest management recommendations. In this study we introduce and test a concept, Critical biomass harvesting. The concept builds on the concept Critical loads, which has been used world-wide for several decades as a bridge between science and policies related to transboundary air pollution and acidification. The basis for the concept is an acidity mass balance, with sources and sinks of acidity. A critical limit defines the highest acceptable acidification status of the water leaving the root zone. Based on the critical limit, the highest allowed biomass harvesting can be calculated, keeping the other parameters constant. In this study the critical limit was set to ANC (Acid Neutralizing Capacity) = 0. Nitrogen was assumed to be affecting acidity only if it leaches from the root zone. The critical biomass harvesting was calculated for almost 12000 National Forest Inventory sites with spruce and pine forest, using the best available data on deposition, weathering and nitrogen leaching. The exceedance of critical biomass harvesting was calculated as the difference between the estimated harvest losses and the critical biomass harvesting. The results were presented as median values in merged catchments in a catchment database, with totally 2079 merged catchments in Sweden. According to the calculations, critical biomass harvesting was exceeded in the southern half of Sweden already at stem harvesting in spruce forests. Whole-tree harvesting expanded the exceedance area, and increased the exceedance levels in southern Sweden. The exceedance in pine forest was lower and affected smaller areas. It was concluded that the concept of critical biomass harvesting can be successfully applied on the same database that has been used for critical load calculations in Sweden, using basically the same approach as has been extensively applied, evaluated and discussed in a critical load context. The results from the calculations in Sweden indicate that whole-tree harvesting, without wood ash recycling, can be expected to further slow down recovery, especially in the most acidified parts of the country, in the southwest.

  • 9. Akselsson, Cecilia
    et al.
    Olsson, Jonas
    Belyazid, Salim
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Capell, René
    Can increased weathering rates due to future warming compensate for base cation losses following whole-tree harvesting in spruce forests?2016In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 128, no 1-2, p. 89-105Article in journal (Refereed)
    Abstract [en]

    Whole-tree harvesting, i.e. harvesting of stems, branches and tops, has become increasingly common during recent decades due to the increased demand for renewable energy. Whole-tree harvesting leads to an increase in base cation losses from the ecosystem, which can counteract recovery from acidification. An increase in weathering rates due to higher temperatures is sometimes suggested as a process that may counteract the acidifying effect of whole-tree harvesting. In this study the potential effect of increasing temperature on weathering rates was compared with the increase in base cation losses following whole-tree harvesting in spruce forests, along a temperature gradient in Sweden. The mechanistic model PROFILE was used to estimate weathering rates at National Forest Inventory sites at today's temperature and the temperature in 2050, as estimated by two different climate projections. The same dataset was used to calculate base cation losses following stem-only and whole-tree harvesting. The calculations showed that the increase in temperature until 2050 would result in an increase in the base cation weathering rate of 20-33 %, and that whole-tree harvesting would lead to an increase in base cation losses of 66 % on average, compared to stem-only harvesting. A sensitivity analysis showed that moisture changes are important for future weathering rates, but the effect of the temperature change was dominating even when the most extreme moisture changes were applied. It was concluded that an increase in weathering rates resulting from higher temperatures would not compensate for the increase in base cation losses following whole-tree harvesting, except in the northernmost part of Sweden.

  • 10.
    Alavaisha, Edmond
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Dar es Salaam, Tanzania.
    Lyon, Steve W.
    Stockholm University, Faculty of Science, Department of Physical Geography. The Nature Conservancy, USA.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Assessment of Water Quality Across Irrigation Schemes: A Case Study of Wetland Agriculture Impacts in Kilombero Valley, Tanzania2019In: Water, ISSN 2073-4441, E-ISSN 2073-4441, Vol. 11, no 4, article id 671Article in journal (Refereed)
    Abstract [en]

    Coupled change in land and water use due to increased farming intensity is a main factor affecting water quality and quantity, ecological functions and biodiversity globally. Prolonging growing seasons and increasing productivity in wetlands through irrigation have been targeted for increasing food security, particularly in developing countries. Nevertheless, irrigation and drainage have often been associated with degradation of water quality through increased agrochemical and fertiliser runoff and leaching at local scales. In this study, we investigated water quality in streams used for irrigation in a wetland area in Kilombero Valley, Tanzania. We measured physical-chemical water parameters and collected macroinvertebrates with different sensitivity to water quality across several small irrigation schemes covering various conditions. Turbidity, temperature, nitrate-N, and ammonium-N were significantly higher at sampling sites downstream of irrigation compared to upstream. Macroinvertebrate diversity, richness and average score per taxa (ASPT) were higher in general in sampling sites upstream of irrigation, with more sensitive macroinvertebrates decreasing in abundance downstream. There was a positive correlation between physical-chemical parameters and macroinvertebrate indices across the sites. We demonstrate that macroinvertebrate indices can be used as a quick assessment of water quality in response to irrigation schemes in small-scale farming systems of Tanzania. This in turn can allow us to track changes affecting wetland ecosystem function and biodiversity at higher trophic levels and across larger scales, thereby providing useful early warnings to help avoid widespread degradation under widespread agricultural intensification.

  • 11.
    Alavaisha, Edmond
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of Dar es Salaam, Tanzania.
    Manzoni, Stefano
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Lindborg, Regina
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Different agricultural practices affect soil carbon, nitrogen and phosphorous in Kilombero -Tanzania2019In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 234, p. 159-166Article in journal (Refereed)
    Abstract [en]

    Converting natural and semi-natural vegetation to agriculture is currently the most significant land use change at global scale. This conversion leads to changes in soil nutrients and increased CO2 emissions. However, knowledge of how soil organic carbon and nutrients change under various farming management is still limited, especially for small scale farming systems. This study evaluated the effects of different farming systems on soil organic carbon (SOC), total nitrogen (TN) and total phosphorous (TP) in subsistence farming at Kilombero, Tanzania. We applied an in-situ experimental setup, comparing maize and rice farming with and without irrigation and difference in fertilizers, with replicated soil sampling at five soil depths to a depth of 60 cm. The results show that irrigation had a positive effect on profile-averaged concentrations of SOC and TN, while fertilization had a positive effect on TN. Higher concentrations and stocks of TN were found in maize field soils compered to rice fields. In the vertical profile, irrigation and fertilization had positive effects on concentrations of SOC and TN of top soil layers, and the interaction between irrigation and fertilization extended the effect to deeper soil layers. Our results indicate that moderate irrigation and fertilization can help to improve carbon storage and nutrient availability (TN) in small-scale farming soils in Africa.

  • 12.
    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.

  • 13. Albert, Aurélie
    et al.
    Auffret, Alistair G.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Cosyns, Eric
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    D'hondt, Bram
    Eichberg, Carsten
    Eycott, Amy E.
    Heinken, Thilo
    Hoffmann, Maurice
    Jaroszewicz, Bogdan
    Malo, Juan E.
    Mårell, Anders
    Mouissie, Maarten
    Pakeman, Robin J.
    Picard, Mélanie
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Poschlod, Peter
    Provoost, Sam
    Schulze, Kiowa Alraune
    Baltzinger, Christophe
    Seed dispersal by ungulates as an ecological filter: a trait-based meta-analysis2015In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 124, no 9, p. 1109-1120Article in journal (Refereed)
    Abstract [en]

    Plant communities are often dispersal-limited and zoochory can be an efficient mechanism for plants to colonize new patches of potentially suitable habitat. We predicted that seed dispersal by ungulates acts as an ecological filter - which differentially affects individuals according to their characteristics and shapes species assemblages - and that the filter varies according to the dispersal mechanism (endozoochory, fur-epizoochory and hoof-epizoochory). We conducted two-step individual participant data meta-analyses of 52 studies on plant dispersal by ungulates in fragmented landscapes, comparing eight plant traits and two habitat indicators between dispersed and non-dispersed plants. We found that ungulates dispersed at least 44% of the available plant species. Moreover, some plant traits and habitat indicators increased the likelihood for plant of being dispersed. Persistent or nitrophilous plant species from open habitats or bearing dry or elongated diaspores were more likely to be dispersed by ungulates, whatever the dispersal mechanism. In addition, endozoochory was more likely for diaspores bearing elongated appendages whereas epizoochory was more likely for diaspores released relatively high in vegetation. Hoof-epizoochory was more likely for light diaspores without hooked appendages. Fur-epizoochory was more likely for diaspores with appendages, particularly elongated or hooked ones. We thus observed a gradient of filtering effect among the three dispersal mechanisms. Endozoochory had an effect of rather weak intensity (impacting six plant characteristics with variations between ungulate-dispersed and non-dispersed plant species mostly below 25%), whereas hoof-epizoochory had a stronger effect (eight characteristics included five ones with above 75% variation), and fur-epizoochory an even stronger one (nine characteristics included six ones with above 75% variation). Our results demonstrate that seed dispersal by ungulates is an ecological filter whose intensity varies according to the dispersal mechanism considered. Ungulates can thus play a key role in plant community dynamics and have implications for plant spatial distribution patterns at multiple scales.

