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  • 101.
    Milbau, Ann
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Graae, Bente Jessen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Shevtsova, Anna
    Research Group of Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium .
    Nijs, Ivan
    Research Group of Plant and Vegetation Ecology, Department of Biology, University of Antwerp, Universiteitsplein 1, B-2610 Wilrijk, Belgium.
    Effects of a warmer climate on seed germination in the Subarctic2009Inngår i: Annals of Botany, ISSN 0305-7364, E-ISSN 1095-8290, Vol. 104, s. 287-296Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and Aims In a future warmer subarctic climate, the soil temperatures experienced by dispersed seeds are likely to increase during summer but may decrease during winter due to expected changes in snow depth, duration and quality. Because little is known about the dormancy-breaking and germination requirements of subarctic species, how warming may influence the timing and level of germination in these species was examined. Methods Under controlled conditions, how colder winter and warmer summer soil temperatures influenced germination was tested in 23 subarctic species. The cold stratification and warm incubation temperatures were derived from real soil temperature measurements in subarctic tundra and the temperatures were gradually changed over time to simulate different months of the year. Key Results Moderate summer warming (+ 2.5 °C) substantially accelerated germination in all but four species but did not affect germination percentages. Optimum germination temperatures (20/10 °C) further decreased germination time and increased germination percentages in three species. Colder winter soil temperatures delayed the germination in ten species and decreased the germination percentage in four species, whereas the opposite was found in Silene acaulis. In most species, the combined effect of a reduced snow cover and summer warming resulted in earlier germination and thus a longer first growing season, which improves the chance of seedling survival. In particular the recruitment of (dwarf ) shrubs (Vaccinium myrtillus, V. vitis-idaea, Betula nana), trees (Alnus incana, Betula pubescens) and grasses (Calamagrostis lapponica, C. purpurea) is likely to benefit from a warmer subarctic climate. Conclusions Seedling establishment is expected to improve in a future warmer subarctic climate, mainly by considerably earlier germination. The magnitudes of the responses are species-specific, which should be taken into account when modelling population growth and migration of subarctic species.

  • 102. Moberg, Karen R.
    et al.
    Aall, Carlo
    Western Norway Research Institute, Sogndal, Norway.
    Dorner, Florian
    Institute of Public Health, Heidelberg University, Heidelberg, Germany.
    Reimerson, Elsa
    Umeå universitet, Samhällsvetenskapliga fakulteten, Statsvetenskapliga institutionen. Umeå universitet, Arktiskt centrum vid Umeå universitet (Arcum). Umeå universitet, Humanistiska fakulteten, Centrum för samisk forskning (CeSam).
    Ceron, Jean-Paul
    Centre International de Recherche sur l’Environnement et le Développement, Paris, France.
    Sköld, Bore
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Sovacool, Benjamin K.
    Science Policy Research Unit (SPRU), School of Business, Management and Economics, University of Sussex, Brighton, UK; Center for Energy Technologies, Department of Business Development and Technology, Aarhus University, Aarhus, Denmark.
    Piana, Valentino
    Economics Web Institute, Monterotondo, Italy.
    Mobility, food and housing: responsibility, individual consumption and demand-side policies in European deep decarbonisation pathways2019Inngår i: Energy Efficiency, ISSN 1570-646X, E-ISSN 1570-6478, Vol. 12, nr 2, s. 497-519Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Brundtland Commission report ‘Our Common Future’ highlighted that residents in high-income countries lead lifestyles incompatible with planetary boundaries. Three decades later, consumption-related greenhouse gas (GHG) emissions have continued to increase. To achieve ‘well below 2°C’ and 1.5 °C goals, consumption-related emissions must be substantially reduced in the coming decades. This paper provides insights on how to pursue 1.5 °C pathways through changes in household consumption. It draws on original data gathered in the project ‘HOusehold Preferences for reducing greenhouse gas Emissions in four European High Income Countries’ (HOPE) to analyse policies targeting and affecting direct and indirect GHG emissions in three household consumption categories (mobility, housing and food) in four countries (France, Germany, Norway and Sweden) and four medium-sized cities. This paper demonstrates discrepancies and similarities between current governmental policy approaches in the four countries and household perceptions of consumption changes with respect to policy mechanisms, responsibilities and space for acting on mitigation. Current demand-side policy strategies rely heavily on instruments of self-governance and nudging behaviour. Whilst some of our data suggests that households broadly accept this, it also suggests that governments could more actively lead and steer demand-side mitigation via adjusting and supplementing a comprehensive list of 20 climate policy measures currently in place in one or more of the case countries. The paper concludes by suggesting areas for more effective policy change and household-level climate change mitigation to feed the next update of climate pledges under the Paris Agreement.

  • 103.
    Monteux, Sylvain
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    A song of ice and mud: Interactions of microbes with roots, fauna and carbon in warming permafrost-affected soils2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Permafrost-affected soils store a large quantity of soil organic matter (SOM) – ca. half of worldwide soil carbon – and currently undergo rapid and severe warming due to climate change. Increased SOM decomposition by microorganisms and soil fauna due to climate change, poses the risk of a positive climate feedback through the release of greenhouse gases. Direct effects of climate change on SOM decomposition, through such mechanisms as deepening of the seasonally-thawing active layer and increasing soil temperatures, have gathered considerable scientific attention in the last two decades. Yet, indirect effects mediated by changes in plant, microbial, and fauna communities, remain poorly understood. Microbial communities, which may be affected by climate change-induced changes in vegetation composition or rooting patterns, and may in turn affect SOM decomposition, are the primary focus of the work described in this thesis.

    We used (I) a field-scale permafrost thaw experiment in a palsa peatland, (II) a laboratory incubation of Yedoma permafrost with inoculation by exotic microorganisms, (III) a microcosm experiment with five plant species grown either in Sphagnum peat or in newly-thawed permafrost peat, and (IV) a field-scale cold season warming experiment in cryoturbated tundra to address the indirect effects of climate change on microbial drivers of SOM decomposition. Community composition data for bacteria and fungi were obtained by amplicon sequencing and phospholipid fatty acid extraction, and for collembola by Tullgren extraction, alongside measurements of soil chemistry, CO2 emissions and root density.

    We showed that in situ thawing of a palsa peatland caused colonization of permafrost soil by overlying soil microbes. Further, we observed that functional limitations of permafrost microbial communities can hamper microbial metabolism in vitro. Relieving these functional limitations in vitro increased cumulative CO2 emissions by 32% over 161 days and introduced nitrification. In addition, we found that different plant species did not harbour different rhizosphere bacterial communities in Sphagnum peat topsoil, but did when grown in newly-thawed permafrost peat. Plant species may thus differ in how they affect functional limitations in thawing permafrost soil. Therefore, climate change-induced changes in vegetation composition might alter functioning in the newly-thawed, subsoil permafrost layer of northern peatlands, but less likely so in the topsoil. Finally, we observed that vegetation encroachment in barren cryoturbated soil, due to reduced cryogenic activity with higher temperatures, change both bacterial and collembola community composition, which may in turn affect soil functioning.

    This thesis shows that microbial community dynamics and plant-decomposer interactions play an important role in the functioning of warming permafrost-affected soils. More specifically, it demonstrates that the effects of climate change on plants can trickle down on microbial communities, in turn affecting SOM decomposition in thawing permafrost.

  • 104. Morin, Samuel
    et al.
    Abegg, Bruno
    Demiroglu, O. Cenk
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för geografi och ekonomisk historia.
    Pons, Marc
    Weber, Fabian
    Amacher-Hoppler, Anna
    François, Hugues
    George, Emmanuelle
    Soubeyroux, Jean-Michel
    Samacoïts, Raphaëlle
    Lafaysse, Matthieu
    Franklin, Sam
    Clifford, Debbie
    Cauchy, Adeline
    Dubois, Ghislain
    The Mountain Component of the Copernicus Climate Change Services - Sectoral Information Service "European Tourism": Towards Pan-European Analysis and Projections of Natural and Managed Snow Conditions2018Konferansepaper (Fagfellevurdert)
  • 105. Morin, Samuel
    et al.
    Samacoïts, Raphaëlle
    Hugues, François
    Abegg, Bruno
    Demiroglu, O. Cenk
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för geografi.
    Pons, Marc
    Lafaysse, Matthieu
    Weber, Fabian
    Amacher Hoppler, Anna
    George, Emmanuelle
    Soubeyroux, Jean-Michel
    Clifford, Debbie
    Cauchy, Adeline
    Dubois, Ghislain
    Pan-European Mountain Tourism Meteorological and Snow Indicators2019Inngår i: Geophysical Research Abstracts, 2019, Vol. 21, artikkel-id EGU2019-4817Konferansepaper (Fagfellevurdert)
  • 106.
    Nilsson, Annika E.
    et al.
    Umeå universitet, Arktiskt centrum vid Umeå universitet (Arcum). Stockholm Environm Inst, Box 24218, SE-10451 Stockholm, Sweden.
    Bay-Larsen, Ingrid
    Carlsen, Henrik
    van Oort, Bob
    Bjorkan, Maiken
    Jylha, Kirsti
    Klyuchnikova, Elena
    Masloboev, Vladimir
    van der Watt, Lize-Marie
    Umeå universitet, Arktiskt centrum vid Umeå universitet (Arcum). Royal Inst Technol KTH, Div Hist Sci Technol & Environm, Sch Architecture & Built Environm, SE-10044 Stockholm, Sweden.
    Towards extended shared socioeconomic pathways: A combined participatory bottom-up and top-down methodology with results from the Barents region2017Inngår i: Global Environmental Change, ISSN 0959-3780, E-ISSN 1872-9495, Vol. 45, s. 124-132Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A major challenge in planning for adaptation to climate change is to assess future development not only in relation to climate but also in relation to social, economic and political changes that affect the capacity for adaptation or otherwise play a role in decision making. One approach is to use scenario methods. This article presents a methodology that combines top-down scenarios and bottom-up approaches to scenario building, with the aim of articulating local so-called extended socio-economic pathways. Specifically, we used the Shared Socioeconomic Pathways (SSPs) of the global scenario framework as developed by the climate research community to present boundary conditions about potential global change in workshop discussion with local and regional actors in the Barents region. We relate the results from these workshops to the different elements of the global SSPs and discuss potential and limitations of the method in relation to use in decision making processes.

  • 107.
    Nilsson, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Keskitalo, E. Carina H.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Vlassova, Tatiana
    Institute of Geography, Russian Academy of Sciences, Moscow, Russia.
    Sutinen, Marja-Liisa
    The Finnish Forest Research Institute, Rovaniemi, Finland.
    Moen, Jon
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Chapin III, F. Stuart
    Institute of Arctic Biology, University of Alaska, Fairbanks, Alaska, USA.
    Challenges to adaptation in northernmost Europe as a result of global climate change2010Inngår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 39, nr 1, s. 81-84Artikkel i tidsskrift (Annet vitenskapelig)
  • 108.
    Nilsson, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Polvi, Lina E
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lind, Lovisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Extreme events in streams and rivers in arctic and subarctic regions in an uncertain future2015Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 60, nr 12, s. 2535-2546Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We review the predicted changes in extreme events following climate change in flowing waters in arctic and subarctic regions. These regions are characterised by tundra or taiga ecosystems in either erosional or depositional glacial landforms or presently glacierised areas of the Northern Hemisphere. The ecological and geomorphic effects of extreme meteorological and hydrological events, such as episodes of strongly increased precipitation, temperatures and flows, can be exacerbated by altered base conditions. For example, winter temperature variations between frost and thaw will become more frequent at many places because mean temperature during the winter is closer to 0 °C, potentially leading to changes in the production of ice and intensified disturbance of riparian and aquatic habitats during extreme floods. Additionally, thawing of permafrost and glaciers can lead to increased bank erosion because of thaw slump and glacial outburst floods. We discuss the abiotic and biotic effects of these and other extreme events, including heavy precipitation, floods, drought and extreme air or water temperatures, and summarise our findings in a model that aims to stimulate further research in this field.

