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  • 1.
    Aalto, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Biodiversity and habitat conditions in reaches with high flow velocity along gradients in hydrological and geomorphological alteration: A study of six rivers in Sweden2021Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The vast majority of rivers in the developed world are affected by human alteration, which in turn negatively affects the species that rely on these highly diverse and species rich areas to survive. Homogenization of previously heterogenic areas due to a change in water discharge and the substrate availability in the rivers is often regarded as the main reason for the loss of species richness in rivers and the riparian zone. Because of this, there are a lot of restoration projects which main goal is to increase heterogeneity. The goal of this thesis is to compare hydrology and geomorphology variables between four types of reaches with high flow velocity (rapids in free-flowing reaches, rapids with regulated flow, impounded reaches and reaches in outlet channels below hydropower plants). In this thesis I wanted to find out how changes in geomorphology and hydrology affect fish species richness, riparian vegetation richness and aquatic vascular plants species richness. The result show that both fish species richness and riparian vegetation species richness are negatively affected by the changes in geomorphology and hydrology. There was no significant difference for aquatic vascular plants when comparing the regulation types. The most altered reach type, outlet channels, had significantly fewer fish species compared to the less altered reach type, impounded reaches. Outlet channels also had less riparian vegetation cover compared to all other regulation types, and fewer riparian vegetation species compared to both free-flowing reaches and impounded reaches. In conclusion, hydropower plants and timber floating have both negatively impacted the riverine ecosystem, and in turn caused a decrease in species richness for fish and riparian plants. The reaches studied in this thesis will continue to be altered and the species richness and species composition will change from an ecosystem that relied on the natural flow regime to an ecosystem more used to the flow regime created by the hydropower plants. 

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  • 2.
    Aalto, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Kanalisering och restaurering av vattendrag påverkar mossamhällen i strandzonen: -En studie av Vindelälvens biflöden2018Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    This study compared three different types of reaches at streams and how bryophyte species richness, diversity and abundance in the riparian zone differ between them. The different types of reaches are those that have been treated by two types of restoration techniques (best practise and advanced) and streams that have still not been restored (channelized). The bryophytes were gathered from 15 tributaries to Vindelälven, which is in northern Sweden. Bryophyte species richness and diversity was highest at the streams that were still not restored, and I found numerous factors that could explain why this was the case. Fourteen environmental variables were tested against the three bryophyte factors to try to explain the variation found in the study. Time since restoration and the amount of tree biomass in the area could explain the species richness found at the different river types. The study shows that short-term effects of restoration on the riparian zone is a decrease in bryophyte species richness and diversity. However, given enough time the bryophytes are expected to recover in regards to species richness and diversity.

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  • 3. Abbott, Benjamin W.
    et al.
    Jones, Jeremy B.
    Schuur, Edward A. G.
    Chapin, F. Stuart, III
    Bowden, William B.
    Bret-Harte, M. Syndonia
    Epstein, Howard E.
    Flannigan, Michael D.
    Harms, Tamara K.
    Hollingsworth, Teresa N.
    Mack, Michelle C.
    McGuire, A. David
    Natali, Susan M.
    Rocha, Adrian V.
    Tank, Suzanne E.
    Turetsky, Merritt R.
    Vonk, Jorien E.
    Wickland, Kimberly P.
    Aiken, George R.
    Alexander, Heather D.
    Amon, Rainer M. W.
    Benscoter, Brian W.
    Bergeron, Yves
    Bishop, Kevin
    Blarquez, Olivier
    Bond-Lamberty, Ben
    Breen, Amy L.
    Buffam, Ishi
    Cai, Yihua
    Carcaillet, Christopher
    Carey, Sean K.
    Chen, Jing M.
    Chen, Han Y. H.
    Christensen, Torben R.
    Cooper, Lee W.
    Cornelissen, J. Hans C.
    de Groot, William J.
    DeLuca, Thomas H.
    Dorrepaal, Ellen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Fetcher, Ned
    Finlay, Jacques C.
    Forbes, Bruce C.
    French, Nancy H. F.
    Gauthier, Sylvie
    Girardin, Martin P.
    Goetz, Scott J.
    Goldammer, Johann G.
    Gough, Laura
    Grogan, Paul
    Guo, Laodong
    Higuera, Philip E.
    Hinzman, Larry
    Hu, Feng Sheng
    Hugelius, Gustaf
    Jafarov, Elchin E.
    Jandt, Randi
    Johnstone, Jill F.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Kasischke, Eric S.
    Kattner, Gerhard
    Kelly, Ryan
    Keuper, Frida
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Kling, George W.
    Kortelainen, Pirkko
    Kouki, Jari
    Kuhry, Peter
    Laudon, Hjalmar
    Laurion, Isabelle
    Macdonald, Robie W.
    Mann, Paul J.
    Martikainen, Pertti J.
    McClelland, James W.
    Molau, Ulf
    Oberbauer, Steven F.
    Olefeldt, David
    Pare, David
    Parisien, Marc-Andre
    Payette, Serge
    Peng, Changhui
    Pokrovsky, Oleg S.
    Rastetter, Edward B.
    Raymond, Peter A.
    Raynolds, Martha K.
    Rein, Guillermo
    Reynolds, James F.
    Robards, Martin
    Rogers, Brendan M.
    Schaedel, Christina
    Schaefer, Kevin
    Schmidt, Inger K.
    Shvidenko, Anatoly
    Sky, Jasper
    Spencer, Robert G. M.
    Starr, Gregory
    Striegl, Robert G.
    Teisserenc, Roman
    Tranvik, Lars J.
    Virtanen, Tarmo
    Welker, Jeffrey M.
    Zimov, Sergei
    Biomass offsets little or none of permafrost carbon release from soils, streams, and wildfire: an expert assessment2016Ingår i: Environmental Research Letters, E-ISSN 1748-9326, Vol. 11, nr 3, artikel-id 034014Artikel i tidskrift (Refereegranskat)
    Abstract [en]

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

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  • 4.
    Abderhalden, Bigna Lu
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Seasonal Reindeer Grazing Effects on Mountain Birch Forests: A 3D Perspective using Drones2024Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Reindeer are important drivers of ecosystem processes in arctic and subarctic ecosystems, changing nutrient conditions and influencing vegetation by grazing and trampling. Mountain birch forests are one of the ecosystems impacted by reindeer grazing, but the effect on the 3D structure of these forests is not well understood. Drones are revolutionising ecological studies, allowing to create high-resolution 3D point clouds at low costs. I investigated the effect of year-round and autumn reindeer grazing on mountain birch forest vegetation in historically separated grazing areas at the Finnish-Norwegian border, using a combination of field data and drone data. The two sampling techniques were further compared to evaluate the possibility to use photogrammetric point clouds to characterise mountain birch forests. I found lower productivity in the year-round grazing regime, coinciding with generally higher vegetation density. Vertically, higher densities were found above browsing height, while the understory showed lower densities compared to autumn grazed areas. These results suggest that mountain birches allocate more biomass to the canopy area, which can be direct or indirect grazing effects. Nevertheless, overall productivity is lowered by grazing indicating changes in vegetation biomass and composition. The point clouds generally matched field data, but the understory vegetation tended to be underrepresented, arising the question if found effects are ecological or technical. As this could not be disentangled, cautious interpretation of my results is required. I conclude that using photogrammetric point clouds is a promising technique for ecological studies, but needs further development to improve accuracy and reliability of results.