  • 14. Alborzi, Aneseh
    et al.
    Mirchi, Ali
    Moftakhari, Hamed
    Mallakpour, Iman
    Alian, Sara
    Nazemi, Ali
    Hassanzadeh, Elmira
    Mazdiyasni, Omid
    Ashraf, Samaneh
    Madani, Kaveh
    Stockholm University, Faculty of Science, Department of Physical Geography. Imperial College London, United Kingdom.
    Norouzi, Hamid
    Azarderakhsh, Marzi
    Mehran, Ali
    Sadegh, Mojtaba
    Castelletti, Andrea
    AghaKouchak, Amir
    Climate-informed environmental inflows to revive a drying lake facing meteorological and anthropogenic droughts2018In: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 13, no 8, article id 084010Article in journal (Refereed)
    Abstract [en]

    The rapid shrinkage of Lake Urmia, one of the world's largest saline lakes located in northwestern Iran, is a tragic wake-up call to revisit the principles of water resources management based on the socio-economic and environmental dimensions of sustainable development. The overarching goal of this paper is to set a framework for deriving dynamic, climate-informed environmental inflows for drying lakes considering both meteorological/climatic and anthropogenic conditions. We report on the compounding effects of meteorological drought and unsustainable water resource management that contributed to Lake Urmia's contemporary environmental catastrophe. Using rich datasets of hydrologic attributes, water demands and withdrawals, as well as water management infrastructure (i.e. reservoir capacity and operating policies), we provide a quantitative assessment of the basin's water resources, demonstrating that Lake Urmia reached a tipping point in the early 2000s. The lake level failed to rebound to its designated ecological threshold (1274 m above sea level) during a relatively normal hydro-period immediately after the drought of record (1998-2002). The collapse was caused by a marked overshoot of the basin's hydrologic capacity due to growing anthropogenic drought in the face of extreme climatological stressors. We offer a dynamic environmental inflow plan for different climate conditions (dry, wet and near normal), combined with three representative water withdrawal scenarios. Assuming effective implementation of the proposed 40% reduction in the current water withdrawals, the required environmental inflows range from 2900 million cubic meters per year (mcm yr(-1)) during dry conditions to 5400 mcm yr(-1) during wet periods with the average being 4100 mcm yr(-1). Finally, for different environmental inflow scenarios, we estimate the expected recovery time for re-establishing the ecological level of Lake Urmia.

  • 15. Alfredsson, H.
    et al.
    Clymans, W.
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Kuhry, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Conley, D. J.
    Estimated storage of amorphous silica in soils of the circum-Arctic tundra region2016In: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 30, no 3, p. 479-500Article in journal (Refereed)
    Abstract [en]

    We investigated the vertical distribution, storage, landscape partitioning, and spatial variability of soil amorphous silica (ASi) at four different sites underlain by continuous permafrost and representative of mountainous and lowland tundra, in the circum-Arctic region. Based on a larger set of data, we present the first estimate of the ASi soil reservoir (0-1m depth) in circum-Arctic tundra terrain. At all sites, the vertical distribution of ASi concentrations followed the pattern of either (1) declining concentrations with depth (most common) or (2) increasing/maximum concentrations with depth. Our results suggest that a set of processes, including biological control, solifluction and other slope processes, cryoturbation, and formation of inorganic precipitates influence vertical distributions of ASi in permafrost terrain, with the capacity to retain stored ASi on millennial timescales. At the four study sites, areal ASi storage (0-1m) is generally higher in graminoid tundra compared to wetlands. Our circum-Arctic upscaling estimates, based on both vegetation and soil classification separately, suggest a storage amounting to 219 +/- 28 and 274 +/- 33 Tmol Si, respectively, of which at least 30% is stored in permafrost. This estimate would account for about 3% of the global soil ASi storage while occupying an equal portion of the global land area. This result does not support the hypothesis that the circum-Arctic tundra soil ASi reservoir contains relatively higher amounts of ASi than other biomes globally as demonstrated for carbon. Nevertheless, climate warming has the potential to significantly alter ASi storage and terrestrial Si cycling in the Arctic.

  • 16. Alfredsson, Hanna
    et al.
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Clymans, Wim
    Stadmark, Johanna
    Kuhry, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Conley, Daniel J.
    Amorphous silica pools in permafrost soils of the Central Canadian Arctic and the potential impact of climate change2015In: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 124, no 1-3, p. 441-459Article in journal (Refereed)
    Abstract [en]

    We investigated the distribution, storage and landscape partitioning of soil amorphous silica (ASi) in a central Canadian region dominated by tundra and peatlands to provide a first estimate of the amount of ASi stored in Arctic permafrost ecosystems. We hypothesize that, similar to soil organic matter, Arctic soils store large amounts of ASi which may be affected by projected climate changes and associated changes in permafrost regimes. Average soil ASi storage (top 1 m) ranged between 9600 and 83,500 kg SiO2 ha(-1) among different land-cover types. Lichen tundra contained the lowest amounts of ASi while no significant differences were found in ASi storage among other land-cover types. Clear differences were observed between ASi storage allocated into the top organic versus the mineral horizon of soils. Bog peatlands, fen peatlands and wet shrub tundra stored between 7090 and 45,400 kg SiO2 ha(-1) in the top organic horizon, while the corresponding storage in lichen tundra, moist shrub- and dry shrub tundra only amounted to 1500-1760 kg SiO2 ha(-1). Diatoms and phytoliths are important components of ASi storage in the top organic horizon of peatlands and shrub tundra systems, while it appears to be a negligible component of ASi storage in the mineral horizon of shrub tundra classes. ASi concentrations decrease with depth in the soil profile for fen peatlands and all shrub tundra classes, suggesting recycling of ASi, whereas bog peatlands appeared to act as sinks retaining stored ASi on millennial time scales. Our results provide a conceptual framework to assess the potential effects of climate change impacts on terrestrial Si cycling in the Arctic. We believe that ASi stored in peatlands are particularly sensitive to climate change, because a larger fraction of the ASi pool is stored in perennially frozen ground compared to shrub tundra systems. A likely outcome of climate warming and permafrost thaw could be mobilization of previously frozen ASi, altered soil storage of biogenically derived ASi and an increased Si flux to the Arctic Ocean.