  • 109.
    Nilsson, Christer
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Riis, Tenna
    Sarneel, Judith M.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Biology Department of Utrecht University, in the Netherlands.
    Svavarsdóttir, Kristín
    Ecological Restoration as a Means of Managing Inland Flood Hazards2018Inngår i: BioScience, ISSN 0006-3568, E-ISSN 1525-3244, Vol. 68, nr 2, s. 89-99Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many streams and rivers experience major floods. Historically, human societies have responded to such floods by moving away from them or by abating them, the latter with large negative impacts on stream and river ecology. Societies are currently implementing a strategy of "living with floods,"which may involve ecological restoration. It further involves flood mapping, forecasting, and warning systems. We evaluate 14 different stream-and river-restoration measures, which differ in their capacity to modify water retention and runoff. We discuss these restoration measures in the light of predicted changes in climate and flooding and discuss future restoration needs. We focus on the Nordic countries, where substantial changes in the water cycle are foreseen. We conclude that sustainable solutions require researchers to monitor the effect of flood management and study the relative importance of individual restoration measures, as well as the side effects of flood attenuation.

  • 110. Nogues-Bravo, David
    et al.
    Rodriguez-Sanchez, Francisco
    Orsini, Luisa
    de Boer, Erik
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Morlon, Helene
    Fordham, Damien A.
    Jackson, Stephen T.
    Cracking the code of biodiversity responses to past climate change2018Inngår i: Trends in Ecology & Evolution, ISSN 0169-5347, E-ISSN 1872-8383, Vol. 33, nr 10, s. 765-776Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    How individual species and entire ecosystems will respond to future climate change are among the most pressing questions facing ecologists. Past biodiversity dynamics recorded in the paleoecological archives show a broad array of responses, yet significant knowledge gaps remain. In particular, the relative roles of evolutionary adaptation, phenotypic plasticity, and dispersal in promoting survival during times of climate change have yet to be clarified. Investigating the paleo-archives offers great opportunities to understand biodiversity responses to future climate change. In this review we discuss the mechanisms by which biodiversity responds to environmental change, and identify gaps of knowledge on the role of range shifts and tolerance. We also outline approaches at the intersection of paleoecology, genomics, experiments, and predictive models that will elucidate the processes by which species have survived past climatic changes and enhance predictions of future changes in biological diversity.

  • 111.
    Norlin, Linnea
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Byström, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Climate Impacts Research Centre (CIRC), Department of Ecology and Environmental Science, Umeå University, Abisko, Sweden.
    Johansson, Martin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Liess, Antonia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Climate change will alter amphibian-mediated nutrient pathways: evidence from Rana temporaria tadpoles in experimental ponds2016Inngår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 61, nr 4, s. 472-485Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    1. With global warming, mean temperatures and brownification of many waterbodies are predicted to increase. This may have unknown consequences on aquatic consumer life histories and nutrient content, consumer-mediated nutrient recycling, and nutrient transport between water and land.

    2. Using a large-scale experimental pond facility, we altered temperature (ambient/+ 4 degrees C) and brownification (clear/humic) in a 2 x 2 factorial design (n = 16 pond sections) to test two aspects of climate change on Rana temporaria tadpole life-history traits and on tadpole-mediated nutrient pathways. On day 16 after hatching, we examined tadpole-mediated nutrient recycling by measuring tadpole nutrient excretion and egestion rates and tadpole body nutrient content. We estimated tadpole growth and development rates from hatching to emergence and measured emergent frog body size and body nutrient content.

    3. Brownification increased total pond water nutrient availability and total pond water nitrogen (N) : phosphorous (P) ratios. Warming positively affected tadpole growth and development rates, whereas browning increased tadpole growth rate only under ambient temperatures. Emergent frog body P content decreased with warming, but only in the clear treatments. But despite these variations in body nutrient content, body stoichiometry remained within a relatively narrow stoichiometric range for both emergent frogs (P content: 1.4-1.8%, N content: 11.4-11.8% and carbon [C] content: 46.9-51.3%) and tadpoles (P content: 1.1-1.2%, N content: 10.1-11.7% and C content: 48.0-50.5%). Warming increased tadpole body P content and browning had a positive effect on tadpole body N content and tadpole N excretion rates, probably mediated by the increased pond water total N availability.

    4. We conclude that warming and brownification will interact in changing aquatic consumer growth and body nutrient stoichiometry. In addition, warming has the potential to affect emergent frog body nutrient content and may thus affect nutrient transport from water to land. Last, by increasing pond water N availability, brownification appears to intensify consumer P limitation and thus amplify consumer-meditated N recycling.

  • 112.
    Olid, Carolina
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Bindler, Richard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Mats B.
    Eriksson, Tobias
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Effects of warming and increased nitrogen and sulfur deposition on boreal mire geochemistry2017Inngår i: Applied Geochemistry, ISSN 0883-2927, E-ISSN 1872-9134, Vol. 78, s. 149-157Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Boreal mire ecosystems are predicted to experience warmer air temperatures as well as changed deposition loads of nitrogen and sulfur during the coming century. In this study, we hypothesized that vegetation changes that accompany these new environmental conditions alter the chemical composition of peat. To test this hypothesis, we quantified changes in peat geochemistry (Al, Ca, Fe, Mg, Na, P, Pb, and Zn) that have occurred in field manipulation plots exposed to 12 years of warming and nitrogen and sulfur additions in a nutrient-poor boreal mire. In Contrast to non-nutrients with a mainly atmospheric origin (i.e. Pb), Al-normalized inventories of micronutrients (Zn and Fe) and macronutrients (P and Ca) were significantly (P < 0.05) higher as a result of warming. For P and Ca, enrichments were also induced by nitrogen additions alone. These results suggest that mires evolving under increasing temperatures and availability of nitrogen are around two times More effective in storing nutrients in the accumulating peat. Our study provides the first empirical evidence that predicted changes in climate and nitrogen deposition scenarios will increase the retention of Ca, Fe, P, and Zn in surface peat of boreal mires in the near future, which may cause a depletion of nutrients released to inland waters dependent on mire inputs.

  • 113.
    Olofsson, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Tommervik, Hans
    Callaghan, Terry V.
    Vole and lemming activity observed from space2012Inngår i: Nature Climate Change, ISSN 1758-678X, E-ISSN 1758-6798, Vol. 2, nr 12, s. 880-883Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Predicting the impacts of present global warming requires an understanding of the factors controlling plant biomass and production. The extent to which they are controlled by bottom-up drivers such as climate, nutrient and water availability, and by top-down drivers such as herbivory and diseases in terrestrial systems is still under debate(1). By annually recording plant biomass and community composition in grazed control plots and in herbivore-free exclosures, at 12 sites in a subArctic ecosystem, we were able to show that the regular interannual density fluctuations of voles and lemmings drive synchronous interannual fluctuations in the biomass of field-layer vegetation. Plant biomass in the field layer was between 12 and 24% lower the year after a vole peak than the year before, and the combined vole and lemming peaks are visible as a reduced normalized difference vegetation index in satellite images over a 770 km(2) area in the following year, despite the wide range of abiotic, biotic and anthropogenic forces that influence the vegetation(2-5). This strongly suggests that the cascading effect of rodents for the function and diversity of tundra plant communities needs to be included in our scenarios of how these ecosystems will respond to environmental changes.

  • 114.
    Orru, Hans
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin. Institute of Family Medicine and Public Health, University of Tartu, Tartu, Estonia.
    Åström, Christofer
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Andersson, Camilla
    Tamm, Tanel
    Ebi, Kristie L.
    Forsberg, Bertil
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin.
    Ozone and heat-related mortality in Europe in 2050 significantly affected by changes in climate, population and greenhouse gas emission2019Inngår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 14, nr 7, artikkel-id 074013Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climate change is expected to increase to extreme temperatures and lead to more intense formation of near-surface ozone. Higher temperatures can cause heat stress and ozone is a highly oxidative pollutant; both increase cardiorespiratory mortality. Using greenhouse gas and ozone precursor emission scenarios, global and regional climate and chemistry-transport models, epidemiological data, and population projections, we projected ozone- and heat-related health risks under a changing climate. European near-surface temperature was modelled with the regional climate model (RCA4), forced by the greenhouse gas emission scenario RCP4.5 and the global climate model EC-EARTH, and near-surface ozone was modelled with the Multi-scale Atmospheric Transport and Chemistry (MATCH) model. Two periods were compared: recent climate in 1991-2000 and future climate in 2046-2055, projecting around a 2 degrees increase in global temperatures by that time. Projections of premature mortality considered future climate, future population, and future emissions separately and jointly to understand the relative importance of their contributions. Ozone currently causes 55 000 premature deaths annually in Europe due to long-term exposure, including a proportion of the estimated 26 000 deaths per year due to short-term exposures. When only taking into account the impact of a changing climate, up to an 11% increase in ozone-associated mortality is expected in some countries in Central and Southern Europe in 2050. However, projected decreases in ozone precursor emissions are expected to result in a decrease in ozone-related mortality (-30% as EUaverage). Due to aging and increasingly susceptible populations, the decrease in 2050 would be smaller, up to -24%. During summer months, ozone risks could combine with increasing temperatures, especially during the hottest periods and in densely populated urban areas. While the heat burden is currently of the same order of magnitude as ozone, due to increasing temperatures and decreasing ozone precursor emissions, heat-related mortality could be twice as large as ozone-related mortality in 2050.

