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  • 401.
    Furberg, Maria
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för klinisk mikrobiologi.
    Hondula, David
    Saha, Michael
    Nilsson, Maria
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk biovetenskap, Patologi.
    In the light of change: correspondence between observational data and perceptions of climate in northern Sweden - a mixed methods study2016Inngår i: International Journal of Circumpolar Health, ISSN 1239-9736, E-ISSN 2242-3982, Vol. 75, s. 12-12, artikkel-id 33200Artikkel i tidsskrift (Fagfellevurdert)
  • 402. Furey, Paula C
    et al.
    Deininger, Anne
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Liess, Antonia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Substratum-Associated Microbiota2016Inngår i: Water environment research, ISSN 1061-4303, E-ISSN 1554-7531, Vol. 88, nr 10, s. 1638-1672Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This survey of literature on substratum associated microbiota from 2015 highlights research findings associated with benthic algae and bacteria from a variety of aquatic environments, but primarily freshwaters. It focuses on topics of interest to the Water Environment Federation along with those of current emerging interest such as global change, oil spills, and environmental contaminants like pharmaceutical compounds, microplastics, nanoparticles and organic pollutants. Other interesting findings briefly covered include areas of general ecology, nutrient cycling, trophic interactions, water quality, nuisance and invasive species, bioindicators, and bioremediation.

  • 403.
    Furey, Paula C.
    et al.
    St. Catherine University, Department Biology, St. Paul, MN 55105, USA.
    Liess, Antonia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Substratum-Associated Microbiota2014Inngår i: Water environment research, ISSN 1061-4303, E-ISSN 1554-7531, Vol. 86, nr 10, s. 1774-1831Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A review of literature on substratrum-associated microbiotia from 2013 covers topics on benthic algae, bacteria and viruses from a range of aquatic environments, but focuses on freshwater ecosystems. Advances in laboratory, field, and assessment methods are highlighted as are updates in taxonomy and systematics. Aspects of water quality, waste-water treatment, biofuels, nutrient cycling, food-web interactions, land use changes, and environmental challenges such as climate change, pollutants, and impacts of medical substances are presented.

  • 404. Furey, Paula C.
    et al.
    Liess, Antonia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Substratum-Associated Microbiota2015Inngår i: Water environment research, ISSN 1061-4303, E-ISSN 1554-7531, Vol. 87, nr 10, s. 1611-1678Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This review of literature on substratum-associated microbiota from 2014 highlights topics on benthic algae and bacteria from a range of aquatic environments, but focuses on freshwater habitats. Advances in pollution and toxin detection, assessment methods, and applications of new technologies are highlighted as are updates in taxonomy and systematics. Aspects of general ecology, water quality, nutrient cycling, trophic interactions, land use changes, biofuels, biofouling, and environmental challenges such as climate change, pollutants, tar sands and fracking, oil spills and nuisance blooms are presented.

  • 405. Furey, Paula C.
    et al.
    Liess, Antonia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Substratum-Associated Microbiota2013Inngår i: Water environment research, ISSN 1061-4303, E-ISSN 1554-7531, Vol. 85, nr 10, s. 1786-1827Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This review of literature published in 2012 covers topics on substratum-associated microbiota (algae and bacteria) from a variety of aquatic environments, especially freshwater ecosystems. It is not a comprehensive review, rather aims to highlight aspects of methods, taxonomy and systematics, ecology, and current environmental issues such as nuisance taxa, pollutants and climate change.

  • 406. Futter, M. N.
    et al.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lucas, R. W.
    Laudon, H.
    Kohler, S. J.
    Uncertainty in silicate mineral weathering rate estimates: source partitioning and policy implications2012Inngår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 7, nr 2, s. 024025-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Precise and accurate estimates of silicate mineral weathering rates are crucial when setting policy targets for long-term forest sustainability, critical load calculations and assessing consequences of proposed geo-engineering solutions to climate change. In this paper, we scrutinize 394 individual silicate mineral weathering estimates from 82 sites on three continents. We show that within-site differences of several hundred per cent arise when different methods are used to estimate weathering rates, mainly as a result of uncertainties related to input data rather than conceptually different views of the weathering process. While different methods tend to rank sites congruently from high to low weathering rates, large within-site differences in estimated weathering rate suggest that policies relying on quantitative estimates based upon a single method may have undesirable outcomes. We recommend the use of at least three independent estimates when making management decisions related to silicate mineral weathering rates.

  • 407. Futter, Martyn N.
    et al.
    Högbom, Lars
    Valinia, Salar
    Sponseller, Ryan A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Laudon, Hjalmar
    Conceptualizing and communicating management effects on forest water quality2016Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 45, s. S188-S202Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We present a framework for evaluating and communicating effects of human activity on water quality in managed forests. The framework is based on the following processes: atmospheric deposition, weathering, accumulation, recirculation and flux. Impairments to water quality are characterized in terms of their extent, longevity and frequency. Impacts are communicated using a "traffic lights" metaphor for characterizing severity of water quality impairments arising from forestry and other anthropogenic pressures. The most serious impairments to water quality in managed boreal forests include (i) forestry activities causing excessive sediment mobilization and extirpation of aquatic species and (ii) other anthropogenic pressures caused by long-range transport of mercury and acidifying pollutants. The framework and tool presented here can help evaluate, summarize and communicate the most important issues in circumstances where land management and other anthropogenic pressures combine to impair water quality and may also assist in implementing the "polluter pays" principle.

  • 408.
    Färe, Rolf
    et al.
    Dept. of Agriculture and Resource Economics, Dept. of Economics, Oregon State University.
    Grosskopf, Shawna
    Dept. of Economics, Oregon State University.
    Lundgren, Tommy
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för miljö- och naturresursekonomi (CERE). SLU.
    Marklund, Per-Olov
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för regionalvetenskap (CERUM). Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för miljö- och naturresursekonomi (CERE).
    Wenchao, Zhou
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för regionalvetenskap (CERUM).
    Productivity: should we include bads?2012Rapport (Annet vitenskapelig)
    Abstract [en]

    This paper studies the interaction between economic and environmental performance. Applying the directional output distance function approach, the purpose is to compare estimates of Luenberger total factor productivity indicators, including and excluding bad outputs. Specifically, based on unique firm level data from Swedish manufacturing covering the period 1990 to 2008, we explore to what extent excluding bad outputs leads to erroneous productivity measurement. The main conclusion is that bad outputs should not only be included in the estimations, but also reduction in bad outputs should be credited. From this point of view the directional output distance function approach and the Luenberger indicator serves as an appropriate basis of productivity measurement.

  • 409.
    Färe, Rolf
    et al.
    Oregon State University.
    Grosskopf, Shawna
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för miljö- och naturresursekonomi (CERE). Oregon State University and SLU.
    Lundgren, Tommy
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för miljö- och naturresursekonomi (CERE). SLU.
    Marklund, Per-Olov
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för miljö- och naturresursekonomi (CERE). Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för regionalvetenskap (CERUM). SLU.
    Wenchao, Zhou
    Umeå universitet, Samhällsvetenskapliga fakulteten, Centrum för regionalvetenskap (CERUM).
    Which bad is worst?: An application of Johansen's capacity model2013Rapport (Annet vitenskapelig)
    Abstract [en]

    The production of desirable (good) outputs is frequently accompanied by unintended production of undesirable (bad) outputs. If two or more of these undesirable outputs are produced as byproducts, one may ask: ‘Which bad is worst?’ By worst we mean which bad inhibits the production of desirable outputs the most if it is regulated. We develop a model based on Leif Johansen’s capacity framework by estimating the capacity limiting effect of the bads. Our model resembles what is referred to as the von Liebig Law of the Minimum, familiar from the agricultural economics literature. To illustrate our model we apply our approach to a firm level data set from the Swedish paper and pulp industry.

  • 410.
    Förster, Johannes
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi, miljö och geovetenskap.
    Metabolic balance and CO2 saturation in a subarctic permafrost lake2005Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
  • 411. Gaillard, Marie-José
    et al.
    Kleinen, Thomas
    Samuelsson, Patrick
    Nielsen, AnneBirgitte
    Bergh, Johan
    Kaplan, Jed
    Poska, Anneli
    Sandström, Camilla
    Department of Wildlife, Fish and Environmental Studies, Swedish University of Agricultural Sciences SLU, Umeå, Sweden.
    Strandberg, Gustav
    Trondman, Anna-Kari
    Wramneby, Anna
    Causes of Regional Change—Land Cover2015Inngår i: Second Assessment of Climate Change for the Baltic Sea Basin, Springer, 2015, s. 453-477Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Anthropogenic land-cover change (ALCC) is one of the few climate forcings for which the net direction of the climate response over the last two centuries is still not known. The uncertainty is due to the often counteracting temperature responses to the many biogeophysical effects and to the biogeochemical versus biogeophysical effects. Palaeoecological studies show that the major transformation of the landscape by anthropogenic activities in the southern zone of the Baltic Sea basin occurred between 6000 and 3000/2500 cal year BP. The only modelling study of the biogeophysical effects of past ALCCs on regional climate in north-western Europe suggests that deforestation between 6000 and 200 cal year BP may have caused significant change in winter and summer temperature. There is no indication that deforestation in the Baltic Sea area since AD 1850 would have been a major cause of the recent climate warming in the region through a positive biogeochemical feedback. Several model studies suggest that boreal reforestation might not be an effective climate warming mitigation tool as it might lead to increased warming through biogeophysical processes.