  • 17.
    Allègre, Xavier
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Different generation of controlled moraines in the glacier foreland of Midtdalsbreen, Norway2018Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    A series of small mounds (< 3m) were sampled in the foreland of Midtdalsbreen outlet glacier, southern Norway. These landforms were interesting, especially at site number 1 because they were located very close to a higher Little Ice Age (LIA) moraine (> 5 m), thereby informing the dynamic of the glacier after the LIA at this location. It was yet to determine if these specific mounds are controlled moraines. If they are controlled moraines, then this would have implication for the glacier dynamics and the geometry of the snout after the LIA. It could be determined, based on the landform record evidence, whether the ice at the snout of Midtdalsbreen was thin and cold shortly after the LIA. Furthermore, whether the landscape was deglaciated by downwasting and then by backwasting was the main question addressed in relation to the nature of the mound and the thickness of ice at the snout during and after the LIA. In order to better understand the nature of the landform record and the mounds near the LIA moraine, satellite imagery coupled with careful field investigations were used in the foreland of the Midtdalsbreen outlet glacier. A geomorphological map was produced, and it was useful to put the mounds in a geographical context. Further sedimentological investigation; including clast-shape analyze, produced more evidence about the inner nature of these landforms. Both few controlled moraines and other landforms throughout the glacier foreland indicate that the ice geometry for Midtdalsbreen, shortly after the LIA was such that the snout of the glacier was a thin sheet of ice flowing against the previously deposited LIA moraine. The sedimentology of the controlled moraine is such that the sediments are deposited in steeply dipping layers, and they could even be misinterpreted as permafrost terrains at first glimpse. However, other sedimentological evidences such as the presence of sorted sand and sometimes dipping beds of gravels in addition to the geomorphological mapping make it meaningful to interpret few of the mounds as controlled moraines. A modern analogue to these controlled moraines is dirt cones present on top of the glacier snout as well as controlled moraines a few hundred of meter from the snout. Observations both on the glacier snout and on the foreland involve that dirt-cones later evolve into these sedimentological hummocky units with steeply dipping layers within the paleo-landscape. These observations constrain the thickness of ice at the snout of Midtdalsbreen after the LIA as well as the glacier dynamic during its melt: for controlled moraines to be generated by glaciers, these accumulations of sediments would have to thaw by downwasting and then by backwasting, directly at the glacier snout. This process -comprising of different stages- allows enough time to deposit controlled moraine. It is then a thin, cold-based sheet of ice which is by the end responsible for the deposition of such a landform record. There was even dead-ice present on the landscape at that point. After deposition of dirt cones on top of the ice, important meltwater action is contributing to the glacifluvial origin of these hummocks which evolve from dirt-cones onto the glacier, to ice-cored moraines, and then to controlled moraines onto the foreland. Details about the multistage processes leading to the formation of controlled moraines is also at the center of the investigations.

  • 18. Ameli, Ali A.
    et al.
    Beven, Keith
    Erlandsson, Martin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Creed, Irena F.
    McDonnell, Jeffrey J.
    Bishop, Kevin
    Primary weathering rates, water transit times, and concentration-discharge relations: A theoretical analysis for the critical zone2017In: Water resources research, ISSN 0043-1397, E-ISSN 1944-7973, Vol. 53, no 1, p. 942-960Article in journal (Refereed)
    Abstract [en]

    The permeability architecture of the critical zone exerts a major influence on the hydrogeochemistry of the critical zone. Water flow path dynamics drive the spatiotemporal pattern of geochemical evolution and resulting streamflow concentration-discharge (C-Q) relation, but these flow paths are complex and difficult to map quantitatively. Here we couple a new integrated flow and particle tracking transport model with a general reversible Transition State Theory style dissolution rate law to explore theoretically how C-Q relations and concentration in the critical zone respond to decline in saturated hydraulic conductivity (K-s) with soil depth. We do this for a range of flow rates and mineral reaction kinetics. Our results show that for minerals with a high ratio of equilibrium concentration ( Ceq) to intrinsic weathering rate ( Rmax), vertical heterogeneity in K-s enhances the gradient of weathering-derived solute concentration in the critical zone and strengthens the inverse stream C-Q relation. As <mml:mfrac>CeqRmax</mml:mfrac> decreases, the spatial distribution of concentration in the critical zone becomes more uniform for a wide range of flow rates, and stream C-Q relation approaches chemostatic behavior, regardless of the degree of vertical heterogeneity in K-s. These findings suggest that the transport-controlled mechanisms in the hillslope can lead to chemostatic C-Q relations in the stream while the hillslope surface reaction-controlled mechanisms are associated with an inverse stream C-Q relation. In addition, as <mml:mfrac>CeqRmax</mml:mfrac> decreases, the concentration in the critical zone and stream become less dependent on groundwater age (or transit time).

  • 19. An, Wenling
    et al.
    Hou, Shugui
    Zhang, Qiong
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Zhang, Wangbin
    Wu, Shuangye
    Xu, Hao
    Pang, Hongxi
    Wang, Yetang
    Liu, Yaping
    Enhanced Recent Local Moisture Recycling on the Northwestern Tibetan Plateau Deduced From Ice Core Deuterium Excess Records2017In: Journal of Geophysical Research - Atmospheres, ISSN 2169-897X, E-ISSN 2169-8996, Vol. 122, no 23, p. 12541-12556Article in journal (Refereed)
    Abstract [en]

    Local moisture recycling plays an essential role in maintaining an active hydrological cycle of the Tibetan Plateau (TP). Previous studies were largely limited to the seasonal time scale due to short and sparse observations, especially for the northwestern TP. In this study, we used a two-component mixing model to estimate local moisture recycling over the past decades from the deuterium excess records of two ice cores (i.e., Chongce and Zangser Kangri) from the northwestern TP. The results show that on average almost half of the precipitation on the northwestern TP is provided by local moisture recycling. In addition, the local moisture recycling ratio has increased evidently on the northwestern TP, suggesting an enhanced hydrological cycle. This recent increase could be due to the climatic and environmental changes on the TP in the past decades. Rapid increases in temperature and precipitation have enhanced evaporation. Changes of land surface of plateau have significantly increased evapotranspiration. All of these have intensified local moisture recycling. However, the mixing model used in this study only includes a limited number of climate factors. Some of the extreme values of moisture recycling ratio could be caused by large-scale atmospheric circulation and other climatic and weather events. Moreover, the potential mechanisms for the increase in local recycling need to be further examined, since the numeric simulations from climate models did not reproduce the increased contribution of local moisture recycling in precipitation.

  • 20. Anchukaitis, Kevin J.
    et al.
    Wilson, Rob
    Briffa, Keith R.
    Buntgen, Ulf
    Cook, Edward R.
    D'Arrigo, Rosanne
    Davi, Nicole
    Esper, Jan
    Frank, David
    Gunnarson, Björn E.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hegerl, Gabi
    Helama, Samuli
    Klesse, Stefan
    Krusic, Paul J.
    Stockholm Univ, Dept Phys Geog, Stockholm, Sweden.
    Linderholm, Hans W.
    Myglan, Vladimir
    Osborn, Timothy J.
    Zhang, Peng
    Rydval, Milos
    Schneider, Lea
    Schurer, Andrew
    Wiles, Greg
    Zorita, Eduardo
    Last millennium Northern Hemisphere summer temperatures from tree rings: Part II, spatially resolved reconstructions2017In: Quaternary Science Reviews, ISSN 0277-3791, E-ISSN 1873-457X, Vol. 163, p. 1-22Article, review/survey (Refereed)
    Abstract [en]

    Climate field reconstructions from networks of tree-ring proxy data can be used to characterize regional scale climate changes, reveal spatial anomaly patterns associated with atmospheric circulation changes, radiative forcing, and large-scale modes of ocean-atmosphere variability, and provide spatiotemporal targets for climate model comparison and evaluation. Here we use a multiproxy network of tree-ring chronologies to reconstruct spatially resolved warm season (May August) mean temperatures across the extratropical Northern Hemisphere (40-90 degrees N) using Point-by-Point Regression (PPR). The resulting annual maps of temperature anomalies (750-1988 CE) reveal a consistent imprint of volcanism, with 96% of reconstructed grid points experiencing colder conditions following eruptions. Solar influences are detected at the bicentennial (de Vries) frequency, although at other time scales the influence of insolation variability is weak. Approximately 90% of reconstructed grid points show warmer temperatures during the Medieval Climate Anomaly when compared to the Little Ice Age, although the magnitude varies spatially across the hemisphere. Estimates of field reconstruction skill through time and over space can guide future temporal extension and spatial expansion of the proxy network.