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    Thesis_Ecology_VT24
  • 5. Abdoullaye, Doukary
    et al.
    Acevedo, I
    Adebayo, Abisola A
    Behrmann-Godel, Jasminca
    Benjamin, RC
    Bock, Dan G
    Born, Celine
    Brouat, Carine
    Caccone, Adalgisa
    Cao, Ling-Zhen
    Casadoamezua, P
    Cataneo, J
    Correa-Ramirez, MM
    Cristescu, Melania E
    Dobigny, Gauthier
    Egbosimba, Emmanuel E
    Etchberger, Lianna K
    Fan, Bin
    Fields, Peter D
    Forcioli, D
    Furla, P
    de Leon, FJ Garcia
    Garcia-Jimenez, R
    Gauthier, Philippe
    Gergs, Rene
    Gonzalez, Clementina
    Granjon, Laurent
    Gutierrez-Rodriguez, Carla
    Havill, Nathan P
    Helsen, P
    Hether, Tyler D
    Hoffman, Eric A
    Hu, Xiangyang
    Ingvarsson, Pär K
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ishizaki, S
    Ji, Heyi
    Ji, XS
    Jimenez, ML
    Kapil, R
    Karban, R
    Keller, Stephen R
    Kubota, S
    Li, Shuzhen
    Li, Wansha
    Lim, Douglas D
    Lin, Haoran
    Liu, Xiaochun
    Luo, Yayan
    Machordom, A
    Martin, Andrew P
    Matthysen, E
    Mazzella, Maxwell N
    McGeoch, Melodie A
    Meng, Zining
    Nishizawa, M
    O'Brien, Patricia
    Ohara, M
    Ornelas, Juan Francisco
    Ortu, MF
    Pedersen, Amy B
    Preston, L
    Ren, Qin
    Rothhaupt, Karl-Otto
    Sackett, Loren C
    Sang, Qing
    Sawyer, GM
    Shiojiri, K
    Taylor, Douglas R
    van Dongen, S
    van Vuuren, Bettine Jansen
    Vandewoestijne, S
    Wang, H
    Wang, JT
    Wang, Le
    Xu, Xiang-Li
    Yang, Guang
    Yang, Yongping
    Zeng, YQ
    Zhang, Qing-Wen
    Zhang, Yongping
    Zhao, Y
    Zhou, Yan
    Permanent genetic resources added to molecular ecology resources database 1 August 2009 - 30 September 20092010Ingår i: Molecular Ecology Resources, ISSN 1755-098X, E-ISSN 1755-0998, Vol. 10, nr 1, s. 232-236Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This article documents the addition of 238 microsatellite marker loci and 72 pairs of Single Nucleotide Polymorphism (SNP) sequencing primers to the Molecular Ecology Resources Database. Loci were developed for the following species: Adelges tsugae, Artemisia tridentata, Astroides calycularis, Azorella selago, Botryllus schlosseri, Botrylloides violaceus, Cardiocrinum cordatum var. glehnii, Campylopterus curvipennis, Colocasia esculenta, Cynomys ludovicianus, Cynomys leucurus, Cynomys gunnisoni, Epinephelus coioides, Eunicella singularis, Gammarus pulex, Homoeosoma nebulella, Hyla squirella, Lateolabrax japonicus, Mastomys erythroleucus, Pararge aegeria, Pardosa sierra, Phoenicopterus ruber ruber and Silene latifolia. These loci were cross-tested on the following species: Adelges abietis, Adelges cooleyi, Adelges piceae, Pineus pini, Pineus strobi, Tubastrea micrantha, three other Tubastrea species, Botrylloides fuscus, Botrylloides simodensis, Campylopterus hemileucurus, Campylopterus rufus, Campylopterus largipennis, Campylopterus villaviscensio, Phaethornis longuemareus, Florisuga mellivora, Lampornis amethystinus, Amazilia cyanocephala, Archilochus colubris, Epinephelus lanceolatus, Epinephelus fuscoguttatus, Symbiodinium temperate-A clade, Gammarus fossarum, Gammarus roeselii, Dikerogammarus villosus and Limnomysis benedeni. This article also documents the addition of 72 sequencing primer pairs and 52 allele specific primers for Neophocaena phocaenoides.

  • 6. Abeli, Thomas
    et al.
    Orsenigo, Simone
    Guzzon, Filippo
    Fae, Matteo
    Balestrazzi, Alma
    Carlsson-Graner, Ulla
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Mueller, Jonas V.
    Mondoni, Andrea
    Geographical pattern in the response of the arctic-alpine Silene suecica (Cariophyllaceae) to the interaction between water availability and photoperiod2015Ingår i: Ecological research, ISSN 0912-3814, E-ISSN 1440-1703, Vol. 30, nr 2, s. 327-335Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We hypothesized a geographical pattern of the plant performance (seedling development, biomass production, relative water content and chlorophyll content) as a result of response to the interaction between photoperiod and water availability in populations of the arctic-alpine Silene suecica from different latitudes, thus experiencing different photoperiods during the growing season. Particularly, we expected a lower drought sensitivity in northern compared to southern populations as a consequence of harsher conditions experienced by the northern populations in terms of water availability. The experiment was carried out under common garden conditions, manipulating the water availability (wet and dry) and the photoperiod (21 and 16 h). We found an interaction between photoperiod and water availability on plant height, leaves, growth, biomass and total chlorophyll. However, the photoperiod neither counteracted nor intensified the effect of drought. Plants exposed to drought compensated for decreasing water availability by reducing their shoot growth. Changes in the chlorophyll content and chlorophyll a/b ratio were observed. Northern populations showed a higher basal growth performance and a greater response to the changed water regime (from wet to dry) than the southern populations. Southern populations showed a reduced ability to respond to drought, but their low basal performance may be advantageous under low water availability, avoiding water loss. In contrast, northern populations showed a stronger plastic response that limited the negative effects of reduced water availability. This study highlights the possibility that the plant response to environmental constraints (specifically water availability) may follow a geographical pattern.

  • 7.
    Abrahamsson, Matilda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Metoder för utredning av inomhusmiljö: En studie inom hälsoskyddet med delsyfte att utföra dammätningar i skolor2012Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Methods for inspection of the indoor environment – a study within health protection where a part of the aim is to perform measurements of dust in schools

    In Sweden the communities are responsible for the health protection in many agencies. The control of the indoor environment can be done in different ways and with different means. The aim of this report was to study in which way the inspectors made this kind of inspections and if there was anything in their approach that could be developed. A part of the aim of the report was to study how fast a clean surface in a school become dusty. Interviewes with healthinspectors in Uppsala, Håbo and Tierp was made. Together with them also some inspections were performed. To get a larger view of methods to investigate the indoor environment some inspections of schools and dwellings were done with an employee at the unit of Arbets- och miljömedicin at the University Hospital in Uppsala. The dust study was performed at two schools in Knivsta. The results were that the inspectors had well developed methods for assessings of the indoor environment. The approach differed in some matters between the larger and the smaller communities. Regardless of the size of the communities the inspectors rarely used instruments as a tool for the inspections. The communication and agreement between the inspectors was also shown as an important part in their work. In general the inspectors felt secure in their role and to make decisions. It appeared some shortcomings in the general advice and guidelines from the national board of health and welfare, which is the national supervisory authority that shall guide inspection of health protection. For example there was shown a lack in the guidelines regarding cleaning in schools and kindergardens. The study of dust in schools showed that there was more dust after five days than after one day.

  • 8.
    Abu Elkhair, Sabrin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Klimatanpassning, lokalisering och miljömål i miljökonsekvensbeskrivningar för villaområden: En jämförelse mellan storstads- och landsbygdskommuner2024Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The increasing focus on sustainability necessitates careful planning of future construction projects, with human health and biodiversity being key factors to protect. Planning projects with significant environmental impacts must conduct an environmental impact assessment, which involves identifying potential environmental effects and propose sustainable measures. The aim of the study was to examine how urban and rural municipalities described and assessed sustainability in environmental impact assessments for residential areas. Using thematic analysis, categories such as climate, localization, and environmental goals were established and divided into representative themes. Chi2-tests were used to test statistical significance between the municipal groups. The results revealed significant differences in two climate-related themes and one localization theme. Municipalities primarily utilized various types of stormwater management to adapt projects to climate changes and incorporate green infrastructure. The differences between municipal groups are likely influenced by factors like population density, resources, and surrounding environment. While national environmental goals were included in all environmental impact assessments, did not all proposed plans take them into account Future studies could include a larger sample to enhance reliability and consider underlying factors that may affect municipal conditions.