  • 115. Plikk, Anna
    et al.
    Helmens, Karin F.
    Fernandez-Fernandez, Maria
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Kylander, Malin
    Löwemark, Ludvig
    Risberg, Jan
    Salonen, J. Sakari
    Valiranta, Minna
    Weckström, Jan
    Development of an Eemian (MIS 5e) Interglacial palaeolake at Sokli (N Finland) inferred using multiple proxies2016Inngår i: Palaeogeography, Palaeoclimatology, Palaeoecology, ISSN 0031-0182, E-ISSN 1872-616X, Vol. 463, s. 11-26Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A 12 m long lacustrine record from Sokli, N Finland, was analyzed for diatoms, non-pollen palynomorphs, macrofossils, pollen and geochemistry in order to reconstruct the development of a high-latitude Eemian lake and investigate the influence of climatic and environmental changes on the lake ecosystem. Based on this multi-proxy dataset we distinguished five major lake phases in the lake's evolution. An initial minerogenic, glacio-lacustrine phase was followed by an organic-rich early Eemian lake phase characterized by anoxic bottom waters, high seasonality and rising nutrient levels. A long open water season, pronounced summer stratification and high productivity characterized the following early mid-Eemian lake phase, corresponding to the Eemian thermal maximum. During the late mid-Eemian lake phase decreasing water depths due to infilling and extensive mixing of the water column resulted in less stable summer stratification and decreased anoxia. The late-Eemian lake phase was characterized by shallow and dynamic conditions and a cooling climate. Superimposed on these general trends are two events characterized by colder and more arid conditions, that possibly match cold and arid events registered in palaeolimnological records on the European continent. In general, the multi-proxy record reflects a nutrient rich lake, where changes in mixing regime associated with climatic forcing and lake level changes asserted a major impact on the aquatic assemblages. The changes in the aquatic assemblages reflect the major patterns of climate change that took place during the Eemian in northern Europe; i.e. a rapid warming and high seasonality during the early Eemian, decreased seasonality during the mid Eemian and a cooling late Eemian with increased seasonality. The high latitude Sokli Eemian palaeolake record lengthens the latitudinal extent of Eemian terrestrial records across Europe, adding to the understanding of climatic gradients and drivers over Europe.

  • 116. Portner, H.
    et al.
    Bugmann, H.
    Wolf, A.
    Forest Ecology, Institute of Terrestrial Ecosystems, Department of Environmental Sciences, ETH Zürich, 8092 Zürich, Switzerland.
    Temperature response functions introduce high uncertainty in modelled carbon stocks in cold temperature regimes2010Inngår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 7, nr 11, s. 3669-3684Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Models of carbon cycling in terrestrial ecosystems contain formulations for the dependence of respiration on temperature, but the sensitivity of predicted carbon pools and fluxes to these formulations and their parameterization is not well understood. Thus, we performed an uncertainty analysis of soil organic matter decomposition with respect to its temperature dependency using the ecosystem model LPJ-GUESS. <br><br> We used five temperature response functions (Exponential, Arrhenius, Lloyd-Taylor, Gaussian, Van’t Hoff). We determined the parameter confidence ranges of the formulations by nonlinear regression analysis based on eight experimental datasets from Northern Hemisphere ecosystems. We sampled over the confidence ranges of the parameters and ran simulations for each pair of temperature response function and calibration site. We analyzed both the long-term and the short-term heterotrophic soil carbon dynamics over a virtual elevation gradient in southern Switzerland. <br><br> The temperature relationship of Lloyd-Taylor fitted the overall data set best as the other functions either resulted in poor fits (Exponential, Arrhenius) or were not applicable for all datasets (Gaussian, Van’t Hoff). There were two main sources of uncertainty for model simulations: (1) the lack of confidence in the parameter estimates of the temperature response, which increased with increasing temperature, and (2) the size of the simulated soil carbon pools, which increased with elevation, as slower turn-over times lead to higher carbon stocks and higher associated uncertainties. Our results therefore indicate that such projections are more uncertain for higher elevations and hence also higher latitudes, which are of key importance for the global terrestrial carbon budget. 

  • 117. Qian, Chaoju
    et al.
    Yin, Hengxia
    Shi, Yong
    Zhao, Jiecai
    Yin, Chengliang
    Luo, Wanyin
    Dong, Zhibao
    Chen, Guoxiong
    Yan, Xia
    Wang, Xiao-Ru
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ma, Xiao-Fei
    Population dynamics of Agriophyllum squarrosum, a pioneer annual plant endemic to mobile sand dunes, in response to global climate change2016Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikkel-id 26613Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climate change plays an important role in the transition of ecosystems. Stratigraphic investigations have suggested that the Asian interior experienced frequent transitions between grassland and desert ecosystems as a consequence of global climate change. Using maternally and bi-parentally inherited markers, we investigated the population dynamics of Agriophyllum squarrosum (Chenopodiaceae), an annual pioneer plant endemic to mobile sand dunes. Phylogeographic analysis revealed that A. squarrosum could originate from Gurbantunggut desert since similar to 1.6 Ma, and subsequently underwent three waves of colonisation into other deserts and sandy lands corresponding to several glaciations. The rapid population expansion and distribution range shifts of A. squarrosum from monsoonal climate zones suggested that the development of the monsoonal climate significantly enhanced the population growth and gene flow of A. squarrosum. These data also suggested that desertification of the fragile grassland ecosystems in the Qinghai-Tibetan Plateau was more ancient than previously suggested and will be aggravated under global warming in the future. This study provides new molecular phylogeographic insights into how pioneer annual plant species in desert ecosystems respond to global climate change, and facilitates evaluation of the ecological potential and genetic resources of future crops for non-arable dry lands to mitigate climate change.

  • 118. Reckien, D.
    et al.
    Salvia, M.
    Pietrapertosa, F.
    Simoes, S. G.
    Olazabal, M.
    Hurtado, S. De Gregorio
    Geneletti, D.
    Lorencova, E. Krkoska
    D'Alonzo, V
    Krook-Riekkola, A.
    Fokaides, P. A.
    Ioannou, B. I.
    Foley, A.
    Orru, Hans
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin. Faculty of Medicine, University of Tartu, Tartu, Estonia.
    Orru, K.
    Wejs, A.
    Flacke, J.
    Church, J. M.
    Feliu, E.
    Vasilie, S.
    Nador, C.
    Matosovic, M.
    Flamos, A.
    Spyridaki, N-A
    Balzan, M. , V
    Fulop, O.
    Grafakos, S.
    Paspaldzhiev, I
    Heidrich, O.
    Dedicated versus mainstreaming approaches in local climate plans in Europe2019Inngår i: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, Vol. 112, s. 948-959Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Cities are gaining prominence committing to respond to the threat of climate change, e.g., by developing local climate plans or strategies. However, little is known regarding the approaches and processes of plan development and implementation, or the success and effectiveness of proposed measures. Mainstreaming is regarded as one approach associated with (implementation) success, but the extent of integration of local climate policies and plans in ongoing sectoral and/or development planning is unclear. This paper analyses 885 cities across the 28 European countries to create a first reference baseline on the degree of climate mainstreaming in local climate plans. This will help to compare the benefits of mainstreaming versus dedicated climate plans, looking at policy effectiveness and ultimately delivery of much needed climate change efforts at the city level. All core cities of the European Urban Audit sample were analyzed, and their local climate plans classified as dedicated or mainstreamed in other local policy initiatives. It was found that the degree of mainstreaming is low for mitigation (9% of reviewed cities; 12% of the identified plans) and somewhat higher for adaptation (10% of cities; 29% of plans). In particular horizontal mainstreaming is a major effort for local authorities; an effort that does not necessarily pay off in terms of success of action implementation. This study concludes that climate change issues in local municipalities are best tackled by either, developing a dedicated local climate plan in parallel to a mainstreamed plan or by subsequently developing first the dedicated and later a mainstreaming plan (joint or subsequent "dual track approach"). Cities that currently provide dedicated local climate plans (66% of cities for mitigation; 26% of cities for adaptation) may follow-up with a mainstreaming approach. This promises effective implementation of tangible climate actions as well as subsequent diffusion of climate issues into other local sector policies. The development of only broad sustainability or resilience strategies is seen as critical.

  • 119. Reckien, Diana
    et al.
    Salvia, Monica
    Heidrich, Oliver
    Church, Jon Marco
    Pietrapertosa, Filomena
    De Gregorio-Hurtado, Sonia
    D'Alonzo, Valentina
    Foley, Aoife
    Simoes, Sofia G.
    Lorencova, Eliska Krkoska
    Orru, Hans
    Umeå universitet, Medicinska fakulteten, Institutionen för folkhälsa och klinisk medicin, Yrkes- och miljömedicin. Faculty of Medicine, University of Tartu, Ravila 19, 51007 Tartu, Estonia.
    Orru, Kati
    Wejs, Anja
    Flacke, Johannes
    Olazabal, Marta
    Geneletti, Davide
    Feliu, Efren
    Vasilie, Sergiu
    Nador, Cristiana
    Krook-Riekkola, Anna
    Matosovic, Marko
    Fokaides, Paris A.
    Ioannou, Byron I.
    Flamos, Alexandros
    Spyridaki, Niki-Artemis
    Balzan, Mario V.
    Fulop, Orsolya
    Paspaldzhiev, Ivan
    Grafakos, Stelios
    Dawson, Richard
    How are cities planning to respond to climate change?: Assessment of local climate plans from 885 cities in the EU-282018Inngår i: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 191, s. 207-219Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Paris Agreement aims to limit global mean temperature rise this century to well below 2 degrees C above pre-industrial levels. This target has wide-ranging implications for Europe and its cities, which are the source of substantial greenhouse gas emissions. This paper reports the state of local planning for climate change by collecting and analysing information about local climate mitigation and adaptation plans across 885 urban areas of the EU-28. A typology and framework for analysis was developed that classifies local climate plans in terms of their alignment with spatial (local, national and international) and other climate related policies. Out of eight types of local climate plans identified in total we document three types of stand-alone local climate plans classified as type Al (autonomously produced plans), A2 (plans produced to comply with national regulations) or A3 (plans developed for international climate networks). There is wide variation among countries in the prevalence of local climate plans, with generally more plans developed by central and northern European cities. Approximately 66% of EU cities have a type Al, A2, or A3 mitigation plan, 26% an adaptation plan, and 17% a joint adaptation and mitigation plan, while about 33% lack any form of stand-alone local climate plan (i.e. what we classify as Al, A2, A3 plans). Mitigation plans are more numerous than adaptation plans, but planning for mitigation does not always precede planning for adaptation. Our analysis reveals that city size, national legislation, and international networks can influence the development of local climate plans. We found that size does matter as about 80% of the cities with above 500,000 inhabitants have a comprehensive and stand-alone mitigation and/or an adaptation plan (Al). Cities in four countries with national climate legislation (A2), i.e. Denmark, France, Slovakia and the United Kingdom, are nearly twice as likely to produce local mitigation plans, and five times more likely to produce local adaptation plans, compared to cities in countries without such legislation. Al and A2 mitigation plans are particularly numerous in Denmark, Poland, Germany, and Finland: while Al and A2 adaptation plans are prevalent in Denmark, Finland, UK and France. The integration of adaptation and mitigation is country-specific and can mainly be observed in two countries where local climate plans are compulsory, i.e. France and the UK. Finally, local climate plans produced for international climate networks (A3) are mostly found in the many countries where autonomous (type Al) plans are less common. This is the most comprehensive analysis of local climate planning to date. The findings are of international importance as they will inform and support decision making towards climate planning and policy development at national, EU and global level being based on the most comprehensive and up-to-date knowledge of local climate planning available to date. 