  • 21.
    Anderberg, Niklas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Betesmarker i Mjölkkrisens Sverige: Mjölkbönder och betesmarken, landskapet och framtiden2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The situation for Swedish dairy farmers has been difficult since 2014. Many are choosing to close down their businesses. At the same time, Sweden has experienced a reduction of important habitats consisting of grazing lands, a trend that is still ongoing. This study explores how dairy farmers look at grasslands, their values, management, and future. Through interviews with dairy farmers it investigates how farmers look at the systems of environmental compensation awarded for the management of pastures and grassland habitats. The study concludes that is primarily an aesthetic landscape value that is the main reason behind the desire to preserve pastures amongst farmers. This can be linked to a personal relationship between the farmers and the landscape he/she grew up in and help create through with their work. Any reduction in grasslands has not been observed by a majority of the interviewed farmers, despite the fact that such a reduction is occurring in their counties as a whole. This suggests that the situation can vary widely at a local level. The opinions concerning the environmental compensations vary among the interviewees, but overall there is a wish for a less bureaucratic system that provides more flexibility for the farmer. This wish for less bureaucracy is also found concerning the system around the law demanding that all cows should be allowed to graze during a period of the year. In the end, it seems important for the future of grazinglands and the habitats they create that profitability returns to the dairy farmers, since without farmers grazing will be further reduced. Today’s difficult situation for the farmers increases the risk of it being difficult to find the workforce of future farmers who are willing and able to perform the work that is done today.

  • 22. Andrei, Constantin-Octavian
    et al.
    Lahtinen, Sonja
    Nordman, Maaria
    Stockholm University, Faculty of Science, Department of Physical Geography. Finnish Geospatial Research Institute FGI, Finland.
    Naranen, Jyri
    Koivula, Hannu
    Poutanen, Markku
    Hyyppa, Juha
    GPS Time Series Analysis from Aboa the Finnish Antarctic Research Station2018In: Remote Sensing, ISSN 2072-4292, E-ISSN 2072-4292, Vol. 10, no 12, article id 1937Article in journal (Refereed)
    Abstract [en]

    Continuous Global Positioning System (GPS) observations have been logged at the Finnish Antarctic research station (Aboa) since February 2003. The station is located in Dronning Maud Land, East Antarctica. Almost 5000 daily observation files have been archived based on yearly scientific expeditions. These files have not been fully analysed until now. This study reports for the first time on the consistent and homogeneous data processing and analysis of the 15-year long time series. Daily coordinates are obtained using Precise Point Positioning (PPP) processing based on two approaches. The first approach is based on the Kalman filter and uses the RTKLIB open source library to produce daily solutions by unconventionally running the filter in the forward and backward direction. The second approach uses APPS web service and is based on GIPSY scientific processing engine. The two approaches show an excellent agreement with less than 3 mm rms error horizontally and 6 mm rms error vertically. The derived position time series is analysed in terms of trend, periodicity and noise characteristics. The noise of the time series was found to be power-law noise model with spectral index closer to flicker noise. In addition, several periodic signals were found at 5, 14, 183 and 362 days. Furthermore, most of the horizontal movement was found to be in the North direction at a rate of 11.23 +/- 0.09 mm/y, whereas the rate in the East direction was estimated to be 1.46 +/- 0.05 mm/y. Lastly, the 15-year long time series revealed a movement upwards at a rate of 0.79 +/- 0.35 mm/y. Despite being an unattended station, Aboa provides one of the most continuous and longest GPS time series in Antarctica. Therefore, we believe that this research increases the awareness of local geophysical phenomena in a less reported area of the Antarctic continent.

  • 23.
    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.

  • 24.
    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.

  • 25. Arabameri, Alireza
    et al.
    Rezaei, Khalil
    Cerdà, Artemi
    Conoscenti, Christian
    Kalantari, Zahra
    Stockholm University, Faculty of Science, Department of Physical Geography.
    A comparison of statistical methods and multi-criteria decision making to map flood hazard susceptibility in Northern Iran2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 660, p. 443-458Article in journal (Refereed)
    Abstract [en]

    In north of Iran, flood is one of the most important natural hazards that annually inflict great economic damages on humankind infrastructures and natural ecosystems. The Kiasar watershed is known as one of the critical areas in north of Iran, due to numerous floods and waste of water and soil resources, as well as related economic and ecological losses. However, a comprehensive and systematic research to identify flood-prone areas, which may help to establish management and conservation measures, has not been carried out yet. Therefore, this study tested four methods: evidential belief function (EBF), frequency ratio (FR), Technique for Order Preference by Similarity To ideal Solution (TOPSIS) and Vlse Kriterijumsk Optimizacija Kompromisno Resenje (VIKOR) for flood hazard susceptibility mapping (FHSM) in this area. These were combined in two methodological frameworks involving statistical and multi-criteria decision making approaches. The efficiency of statistical and multi-criteria methods in FHSM were compared by using area under receiver operating characteristic (AUROC) curve, seed cell area index and frequency ratio. A database containing flood inventory maps and flood-related conditioning factors was established for this watershed. The flood inventory maps produced included 132 flood conditions, which were randomly classified into two groups, for training (70%) and validation (30%). Analytical hierarchy process (AHP) indicated that slope, distance to stream and land use/land cover are of key importance in flood occurrence in the study catchment. In validation results, the EBF model had a better prediction rate (0.987) and success rate (0.946) than FR, TOPSIS and VIKOR (prediction rate 0.917, 0.888, and 0.810; success rate 0.939, 0.904, and 0.735, respectively). Based on their frequency ratio and seed cell area index values, all models except VIKOR showed acceptable accuracy of classification.

  • 26.
    Ardung, Ola
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Closed To Open Sourve GIS: First Steps In Reverse Engineering ESRI's Layer Defintion File Format2017Independent thesis Advanced level (degree of Master (Two Years)), 30 credits / 45 HE creditsStudent thesis
    Abstract [en]

    Visualization of digital geographic data is often accomplished through custom symbology that is saved in a proprietary format called a layer file (.lyr). The sharing of free geographical information system (GIS) data can be limited as the symbology data is bound inthe .lyr file format. This makes it harder and more tedious to work with open software tools since it is not possible to convert or open the .lyr file in free and open GIS software and thus limits the distribution of free GIS data. The aim of this thesis is to increase the interoperability of .lyr data between proprietary and free and open GIS software. This was done by revers eengineering the .lyr file format to document the file structure and to distribute the knowledge and metadata gained from this project to the open source community. Reverse engineering the.lyr format provided a well needed metadata and documentation about the format which increases the interoperability and enable future work to continue to lessen the gap between open source and commercial software. This groundwork can therefore, enable a continued development of data interoperability between proprietary and free and open GIS software.

  • 27.
    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.

  • 28.
    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.

  • 29.
    Aronsson, Johanna
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Användning av tredimensionell geologisk modellering i hydrogeologiska utredningar: En fallstudie inför anläggandet av ett akviferlager i Brunkebergsåsen i Stockholm2015Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [sv]

    Akviferlager är en form av geoenergi där solenergi lagrad i grundvattnet används för att värma och kyla byggnader. Inför anläggandet av ett akviferlager är det viktigt med grundläggande geologiska och hydrogeologiska utredningar för att säkerställa funktion och kapacitet hos akviferlagret, samt minimera eventuell miljöpåverkan. I denna studie utvecklas en tredimensionell geologisk modell för att öka kunskapen om rullstensåsens geologiska uppbyggnad samt bedöma hur geologin kan komma att påverka det planerade akviferlagret. För att undersöka vilken påverkan manuella justeringar och tolkningar av geologin har, togs två geologiska modeller fram för jämförelse. Utifrån de geologiska modellerna uppskattades effektiv hydraulisk konduktivitet för åsen, d.v.s. sammanlagd konduktivitet för hela akviferens mäktighet, samt transporttid mellan akviferlagrets brunnspoler. Studien visar att akviferen består av sammanhängande jordlager med hög hydraulisk konduktivitet. Beroende på tolkningar och justeringar i modelleringsprocessen visar de två olika modellerna på skillnader vad gäller jordlagrens utbredning och mäktighet. Detta medför skillnader i effektiv hydraulisk konduktivitet mellan modellerna, vilket resulterar i relativt stora skillnader vad gäller transporttider mellan brunnspolerna. Tredimensionella geologiska modeller bedöms bidra till förbättrade hydrogeologiska utredningar då det är ett enkelt och effektivt sätt att bygga upp ett områdes geologi för översikt, tolkning och vidare studier i form av exempelvis grundvattenmodellering.

  • 30.
    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.