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  • 9. Adeleke, Rasheed
    et al.
    Bello-Akinosho, Maryam
    Maila, Mphekgo
    Lee, Natuschka
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Lehrstuhl für Mikrobiologie, Technische Universität München.
    Roles of extremophiles in bioremediation of polycyclic aromatic hydrocarbon contaminated soil environment2020Ingår i: Biotechnological applications of extremophilic microorganisms / [ed] Natuschka M. Lee, Walter de Gruyter, 2020, s. 197-230Kapitel i bok, del av antologi (Refereegranskat)
  • 10. Adler, P H
    et al.
    Malmqvist, Björn
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Predation on black flies (Diptera: Simuliidae) by the carnivorous plant Pinguicula vulgaris (Lentibulariaceae) in northern Sweden2004Ingår i: Entomologica Fennica, ISSN 0785-8760, Vol. 15, s. 124-128Artikel i tidskrift (Refereegranskat)
  • 11. Adolf, Carole
    et al.
    Wunderle, Stefan
    Colombaroli, Daniele
    Weber, Helga
    Gobet, Erika
    Heiri, Oliver
    van Leeuwen, Jacqueline F. N.
    Bigler, Christian
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Connor, Simon E.
    Galka, Mariusz
    La Mantia, Tommaso
    Makhortykh, Sergey
    Svitavska-Svobodova, Helena
    Vanniere, Boris
    Tinner, Willy
    The sedimentary and remote-sensing reflection of biomass burning in Europe2018Ingår i: Global Ecology and Biogeography, ISSN 1466-822X, E-ISSN 1466-8238, Vol. 27, nr 2, s. 199-212Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aim: We provide the first European-scale geospatial training set relating the charcoal signal in surface lake sediments to fire parameters (number, intensity and area) recorded by satellite moderate resolution imaging spectroradiometer (MODIS) sensors. Our calibration is intended for quantitative reconstructions of key fire-regime parameters by using sediment sequences of microscopic (MIC from pollen slides, particles 10-500 mu m) and macroscopic charcoal (MAC from sieves, particles > 100 mu m). Location: North-south and east-west transects across Europe, covering the mediterranean, temperate, alpine, boreal and steppe biomes. Time period: Lake sediments and MODIS active fire and burned area products were collected for the years 2012-2015. Methods: Cylinder sediment traps were installed in lakes to annually collect charcoal particles in sediments. We quantitatively assessed the relationships between MIC and MAC influx (particles/cm(2)/year) and the MODIS-derived products to identify source areas of charcoal and the extent to which lake-sediment charcoal is linked to fire parameters across the continent. Results: Source area of sedimentary charcoal was estimated to a 40-km radius around sites for both MIC and MAC particles. Fires occurred in grasslands and in forests, with grass morphotypes of MAC accurately reflecting the burned fuel-type. Despite the lack of local fires around the sites, MAC influx levels reached those reported for local fires. Both MIC and MAC showed strong and highly significant relationships with the MODIS-derived fire parameters, as well as with climatic variation along a latitudinal temperature gradient. Main conclusions: MIC and MAC are suited to quantitatively reconstructing fire number and fire intensity on a regional scale. However, burned area may only be estimated using MAC. Local fires may be identified by using several lines of evidence, e.g. analysis of large particles (> 600 mu m), magnetic susceptibility and sedimentological data. Our results offer new insights and applications to quantitatively reconstruct fires and to interpret available sedimentary charcoal records.

  • 12.
    Adolfsson, Hannah
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Förekomst av törskate (Cronartium pini) i tallungskog i norra Sverige: En studie av törskates utbredning och eventuella faktorer som påverkar förekomst2022Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of the study was to increase the understanding of the distribution of pine stem rust (Cronartium pini) in young pine (Pinus sylvestris) forests in the northern parts of Sweden. In addition, this study also investigates how the density of cow-wheat (Melampyrum spp.), altitude and proportion of deciduous trees in a stand affects the relative frequency of pine stem rust. The results showed a difference in the distribution of pine stem rust between investigated regions, with Norrbotten county having the largest occurrence with an average relative frequency of 6,9 % and Västernorrland/Jämtland county having the lowest with an average of 0,5 %. Furthermore, results showed that investigated areas with a high frequency of cow-wheat had the highest frequency of pine stem rust in almost all parts of data. The result is most likely due to cow-wheat being important host plants for pine stem rust. Weak correlations were found between altitude and pine stem rust as well as between proportion of deciduous trees and pine stem rust. The weak correlations indicates that there are more factors affecting the occurrence of pine stem rust. However, in following studies of collected data all investigated factors needs to be compared to determine their importance and how they interact with each other. Additionally, comparing the two variants of pine stem rust are essential to increase the understanding of their differences.

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  • 13. Aerts, R.
    et al.
    Callaghan, T. V.
    Dorrepaal, E.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Systems Ecology, Department of Ecological Science, VU University Amsterdam, Amsterdam, The Netherlands.
    van Logtestijn, R. S. P.
    Cornelissen, J. H. C.
    Seasonal climate manipulations have only minor effects on litter decomposition rates and N dynamics but strong effects on litter P dynamics of sub-arctic bog species2012Ingår i: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 170, nr 3, s. 809-819Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Litter decomposition and nutrient mineralization in high-latitude peatlands are constrained by low temperatures. So far, little is known about the effects of seasonal components of climate change (higher spring and summer temperatures, more snow which leads to higher winter soil temperatures) on these processes. In a 4-year field experiment, we manipulated these seasonal components in a sub-arctic bog and studied the effects on the decomposition and N and P dynamics of leaf litter of Calamagrostis lapponica, Betula nana, and Rubus chamaemorus, incubated both in a common ambient environment and in the treatment plots. Mass loss in the controls increased in the order Calamagrostis < Betula < Rubus. After 4 years, overall mass loss in the climate-treatment plots was 10 % higher compared to the ambient incubation environment. Litter chemistry showed within each incubation environment only a few and species-specific responses. Compared to the interspecific differences, they resulted in only moderate climate treatment effects on mass loss and these differed among seasons and species. Neither N nor P mineralization in the litter were affected by the incubation environment. Remarkably, for all species, no net N mineralization had occurred in any of the treatments during 4 years. Species differed in P-release patterns, and summer warming strongly stimulated P release for all species. Thus, moderate changes in summer temperatures and/or winter snow addition have limited effects on litter decomposition rates and N dynamics, but summer warming does stimulate litter P release. As a result, N-limitation of plant growth in this sub-arctic bog may be sustained or even further promoted.

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  • 14.
    Aggling, Edith
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Torvtäkternas avtryck: En studie av förändringar i sedimentkvalitet i Håtjärnen, Håsjön och Yttersjön - Baserad på geokemiska analyser2024Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Historically, peat mining has involved drainage processes that alter water chemistry, increase rates of organic matter, release nutrients and therefore impacting downstream recipients. In the catchment of Håtjärnen, Håsjön and Yttersjön, three peat mining sites have been draining into the lakes since the 1980s. This study aimed to investigate the potential impact of these peat mining sites on the lake sediment geochemistry as a complement to a previous study in the area. Four sediment profiles were sampled using an HTH-corer and the sediment geochemistry was analyzed using X-ray fluorescence, Loss on Ignition, Near Infrared spectroscopy, C/N-ratio and Si/Al-ratio. The results from these analyses show that the contribution of peat mining to variations in sediment quality in Håtjärnen, Håsjön and Yttersjön is minimal and that other logical explanations can explain the small variability of the data. In comparison with ratios from other studies, the C/N ratio did not indicate a significant input of organic matter derived from peat. The findings of this study contradict the conclusions from the previous study in the area which highlights the importance of analyzing all the major components of sediment to achive a comprehensive insight of the variations in chemical composition of sediments.

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  • 15.
    Agnemo, Elin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Avfall från dricksvattenkvalitetslaboratorium: En studie om avfallsklassning och hantering av m-Endo agar LES vid Stockholm Vatten.2014Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The purpose of the study was to determine how the waste from m-Endo agar LES (LesEndo) should be categorized and managed, due to its content of the carcinogenic substance basic red 9 in basic fuchsine. The information was obtained by studying legislation and a laboratory practical was performed to verify, if basic fuchsine could remain in LesEndo agar after being heated. This was important to know for the further interpretation how to categorize and manage the waste according to the legislation. LesEndo agar was autoclaved at 121 °C for 15 and 30 minutes. E. coli and coliform bacteria was put to grow on the LesEndo agar. The results from the study showed that all replicas had coliform colonies, which appeared with a metallic fuchsine-sheen. This verified that basic fuchsine was unchanged and that there was no significant difference in growth between replicas with heated agar and the control. The total concentration of basic fuchsine in LesEndo agar was 0.08%. To be categorized as hazardous waste the threshold value for basic red 9 is 0.1%. According to a strict interpretation of the legislation, waste from used LesEndo agar should not be categorized and managed as hazardous waste. However, evaporation has to be taken into consideration and the concentration may be above 0.1%. Therefore my evaluation is that waste from used LesEndo agar should be categorized and managed as hazardous waste to protect humans and the environment from being harmed.