  • 412. Galli, André
    et al.
    Wurz, Peter
    Kallio, Esa
    Ekenbäck, Andreas
    Institutet för rymdfysik (IRF).
    Holmström, Mats
    Institutet för rymdfysik, Kiruna.
    Barabash, Stas
    Institutet för rymdfysik, Kiruna.
    Gregoriev, Alexander
    Futaana, Yoshifumi
    Institutet för rymdfysik, Kiruna.
    Fok, Mei-Ching
    Gunell, H
    The tailward flow of energetic neutral atoms observed at Mars2008Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 113, artikkel-id E12012Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ASPERA-3 experiment on Mars Express provides the first measurements of energetic neutral atoms (ENAs) from Mars. These measurements are used to study the global structure of the interaction of the solar wind with the Martian atmosphere. In this study we describe the tailward ENA flow observed at the nightside of Mars. After characterizing energy spectra of hydrogen ENA signals, we present composite images of the ENA intensities and compare them to theoretical predictions (empirical and MHD models). We find that the tailward flow of hydrogen ENAs is mainly generated by shocked solar wind protons. Despite intensive search, no oxygen ENAs above the instrument threshold are detected. The results challenge existing plasma models and constrain the hydrogen exospheric densities and atmospheric hydrogen and oxygen loss rates at low solar activity.

  • 413.
    Gao, Qiuju
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Blum, Kristin M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Gago-Ferrero, Pablo
    Wiberg, Karin
    Ahrens, Lutz
    Andersson, Patrik L.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Impact of on-site wastewater infiltration systems on organic contaminants in groundwater and recipient waters2019Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 651, s. 1670-1679Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    On-site sewage treatment facilities, particularly septic systems combined with soil infiltration, can be an important source of emerging organic contaminants in groundwater and surface water and thus represent a significant source of environmental and human exposure. Two infiltration systems in Åre municipality, Sweden, were examined to assess the occurrence of contaminants in groundwater and their fate and transport during infiltration. Groundwater samples, recipient surface water samples, and wastewater samples from septic tanks were collected from 2016 to 2017 covering all climatological seasons. These samples were analysed for a total of 103 contaminants, including pharmaceuticals, personal care products, organic phosphorus flame-retardants, plasticisers, perfluoroalkyl substances, and food additives. Fourteen of 103 contaminants showed 100% detection frequency in groundwater at concentrations in the low ng L−1 to low μg L−1 range. Of the compounds analysed, tris(2‑butoxyethyl) phosphate, sucralose, caffeine, and benzophenone showed high abundancy with maximum concentrations in the μg L−1 range. The data were normalised for dilution using chloride and sucralose as commonly applied tracers; however, the level of sucralose decreased significantly during infiltration and it is thus suboptimal as a sewage water tracer. Large differences between the two infiltration sites were observed in detection frequencies and concentrations in groundwater, which could be attributed to the system design and the contaminant's migration time from release to sampling point. Seasonal variation was observed for selected chemicals, and the more hydrophobic chemicals showed a higher tendency for attenuation, indicating sorption as a major retention mechanism. A moderate environmental risk to aquatic organisms was estimated in adjacent surface water for galaxolide, tris(1‑chloro‑2‑propyl) phosphate, and tris(2‑butoxyethyl) phosphate. Due to this site-dependency and potential environmental risks, further studies are needed on infiltration systems in different settings and on alternative treatment techniques to reduce the contaminant discharge from on-site sewage treatment facilities.

  • 414.
    Gao, Qiuju
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Cieplik, Mariusz K
    Budarin, Vitaliy L
    Gronnow, Mark
    Jansson, Stina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Mechanistic evaluation of polychlorinated dibenzo-p-dioxin, dibenzofuran and naphthalene isomer fingerprints in microwave pyrolysis of biomass2016Inngår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 150, s. 168-175Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Isomer distribution patterns of polychlorinated dibenzo-p-dioxins (PCDDs), dibenzofurans (PCDFs) and naphthalenes (PCNs) were investigated in microwave-assisted pyrolysis (MAP) products of woody biomass. The feedstocks included bark and impregnated wood. The results indicated that isomer distributions in MAP are more selective compared to those reported from wood burning and waste incineration. Favored formation of 4-MoCDF and highly selective chlorine substitution at the 2,4-position observed during MAP suggested a preferred formation pathway of PCDFs involving (chloro)phenol precursors followed by subsequent chlorination. The PCDD distribution was dominated by isomers typically formed from chlorophenol condensation at relatively low temperature. The PCN isomer distributions showed a tendency for sequential chlorination from non-substituted naphthalene at successive positions. The presence of isomers such as 1-MoCDD, 4-MoCDF, 1,2,3-TriCN with low thermodynamic stability indicates that kinetic factors may be important in the MAP process.

  • 415.
    Gardeström, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Aquatic Sciences & Assessment, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Ermold, Matti
    Goedkoop, Willem
    McKie, Brendan G.
    Disturbance history influences stressor impacts: effects of a fungicide and nutrients on microbial diversity and litter decomposition2016Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 61, nr 12, s. 2171-2184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Streams draining agricultural catchments are severely degraded by multiple stressors, including nutrient enrichment and pesticides. The understanding of how such stressors interact to alter ecosystem structure and function, and how responses of biota reflect their longer-term disturbance history, remains limited. We conducted a multifactorial stream microcosm experiment to investigate how elevated nutrients and a fungicide (azoxystrobin) interact to affect multiple variables associated with leaf decomposition: the biomass, sporulation rate and diversity of aquatic hyphomycete decomposers, litter decomposition rates and detritivore growth. We further manipulated decomposer species composition by using three distinct fungal assemblages drawn from streams with contrasting histories of agricultural disturbance: a forest stream, a mixed land-use stream subject to nutrient enrichment but little pesticide use, and an agricultural stream subjected to both intensive nutrient and pesticide use. We also varied the presence of the detritivorous isopod Asellus aquaticus. The fungicide azoxystrobin reduced both biomass and diversity of aquatic hyphomycetes and growth of A.aquaticus, and had negative knock-on effects on leaf decomposition and fungal sporulation. These impacts further varied with nutrient concentration. Impacts of the fungicide differed markedly among the three fungal assemblages. The agricultural assemblages were dominated by tolerant species and showed some capacity for maintaining processes under pesticide exposure, whereas diversity and functioning were strongly suppressed in the forest stream assemblage, which was dominated by stress-intolerant species. Pesticides, in interaction with other agricultural stressors, can impact microbial diversity and key ecosystem processes underlying the delivery of ecosystem services from streams. The extent of such impacts vary according to the longer-term disturbance history of the biota, and might be most acute when agricultural activity expands into previously uncultivated catchments, as is currently occurring in many regions of the world.

  • 416.
    Gardeström, Johanna
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Holmqvist, Daniel
    Vindel River Fishery Advisory Board.
    Polvi, Lina E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Demonstration Restoration Measures in Tributaries of the Vindel River Catchment2013Inngår i: Ecology & society, ISSN 1708-3087, E-ISSN 1708-3087, Vol. 18, nr 3, s. Article Number: UNSP 8-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Some ecological restoration projects include elements of trial and error where new measures are repeatedly tried, evaluated, and modified until satisfactory results are achieved. Thereafter, the resulting methods may be applied on larger scales. A difficult step is judging whether developed "best-practice" methods have become reasonably ecologically functional or whether further experimentation "demonstration" methods can lead to yet better results. Here, we use a stream restoration project as a case study for evaluating methods and abiotic effects and outlining stakeholder support for demonstration restoration measures, rather than only using best-practice methods. Our work was located in the Vindel River system, a free-flowing river that is part of the Natura 2000 network. The river was exploited for timber floating from 1850-1976, and rapids in the main channel and tributaries below timberline were channelized to increase timber transport capacity. Several side channels in multi-channeled rapids were blocked and the flow was concentrated to a single channel from which boulders and large wood were removed. Hence, previously heterogeneous environments were replaced by more homogeneous systems with limited habitat for riverine species. The restoration project strives to alleviate the effects of fragmentation and channelization in affected rapids by returning coarse sediment from channel margins to the main channel. However, only smaller, angular sediment is available given blasting of large boulders, and large (old-growth) wood is largely absent; therefore, original levels of large boulders and large wood in channels cannot be achieved with standard restoration practices. In 10 demonstration sites, we compensated for this by adding large boulders and large wood (i.e., entire trees) from adjacent upland areas to previously best-practice restored reaches and compared their hydraulic characteristics with 10 other best-practice sites. The demonstration sites exhibited significantly reduced and more variable current velocities, and wider channels, but with less variation than pre-restoration. The ecological response to this restoration has not yet been studied, but potential outcomes are discussed.

  • 417.
    Garteizgogeascoa, María
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Do riparian plant functional groups from northern Sweden respond differently to hydropeaking?2016Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In recent years, global warming awareness has resulted in an increased demand for clean sources of energy such as hydropower. As a consequence, its impact on riparian vegetation must be studied. In this research, I aimed to assess how different functional riparian groups from northern Sweden respond to hydropeaking (i.e. short-term flow regime changes due to differences in the daily energy requirements). I selected seedlings of eight species natural from Swedish riparian ecosystems which can be grouped in three different guilds (forbs, graminoids and woody) according to their habitat and morphological traits.  A seven week greenhouse experiment in which the seedlings were subjected to two watering treatments that simulated prolonged and deep submergence and frequent and short shallow submergence conditions was developed. I measured the root, stem and leaf biomass, followed leaf changes and stem growth over the weeks and evaluated the health status. The study showed how some species and guilds responded differently to the treatments although survival rates were similar. Forbs was the most resilient group unlike the woody guild.  Graminoids grew longer and thinner roots in frequent submergence situations. Small seedlings appeared to be more sensitive to prolonged submergence. No significant differences were found for leaf variables. Collectively, these results suggest that hydropeaking could significantly modify the riparian vegetation. More and longer studies are needed in order to understand the capacity that hydropower has to modify the riparian vegetation and therefore the riverine ecosystems.