  • 31. Ashraf, Batool
    et al.
    AghaKouchak, Amir
    Alizadeh, Amin
    Baygi, Mohammad Mousavi
    Moftakhari, Hamed R.
    Mirchi, Ali
    Anjileli, Hassan
    Madani, Kaveh
    Stockholm University, Faculty of Science, Department of Physical Geography. Imperial College London, UK.
    Quantifying Anthropogenic Stress on Groundwater Resources2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 12910Article in journal (Refereed)
    Abstract [en]

    This study explores a general framework for quantifying anthropogenic influences on groundwater budget based on normalized human outflow (h(out)) and inflow (h(in)). The framework is useful for sustainability assessment of groundwater systems and allows investigating the effects of different human water abstraction scenarios on the overall aquifer regime (e.g., depleted, natural flow-dominated, and human flow-dominated). We apply this approach to selected regions in the USA, Germany and Iran to evaluate the current aquifer regime. We subsequently present two scenarios of changes in human water withdrawals and return flow to the system (individually and combined). Results show that approximately one-third of the selected aquifers in the USA, and half of the selected aquifers in Iran are dominated by human activities, while the selected aquifers in Germany are natural flow-dominated. The scenario analysis results also show that reduced human withdrawals could help with regime change in some aquifers. For instance, in two of the selected USA aquifers, a decrease in anthropogenic influences by similar to 20% may change the condition of depleted regime to natural flow-dominated regime. We specifically highlight a trending threat to the sustainability of groundwater in northwest Iran and California, and the need for more careful assessment and monitoring practices as well as strict regulations to mitigate the negative impacts of groundwater overexploitation.

  • 32. Ashraf, Samaneh
    et al.
    AghaKouchak, Amir
    Nazemi, Ali
    Mirchi, Ali
    Sadegh, Mojtaba
    Moftakhari, Hamed R.
    Hassanzadeh, Elmira
    Miao, Chi-Yuan
    Madani, Kaveh
    Stockholm University, Faculty of Science, Department of Physical Geography. Imperial College London, UK.
    Baygi, Mohammad Mousavi
    Anjileli, Hassan
    Arab, Davood Reza
    Norouzi, Hamid
    Mazdiyasni, Omid
    Azarderakhsh, Marzi
    Alborzi, Aneseh
    Tourian, Mohammad J.
    Mehran, Ali
    Farahmand, Alireza
    Mallakpour, Iman
    Compounding effects of human activities and climatic changes on surface water availability in Iran2019In: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 152, no 3-4, p. 379-391Article in journal (Refereed)
    Abstract [en]

    By combining long-term ground-based data on water withdrawal with climate model projections, this study quantifies the compounding effects of human activities and climate change on surface water availability in Iran over the twenty-first century. Our findings show that increasing water withdrawal in Iran, due to population growth and increased agricultural activities, has been the main source of historical water stress. Increased levels of water stress across Iran are expected to continue or even worsen over the next decades due to projected variability and change in precipitation combined with heightened water withdrawals due to increasing population and socio-economic activities. The greatest rate of decreased water storage is expected in the Urmia Basin, northwest of Iran, (varying from -8.3mm/year in 2010-2039 to -61.6mm/year in 2070-2099 compared with an observed rate of 4mm/year in 1976-2005). Human activities, however, strongly dominate the effects of precipitation variability and change. Major shifts toward sustainable land and water management are needed to reduce the impacts of water scarcity in the future, particularly in Iran's heavily stressed basins like Urmia Basin, which feeds the shrinking Lake Urmia.

  • 33.
    Asokan, Shilpa M.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Rogberg, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Bring, Arvid
    Stockholm University, Faculty of Science, Department of Physical Geography. University of New Hampshire, USA.
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Climate model performance and change projection for freshwater fluxes: comparison for irrigated areas in Central and South Asia2016In: Journal of Hydrology Regional Studies, ISSN 1070-9428, E-ISSN 1857-8489, Vol. 5, p. 48-65Article in journal (Refereed)
    Abstract [en]

    Study region: The large semi-arid Aral Region in Central Asia and the smaller tropical Mahanadi River Basin (MRB) in India. Study focus: Few studies have so far evaluated the performance of the latest generation ofglobal climate models on hydrological basin scales. We here investigate the performanceand projections of the global climate models in the Coupled Model Intercomparison Project, Phase 5 (CMIP5) for freshwater fluxes and their changes in two regional hydrological basins, which are both irrigated but of different scale and with different climate. New hydrological insights for the region: For precipitation in both regions, model accuracy relative to observations has remained the same or decreased in successive climate model generations until and including CMIP5. No single climate model out-performs other models across all key freshwater variables in any of the investigated basins. Scale effects are not evident from global model application directly to freshwater assessment for the two basins of widely different size. Overall, model results are less accurate and more uncertain for freshwater fluxes than for temperature, and particularly so for model-implied water storage changes. Also, the monsoon-driven runoff seasonality in MRB is not accurately reproduced. Model projections agree on evapotranspiration increase in both regions until the climatic period 2070–2099. This increase is fed by precipitation increase in MRB and by runoff water (thereby decreasing runoff) in the Aral Region.

  • 34.
    Aspenberg, Annika
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Dialog och Samarbete i arbetet med ramdirektivet för vatten: Perspektiv från kommun, länsstyrelse och vattenmyndighet i Norra Östersjöns Vattendistrikt, Sverige2017Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    The EU Water Framework Directive (2000/60/EG) entered into force in the year 2000, with the purpose to enhance water quality in the EU and to guarantee a sustainable water provision for the future. This study focuses on the implementation of the Water Framework Directive in the Northern Baltic Sea drainage basin, Sweden. Sweden is divided into five river basin districts, of which five water authorities are responsible for water management and planning. Every sixth year an action program is written for each of the five river basin districts by the responsible water authority. In this study the development and implementation of the action program for the Northern Baltic Sea drainage basin are examined, with special focus on the communication between municipalities, the county administrative boards and the responsible water authority. Five officials from Uppsala, Stockholm, Heby and Knivsta municipalities, two officials from the Uppsala and Stockholm county administrative boards and one official from the water authority were interviewed about their work to implement the Water Framework Directive and the cooperation and communication around it. The study shows that shortcomings in cooperation and communication between the responsible authorities may hamper the successful implementation of the Water Framework Directive. On the one hand, the county boards and the water authority work closely together and have a continuous dialogue around the development of the action program. On the other hand, the officials from the municipalities are not a part of this tight cooperation and are largely excluded from the development of the action program. There is tendency of the officials from the municipality to doubt the action program and to criticize the suggested strategy for water management, whereas the officials from the county boards and the water authority strongly believe in the usefulness of the action program, which they have developed. The participants from the municipalities express that no clear plan is presented for the funding of the work. They find the time schedule unrealistic and point out that the action program lacks discussions on goal conflicts (in particular, the need to improve the economic situation of farmers is perceived to be in conflict with their planned tasks in the action program). In addition, the officials from the municipalities express that the information flows in the water management system are characterized by one way communication and that their local knowledge is not accounted for properly. In addition, the officials from the municipalities request that the action programme contain more detailed information on the local water bodiesand account for all available local data. In this commentary the participants express a believe that the demands in the action plan could be explained in more exact detail and backed up with evidence and data, i.e. of the consequences of actions in the area (such as emissions from industries or actions taken by the official). The participants from the municipalities also request enhanced contacts with national authorities. They complain that important information from national authorities (such as information on new regulations and guidelines)do not always reach the municipalities, which hampers their ability to act as guiding authorities in water management(as required by the action program).

  • 35.
    Assefa Hassen, Yohannes
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The Impacts of Mining on Arctic Environment and Society from Corporate Social Responsibility and Sustainable Development Perspectives: The Case of Jokkmokk (Kallak) Iron Mines in Northern Sweden2016Independent thesis Advanced level (degree of Master (Two Years)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Extractive industry in Arctic is controversial due  to the ecosystems and communities in the region are highly sensitive to natural and anthropogenic disturbances as it is one of the world’s global change hot-spots, as well as its uniqueness and distinctive social and ecological significance. As mining industry has developed into sophisticated operations, yet the basic causes of environmental pollution and degradation and impacts on the natural environment of the Arctic region remain unchanged. Mining in this environment may be faced with dilemmas as the result of adverse impacts they may cause and their escalating environmental footprints;  as well as reactions from pressure groups and indigenous peoples, which in turn may have a detrimental effect on their reputations and financial performances. This may further have social, environmental and political risks in their present and future roles and operations. Thus, the mining industry ought to recognize the impacts in their operations, and are required to work towards minimizing the adverse impacts and maximizing the substantial benefits of their actions on the environment, the community and local people. Corporate social responsibility (CSR) and sustainability are supposed to be two of several principles used to examine the social and environmental endeavours and results of business activity.