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  • 16. Aguiar, Francisca C.
    et al.
    Segurado, Pedro
    Martins, Maria Joao
    Bejarano, Maria Dolores
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Portela, Maria Manuela
    Merritt, David M.
    The abundance and distribution of guilds of riparian woody plants change in response to land use and flow regulation2018Ingår i: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 55, nr 5, s. 2227-2240Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. Many riparian ecosystems in Mediterranean Europe are affected by land use and flow alteration by dams. We focused on understanding how these stressors and their components affect riparian forests in the region. We asked the following questions: (1) Are there well‐defined, responsive riparian guilds? (2) Do dam‐induced streamflows determine abundance and distribution of riparian guilds? (3) What are the main drivers governing composition and cover of riparian guilds in regulated rivers?

    2. We inventoried the cover of riparian woody species in free‐flowing rivers and downstream of dams. We performed a cluster analysis and ordination to derive riparian guilds, using abundance data from 66 riparian woody species and 26 functional plant traits. We used a reduced set of principal components for the environment, land use and hydrology, and general linear modelling to explore the effect of these factors (separately and combined) on riparian guilds.

    3. We found that: (1) four dominant guilds are responsive to disturbance in southwestern European streams, namely the obligate riparian, water‐stress tolerant, deciduous competitive and Mediterranean evergreen guilds; (2) a set of land use and hydrological variables differentially affect the diverse co‐occurring riparian guilds; (3) frequency and duration of high flow pulses and the low‐flow conditions were major drivers of change in landscapes dominated by intensive agriculture and forestry; (4) storage reservoirs reduced the cover of obligate riparian and Mediterranean evergreen guilds, and increased the abundance of water‐stress tolerant and deciduous competitive guilds, while run‐of‐river dams, having limited water storage, reduced both obligate and deciduous competitive guilds.

    4. Synthesis and applications. Future research in southwestern Europe should address the resilience of riparian guilds and the effects of interacting landscape factors and stressors on guild distribution. Streamflow regulations downstream of reservoirs should focus on specific flow components, namely the magnitude of flows, and frequency and duration of extreme flow events. For successful mitigation of the dam‐induced effects on riparian vegetation, river management plans must incorporate the environmental and land use site‐specific contexts.

  • 17.
    Aguirre Salcedo, Citlali
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Steering ecological restoration efforts through the storm of climate change: the case of tropical dry forest shrub species2024Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Climate change compels a reconsideration of prevailing ecological restoration paradigms and methodologies. The main goal of this thesis thesis was to explore strategies to adapt the practices of ecological restoration to climate change. We studied the potential response of six Fabaceae shrub species from tropical dry forests, previously identified as potential candidates for ecological restoration, to anticipated climate change. We found Fabaceae woody shrub species germinated in a wide range of temperatures, light and darkness, and require mechanical scarification to break their physical dormancy. We combined modelling, laboratory, field and nursery experiments to unravel the potential response of Mimosa luisana to climate change. We found trait differentiation among the lower, central and upper population of the species current distribution range within the Tehuacán-Cuicatlán Valley (TCV), Mexico, but not local adaptation. The climatically suitable area of M. luisana is projected to expand, and experimentally, this species could tolerate a wide range of conditions in terms of temperature and soil moisture. Therefore, not need for. assisted migration was found. Seed size differed among M.luisana populations, and showed a significant effect in early biomass production, but not in relative growth rate. This work has directly implications for restoration practices. First, because it addressed some of the challenges posed by climate change by highlighting methodologies that could be replicated for other species and ecosystems. Second, because it provides concrete guidelines for restoring ecological processes in tropical dry lands as the Tehuacán-Cuicatlán Valley, Mexico, that could be implemented by academics and local communities.

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  • 18.
    Aguirre Salcedo, Citlali
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ceccon, Eliane
    Centro Regional de Investigaciones Multidisciplinarias. Universidad Nacional Autónoma de México, Mexico.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Seed trait differentiation and plant growth among Mimosa luisana populationsManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The arid and semi-arid vegetation zones of the world often harbour high species diversity and significant endemism. They also face elevated levels of environmental pressures due to high human settlement densities and weak institutional systems. This necessitates adequate conservation and ecological restoration efforts, which in turn demand physiological and ecological knowledge of the species involved. Seed traits can be important for plant establishment success and growth, especially at early life stages, when seedlings also are most sensitive. We studied the role of seed traits for early establishment of the woody Fabaceae species Mimosa luisana, a candidate species for use in ecological restoration within the Tehuacán-Cuicatlán Valley (TCV), Mexico. We assessed the relationship between seed traits and biomass production, biomass allocation and relative growth rate (RGR) up to 200 days after germination, in a common garden experiment using three populations that represented the lower, central and upper limit of M. luisana geographical distribution. M. luisana seeds were 1.9-3.9 mm long, 1.7-3.3 mm wide, 1.2-2.9 mm thick, and weighed from 3 to 19 mg. We found the seeds from the lower limit to be lighter, thinner and less spherical than the central and upper populations. Across all populations, 41% of the total biomass consisted of leaves, followed by shoots (33%) and roots (27%). The biomass production and allocation showed no significant difference among populations during the initial harvests; however, discernible differences emerged over time. Seed weight initially had a significant effect on biomass production, but this effect was lost with time. Seed weight alone explained only 0.82% of the total variance of biomass production, while harvest age explained 40.05%, and seed provenance 3.08%. The correlation between seed weight and RGR was slightly negative but not significant. These results have implications for efforts to ecologically restore dry forests in the region as well as how to implement climate change adaptation and conservation translocation actions, as these might imply sowing and establishing M. luisana at new sites. Given the small variance in biomass accumulation explained by seed traits and provenance, efforts to protect M. luisana during germination and establishment are likely to be more important for management success than the seed source used.

  • 19.
    Aguirre Salcedo, Citlali
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ceccon, Eliane
    Centro Regional de Investigaciones Multidisciplinarias. Universidad Nacional Autónoma de México, Mexico.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Trait differentiation and local adaptation of a local endemic shrub along a tropical dry forest gradient: a reciprocal transplant experimentManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Rapid climate change imperils a multitude of species, demanding either swift adaptation or a strategic migration to new areas to safeguard their existence. Species confined to spatially limited habitats face heightened vulnerability as ecological conditions may undergo dramatic shifts across their range. In this study, we delve into the processes shaping the geographic distribution of Mimosa luisana, a species endemic to the Tehuacán-Cuicatlán Valley in Mexico, having high potential for use in ecological restoration. We aimed to forecast the response of M. luisana to climate change and to formulate strategic management guidelines in the face of global change. We conducted a reciprocal translocation and a common garden experiment with three provenances of M. luisana. We used populations originating from the lower, central and upper range-limit of the altitudinal and latitudinal distribution of the species. We found significant differences in the relative growth rate, leaf biomass change and specific leaf area among the three provenances during their early establishment, but found little evidence of local adaptation among the studied populations. Instead, all provenances did best at the central part of the species range. We suggest that cold temperatures might be delimiting the upper limit of M. luisana within the Tehuacán-Cuicatlán Valley, whereas tolerance to drought may set lower limits. M. luisana might respond to climate change not by upward shifts of each locally adapted population distributed along the elevational gradient, but by conditions improving at the high-elevation edge in response to warming. A management implication from our results is that ensuring genetic diversity of the seed batches may be more important than only using local seed sources of M. luisana in ecological restoration actions.