  • 418. Gasparrini, Antonio
    et al.
    Guo, Yuming
    Sera, Francesco
    Vicedo-Cabrera, Ana Maria
    Huber, Veronika
    Tong, Shilu
    de Sousa Zanotti Stagliorio Coelho, Micheline
    Nascimento Saldiva, Paulo Hilario
    Lavigne, Eric
    Matus Correa, Patricia
    Valdes Ortega, Nicolas
    Kan, Haidong
    Osorio, Samuel
    Kyselý, Jan
    Urban, Aleš
    Jaakkola, Jouni J. K.
    Ryti, Niilo R. I.
    Pascal, Mathilde
    Goodman, Patrick G.
    Zeka, Ariana
    Michelozzi, Paola
    Scortichini, Matteo
    Hashizume, Masahiro
    Honda, Yasushi
    Hurtado-Diaz, Magali
    Cesar Cruz, Julio
    Seposo, Xerxes
    Kim, Ho
    Tobias, Aurelio
    Iñiguez, Carmen
    Forsberg, Bertil
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Oudin Åström, Daniel
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin.
    Ragettli, Martina S.
    Guo, Yue Leon
    Wu, Chang-Fu
    Zanobetti, Antonella
    Schwartz, Joel
    Bell, Michelle L.
    Dang, Tran Ngoc
    Van, Dung Do
    Heaviside, Clare
    Vardoulakis, Sotiris
    Hajat, Shakoor
    Haines, Andy
    Armstrong, Ben
    Projections of temperature-related excess mortality under climate change scenarios2017Inngår i: The Lancet Planetary Health, ISSN 2542-5196, Vol. 1, nr 9, s. e360-e367Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background: Climate change can directly affect human health by varying exposure to non-optimal outdoor temperature. However, evidence on this direct impact at a global scale is limited, mainly due to issues in modelling and projecting complex and highly heterogeneous epidemiological relationships across different populations and climates.

    Methods: We collected observed daily time series of mean temperature and mortality counts for all causes or non-external causes only, in periods ranging from Jan 1, 1984, to Dec 31, 2015, from various locations across the globe through the Multi-Country Multi-City Collaborative Research Network. We estimated temperature-mortality relationships through a two-stage time series design. We generated current and future daily mean temperature series under four scenarios of climate change, determined by varying trajectories of greenhouse gas emissions, using five general circulation models. We projected excess mortality for cold and heat and their net change in 1990-2099 under each scenario of climate change, assuming no adaptation or population changes.

    Findings: Our dataset comprised 451 locations in 23 countries across nine regions of the world, including 85 879 895 deaths. Results indicate, on average, a net increase in temperature-related excess mortality under high-emission scenarios, although with important geographical differences. In temperate areas such as northern Europe, east Asia, and Australia, the less intense warming and large decrease in cold-related excess would induce a null or marginally negative net effect, with the net change in 2090-99 compared with 2010-19 ranging from -1·2% (empirical 95% CI -3·6 to 1·4) in Australia to -0·1% (-2·1 to 1·6) in east Asia under the highest emission scenario, although the decreasing trends would reverse during the course of the century. Conversely, warmer regions, such as the central and southern parts of America or Europe, and especially southeast Asia, would experience a sharp surge in heat-related impacts and extremely large net increases, with the net change at the end of the century ranging from 3·0% (-3·0 to 9·3) in Central America to 12·7% (-4·7 to 28·1) in southeast Asia under the highest emission scenario. Most of the health effects directly due to temperature increase could be avoided under scenarios involving mitigation strategies to limit emissions and further warming of the planet.

    Interpretation: This study shows the negative health impacts of climate change that, under high-emission scenarios, would disproportionately affect warmer and poorer regions of the world. Comparison with lower emission scenarios emphasises the importance of mitigation policies for limiting global warming and reducing the associated health risks.

  • 419.
    Gavazov, Konstantin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Swiss Federal Institute for Forest, Snowand Landscape Research, WSL SiteLausanne, Lausanne, Switzerland; Laboratory of Ecological Systems ECOS,School of Architecture, Civil and Environmental Engine ering ENAC, EcolePolytechnique Fédérale de Lausanne EPFL,Lausanne, Switzerland.
    Albrecht, Remy
    Buttler, Alexandre
    Dorrepaal, Ellen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Garnett, Mark H.
    Gogo, Sebastien
    Hagedorn, Frank
    Mills, Robert T. E.
    Robroek, Bjorn J. M.
    Bragazza, Luca
    Vascular plant-mediated controls on atmospheric carbon assimilation and peat carbon decomposition under climate change2018Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 24, nr 9, s. 3911-3921Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climate change can alter peatland plant community composition by promoting the growth of vascular plants. How such vegetation change affects peatland carbon dynamics remains, however, unclear. In order to assess the effect of vegetation change on carbon uptake and release, we performed a vascular plant-removal experiment in two Sphagnum-dominated peatlands that represent contrasting stages of natural vegetation succession along a climatic gradient. Periodic measurements of net ecosystem CO2 exchange revealed that vascular plants play a crucial role in assuring the potential for net carbon uptake, particularly with a warmer climate. The presence of vascular plants, however, also increased ecosystem respiration, and by using the seasonal variation of respired CO2 radiocarbon (bomb-C-14) signature we demonstrate an enhanced heterotrophic decomposition of peat carbon due to rhizosphere priming. The observed rhizosphere priming of peat carbon decomposition was matched by more advanced humification of dissolved organic matter, which remained apparent beyond the plant growing season. Our results underline the relevance of rhizosphere priming in peatlands, especially when assessing the future carbon sink function of peatlands undergoing a shift in vegetation community composition in association with climate change.

  • 420.
    Gavazov, Konstantin
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Arktiskt centrum vid Umeå universitet (Arcum).
    Ingrisch, Johannes
    Hasibeder, Roland
    Mills, Robert T E
    Buttler, Alexandre
    Gleixner, Gerd
    Pumpanen, Jukka
    Bahn, Michael
    Winter ecology of a subalpine grassland: Effects of snow removal on soil respiration, microbial structure and function2017Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 590-591, s. 316-324Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Seasonal snow cover provides essential insulation for mountain ecosystems, but expected changes in precipitation patterns and snow cover duration due to global warming can influence the activity of soil microbial communities. In turn, these changes have the potential to create new dynamics of soil organic matter cycling. To assess the effects of experimental snow removal and advanced spring conditions on soil carbon (C) and nitrogen (N) dynamics, and on the biomass and structure of soil microbial communities, we performed an in situ study in a subalpine grassland in the Austrian Alps, in conjunction with soil incubations under controlled conditions. We found substantial winter C-mineralisation and high accumulation of inorganic and organic N in the topsoil, peaking at snowmelt. Soil microbial biomass doubled under the snow, paralleled by a fivefold increase in its C:N ratio, but no apparent change in its bacteria-dominated community structure. Snow removal led to a series of mild freeze-thaw cycles, which had minor effects on in situ soil CO2 production and N mineralisation. Incubated soil under advanced spring conditions, however, revealed an impaired microbial metabolism shortly after snow removal, characterised by a limited capacity for C-mineralisation of both fresh plant-derived substrates and existing soil organic matter (SOM), leading to reduced priming effects. This effect was transient and the observed recovery in microbial respiration and SOM priming towards the end of the winter season indicated microbial resilience to short-lived freeze-thaw disturbance under field conditions. Bacteria showed a higher potential for uptake of plant-derived C substrates during this recovery phase. The observed temporary loss in microbial C-mineralisation capacity and the promotion of bacteria over fungi can likely impede winter SOM cycling in mountain grasslands under recurrent winter climate change events, with plausible implications for soil nutrient availability and plant-soil interactions.

  • 421.
    Geijer, Erik
    et al.
    Department of Forest Economics, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden.
    Bostedt, Göran
    Department of Forest Economics, Swedish University of Agricultural Sciences, S-901 83 Umeå, Sweden.
    Brännlund, Runar
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för nationalekonomi.
    Damned if you do, damned if you do not: reduced climate impact vs. sustainable forests in Sweden2011Inngår i: Resources and Energy Economics, ISSN 0928-7655, E-ISSN 1873-0221, Vol. 33, nr 1, s. 94-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The main objective of this paper is to analyze the potential goal conflict between two of Sweden's environmental objectives: Sustainable Forests and Reduced Climate Impact – or, more precisely, the conflict between forest conservation and the supply of wood fuel. To accomplish this, we use a forest sector model that includes the suppliers and major users of roundwood. The econometric results, based on a data set that spans 40 years, show that all the own price elasticities have the expected signs. Among the three forestry products, the supply and (long-term) demand of forest fuel seems to be most sensitive to a price change. In a second step, the estimated model is used to simulate the effect of increased forest conservation – the Sustainable Forest objective – on the supply of wood fuel. If oil is used as a substitute, Swedish emissions of greenhouse gases will increase by almost 0.92 percent, which indicates a clear conflict with the Reduced Climate Impact objective.

  • 422. Gentili, Francesco G.
    et al.
    Fick, Jerker
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Algal cultivation in urban wastewater: an efficient way to reduce pharmaceutical pollutants2017Inngår i: Journal of Applied Phycology, ISSN 0921-8971, E-ISSN 1573-5176, Vol. 29, nr 1, s. 255-262Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The purpose of this study was to investigate whether pharmaceutical pollutants in urban wastewater can be reduced during algal cultivation. A mixed population of wild freshwater green algal species was grown on urban wastewater influent in a 650 L photobioreactor under natural light and with the addition of flue gases. Removal efficiencies were very high (> 90 %), moderate (50-90 %), low (10-50 %), and very low or non-quantifiable (< 10 %) for 9, 14, 11, and 18 pharmaceuticals, respectively, over a 7-day period. High reduction was found in the following pharmaceuticals: the beta-blockers atenolol, bispropol, and metoprolol; the antibiotic clarithromycine; the antidepressant bupropion; the muscle relaxant atracurium; hypertension drugs diltiazem and terbutaline used to relive the symptoms of asthma. Regression analysis did not detect any relationship between the reduction in pharmaceutical contents and light intensity reaching the water surface of the algal culture. However, the reduction was positively correlated with light intensity inside the culture and stronger when data collected during the night were excluded. Algae cultivation can remove partially or totally pharmaceutical pollutants from urban wastewater, and this opens up new possibilities for treating urban wastewater.