    The aim of this thesis is to assess the environmental and social impacts associated with major mining operations Arctic region, and to conduct preliminary review of the perspectives of CSR and sustainable development in countries across the Arctic region and subarctic, especially the United States of America (USA), Finland and Sweden. As well as conduct comparative study and analysis on how corporate entities in these countries dealing with the two theoretical frameworks and how they are approached in practice and managed, and information are disclosed. The study also concentrates on how these issues can be handled in the case of Jokkmokk (Kallak) Iron Mines in Sweden. Different methodological approaches and techniques have been adopted in this study. The literature review is supplemented by interviews with strategically important stakeholders. The Environmental Impact Assessment (EIA) statement is reviewed and conceptual modeling is also employed to demonstrate the dynamic effects and consequences of the Kallak North Iron Mines. The findings in this thesis propose that the corporations’ in the USA show differences from those of the European countries in defining and  addressing social and environmental concerns; as well as managing CSR and sustainability issues and communicating them as there are qualitatively different practices and approaches to CSR in these countries. In conclusion, main points are suggested as important recommendations entailing of some clear expectations to fulfill on how CSR and sustainability issues may be handled by extractive industry including the case of Jokkmokk (Kallak North) Iron Mines. 

  • 36.
    Auffret, Alistair G.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Aggemyr, Elsa
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Spatial scale and specialization affect how biogeography and functional traits predict long-term patterns of community turnover2017In: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 31, no 2, p. 436-443Article in journal (Refereed)
    Abstract [en]

    1. Immigration, extirpation and persistence of individual populations of species are key processes determining community responses to environmental change. However, they are difficult to study over long time periods without corresponding historical and modern-day species occurrences.

    2. We used historical and present-day plant species occurrence data from two different spatial scales (resolutions) to investigate the plant community turnover during the 20th century in a Baltic Sea archipelago. Patterns of turnover were analysed in relation to plant functional traits relating to dispersal and competition/persistence, as well as biogeographical variables.

    3. Turnover was largely driven by interactions between functional traits and measures of area, connectivity and distance to mainland. However, the combinations of traits and biogeographical variables that were most important for predicting immigration and extirpation differed between data sets, and between species associated with grassland management and the entire species pool.

    4. Taller plants were more likely to persist regardless of scale and biogeography, reflecting the grazing abandonment that occurred in the study area. Interactions between dispersal traits and biogeography were related to immigrations when the entire species pool was considered. However, increased dispersal potential, a smaller island size and increasing distance to mainland combined to promote extirpations in management-associated species. A perennial life span and seed banking contributed to species persistence. At the larger spatial scale, trait-driven turnover was not mediated by the biogeographical context.

    5. We showed that it is important to consider functional traits, biogeographical variables and their interactions when analysing community turnover over time. Furthermore, we found that the understanding of how combinations of traits and biogeography predict turnover depends on the source and spatial scale of the available data, and the species pool analysed.

  • 37.
    Auffret, Alistair G.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Swedish University of Agricultural Sciences, Sweden; University of York, UK.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Land uplift creates important meadow habitat and a potential original niche for grassland species2018In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 285, no 1876, article id 20172349Article in journal (Refereed)
    Abstract [en]

    Semi-natural grasslands have been severely affected by agricultural land-use change. However, the isostatic land adjustment following deglaciation in the Northern Hemisphere means that new land is continually being created in coastal areas. We modelled isostatic adjustment during the last 4000 years in a region of the Baltic coast to estimate the emergence of potential grassland habitat. We also compared the alpha and beta diversity of existing managed and abandoned coastal meadows, and assessed their contribution to biodiversity at landscape scales. We estimated that half the 7866 km(2) of emerging land had the potential to become coastal meadow habitat, which is an order of magnitude larger than the total area of all valuable semi-natural grassland in the study region today. The small area of managed coastal habitat remaining was found to have a disproportionate influence on the richness of threatened species at landscape scales, but our results also show that continued management is essential for the maintenance of grassland biodiversity. Our combination of approaches identifies uplifted coastal meadows as an additional original niche for grassland plant species, while highlighting that low-intensity disturbance through grassland management is essential for the maintenance of diversity at multiple scales.

  • 38.
    Auffret, Alistair G.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of York, UK.
    Kimberley, Adam
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Skånes, Helle
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Jakobsson, Simon
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Waldén, Emelie
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Wennbom, Marika
    Wood, Heather
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Bullock, James M.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Gartz, Mira
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hooftman, Danny A. P.
    Tränk, Louise
    Stockholm University, Faculty of Science, Department of Physical Geography.
    HistMapR: Rapid digitization of historical land-use maps in R2017In: Methods in Ecology and Evolution, ISSN 2041-210X, E-ISSN 2041-210X, Vol. 8, no 11, p. 1453-1457Article in journal (Refereed)
    Abstract [en]

    Habitat destruction and degradation represent serious threats to biodiversity, and quantification of land-use change over time is important for understanding the consequences of these changes to organisms and ecosystem service provision. Comparing land use between maps from different time periods allows estimation of the magnitude of habitat change in an area. However, digitizing historical maps manually is time-consuming and analyses of change are usually carried out at small spatial extents or at low resolutions. HistMapR contains a number of functions that can be used to semi-automatically digitize historical land use according to a map's colours, as defined by the RGB bands of the raster image. We test the method on different historical land-use map series and compare results to manual digitizations. Digitization is fast, and agreement with manually digitized maps of around 80-90% meets common targets for image classification. We hope that the ability to quickly classify large areas of historical land use will promote the inclusion of land-use change into analyses of biodiversity, species distributions and ecosystem services.

  • 39.
    Auffret, Alistair G.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. Swedish University of Agricultural Sciences, Sweden; University of York, UK.
    Kimberley, Adam
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography. Södertörn University, Sweden.
    Waldén, Emelie
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Super-regional land-use change and effects on the grassland specialist flora2018In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 9, article id 3464Article in journal (Refereed)
    Abstract [en]

    Habitat loss through land-use change is the most pressing threat to biodiversity worldwide. European semi-natural grasslands have suffered an ongoing decline since the early twentieth century, but we have limited knowledge of how grassland loss has affected biodiversity across large spatial scales. We quantify land-use change over 50-70 years across a 175,000 km(2) super-region in southern Sweden, identifying a widespread loss of open cover and a homogenisation of landscape structure, although these patterns vary considerably depending on the historical composition of the landscape. Analysing species inventories from 46,796 semi-natural grasslands, our results indicate that habitat loss and degradation have resulted in a decline in grassland specialist plant species. Local factors are the best predictors of specialist richness, but the historical landscape predicts present-day richness better than the contemporary landscape. This supports the widespread existence of time-lagged biodiversity responses, indicating that further species losses could occur in the future.

  • 40.
    Auffret, Alistair G.
    et al.
    Stockholm University, Faculty of Science, Department of Physical Geography. University of York, UK.
    Rico, Yessica
    Bullock, James M.
    Hooftman, Danny A. P.
    Pakeman, Robin J.
    Soons, Merel B.
    Suarez-Esteban, Alberto
    Traveset, Anna
    Wagner, Helene H.
    Cousins, Sara A. O.
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Plant functional connectivity - integrating landscape structure and effective dispersal2017In: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 105, no 6, p. 1648-1656Article, review/survey (Refereed)
    Abstract [en]

    1. Dispersal is essential for species to survive the threats of habitat destruction and climate change. Combining descriptions of dispersal ability with those of landscape structure, the concept of functional connectivity has been popular for understanding and predicting species' spatial responses to environmental change. 2. Following recent advances, the functional connectivity concept is now able to move beyond landscape structure to consider more explicitly how other external factors such as climate and resources affect species movement. We argue that these factors, in addition to a consideration of the complete dispersal process, are critical for an accurate understanding of functional connectivity for plant species in response to environmental change. 3. We use recent advances in dispersal, landscape and molecular ecology to describe how a range of external factors can influence effective dispersal in plant species, and how the resulting functional connectivity can be assessed. 4. Synthesis. We define plant functional connectivity as the effective dispersal of propagules or pollen among habitat patches in a landscape. Plant functional connectivity is determined by a combination of landscape structure, interactions between plant, environment and dispersal vectors, and the successful establishment of individuals. We hope that this consolidation of recent research will help focus future connectivity research and conservation.