  • 20.
    Aguirre Salcedo, Citlali
    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.
    To move or not to move: assessing the viability of translocating Mimosa luisana for climate adaptation in the Tehuacán-Cuicatlán Valley, MexicoManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Climate change is threatening range-restricted species world-wide, but assessments of vulnerability is lacking in many areas, especially in tropical mountain regions. We assessed the vulnerability of the tropical dry forest species Mimosa luisana, an important nurse plant facilitating the establishment of other species, and provider of ecosystem services to local communities. We projected changes in the geographic distribution and extent of the climatic envelope of M. luisana for the periods 2021-2040, 2041-2060, 2061-2080, using the Maximun Entropy species distribution model (MaxEnt). We also tested the response of local provenances of M. luisana to different climate change scenarios by transplanting them to new elevations. 

    We found that new areas at higher elevation will become climatically suitable for M. luisana in the future, without losing its current geographic range, so that its geographic range may expand by between 50% and 313%. Transplantation showed that M. luisana can grow and survive in a wide range of conditions. Moreover, M. luisana was able to survive when translocated 700 m upwards, to areas above its current elevational limit. 

    We conclude that M. luisana is not in need of assisted migration to escape climate-related extinction, but translocation to areas that become climatically suitable may be beneficial to its conservation. The species may be used in ecological restoration projects in a wide range of conditions, including beyond its present range, increasing the likelihood of success in present and future ecological restoration actions. However, we acknowledge the need for assessing the climate-change effects on reproduction and the dispersal capacity of the species. 

  • 21.
    Aguirre Salcedo, Citlali
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Montaño-Arias, Susana Adriana
    2Departamento de Biología, División de Ciencias Biológicas y de La Salud, Universidad Autónoma MetropolitanaIztapalapa, Ciudad de México, México.
    Jansson, Roland
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Restoration implications of the germination ecology of six dry-forest woody Fabaceae species in MexicoManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Germination kickstarts plant recruitment. Hence, acknowledging this process is a prerequisite for restoration of ecosystems. In dry forests, where opportunities for plant establishment occur in a narrow window of opportunity, seeds must respond to cues to germinate when conditions for growth are suitable. Understanding the strategies and adaptations of seeds to the seasonal dry-forest ecosystems is needed to guide restoration and management actions in the face of climate change. We investigated the effects of scarification, temperature and light in germination percentage, germination time and synchrony of six woody Fabaceae species. The species have ecological potential for restoration and are of cultural and economic importance for the local people in the Tehuacán-Cuicatlán Valley, Mexico. We carried out a multifactorial germination experiment with five temperatures, two light regimes and two scarification conditions for Mimosa luisana, M. polyantha, M. adenantheroides, M. lactiflua, Acaciella angustissima and Vachellia constricta. Responses differed among the species, but they all germinated in a wide range of temperatures (10°C to 40°C). Mechanical scarification highly increased the germination percentage of all species. Higher temperature increased and speeded up germination in dark conditions for most of the species. We found more heterogeneous responses in germination synchrony among species. Despite that the studied species had high germination percentages in warm temperatures, their recruitment in nature might be negatively affected by warmer and drier conditions, and by the loss of shade and seed dispersers due to deforestation and changes in land use. It is crucial to study not just germination percentage and time but also other aspects of the germination process such as the germination synchrony, since it might reveal useful information for management actions.

  • 22.
    Ahlgren, Gunnel
    et al.
    Department of Ecology and Evolution (Limnology), Uppsala University, Uppsala, Sweden.
    Vrede, Tobias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Goedkoop, Willem
    Department of Environmental Assessment, Swedish University of Agricultural Sciences (SLU), Uppsala, Sweden.
    Fatty Acid Ratios in Freshwater Fish, Zooplankton and Zoobenthos - Are There Specific Optima?2009Ingår i: Lipids in Aquatic Ecosystems / [ed] Martin Kainz, Michael T. Brett, Michael T. Arts, New York: Springer-Verlag New York, 2009, s. 147-178Kapitel i bok, del av antologi (Övrigt vetenskapligt)
    Abstract [en]

    Two groups of polyunsaturated fatty acids (PUFA), termed omega-3 and omega-6 in food (or here as n-3 and n-6 PUFA, respectively), are essential for all vertebrates and probably also for nearly all invertebrates. The absolute concentrations of the different PUFA are important, as is an appropriate balance between the two. The optimal ratio of n-3/n-6 is not known for most organisms but is anticipated to be more or less species-specific (Sargent et al. 1995). The three most important PUFA in vertebrates are eicosapentaenoic acid (EPA, 20:5n-3), docosahexaenoic acid (DHA, 22:6n-3) and arachidonic acid (ARA, 20:4n-6). Both EPA and ARA are precursors for biologically active eicosanoids that are vital components of cell membranes and play many dynamic roles in mediating and controlling a wide array of cellular activities (Crawford et al. 1989; Harrison 1990; Henderson et al. 1996; see Chap. 9). Since n-3 and n-6 PUFA cannot be synthesized de novo by most metazoans, they must be included in the diet, either as EPA, DHA and ARA, or as their precursors, such as α-linolenic acid (ALA, 18:3n-3, precursor of EPA and DHA) and linoleic acid (LIN, 18:2n-6, precursor of ARA) (Bell et al. 1986; Sargent et al. 1995). Both ALA and LIN are produced in the thylacoid membranes of algae and plants with chlorophyll (Sargent at al. 1987).

  • 23.
    Ahlinder, Jon
    et al.
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Eriksson, Karolina Ida Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Hellmér, Maria
    Department of Biology, Science Division, Swedish Food Agency, Sweden.
    Salomonsson, Emelie
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Granberg, Malin
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Dacklin, Ingrid
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Elving, Josefine
    Department of Chemistry, Environment and Feed Hygiene, National Veterinary Institute, Sweden.
    Brindefalk, Björn
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Upstream land use with microbial downstream consequences: iron and humic substances link to Legionella spp.Manuskript (preprint) (Övrigt vetenskapligt)
  • 24.
    Ahlinder, Jon
    et al.
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden; Department of Tree Breeding, Skogforsk, Sävar, Sweden.
    Eriksson, Karolina Ida Anna
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Hellmér, Maria
    Department of Biology, Science Division, Swedish Food Agency, Sweden.
    Salomonsson, Emelie
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Granberg, Malin
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Dacklin, Ingrid
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden.
    Elving, Josefine
    Department of Chemistry, Environment and Feed Hygiene, Swedish Veterinary Agency, Sweden.
    Brindefalk, Björn
    Division of CBRN Defence and Security, Swedish Defence Research Agency (FOI), Sweden; Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Sweden.
    Upstream land use with microbial downstream consequences: iron and humic substances link to Legionella spp2024Ingår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 256, artikel-id 121579Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Intensified land use can disturb water quality, potentially increasing the abundance of bacterial pathogens, threatening public access to clean water. This threat involves both direct contamination of faecal bacteria as well as indirect factors, such as disturbed water chemistry and microbiota, which can lead to contamination. While direct contamination has been well described, the impact of indirect factors is less explored, despite the potential of severe downstream consequences on water supply. To assess direct and indirect downstream effects of buildings, farms, pastures and fields on potential water sources, we studied five Swedish lakes and their inflows. We analysed a total of 160 samples in a gradient of anthropogenic activity spanning four time points, including faecal and water-quality indicators. Through species distribution modelling, Random Forest and network analysis using 16S rRNA amplicon sequencing data, our findings highlight that land use indirectly impacts lakes via inflows. Land use impacted approximately one third of inflow microbiota taxa, in turn impacting ∌20–50 % of lake taxa. Indirect effects via inflows were also suggested by causal links between e.g. water colour and lake bacterial taxa, where this influenced the abundance of several freshwater bacteria, such as Polynucleobacter and Limnohabitans. However, it was not possible to identify direct effects on the lakes based on analysis of physiochemical- or microbial parameters. To avoid potential downstream consequences on water supply, it is thus important to consider possible indirect effects from upstream land use and inflows, even when no direct effects can be observed on lakes. Legionella (a genus containing bacterial pathogens) illustrated potential consequences, since the genus was particularly abundant in inflows and was shown to increase by the presence of pastures, fields, and farms. The approach presented here could be used to assess the suitability of lakes as alternative raw water sources or help to mitigate contaminations in important water catchments. Continued broad investigations of stressors on the microbial network can identify indirect effects, avoid enrichment of pathogens, and help secure water accessibility.