  • 423. Gephart, Jessica A.
    et al.
    Rovenskaya, Elena
    Dieckmann, Ulf
    Pace, Michael L.
    Brännström, Åke
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Vulnerability to shocks in the global seafood trade network2016Inngår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 11, nr 3, artikkel-id 035008Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Trade can allow countries to overcome local or regional losses (shocks) to their food supply, but reliance on international food trade also exposes countries to risks from external perturbations. Countries that are nutritionally or economically dependent on international trade of a commodity may be adversely affected by such shocks. While exposure to shocks has been studied in financial markets, communication networks, and some infrastructure systems, it has received less attention in food-trade networks. Here, we develop a forward shock-propagation model to quantify how trade flows are redistributed under a range of shock scenarios and assess the food-security outcomes by comparing changes in national fish supplies to indices of each country's nutritional fish dependency. Shock propagation and distribution among regions are modeled on a network of historical bilateral seafood trade data from UN Comtrade using 205 reporting territories grouped into 18 regions. In our model exposure to shocks increases with total imports and the number of import partners. We find that Central and West Africa are the most vulnerable to shocks, with their vulnerability increasing when a willingness-to-pay proxy is included. These findings suggest that countries can reduce their overall vulnerability to shocks by reducing reliance on imports and diversifying food sources. As international seafood trade grows, identifying these types of potential risks and vulnerabilities is important to build a more resilient food system.

  • 424. Gepharta, Jessica A.
    et al.
    Deutsch, Lisa
    Pacea, Michael L.
    Troell, Max
    Seekell, David
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Arktiskt centrum vid Umeå universitet (Arcum).
    Shocks to fish production: Identification, trends, and consequences2017Inngår i: Global Environmental Change, ISSN 0959-3780, E-ISSN 1872-9495, Vol. 42, s. 24-32Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sudden disruptions, or shocks, to food production can adversely impact access to and trade of food commodities. Seafood is the most traded food commodity and is globally important to human nutrition. The seafood production and trade system is exposed to a variety of disruptions including fishery collapses, natural disasters, oil spills, policy changes, and aquaculture disease outbreaks, aquafeed resource access and price spikes. The patterns and trends of these shocks to fisheries and aquaculture are poorly characterized and this limits the ability to generalize or predict responses to political, economic, and environmental changes. We applied a statistical shock detection approach to historic fisheries and aquaculture data to identify shocks over the period 1976–2011. A complementary case study approach was used to identify possible key social and political dynamics related to these shocks. The lack of a trend in the frequency or magnitude of the identified shocks and the range of identified causes suggest shocks are a common feature of these systems which occur due to a variety, and often multiple and simultaneous, causes. Shocks occurred most frequently in the Caribbean and Central America, the Middle East and North Africa, and South America, while the largest magnitude shocks occurred in Asia, Europe, and Africa. Shocks also occurred more frequently in aquaculture systems than in capture systems, particularly in recent years. In response to shocks, countries tend to increase imports and experience decreases in supply. The specific combination of changes in trade and supply are context specific, which is highlighted through four case studies. Historical examples of shocks considered in this study can inform policy for responding to shocks and identify potential risks and opportunities to build resilience in the global food system.

  • 425.
    Giesler, Reiner
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Esberg, Camilla
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lagerström, Anna
    Graae, Bente J
    Phosphorus availability and microbial respiration across different tundra vegetation types2012Inngår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 108, nr 1-3, s. 429-445Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Phosphorus (P) is an important nutrient in tundra ecosystems that co-limits or in some cases limits primary production. The availability of P is largely driven by soil characteristics, e.g., pH, organic carbon, and abundance of P-sorbing elements such as aluminium (Al) or iron (Fe). We tested how vegetation and soil properties relate to P availability across different tundra vegetation types. The different soil P fractions in the organic horizon were measured and plant foliar nitrogen (N) to P ratio and a plant bioassay was used as indicators of plant nutrient status. Microbial bioassays were used to study microbial respiration kinetics and in response to carbon, N, and P amendments. The distribution of P fractions differed significantly across vegetation types; labile fractions of P were less abundant in meadow sites compared to heath sites. Calcium-phosphates seemed to be an important P-fraction in meadows, but were only found in lower concentrations in the heath. There were only small differences in NaOH–extractable P between the vegetation types and this correlated with the distribution of oxalate-extractable Al. Plant N:P ratios and the plant bioassay indicated decreasing P availability from dry heath to mesic heath to mesic meadow. The microbial bioassay suggests that the heterotrophic microbial community is C-limited with N as a secondary limiting nutrient although there were indications that microbial P availability was lower in the meadow sites. Overall, we suggest that the observed variations in soil P across vegetation types are affecting both plant and microbial function although the differences seem to be relatively small.

  • 426. Gilichinsky, Michael
    et al.
    Sandström, Per
    Reese, Heather
    Kivinen, Sonja
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Mats
    Mapping ground lichens using forest inventory and optical satellite data2011Inngår i: International Journal of Remote Sensing, ISSN 0143-1161, E-ISSN 1366-5901, Vol. 32, nr 2, s. 455-472Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Lichen is a major forage resource for reindeer and may constitute up to 80% of areindeer’s winter diet. The reindeer grazing area in Sweden covers almost half of thecountry, with reindeer using mountainous areas in the summer and forested areas inthe winter. Knowledge about the spatial distribution of ground lichens is importantfor both practical and decision-making purposes. Since the early 1980s, remotesensing research of lichen cover in northern environments has focused on reindeergrazing issues. The objective of this study was to use lichen information collected inthe Swedish National Forest Inventory (NFI) as training data to classify opticalsatellite images into ground lichen cover classes. The study site was located within thereindeer husbandry area in northern Sweden and consisted of the common areabetween two contiguous Satellite Pour l’Observation de la Terre (SPOT)-5 scenesand one Landsat-7 Enhanced Thematic Mapper Plus (ETMþ) scene. Three classificationmethods were tested: Mahalanobis distance, maximum likelihood andspectral mixture analysis. Post-classification calibration was applied using a membershipprobability threshold in order to match the NFI-measured proportions oflichen coverage classes. The classification results were assessed using an independentlycollected field dataset (229 validation areas). The results demonstrated highclassification accuracy of SPOT imagery for the classification of lichen-abundantand lichen-poor areas when using theMahalanobis distance classifier (overall accuracy84.3%, kappa ¼ 0.68). The highest classification accuracy for Landsat wasachieved using a maximum likelihood classification (overall accuracy 76.8%, kappa¼ 0.53). These results provided an initial indication of the utility of NFI data astraining data in the process of mapping lichen classes over large areas.

  • 427.
    Gimmi, Urs
    et al.
    Research Unit Landscape Dynamics, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
    Poulter, Ben
    Research Unit Landscape Dynamics, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland; Laboratoire des Sciences du Climat et l'Environement (LSCE), Gif sur Yvette, France.
    Wolf, Annett
    Forest Ecology, Department of Environmental Sciences, Institute of Terrestrial Ecosystems, Swiss Federal Institute of Technology ETH, .
    Portner, H.
    Forest Ecology, Department of Environmental Sciences, Institute of Terrestrial Ecosystems, Swiss Federal Institute of Technology ETH, .
    Weber, P
    Research Unit Soil Sciences, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
    Bürgi, M.
    Research Unit Landscape Dynamics, Swiss Federal Research Institute WSL, Zürcherstrasse 111, 8903 Birmensdorf, Switzerland.
    Soil carbon pools in Swiss forests show legacy effects from historic forest litter raking2013Inngår i: Landscape Ecology, ISSN 0921-2973, E-ISSN 1572-9761, Vol. 28, nr 5, s. 835-846Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Globally, forest soils contain twice as much carbon as forest vegetation. Consequently, natural and anthropogenic disturbances affecting carbon accumulation in forest soils can alter regional to global carbon balance. In this study, we evaluate the effects of historic litter raking on soil carbon stocks, a former forest use which used to be widespread throughout Europe for centuries. We estimate, for Switzerland, the carbon sink potential in current forest soils due to recovery from past litter raking ('legacy effect'). The year 1650 was chosen as starting year for litter raking, with three different end years (1875/1925/1960) implemented for this forest use in the biogeochemical model LPJ-GUESS. The model was run for different agricultural and climatic zones separately. Number of cattle, grain production and the area of wet meadow have an impact on the specific demand for forest litter. The demand was consequently calculated based on historical statistical data on these factors. The results show soil carbon pools to be reduced by an average of 17 % after 310 years of litter raking and legacy effects were still visible 130 years after abandonment of this forest use (2 % average reduction). We estimate the remaining carbon sink potential in Swiss forest due to legacy effects from past litter raking to amount to 158,000 tC. Integrating historical data into biogeochemical models provides insight into the relevance of past land-use practices. Our study underlines the importance of considering potentially long-lasting effects of such land use practices for carbon accounting.