  • 41. Augustsson, A.
    et al.
    Söderberg, Uddh T.
    Jarsjö, Jerker
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Åström, M.
    Olofsson, B.
    Balfors, B.
    Destouni, Georgia
    Stockholm University, Faculty of Science, Department of Physical Geography.
    The risk of overestimating the risk-metal leaching to groundwater near contaminated glass waste deposits and exposure via drinking water2016In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 566, p. 1420-1431Article in journal (Refereed)
    Abstract [en]

    This study investigates metal contamination patterns and exposure to Sb, As, Ba, Cd and Pb via intake of drinking water in a region in southeastern Sweden where the production of artistic glass has resulted in a large number of contaminated sites. Despite high total concentrations of metals in soil and groundwater at the glassworks sites properties, all drinking water samples from households with private wells, located at a 30-640 m distance from a glassworks site, were below drinking water criteria from the WHO for Sb, As, Ba and Cd. A few drinking water samples showed concentrations of Pb above the WHO guideline, but As was the only element found in concentrations that could result in human exposure near toxicological reference values. An efficient retention of metals in the natural soil close to the source areas, which results in a moderate impact on local drinking water, is implied. Firstly, by the lack of significant difference in metal concentrations when comparing households located upstream and downstream of the main waste deposits, and secondly, by the lack of correlation between the metal concentration in drinking water and distance to the nearest glassworks site. However, elevated Pb and Cd concentrations in drinking water around glassworks sites when compared to regional groundwater indicate that diffuse contamination of the soils found outside the glassworks properties, and not only the glass waste landfills, may have a significant impact on groundwater quality. We further demonstrate that different mobilization patterns apply to different metals. Regarding the need to use reliable data to assess drinking water contamination and human exposure, we finally show that the conservative modelling approaches that are frequently used in routine risk assessments may result in exposure estimates many times higher than those based on measured concentrations in the drinking water that is actually being used for consumption.

  • 42.
    Axelsson, Pia
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Minskad trädtillväxt under Lilla sitiden?: En dendroklimatologisk jämförelse mellan nutid och 1600-talet invid trädgränsen i norra Skandinavien2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    During the period called Little Ice Age (1400 ~ 1900) the climate of northern Europe was in an annual year-basis overall colder than it was before and after that period. The numbers of short, cold and rainy summers and long, bitter-cold winters where often repetitive under the approximately 500-years the period lasted. In Scandinavia, the coldest time during this period is estimated to have started around the end of the 16th century and lasted to the beginning of the 18th century. Trees growing at the tree-line are limited by temperature for their annual growth and hence showing differences of growth during changes in the climate,  a method called dendroclimatology. The variations of growth can be read in the tree-rings either by analyze the width of the ring or by look into the density of the wood and is used to reconstruct past climates. The aim of this study is to investigate how the tree-growth responded to the colder temperatures compared to today. Trees (Scots pine) close to the tree-line in northern Scandinavia where used to enhance the temperature signal in the data.  The proxy used is the growth density (MXD – maximum latewood density). The result reveals that during the coldest century, the trees show a larger number of negative growth-years with comparison with the 20th century and the negative and positive growth follows a more united trend. The result also shows a great number of negative growth-years at the end of the Little Ice Age, with a lot of extreme low growth - indexes (lower than -1.5). The conclusion then leans towards a cooler climate with overall lower temperatures under the 17th century compared to 1900-2004. 

  • 43.
    Axiotou, Anna-Maria
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Enkätundersökning om attityder gentemot källsortering bland invånarna i Kiruna centralort2017Independent thesis Advanced level (degree of Master (One Year)), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Recycling is one of the most significant action we can do to reduce the environmental impactof waste. More efficient use of natural resources and the reduced greenhouse gas emissions is two major environmental benefits. The people that live on this planet have a key role in increasing recycling by sorting their household waste. Therefore, residents must take a responsibility for their consumption and the use of the planets resources. People's attitudes tosort waste is therefore essential for understand recycling behaviour and intensions.

    This study aims to examine waste recycling behaviour, with a focus on attitudes and factors that affect the recycling behaviour among residents in Kiruna, the northern most municipalityof Sweden. 97 inhabitants in the central part of Kiruna participated in the survey. It was found that lack of recycling stations and curbside collection were factors that affected people to recycle. The study also showed that the residents had a positive attitude to recycle because ofthe level of knowledge about the benefits of recycling.

  • 44. Babbar-Sebens, Meghna
    et al.
    Root, Elizabeth
    Rosenberg, David E.
    Watkins, David
    Mirchi, Ali
    Giacomoni, Marcio
    Madani, Kaveh
    Stockholm University, Faculty of Science, Department of Physical Geography. Imperial College London, United Kingdom.
    Training Water Resources Systems Engineers to Communicate: Acting on Observations from On-the-Job Practitioners2019In: Journal of professional issues in engineering education and practice, ISSN 1052-3928, E-ISSN 1943-5541, Vol. 145, no 4, article id 04019012Article in journal (Refereed)
    Abstract [en]

    Engineers face the ongoing challenge to effectively communicate for diverse purposes and audiences across multiple settings. The authors interviewed 10 practicing water resources systems engineers to collect their lived experiences of the use of water resources systems analysis in their workplaces. Thematic analysis was used to identify three key communications hurdles practitioners face: stakeholder influence over the communication process, engineers as central to communication and decision making, and communication as an opportunity to educate stakeholders and engineers. Practitioners recommended classroom activities to overcome these hurdles and better integrate communications training into curricula. Recommendations include (1) expanding the use of case studies, (2) adding opportunities for role plays and team activities, (3) providing students with more practice on how to hold effective discussions, facilitate teamwork, and resolve conflicts, and (4) providing students with the broader contexts for class problems, including how political/institutional constraints, bureaucracies, and social issues may constrain communication and technical solutions. This study shares 22 example activities as online educational resources in a free, open, searchable repository and shows how activities can serve as a bottom-up approach to integrate communications training into the engineering curriculum.

  • 45. Bagger-Sjöbäck, Dan
    et al.
    Strömbäck, Karin
    Hakizimana, Pierre
    Plue, Jan
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Larsson, Christina
    Hultcrantz, Malou
    Papatziamos, Georgios
    Smeds, Henrik
    Danckwardt-Lillieström, Niklas
    Hellström, Sten
    Johansson, Ann
    Tideholm, Bo
    Fridberger, Anders
    A Randomised, Double Blind Trial of N-Acetylcysteine for Hearing Protection during Stapes Surgery2015In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 10, no 3, article id e0115657Article in journal (Refereed)
    Abstract [en]

    Background Otosclerosis is a disorder that impairs middle ear function, leading to conductive hearing loss. Surgical treatment results in large improvement of hearing at low sound frequencies, but high-frequency hearing often suffers. A likely reason for this is that inner ear sensory cells are damaged by surgical trauma and loud sounds generated during the operation. Animal studies have shown that antioxidants such as N-Acetylcysteine can protect the inner ear from noise, surgical trauma, and some ototoxic substances, but it is not known if this works in humans. This trial was performed to determine whether antioxidants improve surgical results at high frequencies. Methods We performed a randomized, double-blind and placebo-controlled parallel group clinical trial at three Swedish university clinics. Using block-stratified randomization, 156 adult patients undergoing stapedotomy were assigned to intravenous N-Acetylcysteine (150 mg/kg body weight) or matching placebo (1:1 ratio), starting one hour before surgery. The primary outcome was the hearing threshold at 6 and 8 kHz; secondary outcomes included the severity of tinnitus and vertigo. Findings One year after surgery, high-frequency hearing had improved 2.7 +/- 3.8 dB in the placebo group (67 patients analysed) and 2.4 +/- 3.7 dB in the treated group (72 patients; means +/- 95% confidence interval, p = 0.54; linear mixed model). Surgery improved tinnitus, but there was no significant intergroup difference. Post-operative balance disturbance was common but improved during the first year, without significant difference between groups. Four patients receiving N-Acetylcysteine experienced mild side effects such as nausea and vomiting. Conclusions N-Acetylcysteine has no effect on hearing thresholds, tinnitus, or balance disturbance after stapedotomy.