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  • 25.
    Ahlinder, Jon
    et al.
    Division of CBRN Defence and Security, Swedish Defence Research Agency, Umeå, Sweden.
    Giles, Barbara
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    García-Gil, M. Rosario
    Department of Forest Genetics and Plant Physiology, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Life stage-specific inbreeding depression in long-lived Pinaceae species depends on population connectivity2021Ingår i: Scientific Reports, E-ISSN 2045-2322, Vol. 11, nr 1, artikel-id 8834Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Inbreeding depression (ID) is a fundamental selective pressure that shapes mating systems and population genetic structures in plants. Although it has been shown that ID varies over the life stages of shorter-lived plants, less is known about how the fitness effects of inbreeding vary across life stages in long-lived species. We conducted a literature survey in the Pinaceae, a tree family known to harbour some of the highest mutational loads ever reported. Using a meta-regression model, we investigated distributions of inbreeding depression over life stages, adjusting for effects of inbreeding levels and the genetic differentiation of populations within species. The final dataset contained 147 estimates of ID across life stages from 41 studies. 44 Fst estimates were collected from 40 peer-reviewed studies for the 18 species to aid genetic differentiation modelling. Partitioning species into fragmented and well-connected groups using Fst resulted in the best way (i.e. trade-off between high goodness-of-fit of the model to the data and reduced model complexity) to incorporate genetic connectivity in the meta-regression analysis. Inclusion of a life stage term and its interaction with the inbreeding coefficient (F) dramatically increased model precision. We observed that the correlation between ID and F was significant at the earliest life stage. Although partitioning of species populations into fragmented and well-connected groups explained little of the between-study heterogeneity, the inclusion of an interaction between life stage and population differentiation revealed that populations with fragmented distributions suffered lower inbreeding depression at early embryonic stages than species with well-connected populations. There was no evidence for increased ID in late life stages in well-connected populations, although ID tended to increase across life stages in the fragmented group. These findings suggest that life stage data should be included in inbreeding depression studies and that inbreeding needs to be managed over life stages in commercial populations of long-lived plants.

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  • 26.
    Ahlinder, Jon
    et al.
    Division of CBRN Defence and Security, FOI, Swedish Defence Research Agency, Umeå, Sweden.
    Mathisen, Peter
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Sjödin, Andreas
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Kemiska institutionen. Division of CBRN Defence and Security, FOI, Swedish Defence Research Agency, Umeå, Sweden.
    Nilsson, Elin
    Division of CBRN Defence and Security, FOI, Swedish Defence Research Agency, Umeå, Sweden.
    Forsman, Mats
    Division of CBRN Defence and Security, FOI, Swedish Defence Research Agency, Umeå, Sweden.
    Andersson, Agneta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Thelaus, Johanna
    Division of CBRN Defence and Security, FOI, Swedish Defence Research Agency, Umeå, Sweden.
    Oligotyping reveals divergent responses of predation resistant bacteria to aquatic productivity and plankton compositionManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Predation-resistance has been suggested to be a key for persistence of pathogenic bacteria in aquatic environments. Little is known about driving factors for different types of protozoa resistant bacteria (PRB). We studied if presence of PRB is linked to specific plankton taxa, the aquatic nutrient state, or predation pressure on bacteria. Nineteen freshwater systems were sampled and analyzed for PRB, plankton composition and physicochemical variables. Three PRB genera were identified; Pseudomonas, Mycobacterium and Rickettsia. Use of minimum entropy decomposition algorithm and phylogenetic analysis showed that different nodes (representing OTUs of high taxonomic resolution) matched to environmental isolates of the three genera. Links between the PRB genera and specific plankton taxa were found, but showed different relationships depending on if 18S rRNA OTU or microscopy data were used in the analysis. Mycobacterium spp. was negatively correlated to aquatic nutrient state, while Pseudomonas showed the opposite pattern. Rickettsia spp. was positively related to predation pressure on bacteria. Both Mycobacterium and Rickettsia were more abundant in systems with high eukaryotic diversity, while Pseudomonas occurred abundantly in waters with low prokaryotic diversity. The different drivers may be explained by varying ecological strategies, where Mycobacterium and Rickettsia are slow growing and have an intracellular life style, while Pseudomonas is fast growing and opportunistic. Here we give an insight to the possibilities of newly advanced methods such as sequencing and oligotyping to link potential pathogens with biomarkers. This as a tool to assist predictions of the occurrence and persistence of environmental pathogens.

  • 27.
    Ahlm, Kristoffer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Prey specialization and diet of frogs in Borneo2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Earlier studies of the diet of frogs indicate that most adult frogs are mainly insectivorous. Overall, frogs are viewed more as generalists than specialists in terms of their diet. However, despite earlier studies, there are still gaps in our knowledge regarding what frogs tend to eat and the degree of specialization. The aim of this study was to investigate the diet choice of frogs in a tropical ecosystem. The present study was conducted in a well-known hotspot for frogs with 66 of the 156 known frog species in Borneo found in a protected area comprising of primary rainforest.

     

    Frogs were caught in the field and their stomachs were flushed. The stomach content was retrieved, sorted to prey categories, and the diet analysed. In addition, the frogs were identified to species level. The frogs belonged to five families: Bufonidae, Dicroglossidae, Megophryidae, Microhylidae and Ranidae. My results show that the most common food source was ants, which constituted 63.7 % of the total food for all studied frog families. Termites, beetles and spiders made up 11.7 %, 4.2 % and 2.8 % of the total prey, respectively. The results from the analysis of Shannon’s diversity index supported two diet specialist families, the Bufonidae and Megophridae, which had a significantly lower mean diversity index compared to the generalist Dicroglossidae. To better reveal differences in frog’s diet in this ecosystem, further studies using larger sample size are needed.

     

     

     

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  • 28.
    Ahlström, Anders
    et al.
    Department of Physical Geography and Ecosystem Science, Lund University, Lund, Sweden.
    Canadell, Josep G.
    Global Carbon Project, CSIRO Oceans and Atmosphere, ACT, Canberra, Australia.
    Metcalfe, Daniel B.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Widespread Unquantified Conversion of Old Boreal Forests to Plantations2022Ingår i: Earth's Future, E-ISSN 2328-4277, Vol. 10, nr 11, artikel-id e2022EF003221Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Across the boreal biome, clear-cutting of old, previously non clear-cut forests with high naturalness followed by tree planting or seeding is a major land use change. However, how much previously uncut forest has been converted to plantations remains unquantified. We combine Swedish national databases on clear-cuts and forest inventories to show that at least 19% of all clear-cuts since 2003 have occurred in old forests that were most likely not previously cut and planted or seeded. Old forests have been cut and lost at a steady rate of ∼1.4% per year for the same period, and at this rate they will disappear by the 2070s. There is further evidence that this type of unreported forest conversion is occurring across much of the world's boreal forest.

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  • 29. Aho, Kelly S.
    et al.
    Fair, Jennifer H.
    Hosen, Jacob D.
    Kyzivat, Ethan D.
    Logozzo, Laura A.
    Rocher-Ros, Gerard
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Arktiskt centrum vid Umeå universitet (Arcum).
    Weber, Lisa C.
    Yoon, Byungman
    Raymond, Peter A.
    Distinct concentration-discharge dynamics in temperate streams and rivers: CO2 exhibits chemostasis while CH4 exhibits source limitation due to temperature control2021Ingår i: Limnology and Oceanography, ISSN 0024-3590, E-ISSN 1939-5590, Vol. 66, nr 10, s. 3656-3668Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Streams and rivers are significant sources of carbon dioxide (CO2) and methane (CH4) to the atmosphere. However, the magnitudes of these fluxes are uncertain, in part, because dissolved greenhouse gases (GHGs) can exhibit high spatiotemporal variability. Concentration-discharge (C-Q) relationships are commonly used to describe temporal variability stemming from hydrologic controls on solute production and transport. This study assesses how the partial pressures of two GHGs—pCO2 and pCH4—vary across hydrologic conditions over 4 yr in eight nested streams and rivers, at both annual and seasonal timescales. Overall, the range of pCO2 was constrained, ranging from undersaturated to nine times oversaturated, while pCH4 was highly variable, ranging from 3 to 500 times oversaturated. We show that pCO2 exhibited chemostatic behavior (i.e., no change with Q), in part, due to carbonate buffering and seasonally specific storm responses. In contrast, we show that pCH4 generally exhibited source limitation (i.e., a negative relationship with Q), which we attribute to temperature-mediated production. However, pCH4 exhibited chemostasis in a wetland-draining stream, likely due to hydrologic connection to the CH4-rich wetland. These findings have implications for CO2 and CH4 fluxes, which are controlled by concentrations and gas transfer velocities. At high Q, enhanced gas transfer velocity acts on a relatively constant CO2 stock but on a diminishing CH4 stock. In other words, CO2 fluxes increase with Q, while CH4 fluxes are modulated by the divergent Q dynamics of gas transfer velocity and concentration.