  • 428. Gimmi, Urs
    et al.
    Wolf, Annett
    Umeå universitet. Swiss Fed Inst Technol, Inst Terr Ecosyst, Dept Environm Sci, CH-8092 Zurich, Switzerland.
    Buergi, Matthias
    Scherstjanoi, Marc
    Bugmann, Harald
    Quantifying disturbance effects on vegetation carbon pools in mountain forests based on historical data2009Inngår i: Regional Environmental Change, ISSN 1436-3798, E-ISSN 1436-378X, Vol. 9, nr 2, s. 121-130Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Although the terrestrial carbon budget is of key importance for atmospheric CO(2) concentrations, little is known on the effects of management and natural disturbances on historical carbon stocks at the regional scale. We reconstruct the dynamics of vegetation carbon stocks and flows in forests across the past 100 years for a valley in the eastern Swiss Prealps using quantitative and qualitative information from forest management plans. The excellent quality of the historical information makes it possible to link dynamics in growing stocks with high-resolution time series for natural and anthropogenic disturbances. The results of the historical reconstruction are compared with modelled potential natural vegetation. Forest carbon stock at the beginning of the twentieth century was substantially reduced compared to natural conditions as a result of large scale clearcutting lasting until the late nineteenth century. Recovery of the forests from this unsustainable exploitation and systematic forest management were the main drivers of a strong carbon accumulation during almost the entire twentieth century. In the 1990s two major storm events and subsequent bark beetle infestations significantly reduced stocks back to the levels of the mid-twentieth century. The future potential for further carbon accumulation was found to be strongly limited, as the potential for further forest expansion in this valley is low and forest properties seem to approach equilibrium with the natural disturbance regime. We conclude that consistent long-term observations of carbon stocks and their changes provide rich information on the historical range of variability of forest ecosystems. Such historical information improves our ability to assess future changes in carbon stocks. Further, the information is vital for better parameterization and initialization of dynamic regional scale vegetation models and it provides important background for appropriate management decisions.

  • 429. Glaas, Erik
    et al.
    Keskitalo, E. Carina H.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för geografi och ekonomisk historia.
    Hjerpe, Mattias
    Insurance sector management of climate change adaptation in three Nordic countries: the influence of policy and market factors2017Inngår i: Journal of Environmental Planning and Management, ISSN 0964-0568, E-ISSN 1360-0559, Vol. 60, nr 9, s. 1601-1621Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The insurance industry is important for facilitating climate change adaptation. Insurance companies' involvement is, however, influenced by national adaptation policy. The literature suggests that especially policy factors - government interventions, political priorities and public-private cooperation - and market factors - cost offset, cost mitigation, planning flexibility and business opportunities - shape private actor approaches. To increase the understanding of insurance company involvement in adaptation, this study examines how insurance companies' approaches are influenced by policy and market factors in three countries: Denmark, Norway and Sweden. The study found that the policy factors tested significantly shaped the approaches of the companies assessed, while market factors currently appear less influential. This is likely due to the absence of climate risk and adaptation in political debates and among insurance policyholders. The study discusses the potential role of the insurance industry in adaptation governance and suggests how barriers facing insurance companies could be overcome.

  • 430. Goettel, Holger
    et al.
    Alexander, Jorn
    Keup-Thiel, Elke
    Rechid, Diana
    Hagemann, Stefan
    Blome, Tanja
    Wolf, Annett
    Umeå universitet. ETH Zentrum, CH-8092 Zurich, Switzerland.
    Jacob, Daniela
    Influence of changed vegetations fields on regional climate simulations in the Barents Sea Region2008Inngår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 87, nr 1-2, s. 35-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In the context of the EU-Project BALANCE (http://balance-eu.info) the regional climate model REMO was used for extensive calculations of the Barents Sea climate to investigate the vulnerability of this region to climate change. The regional climate model REMO simulated the climate change of the Barents Sea Region between 1961 and 2100 (Control and Climate Change run, CCC-Run). REMO on similar to 50 km horizontal resolution was driven by the transient ECHAM4/OPYC3 IPCC SRES B2 scenario. The output of the CCC-Run was applied to drive the dynamic vegetation model LPJ-GUESS. The results of the vegetation model were used to repeat the CCC-Run with dynamic vegetation fields. The feedback effect of the modified vegetation on the climate change signal is investigated and discussed with focus on precipitation, temperature and snow cover. The effect of the offline coupled vegetation feedback run is much lower than the greenhouse gas effect.

  • 431. Goncalves, Ines Braga
    et al.
    Mobley, Kenyon B
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ahnesjö, Ingrid
    Sagebakken, Gry
    Jones, Adam G
    Kvarnemo, Charlotta
    Reproductive compensation in broad-nosed pipefish females2010Inngår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 277, nr 1687, s. 1581-1587Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The differential allocation hypothesis assumes that animals should weigh costs and benefits of investing into reproduction with a current mate against the expected quality of future mates, and predicts that they should invest more into reproduction when pairing with a high-quality mate. In the broad-nosed pipefish (Syngnathus typhle), males care for the embryos in a brood pouch and females compete for access to male mating partners. Both sexes prefer mating with large partners. In the present study, we show that the same female provides both large and small mating partners with eggs of similar size, weight and lipid content when mated to two males in succession. Importantly, however, eggs provided to small males (less preferred) had higher egg protein content (11% more) than those provided to large males (preferred). Thus, contrary to the differential allocation hypothesis, eggs did not contain more resources when females mated with a larger male. Instead, the pattern observed in our results is consistent with a compensatory reproductive strategy.

  • 432. Gong, Peichen
    et al.
    Löfgren, Karl-Gustaf
    Umeå universitet, Samhällsvetenskapliga fakulteten, Handelshögskolan vid Umeå universitet, Nationalekonomi.
    Impact of risk aversion on the optimal rotation with stochastic price2008Inngår i: Natural Resource Modeling, ISSN 0890-8575, E-ISSN 1939-7445, Vol. 21, nr 3, s. 385-415Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    This paper examines the effect of risk aversion on the optimal rotation when the stumpage price is stochastic. Assuming that the stumpage price is normally distributed, we show that the optimal rotation under risk aversion may be shorter than, equal to, or longer than the corresponding optimal rotation under risk neutrality. Which of these cases holds true depends on the interest rate and the real regeneration cost, and can be determined based on the marginal variance (i.e., the derivative of the variance function with respect to rotation age) evaluated at the optimal rotation under risk neutrality. Furthermore, we show that there exists a monotone continuous curve, which divides the interest rate-regeneration cost space into two regions where risk aversion affects the optimal rotation differently. For a given interest rate, risk aversion shortens (prolongs) the optimal rotation if the regeneration cost lies below (above) the curve. Along the separating curve the optimal rotation under risk aversion coincides with the optimal rotation under risk neutrality. Two examples are presented to demonstrate the separating curve and the impacts of risk aversion on the optimal rotation.

  • 433. González, Jonatan A.
    et al.
    Rodríguez-Cortés, Francisco J.
    Cronie, Ottmar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Mateu, Jorge
    Spatio-temporal point process statistics: a review2016Inngår i: Spatial Statistics, E-ISSN 2211-6753, Vol. 18, nr Part B, s. 505-544Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    Spatio-temporal point process data have been analysed quite a bit in specialised fields, with the aim of better understanding the inherent mechanisms that govern the temporal evolution of events placed in a planar region. In particular, in the last decade there has been an acceleration of methodological developments, accompanied by a broad collection of applications as spatiotemporally indexed data have become more widely available in many scientific fields. We present a self-contained review describing statistical models and methods that can be used to analyse patterns of points in space and time when the questions of scientific interest concern both their spatial and their temporal behaviour. We revisit moment characteristics that define summary statistics, as well as conditional intensities which uniquely characterise certain spatiotemporal point processes. We make use of these concepts to describe models and associated methods of inference for spatiotemporal point process data. Three new motivating real-data examples are described and analysed throughout the paper to illustrate the most relevant techniques, discussing the pros and cons of the different considered approaches.

  • 434.
    Graae, Bente Jessen
    et al.
    University of Copenhagen Arctic Station 3953 Qeqertarsuaq Greenland.
    Ejrnaes, R
    University of Copenhagen Arctic Station 3953 Qeqertarsuaq Greenland.
    Marchand, FL
    University of Antwerp, Campus Drie Eiken Research Group Plant and Vegetation Ecology, Department of Biology Universiteitsplein 1 2610 Wilrijk Belgium.
    Milbau, Ann
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Shevtsova, A
    University of Antwerp, Campus Drie Eiken Research Group Plant and Vegetation Ecology, Department of Biology Universiteitsplein 1 2610 Wilrijk Belgium.
    Beyens, L
    University of Antwerp, Campus Drie Eiken Research Group Polar Ecology, Limnology and Geomorphology, Department of Biology Universiteitsplein 1 2610 Wilrijk Belgium.
    Nijs, I
    University of Antwerp, Campus Drie Eiken Research Group Plant and Vegetation Ecology, Department of Biology Universiteitsplein 1 2610 Wilrijk Belgium.
    The effect of an early-season short-term heat pulse on plant recruitment in the Arctic2009Inngår i: Polar Biology, ISSN 0722-4060, E-ISSN 1432-2056, Vol. 32, nr 8, s. 1117-1126Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climate change will cause large-scale plant migration. Seedling recruitment constitutes a bottleneck in the migration process but is itself climate-dependent. We tested the effect of warming on early establishment of three Arctic pioneer species, while holding other environmental variables constant. Seeds and bulbils were sown in artificial gaps in dry Arctic tundra and subjected to a 13-day heating of the soil surface by 2-8°C, simulating temperature increases ranging from the general summer warming to heat waves projected to occur more frequently with global warming. All species showed decreased establishment with increasing soil surface temperature. The short-term heat pulse decreased establishment of Polygonum viviparum and Saxifraga cernua, whereas establishment of Cerastium alpinum decreased with temperature due to more permanent natural variation in micro-climate. The treatment effects increased by the quadrat of the temperature increase. Warming and in particular heat waves may result in declining establishment of Arctic plants in dry tundra regions. Electronic supplementary material The online version of this article (doi:10.1007/s00300-009-0608-3) contains supplementary material, which is available to authorized users.