  • 120.
    Reyer, C.P.O.
    et al.
    Potsdam Inst Climate Impact Res, D-14412 Potsdam, Germany.
    Leuzinger, S
    Auckland Univ Technol, Sch Appl Sci, Auckland 1142, New Zealand; ETH, Inst Terr Ecosyst ITES, CH-8092 Zurich, Switzerland; Univ Basel, Inst Bot, CH-4056 Basel, Switzerland.
    Rammig, A
    Potsdam Inst Climate Impact Res, D-14412 Potsdam, Germany.
    Wolf, A
    ETH, Inst Terr Ecosyst ITES, CH-8092 Zurich, Switzerland.
    Bartholomeus, R.P.
    KWR Watercycle Res Inst, NL-3430 BB Nieuwegein, Netherlands.
    Bonfante, A.
    Natl Res Council Italy, Inst Mediterranean Agr & Forest Syst CNR ISAFoM, I-80056 Ercolano, NA, Italy.
    de Lorenzi, F
    Natl Res Council Italy, Inst Mediterranean Agr & Forest Syst CNR ISAFoM, I-80056 Ercolano, NA, Italy.
    Dury, M.
    Univ Liege, Unite Modelisat Climat & Cycles Biogeochim, B-4000 Liege, Belgium.
    Gloning, P.
    Tech Univ Munich, Chair Ecoclimatol, D-85354 Freising Weihenstephan, Germany.
    Abou Jaoude, R.
    Univ Tuscia, Dept Innovat Biol Agrofood & Forest Syst DIBAF, I-01100 Viterbo, Italy.
    Klein, T
    Weizmann Inst Sci, Dept Environm Sci & Energy Res, IL-76100 Rehovot, Israel.
    Kuster, T.M.
    ETH, Inst Terr Ecosyst ITES, CH-8092 Zurich, Switzerland; Swiss Fed Res Inst WSL, CH-8903 Birmensdorf, Switzerland.
    Martins, M.
    Univ Lisbon, Inst Geog & Spatial Planning IGOT, P-1600214 Lisbon, Portugal.
    Niedrist, G.
    European Acad Bolzano Bozen, Inst Alpine Environm, I-39100 Bolzano, Italy; Univ Innsbruck, Inst Ecol, A-6020 Innsbruck, Austria.
    Riccardi, M.
    Natl Res Council Italy, Inst Mediterranean Agr & Forest Syst CNR ISAFoM, I-80056 Ercolano, NA, Italy.
    Wohlfahrt, G
    Univ Innsbruck, Inst Ecol, A-6020 Innsbruck, Austria.
    de Angelis, P.
    Univ Tuscia, Dept Innovat Biol Agrofood & Forest Syst DIBAF, I-01100 Viterbo, Italy.
    Francois, F.
    Univ Liege, Unite Modelisat Climat & Cycles Biogeochim, B-4000 Liege, Belgium.
    Menzel, A.
    Tech Univ Munich, Chair Ecoclimatol, D-85354 Freising Weihenstephan, Germany.
    Pereira, M
    Univ Evora, Dept Landscape Environm & Planning, P-7000671 Evora, Portugal.
    A plant's perspective of extremes: terrestrial plant responses to changing climatic variability2013Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 19, nr 1, s. 75-89Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We review observational, experimental, and model results on how plants respond to extreme climatic conditions induced by changing climatic variability. Distinguishing between impacts of changing mean climatic conditions and changing climatic variability on terrestrial ecosystems is generally underrated in current studies. The goals of our review are thus (1) to identify plant processes that are vulnerable to changes in the variability of climatic variables rather than to changes in their mean, and (2) to depict/evaluate available study designs to quantify responses of plants to changing climatic variability. We find that phenology is largely affected by changing mean climate but also that impacts of climatic variability are much less studied, although potentially damaging. We note that plant water relations seem to be very vulnerable to extremes driven by changes in temperature and precipitation and that heatwaves and flooding have stronger impacts on physiological processes than changing mean climate. Moreover, interacting phenological and physiological processes are likely to further complicate plant responses to changing climatic variability. Phenological and physiological processes and their interactions culminate in even more sophisticated responses to changing mean climate and climatic variability at the species and community level. Generally, observational studies are well suited to study plant responses to changing mean climate, but less suitable to gain a mechanistic understanding of plant responses to climatic variability. Experiments seem best suited to simulate extreme events. In models, temporal resolution and model structure are crucial to capture plant responses to changing climatic variability. We highlight that a combination of experimental, observational, and/or modeling studies have the potential to overcome important caveats of the respective individual approaches.

  • 121. Rice, Stephen
    et al.
    Stoffel, Markus
    Turowski, Jens M
    Wolf, Annett
    Swiss Fed Inst Technol, Inst Terr Ecosyst, Dept Environm Sci, CH-8092 Zurich, Switzerland.
    Disturbance regimes at the interface of geomorphology and ecology2012Inngår i: Earth Surface Processes and Landforms, ISSN 0197-9337, E-ISSN 1096-9837, Vol. 37, nr 15, s. 1678-1682Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Geomorphological processes are an integral part of ecosystem functioning and ecosystem functioning affects geomorphological processes. Increasingly widespread acknowledgement of this simple idea is manifest in a vigorous research community engaged with questions that address the two-way interaction between biota and geomorphology, at a range of scales and in a variety of terrestrial and aquatic environments. Geomorphological disturbances are a core element of biogeomorphological interest, and although the disciplines of geomorphology and ecology have each developed languages and theories that help to explore, model and understand disturbance events, little attempt has been made to draw together these approaches. Following a brief review of these issues, we introduce thirteen papers that investigate the interactions and feedbacks between geomorphological disturbance regimes and ecosystem functions. These papers reveal the singularity of wildfire impacts, the importance of landsliding for carbon budgeting and of vegetation accumulation for landsliding, the zoogeomorphic role of iconic and Cinderella animals in fluvial geomorphology, biophysical interactions in aeolian, fluvial and torrential environments and the utility of living ecosystems as archives of geomorphic events. Most of these papers were first presented in a conference session at the European Geoscience Union General Assembly in 2010 and several others are from recent volumes of Earth Surface Processes and Landforms.

  • 122. Roderfeld, Hedwig
    et al.
    Blyth, Eleanor
    Dankers, Rutger
    Huse, Geir
    Slagstad, Dag
    Ellingsen, Ingrid
    Wolf, Annett
    Umeå universitet. ETH Zentrum, CH-8092 Zurich, Switzerland.
    Lange, Manfred A.
    Potential impact of climate change on ecosystems of the Barents Sea Region2008Inngår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 87, nr 1-2, s. 283-303Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The EU project BALANCE (Global Change Vulnerabilities in the Barents region: Linking Arctic Natural Resources, Climate Change and Economies) aims to assess vulnerability to climate change in the Barents Sea Region. As a prerequisite the potential impact of climate change on selected ecosystems of the study area has to be quantified, which is the subject of the present paper. A set of ecosystem models was run to generate baseline and future scenarios for 1990, 2020, 2050 and 2080. The models are based on data from the Regional Climate Model (REMO), driven by a GCM which in turn is forced by the IPCC-B2 scenario. The climate change is documented by means of the Koppen climate classification. Since the multitude of models requires the effect of climate change on individual terrestrial and marine systems to be integrated, the paper concentrates on a standardised visualisation of potential impacts by use of a Geographical Information System for the timeslices 2050 and 2080. The resulting maps show that both terrestrial and marine ecosystems of the Barents region will undergo significant changes until both 2050 and 2080.

  • 123.
    Rodríguez-Castañeda, Genoveva
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Ecology and Evolution Department, Stony Brook University, Stony Brook, NY, USA.
    The world and its shades of green: a meta-analysis on trophic cascades across temperature and precipitation gradients2013Inngår i: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 22, nr 1, s. 118-130Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: To assess effects of current global temperature and precipitation gradients on the trophic function of plant-herbivore-predator interactions. Specifically, I study effects of climatic gradients on factors that control herbivore abundances: top-down, bottom-up trophic cascades and plant defences. I include predictions of climate change on shifts in trophic function, under the assumption that temperature and precipitation affect the physiology and performance of plants, herbivores and predators.

    Location: Global.

    Methods: A search of the relevant experiments on trophic interactions was conducted using the Web of Science and Scielo databases. Strength of trophic interactions from each experiment was studied by the calculation of the log ratio effect size (Ln R) of the control and experimental means. Each study was georeferenced and mean annual temperature (MAT) and total annual precipitation (TAP) were determined for each study location. Effect size of trophic interaction studies across the world were correlated with these environmental variables.

    Results: In total, 387 effect sizes were extracted from the literature. With the exception of bottom-up trophic cascades, trophic interactions and factors controlling herbivore abundance exhibited significant linear or quadratic relationships with either temperature or precipitation gradients: plant growth, predation and the effect of plant defence on herbivores increased with temperature. In contrast, plant growth and herbivory increased with precipitation across ecosystems. Finally, top-down trophic cascades increased towards the extremes of MAT and TAP gradients.

    Main conclusions: This study shows climatic gradients not only affect species geographic distributions and physiological tolerance but also the strength of their trophic functionality. This is especially true for the main biotic controls of herbivore populations (i.e. predation, top-down trophic cascades and plant defences). These results suggest future climate change will cause shifts in the strength of trophic interactions, resulting in increased or reduced population control of herbivores across global ecosystems.

  • 124.
    Rydberg, Johan
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Martinez-Cortizas, A.
    Geochemical assessment of an annually laminated lake sediment record from northern Sweden: a multi-core, multi-element approach2014Inngår i: Journal of Paleolimnology, ISSN 0921-2728, E-ISSN 1573-0417, Vol. 51, nr 4, s. 499-514Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    We used seven annually laminated (varved) sediment cores from Nylandssjon, a lake in northern Sweden, to assess between-core variation and diagenetic changes at annual resolution. By using several cores, multiple elements and employing principal components analysis (PCA), we also studied how the geochemical composition changed over time, and assessed to what extent these changes were related to variations in the weather. There are between-core differences for aluminum, silica, lead, titanium, zirconium and dry-mass accumulation rate. Diagenesis causes a decrease in bromine, as well as carbon, nitrogen and varve thickness, as reported in previous publications. In spite of anoxic bottom waters phosphorus is not lost from the sediment. In fact, there is an increase in phosphorus concentrations with time. The PCA identified four principal components (PCs). PC-1 accounts for the relative content of mineral and organic material; PC-2 represents mineral-particle grain size; PC-3 reflects phosphorus loading and PC-4 reflects atmospheric pollution. Variations in the weather partly explain the temporal patterns in PC-1 and PC-2: cold winters, i.e. more accumulation of snow, resulted in more mineral than organic matter (i.e. higher PC-1 scores), and increased the relative amount of coarse-grained mineral particles in the sediment (i.e. lower PC-2 scores). Increased spring precipitation had a weak positive effect on the PC-2 scores by promoting the transport of fine-grained material. However, the influence of weather is weak, explaining at most 30 % of the variance, and hence, other factors, e.g. land use and its effect on soil erosion, seem to be more important for the sediment geochemical composition. The importance of land use is also exemplified by an increase in PC-3 scores in the late 1970s, which can be attributed to a shift in agricultural practices that resulted in increased phosphorus loading to the lake. In summary, our findings show that down-core trends are reproducible between cores, but between-core variability and diagenesis need to be considered when interpreting some elements. We also conclude that there is a need to constrain temporal changes in land use before using lake sediments to study changes in weather or climate.