  • 30.
    Ahonen, Jani
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Can morphologic restoration of hydropower outlet channels create hydraulically suitable spawning and larvae habitats for grayling?: Modelling the effects of environmental measures with HEC-RAS.2018Självständigt arbete på avancerad nivå (masterexamen), 20 poäng / 30 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The aim of this study was to model if hydraulically suitable habitats for juvenile and spawning grayling could be created by morphological restoration alone in the Bjurfors Övre hydropower outlet channel in the Ume River Basin. The study was done by 2D modelling with HEC-RAS using hourly water flow and level data collected during the period 20160521-20161029. Suitable water depth and velocity values for larvae and spawning grayling were collected from literature. Environmental measures for the Bjurfors Övre outlet channel were designed based on the morphology in outlet channels with documented reproducing grayling populations and large habitat diversities. The outlet channel at present morphology and after morphological modifications were modelled at different flow scenarios (0-369m3/s) and areas of suitable water velocities and depths before and after proposed measures were compared. Results show that suitable velocity areas would increase with a factor of between 1,03-1,81 and the suitable depth areas with a factor of 2,34-19,09 and that suitable depths may be the major limiting factor in current conditions. Results also show that zero-flow events at Bjurfors Övre hydropower plant create unsuitable velocities for larvae and spawning grayling and that the frequency and duration of such events could be more limiting than the mere occurrence of such events. The study indicates that the morphological restoration in hydropeaking outlet channels could improve the availability of habitats with suitability water depth and velocity not only for larvae and spawning grayling, but for other lotic organisms. The study also showed that HEC-RAS modelling is a potential resource effective way to assess to what extent certain proposed environmental measures may create suitable water depths and velocities in hydropeaking outlet channels.

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  • 31.
    Ahonen, Jani
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Korttidsregleringsmönster i Ångermanälvens avrinningsområde: Har elmarknadens avreglering påverkat regleringsintensiteten?2013Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The effects of the deregulation of the electricity market 1996 in Sweden on short-term hydropower regulation are unknown. This report investigates patterns in subdaily regulation in the Ångerman River Basin during the period 1993-2011. Differences in subdaily flows and zero flow events between the periods 1993-1995 and 1996-2011 were studied by analyzing hourly data from 8 regulated and 8 unregulated locations with four subdaily flow variation indices. No correlations between the market deregulation and the regulation intensity in the Ångerman River basin were detected. The number of days natural ranges of variability were exceeded and the magnitude of subdaily variation were significantly higher at regulated locations. Zero flow events increased substantially when the periods 1993-2007 and 2008-2011 were compared. Significant correlations were detected in the summer periods between dry years and high magnitudes for the indices that measured variation in volume and low magnitudes for subdaily flow reversals. Zero flow events in the summer periods increased during dry years if the period 2008-2011 were excluded. The major conclusions are that the deregulation of the electricity market has not affected the subdaily regulation of the Ångerman River and that the regulated sites show highly unnatural subdaily variations. Regulation intensity and zero flows events increases during summertime in dry years and the latter also increased substantially after 2007. The current regulation regime is considered harmful for riverine ecosystems and the high and increasing levels of subdaily flow alteration shows the urgent need of national directives for subdaily hydropower operation.

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  • 32.
    Aksnes, Dag W.
    et al.
    Nordic Institute for Studies in Innovation, Research & Education (NIFU), Norway.
    Blöcker, Christopher
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysik.
    Colliander, Cristian
    Umeå universitet, Samhällsvetenskapliga fakulteten, Sociologiska institutionen. Umeå universitet, Umeå universitetsbibliotek (UB).
    Nilsson, Lena Maria
    Umeå universitet, Arktiskt centrum vid Umeå universitet (Arcum). Umeå universitet, Medicinska fakulteten, Institutionen för epidemiologi och global hälsa.
    Kullerud, Lars (Medarbetare/bidragsgivare)
    UArctic.
    Larson, Keith (Medarbetare/bidragsgivare)
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    SCITE team, (Medarbetare/bidragsgivare)
    Arctic Research Trends: Bibliometrics 2016-20222023Rapport (Övrigt vetenskapligt)
    Abstract [en]

    This work was conducted by the UArctic Thematic Network on Research Analytics and Bibliometrics. It was supported by Global Affairs Canada through the Global Arctic Leadership Initiative.

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  • 33.
    Aktas, Filiz
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Påverkar daggmask kvicksilverupptaget i arktisk vegetation?: En analys av kvicksilverkoncentration i fårsvingel (Festuca ovina) i hed- och ängsvegetation2021Självständigt arbete på avancerad nivå (magisterexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
  • 34. Ala-aho, P.
    et al.
    Soulsby, C.
    Pokrovsky, O. S.
    Kirpotin, S. N.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Serikova, Svetlana
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Manasypov, R.
    Lim, A.
    Krickov, I.
    Kolesnichenko, L. G.
    Laudon, H.
    Tetzlaff, D.
    Permafrost and lakes control river isotope composition across a boreal Arctic transect in the Western Siberian lowlands2018Ingår i: Environmental Research Letters, E-ISSN 1748-9326, Vol. 13, nr 3, s. =20-=20, artikel-id 034028Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The Western Siberian Lowlands (WSL) store large quantities of organic carbon that will be exposed and mobilized by the thawing of permafrost. The fate of mobilized carbon, however, is not well understood, partly because of inadequate knowledge of hydrological controls in the region which has a vast low-relief surface area, extensive lake and wetland coverage and gradually increasing permafrost influence. We used stable water isotopes to improve our understanding of dominant landscape controls on the hydrology of the WSL. We sampled rivers along a 1700 km South-North transect from permafrost-free to continuous permafrost repeatedly over three years, and derived isotope proxies for catchment hydrological responsiveness and connectivity. We found correlations between the isotope proxies and catchment characteristics, suggesting that lakes and wetlands are intimately connected to rivers, and that permafrost increases the responsiveness of the catchment to rainfall and snowmelt events, reducing catchment mean transit times. Our work provides rare isotope-based field evidence that permafrost and lakes/wetlands influence hydrological pathways across a wide range of spatial scales (10-105 km2) and permafrost coverage (0%-70%). This has important implications, because both permafrost extent and lake/wetland coverage are affected by permafrost thaw in the changing climate. Changes in these hydrological landscape controls are likely to alter carbon export and emission via inland waters, which may be of global significance.

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  • 35. Ala-aho, P.
    et al.
    Soulsby, C.
    Pokrovsky, O. S.
    Kirpotin, S. N.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Serikova, Svetlana
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Vorobyev, S. N.
    Manasypov, R. M.
    Loiko, S.
    Tetzlaff, D.
    Using stable isotopes to assess surface water source dynamics and hydrological connectivity in a high-latitude wetland and permafrost influenced landscape2018Ingår i: Journal of Hydrology, ISSN 0022-1694, E-ISSN 1879-2707, Vol. 556, s. 279-293Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Climate change is expected to alter hydrological and biogeochemical processes in high-latitude inland waters. A critical question for understanding contemporary and future responses to environmental change is how the spatio-temporal dynamics of runoff generation processes will be affected. We sampled stable water isotopes in soils, lakes and rivers on an unprecedented spatio-temporal scale along a 1700 km transect over three years in the Western Siberia Lowlands. Our findings suggest that snowmelt mixes with, and displaces, large volumes of water stored in the organic soils and lakes to generate runoff during the thaw season. Furthermore, we saw a persistent hydrological connection between water bodies and the landscape across permafrost regions. Our findings help to bridge the understanding between small and large scale hydrological studies in high-latitude systems. These isotope data provide a means to conceptualise hydrological connectivity in permafrost and wetland influenced regions, which is needed for an improved understanding of future biogeochemical changes.