  • 435.
    Graae, BJ
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Verheyen, K
    Kolb, A
    Van Der Veken, S
    Heinken, T
    Chabrerie, O
    Diekmann, M
    Valtinat, K
    Zindel, R
    Karlsson, E
    Ström, Lotta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Decocq, G
    Hermy, M
    Baskin, CC
    Germination requirements and seed mass of slow- and fast-colonizing temperate forest herbs along a latitudinal gradient2009Inngår i: Ecoscience, ISSN 1195-6860, Vol. 16, s. 248-257Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Predictions on displacement of suitable habitats due to climate change suggest that plant species with poor colonization ability may be unable to move fast enough to match forecasted climate-induced changes in habitat distribution. However, studies on early Holocene plant migration show fast migration of many plant species that are poor colonizers today We hypothesize that warmer temperatures during the early Holocene yielded higher seed quality, contributing to explaining the fast migration. We studied how the 3 seed quality variables, seed mass, germinability, and requirements for break of seed dormancy, vary for seeds of 11 forest herb species with varying colonization capacity collected along a 1400-km latitudinal gradient. Within species, seed mass showed a positive correlation with latitude, whereas germinability was more positively correlated with temperature (growing degree hours obtained at time of seed collection). Only slow-colonizing species increased germinability with temperature, whereas only fast-colonizing species increased germinability with latitude. These interactions were only detectable when analyzing germinability of the seeds, even though this trait and seed mass were correlated. The requirement for dormancy break did not correlate with latitude or temperature. The results indicate that seed development of slow colonizers may be favoured by a warmer climate, which in turn may be important for their migration capacity.

  • 436.
    Grabic, Roman
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Institute of Public Health Ostrava, Czech Republic.
    Jurcikova, Jana
    Tomsejova, Sarka
    Ocelka, Tomas
    Halirova, Jarmila
    Hypr, Dusan
    Kodes, Vit
    Passive sampling methods for monitoring endocrine disruptors in the Svratka and Svitava rivers in the Czech Republic2010Inngår i: Environmental Toxicology and Chemistry, ISSN 0730-7268, E-ISSN 1552-8618, Vol. 29, nr 3, s. 550-555Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Endocrine-disrupting chemicals (EDC) are manmade or natural chemicals that have the ability to interfere with the endocrine system of animals. They have not been monitored systematically in the Czech Republic. The goal of the present study was the characterization of aquatic environmental pollution from the Brno (Czech Republic) city agglomeration focusing on EDC. Passive sampling devices, as well as semipermeable membrane devices (SPMD) and polar organic chemical integrative samplers (POCIS), were used for the pilot assessment of EDC. They were deployed for 21- to 28-d periods at nine locations in the Svratka and Svitava Rivers, Brno, Czech Republic, including at the inlet and outlet of Brno's wastewater treatment plant. The SPMDs were used to monitor nonpolar compounds such as polychlorinated biphenyls (PCBs), polynuclear aromatic hydrocarbons (PAHs), and organochlorinated pesticides (OCP). The POCIS were used to monitor polar compounds such as pesticides and their metabolites, perfluoro-organic compounds (PFOC), and pharmaceuticals. The passive samplers allowed very low detection limits for soluble (bioavailable) fractions of pollutants. The contribution of PAH, PCB, and HCB in sewage water to pollution of the Svratka River was low. The Brno wastewater treatment plant was identified as the main source of pharmaceuticals, triclosan, methyl triclosan, and some polar pesticides.

  • 437. Grabicova, Katerina
    et al.
    Grabic, Roman
    Fedorova, Ganna
    Fick, Jerker
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Cerveny, Daniel
    Kolarova, Jitka
    Turek, Jan
    Zlabek, Vladimir
    Randak, Tomas
    Bioaccumulation of psychoactive pharmaceuticals in fish in an effluent dominated stream2017Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 124, s. 654-662Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The treated effluent from sewage treatment plants (STP) is a major source of active pharmaceutical ingredients (APIs) that enter the aquatic environment. Bioaccumulation of 11 selected psychoactive pharmaceuticals (citalopram, clomipramine, haloperidol, hydroxyzine, levomepromazine, mianserin, mirtazapine, paroxetine, sertraline, tramadol and venlafaxine) was examined in Zivny Stream (tributary of the Blanice River, the Czech Republic), which is a small stream highly affected by effluent from the Prachatice STP. Six of the 11 pharmaceuticals were detected in grab water samples and in passive samplers. All pharmaceuticals were found in fish exposed to the stream for a defined time. The organs with highest presence of the selected pharmaceuticals were the liver and kidney; whereas only one pharmaceutical (sertraline) was detected in the brain of exposed fish. Fish plasma and muscle samples were not adequate in revealing exposure because the number of hits was much lower than that in the liver or kidney. Using the criterion of a bioaccumulation factor (BAF) >= 500, citalopram, mianserin, mirtazapine and sertraline could be classified as potential bioaccumulative compounds. In combination, data from integrative passive samplers and fish liver or kidney tissue samples were complimentary in detection of target compounds and simultaneously helped to distinguish between bioconcentration and bioaccumulation.

  • 438. Grabicova, Katerina
    et al.
    Lindberg, Richard H
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Östman, Marcus
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Grabic, Roman
    Randak, Tomas
    Larsson, DG Joakim
    Fick, Jerker
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen.
    Tissue-specific bioconcentration of antidepressants in fish exposed to effluent from a municipal sewage treatment plant2014Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 488, s. 46-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Tissue-specific bioconcentration of selected antidepressants was studied in rainbow trout (Oncorhynchus mykiss) exposed to undiluted effluent from a Swedish municipal sewage treatment plant for 13 days. Citalopram, sertraline and venlafaxine were found in the brains and livers of most fish, but not in blood plasma or muscle. Venlafaxine was the only drug found in plasma (3/20 fish). Fluoxetine was not detected in any fish tissue, in accordance with a low concentration in the effluent and a comparably high limit of quantification in tissues. Concentrations of citalopram, sertraline and venlafaxine in fish brain were up to 1/12, 1/8 and 1/26, respectively, of the lowest concentrations found in the brains of mammals treated with therapeutic doses. Thus, given coexposure to several antidepressants and an assumed similar potency in fish, the margin of safety for targetrelated effects in fish residing in effluent-dominated streams is relatively low. Furthermore, the non-detectable levels of these drugs in blood plasma suggest that analyses of concentrations in target tissues (brain) would be more informative in field studies and other studies with environmentally realistic exposure concentrations.

    (C) 2014 Elsevier B.V. All rights reserved.

  • 439. Granath, Gustaf
    et al.
    Wiedermann, Magdalena M
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Strengbom, Joachim
    Physiological responses to nitrogen and sulphur addition and raised temperature in Sphagnum balticum2009Inngår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 161, nr 3, s. 481-490Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Sphagnum, the main genus which forms boreal peat, is strongly affected by N and S deposition and raised temperature, but the physiological mechanisms behind the responses are largely unknown. We measured maximum photosynthetic rate (NP(max)), maximum efficiency of photosystem II [variable fluorescence (F (v))/maximum fluorescence yield (F (m))] and concentrations of N, C, chlorophyll and carotenoids as responses to N and S addition and increased temperature in Sphagnum balticum (a widespread species in the northern peatlands) in a 12-year factorial experiment. NP(max) did not differ between control (0.2 g N m(-2) year(-1)) and high N (3.0 g N m(-2) year(-1)), but was higher in the mid N treatment (1.5 g N m(-2) year(-1)). N, C, carotenoids and chlorophyll concentration increased in shoot apices after N addition. F (v)/F (m) did not differ between N treatments. Increased temperature (+3.6A degrees C) had a small negative effect on N concentration, but had no significant effect on NP(max) or F (v)/F (m). Addition of 2 g S m(-2) year(-1) showed a weak negative effect on NP(max) and F (v)/F (m). Our results suggest a unimodal response of NP(max) to N addition and tissue N concentration in S. balticum, with an optimum N concentration for photosynthetic rate of similar to 13 mg N g(-1). In conclusion, high S deposition may reduce photosynthetic capacity in Sphagnum, but the negative effects may be relaxed under high N availability. We suggest that previously reported negative effects on Sphagnum productivity under high N deposition are not related to negative effects on the photosynthetic apparatus, but differences in optimum N concentration among Sphagnum species may affect their competitive ability under different N deposition regimes.

  • 440.
    Grellmann, Doris
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Top-down and bottom-up effects in a Fennoscandian tundra community2001Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    The objective of this thesis was to investigate the effects of mammalian grazers, such as microtine rodents and reindeer, (top-down effects) and nutrient availability (bottom- up effects) on the plant community of a tundra heath.

    I conducted a large-scale fertilization experiment and studied the impact of grazers using exclosures. I measured the effects of fertilization and grazing on soil microbial activity and nutrient cycling. I investigated the responses to fertilization of the invertebrate community, I studied the effects on the quality of bilberry as food for mammalian herbivores, and I looked at how concentrations of nutrients and carbon-based secondary defences against herbivory fluctuated between seasons in unfertilized and fertilized treatments.

    The results of my thesis show that the plant community investigated is exposed to a strong top-down control by mammalian herbivores. On the fertilized and grazed areas the aboveground biomass of the vascular plant community did not increase compared to unfertilized areas. However, the productivity of the plant community was clearly nutrient- limited. During the eight years of the experiment, on the fertilized areas plant biomass was significantly increased inside the herbivore exclosures

    In my study mammalian herbivores at comparatively low densities and grazing outside the growing season were sufficient to control the biomass of a heterogeneous plant community. Microtine rodents (Norwegian lemmings and grey-sided voles) preferred the fertilized areas for overwintering. The food plant quality of bilberry for grey-sided voles was improved on the fertilized areas throughout the year. Grazing decreased the nitrogen storage in the aboveground plant biomass. Reindeer and rodents had also important indirect effects on the plant community by decelerating soil nutrient cycling and soil microbial activity. This effect may be accelerated by the impact of herbivore on plant species composition. Graminoids, which contained the highest nitrogen concentrations in their tissues, increased rapidly on the fertilized areas, but their abundance was significantly lower on grazed fertilized areas.

    The invertebrate community was detritus-based and received their energy indirectly from the litter via soil microbes and detritivores. Fertilization increased the biomass of invertebrate carnivores, but had no effect on the biomass of invertebrate herbivores. Apparent competition between detritivores and invertebrate herbivores, mediated by carnivorous invertebrates predating on both of them, is supposed to keep the densities and grazing pressure of invertebrate herbivores low. Grazing damage by invertebrates was very low and only 0.021 % of the total vascular plant biomass was removed.