  • 125. Schlaepfer, Daniel R.
    et al.
    Bradford, John B.
    Lauenroth, William K.
    Munson, Seth M.
    Tietjen, Britta
    Hall, Sonia A.
    Wilson, Scott D.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Biology, University of Regina, Regina, Saskatchewan, Canada.
    Duniway, Michael C.
    Jia, Gensuo
    Pyke, David A.
    Lkhagva, Ariuntsetseg
    Jamiyansharav, Khishigbayar
    Climate change reduces extent of temperate drylands and intensifies drought in deep soils2017Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 8, artikkel-id 14196Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Drylands cover 40% of the global terrestrial surface and provide important ecosystem services. While drylands as a whole are expected to increase in extent and aridity in coming decades, temperature and precipitation forecasts vary by latitude and geographic region suggesting different trajectories for tropical, subtropical, and temperate drylands. Uncertainty in the future of tropical and subtropical drylands is well constrained, whereas soil moisture and ecological droughts, which drive vegetation productivity and composition, remain poorly understood in temperate drylands. Here we show that, over the twenty first century, temperate drylands may contract by a third, primarily converting to subtropical drylands, and that deep soil layers could be increasingly dry during the growing season. These changes imply major shifts in vegetation and ecosystem service delivery. Our results illustrate the importance of appropriate drought measures and, as a global study that focuses on temperate drylands, highlight a distinct fate for these highly populated areas.

  • 126.
    Seekell, David A.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia, USA.
    Carr, Joel A.
    Department of Environmental Sciences, University of Virginia, Charlottesville, Virginia, USA.
    Gudasz, Cristian
    Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey, USA.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Upscaling carbon dioxide emissions from lakes2014Inngår i: Geophysical Research Letters, ISSN 0094-8276, E-ISSN 1944-8007, Vol. 41, nr 21, s. 7555-7559Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quantifying CO2 fluxes from lakes to the atmosphere is important for balancing regional and global-scale carbon budgets. CO2 emissions are estimated through statistical upscaling procedures that aggregate data from a large number of lakes. However, aggregation can bias flux estimates if the physical and chemical factors determining CO2 exchange between water and the atmosphere are not independent. We evaluated the magnitude of aggregation biases with moment expansions and pCO(2) data from 5140 Swedish lakes. The direction of the aggregation bias depends on lake size; mean flux was overestimated by 4% for small lakes (0.01-0.1 km(2)) but underestimated by 13% for large lakes (100-1000 km(2)). Simple covariance-based correction factors were generated to adjust for upscaling biases. These correction factors represent an easily interpretable and implemented approach to improving the accuracy of regional and global estimates of lake CO2 emissions.

  • 127.
    Serikova, Svetlana
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Climate Impacts Research Centre (CIRC), Umeå University, Umeå, Sweden.
    Pokrovsky, O. S.
    Laudon, H.
    Krickov, I. , V
    Lim, A. G.
    Manasypov, R. M.
    Karlsson, J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    High carbon emissions from thermokarst lakes of Western Siberia2019Inngår i: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 10, artikkel-id 1552Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The Western Siberia Lowland (WSL), the world's largest permafrost peatland, is of importance for understanding the high-latitude carbon (C) cycle and its response to climate change. Warming temperatures increase permafrost thaw and production of greenhouse gases. Also, permafrost thaw leads to the formation of lakes which are hotspots for atmospheric C emissions. Although lakes occupy similar to 6% of WSL, lake C emissions from WSL remain poorly quantified. Here we show high C emissions from lakes across all permafrost zones of WSL. The C emissions were especially high in shoulder seasons and in colder permafrost-rich regions. The total C emission from permafrost-affected lakes of WSL equals similar to 12 +/- 2.6 Tg C yr(-1) and is 2-times greater than region's C export to the Arctic coast. The results show that C emission from WSL lakes is a significant component in the high-latitude C cycle, but also suggest that C emission may decrease with warming.

  • 128. Shumilova, Oleksandra
    et al.
    Zak, Dominik
    Datry, Thibault
    von Schiller, Daniel
    Corti, Roland
    Foulquier, Arnaud
    Obrador, Biel
    Tockner, Klement
    Allan, Daniel C.
    Altermatt, Florian
    Isabel Arce, Maria
    Arnon, Shai
    Banas, Damien
    Banegas-Medina, Andy
    Beller, Erin
    Blanchette, Melanie L.
    Blanco-Libreros, Juan F.
    Blessing, Joanna
    Boechat, Iola Goncalves
    Boersma, Kate
    Bogan, Michael T.
    Bonada, Nuria
    Bond, Nick R.
    Brintrup, Kate
    Bruder, Andreas
    Burrows, Ryan
    Cancellario, Tommaso
    Carlson, Stephanie M.
    Cauvy-Fraunie, Sophie
    Cid, Nuria
    Danger, Michael
    de Freitas Terra, Bianca
    De Girolamo, Anna Maria
    del Campo, Ruben
    Dyer, Fiona
    Elosegi, Arturo
    Faye, Emile
    Febria, Catherine
    Figueroa, Ricardo
    Four, Brian
    Gessner, Mark O.
    Gnohossou, Pierre
    Cerezo, Rosa Gomez
    Gómez-Gener, Lluís
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Graca, Manuel A. S.
    Guareschi, Simone
    Guecker, Bjoern
    Hwan, Jason L.
    Kubheka, Skhumbuzo
    Langhans, Simone Daniela
    Leigh, Catherine
    Little, Chelsea J.
    Lorenz, Stefan
    Marshall, Jonathan
    McIntosh, Angus
    Mendoza-Lera, Clara
    Meyer, Elisabeth Irmgard
    Milisa, Marko
    Mlambo, Musa C.
    Moleon, Marcos
    Negus, Peter
    Niyogi, Dev
    Papatheodoulou, Athina
    Pardo, Isabel
    Paril, Petr
    Pesic, Vladimir
    Rodriguez-Lozano, Pablo
    Rolls, Robert J.
    Sanchez-Montoya, Maria Mar
    Savic, Ana
    Steward, Alisha
    Stubbington, Rachel
    Taleb, Amina
    Vander Vorste, Ross
    Waltham, Nathan
    Zoppini, Annamaria
    Zarfl, Christiane
    Simulating rewetting events in intermittent rivers and ephemeral streams: A global analysis of leached nutrients and organic matter2019Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 25, nr 5, s. 1591-1611Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climate change and human pressures are changing the global distribution and the extent of intermittent rivers and ephemeral streams (IRES), which comprise half of the global river network area. IRES are characterized by periods of flow cessation, during which channel substrates accumulate and undergo physico-chemical changes (preconditioning), and periods of flow resumption, when these substrates are rewetted and release pulses of dissolved nutrients and organic matter (OM). However, there are no estimates of the amounts and quality of leached substances, nor is there information on the underlying environmental constraints operating at the global scale. We experimentally simulated, under standard laboratory conditions, rewetting of leaves, riverbed sediments, and epilithic biofilms collected during the dry phase across 205 IRES from five major climate zones. We determined the amounts and qualitative characteristics of the leached nutrients and OM, and estimated their areal fluxes from riverbeds. In addition, we evaluated the variance in leachate characteristics in relation to selected environmental variables and substrate characteristics. We found that sediments, due to their large quantities within riverbeds, contribute most to the overall flux of dissolved substances during rewetting events (56%-98%), and that flux rates distinctly differ among climate zones. Dissolved organic carbon, phenolics, and nitrate contributed most to the areal fluxes. The largest amounts of leached substances were found in the continental climate zone, coinciding with the lowest potential bioavailability of the leached OM. The opposite pattern was found in the arid zone. Environmental variables expected to be modified under climate change (i.e. potential evapotranspiration, aridity, dry period duration, land use) were correlated with the amount of leached substances, with the strongest relationship found for sediments. These results show that the role of IRES should be accounted for in global biogeochemical cycles, especially because prevalence of IRES will increase due to increasing severity of drying events.

  • 129.
    Sullivan, Alexis R.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. School of Forest Resources and Environmental Science, Michigan Technological Univ., 1400 Townsend Drive, Houghton, MI 49931, USA.
    Flaspohler, David J.
    Froese, Robert E.
    Ford, Daena
    Climate variability and the timing of spring raptor migration in eastern North America2016Inngår i: Journal of Avian Biology, ISSN 0908-8857, E-ISSN 1600-048X, Vol. 47, nr 2, s. 208-218Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Many birds have advanced their spring migration and breeding phenology in response to climate change, yet some long-distance migrants appear constrained in their adjustments. In addition, bird species with long generation times and those in higher trophic positions may also be less able to track climate-induced shifts in food availability. Migratory birds of prey may therefore be particularly vulnerable to climate change because: 1) most are long-lived and have relatively low reproductive capacity, 2) many feed predominately on insectivorous passerines, and 3) several undertake annual migrations totaling tens of thousands of kilometers. Using multi-decadal datasets for 14 raptor species observed at six sites across the Great Lakes region of North America, we detected phenological shifts in spring migration consistent with decadal climatic oscillations and global climate change. While the North Atlantic and El Nino Southern Oscillations exerted heterogeneous effects on the phenology of a few species, arrival dates more generally advanced by 1.18 d per decade, a pattern consistent with the effects of global climate change. After accounting for heterogeneity across observation sites, five of the 10 most abundant species advanced the bulk of their spring migration phenology. Contrary to expectations, we found that long-distance migrants and birds with longer generation times tended to make the greatest advancements to their spring migration. Such results may indicate that phenotypic plasticity can facilitate climatic responses among these long-lived predators.

  • 130.
    Sundqvist, Maja
    et al.
    Institutionen för skogens ekologi och skötsel, SLU, Umeå.
    Giesler, Reiner
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Wardle, David
    Institutionen för skogens ekologi och skötsel, SLU, Umeå.
    Höjdgradienter hjälper oss att förstå den globala uppvärmningens påverkan i Arktis2013Rapport (Annet (populærvitenskap, debatt, mm))
    Abstract [en]

    Framtidens temperaturökningar orsakade av den globala uppvärmningen förväntas vara högst på högre breddgrader. Arktis ekosystem, där växtligheten är starkt begränsad av både låga temperaturer och låg näringstillgänglighet, är troligtvis också väldigt känsliga för denna temperaturökning. Mycket forskning i Arktis syftar till att förstå hur ekosystemen kommer att påverkas av framtida klimatförändringar och konsekvenserna av dessa för viktiga natur- och samhällsvärden. Eftersom temperaturen sjunker med ökad höjd har biologer länge använt sig av höjdgradienter för att studera hur växt- och djursamhällen påverkas av naturliga variationer i temperatur. Fjällen kring Abisko i norra Sverige erbjuder därför möjligheter för en ökad förståelse av hur Arktis växtlighet kan komma att påverkas av framtida klimatförändringar. Under 2007 och 2008 påbörjades undersökningar av förändringar i artsammansättning och näringsstatus (kväve och fosfor) för fattig hed och rikare ängsvegetation längs en höjdgradient (500–1000 meter) i närheten av Abisko, nordligaste Sverige. Temperaturen i mitten av sommaren sjunker med ungefär 0,6° per 100 meter höjdökning eller 3°C från den lägsta till högsta höjden längs den här gradienten. Artsammansättningen förändras mer för ängsvegetation än för hedvegetationen längs höjdgradienten. Växtsamhället under 2008 innehöll även mindre kväve relativt fosfor på de lägre (varmare) höjderna än på de högre och kallare höjderna. Förändringen i kväve- och fosforkvoter var också större för ängsvegetationen. Detta tyder på att förändringar i växtsamhällens artsammansättning, näringsstatus och näringsbegränsning med ökade temperaturer i Arktis kommer att skilja sig markant åt mellan rik och fattig vegetation.