  • 46.
    Barliaev, Aleftin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Paleogeography and shore displacement of Eastern Gotland between 9.5 and 2.8 ka cal BP2017Independent thesis Advanced level (degree of Master (Two Years)), 40 credits / 60 HE creditsStudent thesis
    Abstract [en]

    Located in the middle part of the Baltic, the island of Gotland underwent major environmental changes, associated with different stages of the development of the basin during the Holocene, and therefore represents a promising location for shore-displacement studies. This thesis is focused on a palaeohydrological evolution of the Lina Mire, central eastern part of Gotland, in the Middle Holocene and aims to reconstruct the timing and environment of the Littorina transgression. The research is based on a multi-proxy approach and carried out, applying lithostratigraphical, biostratigraphical (diatom analysis) and geochemical methods (XRF, organic and carbonate content) along with radiocarbon dating. The initiation of the Littorina transgression was constrained at 8.5 ka cal BP, however, probably proceeded by a hiatus. A two-folded pattern oft he maximum sub-phases is suggested. Acquired results fit well with previous studies on areas with the similar rate of apparent land uplift, suggesting an average rate of 2 mm/yr for the last 2.8 ka.

  • 47. Barlow, Natasha L. M.
    et al.
    McClymont, Erin L.
    Whitehouse, Pippa L.
    Stokes, Chris R.
    Jamieson, Stewart S. R.
    Woodroffe, Sarah A.
    Bentley, Michael J.
    Callard, S. Louise
    Ó Cofaigh, Colm
    Evans, David J. A.
    Horrocks, Jennifer R.
    Lloyd, Jerry M.
    Long, Antony J.
    Margold, Martin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Roberts, David H.
    Sanchez-Montes, Maria L.
    Lack of evidence for a substantial sea-level fluctuation within the Last Interglacial2018In: Nature Geoscience, ISSN 1752-0894, E-ISSN 1752-0908, Vol. 11, no 9, p. 627-634Article, review/survey (Refereed)
    Abstract [en]

    During the Last Interglacial, global mean sea level reached approximately 6 to 9 m above the present level. This period of high sea level may have been punctuated by a fall of more than 4 m, but a cause for such a widespread sea-level fall has been elusive. Reconstructions of global mean sea level account for solid Earth processes and so the rapid growth and decay of ice sheets is the most obvious explanation for the sea-level fluctuation. Here, we synthesize published geomorphological and stratigraphic indicators from the Last Interglacial, and find no evidence for ice-sheet regrowth within the warm interglacial climate. We also identify uncertainties in the interpretation of local relative sea-level data that underpin the reconstructions of global mean sea level. Given this uncertainty, and taking into account our inability to identify any plausible processes that would cause global sea level to fall by 4 m during warm climate conditions, we question the occurrence of a rapid sea-level fluctuation within the Last Interglacial. We therefore recommend caution in interpreting the high rates of global mean sea-level rise in excess of 3 to 7 m per 1,000 years that have been proposed for the period following the Last Interglacial sea-level lowstand.

  • 48. Bartsch, Annett
    et al.
    Widhalm, Barbara
    Kuhry, Peter
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Hugelius, Gustaf
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Palmtag, Juri
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Siewert, Matthias Benjamin
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Can C-band synthetic aperture radar be used to estimate soil organic carbon storage in tundra?2016In: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 13, no 19, p. 5453-5470Article in journal (Refereed)
    Abstract [en]

    A new approach for the estimation of soil organic carbon (SOC) pools north of the tree line has been developed based on synthetic aperture radar (SAR; ENVISAT Advanced SAR Global Monitoring mode) data. SOC values are directly determined from backscatter values instead of upscaling using land cover or soil classes. The multi-mode capability of SAR allows application across scales. It can be shown that measurements in C band under frozen conditions represent vegetation and surface structure properties which relate to soil properties, specifically SOC. It is estimated that at least 29 Pg C is stored in the upper 30 cm of soils north of the tree line. This is approximately 25% less than stocks derived from the soil-map-based Northern Circumpolar Soil Carbon Database (NCSCD). The total stored carbon is underestimated since the established empirical relationship is not valid for peatlands or strongly cryoturbated soils. The approach does, however, provide the first spatially consistent account of soil organic carbon across the Arctic. Furthermore, it could be shown that values obtained from 1 km resolution SAR correspond to accounts based on a high spatial resolution (2 m) land cover map over a study area of about 7 x 7 km in NE Siberia. The approach can be also potentially transferred to medium-resolution C-band SAR data such as ENVISAT ASAR Wide Swath with similar to 120m resolution but it is in general limited to regions without woody vegetation. Global Monitoring-mode-derived SOC increases with unfrozen period length. This indicates the importance of this parameter for modelling of the spatial distribution of soil organic carbon storage.

  • 49. Baskaran, Preetisri
    et al.
    Hyvönen, Riitta
    Berglund, S. Linnea
    Clemmensen, Karina E.
    Ågren, Göran I.
    Lindahl, Björn D.
    Manzoni, Stefano
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Modelling the influence of ectomycorrhizal decomposition on plant nutrition and soil carbon sequestration in boreal forest ecosystems2017In: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 213, no 3, p. 1452-1465Article in journal (Refereed)
    Abstract [en]

    Tree growth in boreal forests is limited by nitrogen (N) availability. Most boreal forest trees form symbiotic associations with ectomycorrhizal (ECM) fungi, which improve the uptake of inorganic N and also have the capacity to decompose soil organic matter (SOM) and to mobilize organic N (ECM decomposition'). To study the effects of ECM decomposition' on ecosystem carbon (C) and N balances, we performed a sensitivity analysis on a model of C and N flows between plants, SOM, saprotrophs, ECM fungi, and inorganic N stores. The analysis indicates that C and N balances were sensitive to model parameters regulating ECM biomass and decomposition. Under low N availability, the optimal C allocation to ECM fungi, above which the symbiosis switches from mutualism to parasitism, increases with increasing relative involvement of ECM fungi in SOM decomposition. Under low N conditions, increased ECM organic N mining promotes tree growth but decreases soil C storage, leading to a negative correlation between C stores above- and below-ground. The interplay between plant production and soil C storage is sensitive to the partitioning of decomposition between ECM fungi and saprotrophs. Better understanding of interactions between functional guilds of soil fungi may significantly improve predictions of ecosystem responses to environmental change.

  • 50.
    Belin, Klas
    Stockholm University, Faculty of Science, Department of Physical Geography.
    Exkursioners bidrag till elevers kunskapsutveckling: En klassificering av exkursionsguider med hjälp av Blooms reviderade taxonomi2015Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    Denna studie syftar till att ta reda på vilka kunskaper och kognitiva processer elever kan få underexkursioner i ämnet geografi. Utöver detta undersöktes hur exkursioner bedrivs i Stockholms län.Undersökningen genomfördes genom en insamling av exkursionsguider som sedan analyserades medhjälp av Blooms reviderade taxonomi. För att få ett bredare underlag kring hur exkursioner utövasskickades webbenkäter ut till ett flertal lärare.Överlag är begreppskunskapen den mest framträdande kunskapen under de undersökta exkursionernavilket stämmer överens med den tidigare forskningen inom detta område. Exkursionsguiderna visaräven att majoriteten av exkursionsuppgifterna vill få eleven till den lägre nivån av kognitivt tänkande ioch med att uppgifterna syftar till att eleven ska förstå begrepp. Resultatet visar dock att det finns entendens att elever ges en möjlighet till en högre nivå av tänkande under de exkursioner där eleven äraktiv och försöker hitta svar på uppgifterna de fått av läraren.

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