  • 441. Grill, G.
    et al.
    Lehner, B.
    Thieme, M.
    Geenen, B.
    Tickner, D.
    Antonelli, F.
    Babu, S.
    Borrelli, P.
    Cheng, L.
    Crochetiere, H.
    Macedo, H. Ehalt
    Filgueiras, R.
    Goichot, M.
    Higgins, J.
    Hogan, Z.
    Lip, B.
    McClain, M. E.
    Meng, J.
    Mulligan, M.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Olden, J. D.
    Opperman, J. J.
    Petry, P.
    Liermann, C. Reidy
    Saenz, L.
    Salinas-Rodriguez, S.
    Schelle, P.
    Schmitt, R. J. P.
    Snider, J.
    Tan, F.
    Tockner, K.
    Valdujo, P. H.
    van Soesbergen, A.
    Zarfl, C.
    Mapping the world's free-flowing rivers2019Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 569, nr 7755, s. 215-221Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Free-flowing rivers (FFRs) support diverse, complex and dynamic ecosystems globally, providing important societal and economic services. Infrastructure development threatens the ecosystem processes, biodiversity and services that these rivers support. Here we assess the connectivity status of 12 million kilometres of rivers globally and identify those that remain free-flowing in their entire length. Only 37 per cent of rivers longer than 1,000 kilometres remain free-flowing over their entire length and 23 per cent flow uninterrupted to the ocean. Very long FFRs are largely restricted to remote regions of the Arctic and of the Amazon and Congo basins. In densely populated areas only few very long rivers remain free-flowing, such as the Irrawaddy and Salween. Dams and reservoirs and their up- and downstream propagation of fragmentation and flow regulation are the leading contributors to the loss of river connectivity. By applying a new method to quantify riverine connectivity and map FFRs, we provide a foundation for concerted global and national strategies to maintain or restore them.

  • 442.
    Gudasz, Cristian
    et al.
    Limnology, Department of Ecology and Evolution, Uppsala University, Norbyvägen 18D, SE-752 36 Uppsala, Sweden.
    Bastviken, David
    Steger, Kristin
    Premke, Katrin
    Sobek, Sebastian
    Tranvik, Lars J
    Temperature-controlled organic carbon mineralization in lake sediments2010Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 466, nr 7305, s. 478-481Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Peatlands, soils and the ocean floor are well-recognized as sites of organic carbon accumulation and represent important global carbon sinks. Although the annual burial of organic carbon in lakes and reservoirs exceeds that of ocean sediments, these inland waters are components of the global carbon cycle that receive only limited attention. Of the organic carbon that is being deposited onto the sediments, a certain proportion will be mineralized and the remainder will be buried over geological timescales. Here we assess the relationship between sediment organic carbon mineralization and temperature in a cross-system survey of boreal lakes in Sweden, and with input from a compilation of published data from a wide range of lakes that differ with respect to climate, productivity and organic carbon source. We find that the mineralization of organic carbon in lake sediments exhibits a strongly positive relationship with temperature, which suggests that warmer water temperatures lead to more mineralization and less organic carbon burial. Assuming that future organic carbon delivery to the lake sediments will be similar to that under present-day conditions, we estimate that temperature increases following the latest scenarios presented by the Intergovernmental Panel on Climate Change could result in a 4-27 per cent (0.9-6.4 Tg C yr(-1)) decrease in annual organic carbon burial in boreal lakes.

  • 443. Guedron, S.
    et al.
    Tolu, Julie
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Eawag, Swiss Federal Institute of Aquatic Science and Technology, Dübendorf, Switzerland; ETH Zürich, Zürich, Switzerland.
    Brisset, E.
    Sabatier, P.
    Perrot, V.
    Bouchet, S.
    Develle, A. L.
    Bindler, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Cossa, D.
    Fritz, S. C.
    Baker, P. A.
    Late Holocene volcanic and anthropogenic mercury deposition in the western Central Andes (Lake Chungará, Chile)2019Inngår i: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 662, s. 903-914Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Volcanismis one of the major natural processes emitting mercury (Hg) to the atmosphere, representing a significant component of the global Hg budget. The importance of volcanic eruptions for local-scale Hg deposition was investigated using analyses of Hg, inorganic elemental tracers, and organic biomarkers in a sediment sequence from Lake Chungara (4520 m a.s.l.). Environmental change and Hg deposition in the immediate vicinity of the Parinacota volcano were reconstructed over the last 2700 years, encompassing the pre-anthropogenic and anthropogenic periods. Twenty eruptions delivering large amounts of Hg (1 to 457 mu g Hg m(-2) yr(-1) deposited at the timescale of the event) were locally recorded. Peaks of Hg concentration recorded after most of the eruptions were attributed to a decrease in sedimentation rate together with the rapid re-oxidation of gaseous elemental Hg and deposition with fine particles and incorporation into lake primary producers. Over the study period, the contribution of volcanic emissions has been estimated as 32% of the total Hg input to the lake. Sharp depletions in primary production occurred at each eruption, likely resulting from massive volcaniclastic inputs and changes in the lake-water physico-chemistry. Excluding the volcanic deposition periods, Hg accumulation rates rose from natural background values (1.9 +/- 0.5 mu g m(-2) yr(-1)) by a factor of 2.3 during the pre-colonial mining period (1400-900 yr cal. BP), and by a factor of 6 and 7.6, respectively, during the Hispanic colonial epoch (400-150 yr cal. BP) and the industrial era (similar to 140 yr cal. BP to present). Altogether, the dataset indicates that lake primary production has been the main, but not limiting, carrier for Hg to the sediment. Volcanic activity and climate change are only secondary drivers of local Hg deposition relative to the magnitude of regional and global anthropogenic emissions.

  • 444.
    Guindal Estévez, Guillermo
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Impacts of hydropower dams operations on plants: A greenhouse experiment on the response of germination and performance and survival of plant seedlings to direct and indirect effects of hydrological alterations resulting from hydropower dam operations2015Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    This work helps increasing our general understanding of how plants behave under altered hydrological conditions which occur along rivers regulated by hydropower dams. Usually, natural-real environments are highly unpredictable. Consequently, research based on field data becomes challenging and results may contain uncertainty. Here, an experimental design in a greenhouse is developed. Several measured attributes of selected plant species related to germinability, performance and survival were used as indicators of the impact of watering treatments which mimic hydrological regime spilled through hydropower dams. Specifically, direct effect of water availability changes, water fluctuation and water flooding, and indirect effect through derived erosion, were tested. Results benefitted from indoors controlled conditions. They showed significant different responses depending on species and hydrological changes. In general, Helianthus annuus was slightly affected. It deal well flooding conditions, and was comparatively more affected by water fluctuation and stress. Carex and Filipendula species showed the highest sensitivities to flow. They hardly germinated under any water treatment (few germinations under flooding for Carex and few under water fluctuation for Filipendula) and performance was very low for germinates. Betula pubescens was in between. Contrarily to Helianthus, it was severely affected by flooding, and also for water fluctuation. It survived water stress better than Helianthus, but looked unhealthy. All species seeds but Helianthus were highly eroded. However, erosion resulting from water fluctuation was relatively higher than from prolonged flooding. Differing responses are the result of morphological and physiological characteristics of the species which enable them to success under certain stressful conditions, such as water scarcity and anoxia. These results objectively inform about tolerance limits of selected species to key hydrological conditions and are useful for riparian areas management and environmental flows designs.

  • 445. Gundale, Michael J.
    et al.
    Bach, Lisbet H.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nordin, Annika
    The impact of simulated chronic nitrogen deposition on the biomass and N-2-fixation activity of two boreal feather moss-cyanobacteria associations2013Inngår i: Biology Letters, ISSN 1744-9561, E-ISSN 1744-957X, Vol. 9, nr 6, s. 20130797-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Bryophytes achieve substantial biomass and play several key functional roles in boreal forests that can influence how carbon (C) and nitrogen (N) cycling respond to atmospheric deposition of reactive nitrogen (N-r). They associate with cyanobacteria that fix atmospheric N-2, and downregulation of this process may offset anthropogenic Nr inputs to boreal systems. Bryophytes also promote soil C accumulation by thermally insulating soils, and changes in their biomass influence soil C dynamics. Using a unique large-scale (0.1 ha forested plots), long-term experiment (16 years) in northern Sweden where we simulated anthropogenic Nr deposition, we measured the biomass and N-2-fixation response of two bryophyte species, the feather mosses Hylocomium splendens and Pleurozium schreberi. Our data show that the biomass declined for both species; however, N-2-fixation rates per unit mass and per unit area declined only for H. splendens. The low and high treatments resulted in a 29% and 54% reduction in total feather moss biomass, and a 58% and 97% reduction in total N-2-fixation rate per unit area, respectively. These results help to quantify the sensitivity of feather moss biomass and N-2 fixation to chronic Nr deposition, which is relevant for modelling ecosystem C and N balances in boreal ecosystems.