  • 131.
    te Beest, Mariska
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Community and Conservation Ecology Group, University of Groningen, Groningen, The Netherlands.
    Elschot, Kelly
    Olff, Han
    Etienne, Rampal S.
    Invasion success in a marginal habitat: an experimental test of competitive ability and drought tolerance in Chromolaena odorata2013Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 8, nr 8, artikkel-id e68274Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climatic niche models based on native-range climatic data accurately predict invasive-range distributions in the majority of species. However, these models often do not account for ecological and evolutionary processes, which limit the ability to predict future range expansion. This might be particularly problematic in the case of invaders that occupy environments that would be considered marginal relative to the climatic niche in the native range of the species. Here, we assess the potential for future range expansion in the shrub Chromolaena odorata that is currently invading mesic savannas (>650 mm MAP) in South Africa that are colder and drier than most habitats in its native range. In a greenhouse experiment we tested whether its current distribution in South Africa can be explained by increased competitive ability and/or differentiation in drought tolerance relative to the native population. We compared aboveground biomass, biomass allocation, water use efficiency and relative yields of native and invasive C. odorata and the resident grass Panicum maximum in wet and dry conditions. Surprisingly, we found little differentiation between ranges. Invasive C. odorata showed no increased competitive ability or superior drought tolerance compared to native C. odorata. Moreover we found that P. maximum was a better competitor than either native or invasive C. odorata. These results imply that C. odorata is unlikely to expand its future range towards more extreme, drier, habitats beyond the limits of its current climatic niche and that the species' invasiveness most likely depends on superior light interception when temporarily released from competition by disturbance. Our study highlights the fact that species can successfully invade habitats that are at the extreme end of their ranges and thereby contributes towards a better understanding of range expansion during species invasions.

  • 132. Tennberg, Monica
    et al.
    Dale, Brigt
    Klyuchnikova, Elena
    Löf, Annette
    Umeå universitet, Humanistiska fakulteten, Centrum för samisk forskning (CeSam).
    Masloboev, Vladimir
    Scheepstra, Annette
    Kietaevaeinen, Asta
    Naskali, Päivi
    Rautio, Arja
    Local and regional perspectives on adaptation2017Inngår i: Adaptation actions for a changing Arctic: perspectives from the Barents area / [ed] Carolyn Symon, Oslo: Arctic Monitoring and Assessment Programme (AMAP) , 2017, s. 47-58Kapittel i bok, del av antologi (Fagfellevurdert)
  • 133. Tietjen, Britta
    et al.
    Schlaepfer, Daniel R.
    Bradford, John B.
    Lauenroth, William K.
    Hall, Sonia A.
    Duniway, Michael C.
    Hochstrasser, Tamara
    Jia, Gensuo
    Munson, Seth M.
    Pyke, David A.
    Wilson, Scott D.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Department of Biology, University of Regina, Regina, SK S4S 0A2, Canada.
    Climate change-induced vegetation shifts lead to more ecological droughts despite projected rainfall increases in many global temperate drylands2017Inngår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 23, nr 7, s. 2743-2754Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Drylands occur worldwide and are particularly vulnerable to climate change because dryland ecosystems depend directly on soil water availability that may become increasingly limited as temperatures rise. Climate change will both directly impact soil water availability and change plant biomass, with resulting indirect feedbacks on soil moisture. Thus, the net impact of direct and indirect climate change effects on soil moisture requires better understanding. We used the ecohydrological simulation model SOILWAT at sites from temperate dryland ecosystems around the globe to disentangle the contributions of direct climate change effects and of additional indirect, climate changeinduced changes in vegetation on soil water availability. We simulated current and future climate conditions projected by 16 GCMs under RCP 4.5 and RCP 8.5 for the end of the century. We determined shifts in water availability due to climate change alone and due to combined changes of climate and the growth form and biomass of vegetation. Vegetation change will mostly exacerbate low soil water availability in regions already expected to suffer from negative direct impacts of climate change (with the two RCP scenarios giving us qualitatively similar effects). By contrast, in regions that will likely experience increased water availability due to climate change alone, vegetation changes will counteract these increases due to increased water losses by interception. In only a small minority of locations, climate change-induced vegetation changes may lead to a net increase in water availability. These results suggest that changes in vegetation in response to climate change may exacerbate drought conditions and may dampen the effects of increased precipitation, that is, leading to more ecological droughts despite higher precipitation in some regions. Our results underscore the value of considering indirect effects of climate change on vegetation when assessing future soil moisture conditions in water-limited ecosystems.

  • 134. Tiwari, Tejshree
    et al.
    Sponseller, Ryan A.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Laudon, Hjalmar
    Contrasting responses in dissolved organic carbon to extreme climate events from adjacent boreal landscapes in Northern Sweden2019Inngår i: Environmental Research Letters, ISSN 1748-9326, E-ISSN 1748-9326, Vol. 14, nr 8, artikkel-id 084007Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ongoing pressures of climate change, as expressed by the increased intensity, duration, and frequency of temperature and precipitation events, threatens the storage of carbon in northern latitudes. One key concern is how these events will affect the production, mobilization, and export of dissolved organic carbon (DOC), the main form of aquatic carbon export in these regions. In this study, we retrospectively show contrasting effects of climate extremes over 23 years on two adjacent boreal catchments, one dominated by forest cover and the other draining a mire (wetland), despite experiencing the same extreme climate events. During the peak snowmelt, DOC concentrations ranged from 20 to 33 mg l(-1) in the forest catchment and 10-28 mg l(-1) in the mire catchment respectively, highlighting large inter-annual variation in the springtime hydrologicCexport at both sites. Weused climate and discharge variables to predict this variation, and found that DOC from the forested catchment, which is derived largely from riparian soils, had the highest concentrations following cold summers, dry autumns, and winters with high precipitation. By contrast, in the mire outlet, where DOC is primarily derived from decomposing peat, the highest DOC concentrations in the spring followed cold/dry winters and dry summers. Our results indicate that processes regulating stream DOC concentrations during spring in both catchments were dependent on both temperature and precipitation in multiple seasons. Together, these patterns suggest that DOC responses to climatic extremes are complex and generate variable patterns in springtime concentrations that are strongly dependent upon landscape context.

  • 135.
    Toreti, Andrea
    et al.
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Belward, Alan
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Perez-Dominguez, Ignacio
    European Commission, Joint Research Centre (JRC), Seville, Spain.
    Naumann, Gustavo
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Luterbacher, Jürg
    Dept. of Geography, Climatology, Climate Dynamics and Climate Change, and Centre for International Development and Environmental Research, Justus-Liebig University of Giessen, Germany.
    Cronie, Ottmar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Seguini, Lorenzo
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Manfron, Giacinto
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Lopez Lozano, Raul
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Baruth, Bettina
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    van den Berg, Maurits
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Dentener, Frank
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Ceglar, Andrej
    Joint Research Centre (JRC), European Commission, Ispra (VA), Italy.
    Chatzopoulos, Thomas
    Joint Research Centre (JRC), European Commission, Seville, Spain.
    Zampieri, Matteo
    Joint Research Centre, European Commission, Ispra (VA), Italy.
    The exceptional 2018 European water seesaw calls for action on adaptation2019Inngår i: Earth's Future, ISSN 1384-5160, E-ISSN 2328-4277, Vol. 7, nr 6, s. 652-663Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Temperature and precipitation are the most important factors responsible for agricultural productivity variations. In 2018 spring/summer growing season, Europe experienced concurrent anomalies of both. Drought conditions in central and northern Europe caused yield reductions up to 50% for the main crops, yet wet conditions in southern Europe saw yield gains up to 34%, both with respect to the previous 5‐years' mean. Based on the analysis of documentary and natural proxy based seasonal paleoclimate reconstructions for the past half millennium, we show that the 2018 combination of climatic anomalies in Europe was unique. The water seesaw, a marked dipole of negative water anomalies in central Europe and positive ones in southern Europe, distinguished 2018 from the five previous similar droughts since 1976. Model simulations reproduce the 2018 European water seesaw in only four years out of 875 years in historical runs and projections. Future projections under the RCP8.5 scenario show that 2018‐like temperature and rainfall conditions, favourable to crop growth, will occur less frequent in southern Europe. In contrast, in central Europe high‐end emission scenario climate projections show that droughts as intense as 2018 could become a common occurrence as early as 2043. Whilst integrated European and global agricultural markets limited agro‐economic shocks caused by 2018's extremes, there is an urgent need for adaptation strategies for European agriculture to consider futures without the benefits of any water seesaw.

  • 136.
    Toreti, Andrea
    et al.
    European Commission, Ispra (VA), Italy.
    Cronie, Ottmar
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för matematik och matematisk statistik.
    Zampieri, Matteo
    European Commission, Ispra (VA), Italy.
    Concurrent climate extremes in the key wheat producing regions of the world2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikkel-id 5493Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Climate extremes have profound impacts on key socio-economic sectors such as agriculture. In a changing climate context, characterised by an intensification of these extremes and where the population is expected to grow, exposure and vulnerability must be accurately assessed. However, most risk assessments analyse extremes independently, thus potentially being overconfident in the resilience of the socio-economic sectors. Here, we propose a novel approach to defining and characterising concurrent climate extremes (i.e. extremes occurring within a specific temporal lag), which is able toidentify spatio-temporal dependences without making any strict assumptions. the method is applied to large-scale heat stress and drought events in the key wheat producing regions of the world, as these extremes can cause serious yield losses and thus trigger market shocks. Wheat regions likely to haveconcurrent extremes (heat stress and drought events) are identified, as well as regions independent ofeach other or inhibiting each other in terms of these extreme events. this tool may be integrated in all risk assessments but could also be used to explore global climate teleconnections.

  • 137. Vaisanen, Maria
    et al.
    Ylanne, Henni
    Kaarlejärvi, Elina
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Sjoegersten, Sofie
    Olofsson, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Crout, Neil
    Stark, Sari
    Consequences of warming on tundra carbon balance determined by reindeer grazing history2014Inngår i: Nature Climate Change, ISSN 1758-678X, E-ISSN 1758-6798, Vol. 4, nr 5, s. 384-388Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Arctic tundra currently stores half of the global soil carbon (C) stock(1). Climate warming in the Arctic may lead to accelerated CO2 release through enhanced decomposition and turn Arctic ecosystems from a net C sink into a net C source, if warming enhances decomposition more than plant photosynthesis(2). A large portion of the circumpolar Arctic is grazed by reindeer/caribou, and grazing causes important vegetation shifts in the long-term. Using a unique experimental set-up, where areas experiencing more than 50 years of either light (LG) or heavy (HG) grazing were warmed and/or fertilized, we show that under ambient conditions areas under LG were a 70% stronger C sink than HG areas. Although warming decreased the C sink by 38% under LG, it had no effect under HG. Grazing history will thus be an important determinant in the response of ecosystem C balance to climate warming, which at present is not taken into account in climate change models.

  • 138. Veen, G. F. (Ciska)
    et al.
    De Long, Jonathan R.
    Kardol, Paul
    Sundqvist, Maja K.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Center for Macroecology, Evolution and Climate, Natural History Museum of Denmark, Univ. of Copenhagen, Copenhagen, Denmark.
    Snoek, L. Basten
    Wardle, David A.
    Coordinated responses of soil communities to elevation in three subarctic vegetation types2017Inngår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 126, nr 11, s. 1586-1599Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Global warming has begun to have a major impact on the species composition and functioning of plant and soil communities. However, long-term community and ecosystem responses to increased temperature are still poorly understood. In this study, we used a well-established elevational gradient in northern Sweden to elucidate how plant, microbial and nematode communities shift with elevation and associated changes in temperature in three highly contrasting vegetation types (i.e. heath, meadow and Salix vegetation). We found that responses of both the abundance and composition of microbial and nematode communities to elevation differed greatly among the vegetation types. Within vegetation types, changes with elevation of plant, microbial and nematode communities were mostly linked at fine levels of taxonomic resolution, but this pattern disappeared when coarser functional group levels were considered. Further, nematode communities shifted towards more conservative nutrient cycling strategies with increasing elevation in heath and meadow vegetation. Conversely, in Salix vegetation microbial communities with conservative strategies were most pronounced at the mid-elevation. These results provide limited support for increasing conservative nutrient cycling strategies at higher elevation (i.e. with a harsher climate). Our findings indicate that climate-induced changes in plant community composition may greatly modify or counteract the impact of climate change on soil communities. Therefore, to better understand and predict ecosystem responses to climate change, it will be crucial to consider vegetation type and its specific interactions with soil communities.

  • 139.
    Vickers, Kim
    et al.
    Department of Archaeology, University of Sheffield, UK.
    Buckland, Philip I
    Umeå universitet, Humanistiska fakulteten, Institutionen för idé- och samhällsstudier, Miljöarkeologiska laboratoriet.
    Predicting island beetle faunas by their climate ranges: the tabula rasa/refugia theory in the North Atlantic2015Inngår i: Journal of Biogeography, ISSN 0305-0270, E-ISSN 1365-2699, Vol. 42, nr 11, s. 2031-2048Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: This paper addresses two opposing theories put forward for the origins of the beetle fauna of the North Atlantic islands. The first is that the biota of the isolated oceanic islands of the Faroes, Iceland and Greenland immigrated across a Palaeogene–Neogene land bridge from Europe, and survived Pleistocene glaciations in ameliorated refugia. The second argues for a tabula rasa in which the biota of the islands was exterminated during glaciations and is Holocene in origin. The crux of these theories lies in the ability of the flora and fauna to survive in a range of environmental extremes. This paper sets out to assess the viability of the refugia hypothesis using the climatic tolerances of one aspect of the biota: the beetle fauna. Location: The paper focuses on Iceland, the Faroe Islands and Greenland. Methods: The known temperature requirements of the recorded beetle faunas of the North Atlantic islands were compared with published proxy climate reconstructions for successive climate periods since the severing of a North Atlantic land bridge. We used the MCR (mutual climatic range) method available in the open access BugsCEP database software. Results: We show that most of the MCR faunas of the North Atlantic islands could not have survived in situ since the Palaeogene–Neogene, and are likely to have been exterminated by the Pleistocene glaciations. Main conclusions: The discrepancy between the climatic tolerances of the North Atlantic beetle fauna and the estimated climatic regimes since the severing of a land bridge strongly support the tabula rasa theory and suggests that the North Atlantic coleopteran fauna is Holocene in origin.

  • 140.
    Viippola, Lotta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Citizen Science i Abisko: Hur ser förutsättningarna ut inom forskning i nordliga ekosystem?2015Independent thesis Basic level (university diploma), 10 poäng / 15 hpOppgave
    Abstract [en]

    In this paper I examine the possibilities for researchers in the field of climate change in the arctic ecosystems to collaborate with people of the common public for monitoring or to answer scientific questions, sometimes called Citizen Science. I have done this by focusing on the research community of Abisko, northern Sweden. I present a number of examples of possible projects that I have collected through literature, interviews and field work with researchers. Furthermore, I argue that Citizen Science projects might be a tool for nature guides in reaching adventurous visitors searching for more understanding of climate change, ecosystems, and who also want to contribute to real science. However, Citizen Science can also be a part of the democratization of a community when local people get engaged. Thus different aspects of Citizen Science are suitable for different target groups.

  • 141.
    Viitasalo, Markku
    et al.
    SYKE.
    Blenckner, Thorsten
    Stockholms universitet.
    Gårdmark, Anna
    Sveriges Lantbruksuniversitet.
    Kaartokallio, Hermanni
    Kautsky, Lena
    Stockholms universitet.
    Kuosa, Harri
    SYKE, Finland.
    Lindegren, Martin
    Norkko, Alf
    Olli, Kalle
    Wikner, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Environmental Impacts—Marine Ecosystems2015Inngår i: Second Assessment of Climate Change for the Baltic Sea Basin / [ed] The BACC II Author Team, London: Springer, 2015, s. 363-380Kapittel i bok, del av antologi (Annet vitenskapelig)
    Abstract [en]

    Increase in sea surface temperature is projected to change seasonal succession and induce dominance shifts in phytoplankton in spring and promote the growth of cyanobacteria in summer. In general, climate change is projected to worsen oxygen conditions and eutrophication in the Baltic Proper and the Gulf of Finland. In the Gulf of Bothnia, the increasing freshwater discharge may increase the amount of dissolved organic carbon (DOC) in the water and hence reduce phytoplankton productivity. In winter, reduced duration and spatial extent of sea ice will cause habitat loss for ice-dwelling organisms and probably induce changes in nutrient dynamics within and under the sea ice. The projected salinity decline will probably affect the functional diversity of the benthic communities and induce geographical shifts in the distribution limits of key species such as bladder wrack and blue mussel. In the pelagic ecosystem, the decrease in salinity together with poor oxygen conditions in the deep basins will negatively influence the main Baltic Sea piscivore, cod. This has been suggested to cause cascading effects on clupeids and zooplankton.

  • 142.
    Väisänen, Maria
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Arctic Centre, University of Lapland, Rovaniemi, Finland.
    Krab, Eveline J.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Dorrepaal, Ellen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Carbon dynamics at frost-patterned tundra driven by long-term vegetation change rather than by short-term non-growing season warming2017Inngår i: Biogeochemistry, ISSN 0168-2563, E-ISSN 1573-515X, Vol. 136, nr 1, s. 103-117Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Frost-patterned grounds, such as mostly barren frost boils surrounded by denser vegetation, are typical habitat mosaics in tundra. Plant and microbial processes in these habitats may be susceptible to short-term warming outside the growing season, while the areal cover of barren frost boils has decreased during the past decades due to climate warming-induced shrub expansion. The relative importance of such short-term and long-term climate impacts on carbon (C) dynamics remains unknown. We measured ecosystem CO2 uptake and release (in the field), microbial respiration (in the laboratory), as well as microbial biomass N and soil extractable N in frost boils and the directly adjacent heath in late spring and late summer. These habitats had been experimentally warmed with insulating fleeces from late September until late May for three consecutive years, which allowed us to investigate the direct short-term effects of warming and longer-term, indirect climate effects via vegetation establishment into frost boils. Non-growing season warming increased C uptake at the frost boils in late spring and decreased it in late summer, while the timing and direction of responses was opposite for the heath. Experimental warming had no effects on microbial or ecosystem C release or soil N at either of the habitats. However, C cycling was manifold higher at the heath compared to the frost boils, likely because of a higher SOM stock in the soil. Short-term climate change can thus directly alter ecosystem C uptake at frost-patterned grounds but will most likely not affect microbial C release. We conclude that the C dynamics at frost-patterned grounds under a changing climate depend most strongly on the potential of vegetation to encroach into frost boils in the long-term.

  • 143.
    Weber, Christine
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lind, Lovisa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Alfredsen, Knut T
    Polvi, Lina E
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Winter disturbances and riverine fish in temperate and cold regions2013Inngår i: BioScience, ISSN 0006-3568, E-ISSN 1525-3244, Vol. 63, nr 3, s. 199-210Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Winter is a critical period for aquatic organisms; however, little is known about the ecological significance of its extreme events. Here, we link winter ecology and disturbance research by synthesizing the impacts of extreme winter conditions on riverine habitats and fish assemblages in temperate and cold regions. We characterize winter disturbances by their temporal pattern and abiotic effects, explore how various drivers influence fish, and discuss human alterations of winter disturbances and future research needs. We conclude that (a) more data on winter dynamics are needed to identify extreme events, (b) winter ecology and disturbance research should test assumptions of practical relevance for both disciplines, (c) hydraulic and population models should incorporate winter- and disturbance-specific aspects, and (d) management for sustainability requires that river managers work proactively by including anticipated future alterations in the design of restoration and conservation activities.

  • 144.
    Westerhoff, Lisa
    et al.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för geografi och ekonomisk historia, Kulturgeografi.
    Keskitalo, E. Carina H.
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för geografi och ekonomisk historia, Kulturgeografi.
    Juhola, Sirkku
    Umeå universitet, Samhällsvetenskapliga fakulteten, Institutionen för geografi och ekonomisk historia, Kulturgeografi.
    Capacities across scales: local to national adaptation policy in four European countries2011Inngår i: Climate Policy, ISSN 1469-3062, E-ISSN 1752-7457, Vol. 11, nr 4, s. 1071-1085Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A framework of adaptive capacity and prerequisites for planned adaptation are used to identify the resources and conditions that have enabled or constrained the development of planned adaptation at national to local levels in Italy, Sweden, Finland and the UK. Drawing on 94 semi-structured interviews with climate change actors at each scale, the study demonstrates that planned adaptation measures occur as a result of several inter-relating factors, including the existence of political will, public support (and relevant media portrayal of climate change), adequate financial resources, the ability to produce or access climate and other information, and the extent of stakeholder involvement in the design and application of adaptation measures. Specific national adaptation measures affect local capacities to implement planned adaptations, but in some cases have been complemented or substituted by internal and external networks that connect local authorities to information and resources. The study demonstrates that opportunities to engage in planned adaptation at local levels may occur given adequate interest and resources; however, both national authorities and non-governmental organizations continue to play an important role in fostering local capacities.

  • 145.
    Wieloch, Thomas
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Intramolecular isotope analysis reveals plant ecophysiological signals covering multiple timescales2019Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Our societies' wellbeing relies on stable and healthy environments. However, our current lifestyles, growth-oriented economic policies and the population explosion are leading to potentially catastrophic degradation of ecosystems and progressive disruption of food chains. Hopefully, more clarity about what the future holds in store will trigger stronger efforts to find, and adopt, problem-focused coping strategies and encourage environmentally friendly lifestyles.