  • 446. Gundale, Michael J.
    et al.
    From, Fredrik
    Bach, Lisbet H.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nordin, Annika
    Anthropogenic nitrogen deposition in boreal forests has a minor impact on the global carbon cycle2014Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 20, nr 1, s. 276-286Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    It is proposed that increases in anthropogenic reactive nitrogen (N-r) deposition may cause temperate and boreal forests to sequester a globally significant quantity of carbon (C); however, long-term data from boreal forests describing how C sequestration responds to realistic levels of chronic N-r deposition are scarce. Using a long-term (14-year) stand-scale (0.1ha) N addition experiment (three levels: 0, 12.5, and 50kgNha(-1)yr(-1)) in the boreal zone of northern Sweden, we evaluated how chronic N additions altered N uptake and biomass of understory communities, and whether changes in understory communities explained N uptake and C sequestration by trees. We hypothesized that understory communities (i.e. mosses and shrubs) serve as important sinks for low-level N additions, with the strength of these sinks weakening as chronic N addition rates increase, due to shifts in species composition. We further hypothesized that trees would exhibit nonlinear increases in N acquisition, and subsequent C sequestration as N addition rates increased, due to a weakening understory N sink. Our data showed that understory biomass was reduced by 50% in response to the high N addition treatment, mainly due to reduced moss biomass. A N-15 labeling experiment showed that feather mosses acquired the largest fraction of applied label, with this fraction decreasing as the chronic N addition level increased. Contrary to our hypothesis, the proportion of label taken up by trees was equal (ca. 8%) across all three N addition treatments. The relationship between N addition and C sequestration in all vegetation pools combined was linear, and had a slope of 16kgCkg(-1)N. While canopy retention of N-r deposition may cause C sequestration rates to be slightly different than this estimate, our data suggest that a minor quantity of annual anthropogenic CO2 emissions are sequestered into boreal forests as a result of N-r deposition.

  • 447. Gunell, H
    et al.
    Andersson, L
    De Keyser, J
    Mann, Ingrid
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik. EISCAT Scientific Association, Kiruna, Sweden.
    Self-consistent electrostatic simulations of reforming double layers in the downward current region of the aurora2015Inngår i: Annales Geophysicae, ISSN 0992-7689, E-ISSN 1432-0576, Vol. 33, nr 10, s. 1331-1342Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The plasma on a magnetic field line in the downward current region of the aurora is simulated using a Vlasov model. It is found that an electric field parallel to the magnetic fields is supported by a double layer moving toward higher altitude. The double layer accelerates electrons upward, and these electrons give rise to plasma waves and electron phase-space holes through beam-plasma interaction. The double layer is disrupted when reaching altitudes of 12 Earth radii where the Langmuir condition no longer can be satisfied due to the diminishing density of electrons coming up from the ionosphere. During the disruption the potential drop is in part carried by the electron holes. The disruption creates favourable conditions for double layer formation near the ionosphere and double layers form anew in that region. The process repeats itself with a period of approximately 1 min. This period is determined by how far the double layer can reach before being disrupted: a higher disruption altitude corresponds to a longer repetition period. The disruption altitude is, in turn, found to increase with ionospheric density and to decrease with total voltage. The current displays oscillations around a mean value. The period of the oscillations is the same as the recurrence period of the double layer formations. The oscillation amplitude increases with increasing voltage, whereas the mean value of the current is independent of voltage in the 100 to 800 V range covered by our simulations. Instead, the mean value of the current is determined by the electron density at the ionospheric boundary.

  • 448. Gunnarson, Björn E
    et al.
    Josefsson, Torbjörn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Linderholm, Hans W
    Östlund, Lars
    Legacies of pre-industrial land use can bias modern tree-ring climate calibrations2012Inngår i: Climate Research (CR), ISSN 0936-577X, E-ISSN 1616-1572, Vol. 53, nr 1, s. 63-76Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In Scandinavia, dendrochronological reconstructions of past climate have mostly been based on tree-ring data from forests in which there has been, supposedly, very little or no human impact. However, human land use in sub-alpine forests has a substantially longer history and more profound effects on the forest ecosystems than previously acknowledged. Therefore, to assess human influence on tree-ring patterns over the last 500 yr, we have analyzed tree-ring patterns using trees from 2 abandoned Sami settlements and a reference site with no human impact-all situated in the Tjeggelvas Nature Reserve in north-west Sweden. The hypothesis was that land use legacies have affected tree-ring patterns, and in turn, the resulting palaeoclimate inferences that have been made from these patterns. Our results show that climate signals are strongest at the reference site and weakest at one of the settlement sites. From the 1940s to the present, tree growth at this settlement site has been significantly lower than at the reference site. Lower tree growth at old settlements may have resulted from rapid changes in the traditional land use, or following the abrupt change when the settlements were abandoned. Without site-specific know ledge of past land use, there is a high risk of accidently sampling trees that have been affected by human-induced disturbances in the past. This may create bias in the climate signals inferred from such trees, and hence bias the outcome of climate reconstructions. We therefore recommend sampling several separate sites in study areas to improve the robustness of inferences.

  • 449.
    Gustavsson, Leif
    et al.
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Mahapatra, Krushna
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Nair, Gireesh
    Mittuniversitetet, Institutionen för teknik och hållbar utveckling.
    Implementering av energieffektiviseringsåtgärder i befintlig bebyggelse: Report prepared for the Swedish Energy Agency2010Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    There is great potential to improve energy efficiency in existing Swedish residential buildings. However, the successful implementation of efficiency measures depends on economical and technical factors, as well as on the attitudes and perceptions of the relevant actors. A better understanding of their attitudes and perceptions may influence the design of suitable policy measures that increase the adoption of energy efficiency measures. In this context, we conducted mail-in surveys completed by owners of detached houses, chairmen of co-operative housing associations (bostadsrättsförening) and municipality energy advisers in Sweden. We also interviewed window sellers/installers in Jämtland.

    Results show that it was important for the majority of homeowners to reduce their household energy use, with most undertaking no-cost measures (e.g., switching off lights). However, 70–90% of the responding homeowners had no intention of adopting building envelope measures over the next 10 years. The main reason for non-adoption was that homeowners were satisfied with the physical condition and thermal performance of their existing building envelope components. Homeowners who thought their energy cost was high were more likely to adopt an investment measure compared to those who thought their energy cost was low. Investment costs and annual energy cost savings were the most important factors in adoption of energy efficient building envelope measures. Therefore, economic incentives may induce homeowners to adopt energy efficiency investment measures. However, a large percentage (64%) of homeowners was unaware of the existence of government support for reducing household energy use. Information campaigns announcing the availability of economic incentives and the cost advantages of energy efficiency measures may be helpful in the adoption decision.

    Homeowners‘ considered interpersonal sources, builders, installers and energy advisers as important sources of information for their adoption of energy efficiency measures. Though a large percentage of respondents considered energy advisers as an important source of information, only 14% of homeowners had contacted an energy adviser in the past. Our findings suggest that the energy advice service is important for homeowners, but more efforts are needed to increase homeowners‘ awareness of and satisfaction with such services. The majority of municipal energy advisers were of the opinion that more training in technical aspects of energy issues and increased financial support could improve their performance.

    Installers and material suppliers are important actors in homeowners‘ adoption of energy efficiency measures. For example, approximately 53% of responding homeowners to a survey in Jämtland/Västernorrland stated that the window seller/installer from whom they had bought windows had recommended a particular type of window, and 97% had installed the windows that were recommended. The window sellers/installers in Jämtland prefer a window that is ―reasonably‖ energy efficient. They believe that windows with a U-value of 1.2 W/m2K are good and there is no reason to further improve the energy efficiency. The majority did not recommend windows with U-value <1.2 W/m2K. They were concerned about the condensation issues and high prices of such windows. This may influence the diffusion of very energy efficient windows in Swedish detached houses.

    About 80-95% of chairmen in co-operative housing associations who responded to our survey had no intention of adopting building envelope measures over the next 10 years. They were satisfied with the existing building envelope components, which may be one of the reasons for this lack of intention. As in the case of owners of detached houses, economic factors, like annual energy cost savings and investment costs, guide the implementation of energy efficiency investment measures in co-operative housing associations. However, about 66% of the responding chairmen did not consider financial constraint as a barrier to implementing investment intensive energy efficiency measures. For 54% of the respondents limited in-house competency to evaluate the benefits of energy efficiency measures was the main barrier.

    The majority of owners of detached houses (80%) and chairmen of co-operative housing associations (70%) perceived that economic policy instruments, such as investment subsidies and tax deductions, would encourage them to implement energy efficiency measures. Other policy instruments, especially information instruments, were perceived as less effective. Among various information policies, increasing the frequency of meter reading received the highest approval with 38% of homeowners, whereas approximately 41% of housing association chairmen thought that individual metering of heating and hot water use could be effective. Approximately 30% of homeowners and housing association chairmen thought that energy declaration was effective.

  • 450.
    Gydemo Östbom, Viktor
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lake water chemistry and the changing arctic environment: Topographic or climatic control?2019Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    The arctic is expected to be one of the regions most affected by ongoing climate change, with relative changes in air temperatures significantly higher than the global mean. Lakes are recognized for their potential role in the global climate system and as ecosystems of importance for local societies. As such, there is a scientific interest regarding how arctic lakes and their geochemistry will respond to climatic changes. Lakes around Kangerlussuaq (66.99 N, 51.07 W), south-west Greenland, are known for their unique geochemical composition, including oligosaline lakes, of which some are enriched in colourless dissolved organic carbon (DOC). The origin of this DOC and the importance of local catchment properties for the general water chemistry is currently being debated. This thesis aimed at: i) exploring the extent and effect of catchment morphology on lake-water chemistry in the Kangerlussuaq area; ii) determine the predominant origin of DOC, aquatic or terrestrial. I used a remote-sensing approach based on satellite imagery and digital elevation model (DEM) in deciding landscape influence on water chemistry (pH, alkalinity, conductivity, base cations, sulphate, nitrogen and absorbance). To trace the origin of the organic sources behind DOC lake water and sediments, I used a hydrogen isotope tracing method. The remote sensing approach revealed that morphological characteristics serving as proxies for lake water residence time and hydrologic connectivity (e.g. lake altitude difference and absence of outlets) explained up to 77% of the variations in lake water chemistry. The hydrogen isotopic signature of the DOC indicated a predominantly autochthonous origin, i.e. 59 to 78% was estimated to originate from algae. I conclude that lake water chemistry of the lakes in the study area is primarily controlled by the precipitation : evaporation balance, enhanced by static catchment characteristics regulating water age. Thus, the examined lake water chemical properties are likely to remain across future climatic scenarios, providing the current precipitation : evaporation balance prevails.

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