    Forecasting environmental change/destruction is complicated (inter alia) by lack of complete understanding of plant-environment interactions, particularly those involved in slow processes such as plant acclimatisation and adaptation. This stems from deficiencies in tools to analyse such slow processes. The present work aims at developing tools that can provide retrospective ecophysiological information covering timescales from days to millennia.

    Natural archives, such as tree-rings, preserve plant metabolites over long timescales. Analyses of intramolecular isotope abundances in plant metabolites have the potential to provide retrospective information about metabolic processes and underlying environmental controls. Thus, my colleagues and I (hereafter we) analysed intramolecular isotope patterns in tree rings to develop analytical tools that can convey information about clearly-defined plant metabolic processes over multiple timescales. Such tools might help (inter alia) to constrain plants' capacities to sequester excess amounts of anthropogenic CO2; the so-called CO2 fertilisation effect. This, in turn, might shed light on plants' sink strength for the greenhouse gas CO2, and future plant performance and growth under climate change.

    In the first of three studies, reported in appended papers, we analysed intramolecular 13C/12C ratios in tree-ring glucose. In six angiosperm and six gymnosperm species we found pronounced intramolecular 13C/12C differences, exceeding 10‰. These differences are transmitted into major global C pools, such as soil organic matter. Taking intramolecular 13C/12C differences into account might improve isotopic characterisation of soil metabolic processes and soil CO2 effluxes. In addition, we analysed intramolecular 13C/12C ratios in a Pinus nigra tree-ring archive spanning the period 1961 to 1995. These data revealed new ecophysiological 13C/12C signals, which can facilitate climate reconstructions and assessments of plant-environment interactions at higher resolution; thus providing higher quality information. We proposed that 13C/12C signals at glucose C-1 to C-2 derive from carbon injection into the Calvin-Benson cycle via the oxidative pentose phosphate pathway. We concluded that intramolecular 13C/12C measurements provide valuable new information about long-term metabolic dynamics for application in biogeochemistry, plant physiology, plant breeding, and paleoclimatology.

    In the second study, we developed a comprehensive theory on the metabolic and ecophysiological origins of 13C/12C signals at tree-ring glucose C-5 and C-6. According to this theory and theoretical implications of the first study on signals at C-1 to C-3, analysis of such intramolecular signals can provide information about several metabolic processes. At C-3, a well-known signal reflecting CO2 uptake is preserved. The glucose-6-phosphate shunt around the Calvin-Benson cycle affects 13C/12C compositions at C-1 and C-2, while the 13C/12C signals at C-5 and C-6 reflect carbon fluxes into downstream metabolism. This theoretical framework enables further experimental studies to be conducted in a hypothesis-driven manner. In conclusion, the intramolecular approach provides information about carbon allocation in plant leaves. Thus, it gives access to long-term information on key ecophysiological processes, which could not be acquired by previous approaches.

    The abundance of the hydrogen isotope deuterium, δD, is important for linking the water cycle with plant ecophysiology. The main factors affecting δD in plant organic matter are commonly assumed to be the δD in source water and leaf-level evaporative enrichment. Current δD models incorporate biochemical D fractionations as constants. In the third study we showed that biochemical D fractionations respond strongly to low ambient CO2 levels and low light intensity. Thus, models of δD values in plant organic matter should incorporate biochemical fractionations as variables. In addition, we found pronounced leaf-level δD differences between α-cellulose and wax n-alkanes. We explained this by metabolite-specific contributions of distinct hydrogen sources during biosynthesis.

    Overall, this work advances our understanding of isotope distributions and isotope fractionations in plants. It reveals the immense potential of intramolecular isotope analyses for retrospective assessment of plant metabolism and associated environmental controls.

  • 146.
    Wieloch, Thomas
    et al.
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Sharkey, Thomas David
    Werner, Roland Anton
    Schleucher, Jürgen
    Umeå universitet, Medicinska fakulteten, Institutionen för medicinsk kemi och biofysik.
    Intramolecular 13C/12C signals reflect carbon allocation in plant leavesManuskript (preprint) (Annet vitenskapelig)
  • 147. Winder, Monika
    et al.
    Bouquet, Jean-Marie
    Bermudez, J. Rafael
    Berger, Stella A.
    Hansen, Thomas
    Brandes, Jay
    Sazhin, Andrey F.
    Nejstgaard, Jens C.
    Båmstedt, Ulf
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jakobsen, Hans H.
    Dutz, Joerg
    Frischer, Marc E.
    Troedsson, Christofer
    Thompson, Eric M.
    Increased appendicularian zooplankton alter carbon cycling under warmer more acidified ocean conditions2017Inngår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 62, nr 4, s. 1541-1551Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Anthropogenic atmospheric loading of CO2 raises concerns about combined effects of increasing ocean temperature and acidification, on biological processes. In particular, the response of appendicularian zooplankton to climate change may have significant ecosystem implications as they can alter biogeochemical cycling compared to classical copepod dominated food webs. However, the response of appendicularians to multiple climate drivers and effect on carbon cycling are still not well understood. Here, we investigated how gelatinous zooplankton (appendicularians) affect carbon cycling of marine food webs under conditions predicted by future climate scenarios. Appendicularians performed well in warmer conditions and benefited from low pH levels, which in turn altered the direction of carbon flow. Increased appendicularians removed particles from the water column that might otherwise nourish copepods by increasing carbon transport to depth from continuous discarding of filtration houses and fecal pellets. This helps to remove CO2 from the atmosphere, and may also have fisheries implications.

  • 148.
    Wolf, Annett
    et al.
    Umeå universitet. Lund Univ, Dept Phys Geog & Ecosyst Anal, Lund, Sweden; Abisko Sci Res Stn, Abisko, Sweden.
    Callaghan, Terry V.
    Larson, Karin
    Future changes in vegetation and ecosystem function of the Barents Region2008Inngår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 87, nr 1-2, s. 51-73Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The dynamic vegetation model (LPJ-GUESS) is used to project transient impacts of changes in climate on vegetation of the Barents Region. We incorporate additional plant functional types, i.e. shrubs and defined different types of open ground vegetation, to improve the representation of arctic vegetation in the global model. We use future climate projections as well as control climate data for 1981-2000 from a regional climate model (REMO) that assumes a development of atmospheric CO(2)-concentration according to the B2-SRES scenario [IPCC, Climate Change 2001: The scientific basis. Contribution working group I to the Third assessment report of the IPCC. Cambridge University Press, Cambridge (2001)]. The model showed a generally good fit with observed data, both qualitatively when model outputs were compared to vegetation maps and quantitatively when compared with observations of biomass, NPP and LAI. The main discrepancy between the model output and observed vegetation is the overestimation of forest abundance for the northern parts of the Kola Peninsula that cannot be explained by climatic factors alone. Over the next hundred years, the model predicted an increase in boreal needle leaved evergreen forest, as extensions northwards and upwards in mountain areas, and as an increase in biomass, NPP and LAI. The model also projected that shade-intolerant broadleaved summergreen trees will be found further north and higher up in the mountain areas. Surprisingly, shrublands will decrease in extent as they are replaced by forest at their southern margins and restricted to areas high up in the mountains and to areas in northern Russia. Open ground vegetation will largely disappear in the Scandinavian mountains. Also counter-intuitively, tundra will increase in abundance due to the occupation of previously unvegetated areas in the northern part of the Barents Region. Spring greening will occur earlier and LAI will increase. Consequently, albedo will decrease both in summer and winter time, particularly in the Scandinavian mountains (by up to 18%). Although this positive feedback to climate could be offset to some extent by increased CO(2) drawdown from vegetation, increasing soil respiration results in NEE close to zero, so we cannot conclude to what extent or whether the Barents Region will become a source or a sink of CO(2).

  • 149.
    Wolf, Annett
    et al.
    Umeå universitet. ETH Zentrum, CH-8092 Zurich, Switzerland.
    Kozlov, Mikhail V.
    Callaghan, Terry V.
    Impact of non-outbreak insect damage on vegetation in northern Europe will be greater than expected during a changing climate2008Inngår i: Climatic Change, ISSN 0165-0009, E-ISSN 1573-1480, Vol. 87, nr 1-2, s. 91-106Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background insect herbivory, in addition to insect outbreaks, can have an important long term influence on the performance of tree species. Since a projected warmer climate may favour insect herbivores, we use a dynamic ecosystem model to investigate the impacts of background herbivory on vegetation growth and productivity, as well as distribution and associated changes in terrestrial ecosystems of northern Europe. We used the GUESS ecosystem modelling framework and a simple linear model for including the leaf area loss of Betula pubescens in relation to mean July temperature. We tested the sensitivity of the responses of the simulated ecosystems to different, but realistic, degrees of insect damage. Predicted temperature increases are likely to enhance the potential insect impacts on vegetation. The impacts are strongest in the eastern areas, where potential insect damage to B. pubescens can increase by 4-5%. The increase in insect damage to B. pubescens results in a reduction of total birch leaf area (LAI), total birch biomass and birch productivity (Net Primary Production). This effect is stronger than the insect damage to leaf area alone would suggest, due to its second order effect on the competition between tree species. The model’s demonstration that background herbivory may cause changes in vegetation structure suggests that insect damage, generally neglected by vegetation models, can change predictions of future forest composition. Carbon fluxes and albedo are only slightly influenced by background insect herbivory, indicating that background insect damage is of minor importance for estimating the feedback of terrestrial ecosystems to climate change.

  • 150.
    Yurova, Alla
    et al.
    Lund Univ, Dept Phys Geog & Ecosyst Anal, Solvegatan 12, SE-22362 Lund, Sweden..
    Wolf, Annett
    Umeå universitet. Lund Univ, Dept Phys Geog & Ecosyst Anal, Solvegatan 12, SE-22362 Lund, Sweden..
    Sagerfors, Jorgen
    Nilsson, Mats
    Variations in net ecosystem exchange of carbon dioxide in a boreal mire: Modeling mechanisms linked to water table position2007Inngår i: Journal of Geophysical Research, ISSN 0148-0227, E-ISSN 2156-2202, Vol. 112, nr G2Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    [1] In mires, which occupy large areas of the boreal region, net ecosystem CO2 exchange ( NEE) rates vary significantly over various timescales. In order to examine the effect of one of the most influencing variables, the water table depth, on NEE the general ecosystem model GUESS-ROMUL was modified to predict mire daily CO2 exchange rates. A simulation was conducted for a lawn, the most common microtopographical feature of boreal oligotrophic minerotrophic mires. The results were validated against eddy covariance CO2 flux measurements from Degero Stormyr, northern Sweden, obtained during the period 2001 - 2003. Both measurements and model simulations revealed that CO2 uptake was clearly controlled by interactions between water table depth and temperature. Maximum uptake occurred when the water table level was between 10 and 20 cm and the air temperature was above 15 degrees C. When the water table was higher, the CO2 uptake rate was lower, owing to reduced rates of photosynthetic carbon fixation. When the water table was lower, NEE decreased owing to the increased rate of decomposition of organic matter. When the water table level was between 10 and 20 cm, the NEE was quite stable and relatively insensitive to both changes within this range and any air temperature changes above + 15 degrees C. The optimal water table level range for NEE corresponds to that characteristic of mire lawn plant communities, indicating that the annual NEE will not change dramatically if climatic conditions remain within the optimal range for the current plant community.

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