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  • 36.
    Alapää, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Soil geochemical mapping of manganese in Norrbotten: Delineation of the spatial and statistical distribution of manganese and correlated elements in glacial tills2015Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Information from soil geochemical mapping programmes is useful within a number of different fields including for example mineral exploration and environmental research. The purpose of this thesis was to investigate the relationship between soil metal concentrations and geological factors such as bedrock lithology, structural geology, mineralizations etc. The study used data acquired in association with a nationwide soil geochemical mapping programme conducted by the Geological Survey of Sweden, SGU. These data contained both total element concentrations measured via X-ray fluorescence spectroscopy and acid leached concentrations measured with plasma technique. Basic statistical compilations were made, including classification of element concentrations into percentiles according to SGU standards, calculation of leachability and correlation analyses. Spatial analyses were also done, using GIS-software. The results showed that all investigated elements except zinc had elevated median values for total concentrations in the project area compared to the natural median values. The strongest correlation for total element concentrations was that between iron and cobalt with Spearman ρ=0.88. Furthermore, the results of this study indicated that sampling sites superimposing volcanic rocks contained the highest total concentrations of manganese. The results also suggested that manganese content increased with increasing age of the underlying bedrock. The highest median concentration of 0.80 g/kg was found in Archean rocks. Known mineralizations were often reflected in the form of positive element anomalies in the till geochemistry. The obtained results were also consistent with the average composition of the bedrock. No clear connections with any of the other investigated geological factors could be made.

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  • 37.
    Albrectsen, Benedicte R.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Björkén, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Varad, Akkamahadevi
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Hagner, Åsa
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Wedin, Mats
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Jansson, Stefan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Endophytic fungi in European aspen (Populus tremula) leaves - diversity, detection, and a suggested correlation with herbivory resistance2010Ingår i: Fungal diversity, ISSN 1560-2745, E-ISSN 1878-9129, Vol. 41, nr 1, s. 17-28Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    According to the geographic mosaic theory of coevolution (GMTC), clines of traits reflecting local co-adaptation (including resistance genes) should be common between a host and its parasite and should persist across time. To test the GMTC-assumption of persistent clinal patterns we compared the natural prevalence of two parasites on aspen Populus tremula trees: mining moths of the genus Phyllocnistis and leaf rust Melampsora spp. Damage data were collated from the Swedish National Forest Damage Inventory (2004–2006). In addition, occurrence of the parasites was scored in field conditions in two common gardens in the north and south of Sweden over five growing seasons (2004–2008), then related to biomass (stem height and diameter) and to concentrations of eleven leaf phenolics. Phyllocnistis mainly occurred in the northern garden, a distribution range which was confirmed by the countrywide inventory, although Phyllocnistis was more abundant on southern clones, providing evidence for possible local maladaptation. Melampsora occurred all over the country and in both gardens, but built up more quickly on northern clones, which suggests a centre of local clone maladaptation in the north. Stem growth also followed a clinal pattern as did the concentration of three phenolic compounds: benzoic acid, catechin and cinnamic acid. However, only benzoic acid was related to parasite presence: negatively to Phyllocnistis and positively to Melampsora and it could thus be a potential trait under selection.

    In conclusion, clines of Phyllocnistis were stronger and more persistent compared to Melampsora, which showed contrasting clines of varying strength. Our data thus support the assumption of the GMTC model that clines exist in the border between hot and cold spots and that they may be less persistent for parasites with an elevated gene flow, and/or for parasites which cover relatively larger hot spots surrounded by fewer cold spots.

  • 38.
    Albrectsen, Benedicte R.
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå Plant Science Centre (UPSC).
    Ericson, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Lundberg, Per
    Nutrient addition extends flowering display, which gets tracked by seed predators, but not by their parasitoids2008Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 117, s. 473-480Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although phenological matching between two and three trophic interactions has received some attention, it has largely been disregarded in explaining the lack of strong cascade dynamics in terrestrial systems. We studied the response of the specialist seed predator, Paroxyna plantaginis (Tephritidae) and associated generalist parasitoids (Chalcidoidea) to controlled fertilisation of individuals of naturally growing Tripolium vulgare (Asteraceae) on four island populations (Skeppsvik Archipelago, Sweden). We consistently found evidence of nutrient limitation: fertilised plants increased their biomass, produced more capitula (the oviposition units for tephritid flies), were more at risk of attack by the tephritids, and puparia were heavier in fertilised plants. During some parts of the season tephritids became more heavily parasitized, supporting the presence of cascade dynamics, however net parasitism over season decreased in response to nutrient addition. We found no evidence that capitulum size complicated parasitoid access to the tephritids, however the extended bud production prolonged the flowering season. Thus, tephritids utilized the surplus production of capitula throughout the entire season, while parasitoids did not expand their oviposition time window accordingly. Implications for top down regulation and cascade dynamics in the system are discussed.

  • 39.
    Albrectsen, Benedicte Riber
    et al.
    Dept of Biology, Vassar College, Poughkeepsie, USA.
    Gardfjell, Hans
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Orians, Colin M.
    Murray, Brittany
    Fritz, Robert S.
    Slugs, willow seedlings and nutrient fertilization: intrinsic vigor inversely affects palatability2004Ingår i: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 105, s. 268-278Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    This study evaluates how preference by a generalist slug herbivore Arion subfuscus changes inversely with seedling size across three levels of fertilization for three full‐sib families of willow seedlings. We analyzed seedlings for condensed tannin and protein concentration, and related these data to changes in palatability. In preference tests over time, leaf discs from more fertilized seedlings experienced an extended window of vulnerability compared to discs from less fertilized seedlings, which were also more tannin‐rich. In a whole seedling selection study, slugs readily attacked smaller seedlings (<5 cm) but rarely attacked taller seedlings (>10 cm). However, a general difference in risk of damage close to 50% existed when comparing shorter and taller individuals within each family and level of fertilizer. The decrease in palatability with height of the seedlings was positively correlated with an increase in condensed tannin concentration. We found no effect of seedling size on protein concentration. Akaiki index criterion model comparisons suggested that only main effects were important for explaining seedling choice by slugs as well as the ratio between proteins and condensed tannins. Seedling size, had the largest effect, followed by fertilizer level and family. Surprisingly, seedling size and fertilizer treatment had opposite effects on palatability to slugs. Size decreased probability of damage, whereas fertilization extended the window of susceptibility. Because the seedlings were even‐aged, differences in size are interpreted as differences in growth rate or vigor. The positive phenotypic correlation found between size and tannin production in the less preferred willow seedlings confirms that several plant defense traits may be selected for simultaneously, because fast growth may allow an early development of plant defenses. We discuss these results in the light of plant‐defense theories that predict a negative correlation between the allocation to growth and the production of secondary defense compounds.

  • 40. Aldea, Jorge
    et al.
    Ruiz-Peinado, Ricardo
    del Rio, Miren
    Pretzsch, Hans
    Heym, Michael
    Brazaitis, Gediminas
    Jansons, Aris
    Metslaid, Marek
    Barbeito, Ignacio
    Bielak, Kamil
    Granhus, Aksel
    Holm, Stig-Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nothdurft, Arne
    Sitko, Roman
    Lof, Magnus
    Species stratification and weather conditions drive tree growth in Scots pine and Norway spruce mixed stands along Europe2021Ingår i: Forest Ecology and Management, ISSN 0378-1127, E-ISSN 1872-7042, Vol. 481, artikel-id 118697Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Mixed forests are suggested as a strategic adaptation of forest management to climate change. Scots pine (Pinus sylvestris L.) and Norway spruce (Picea abies (L.) Karst.) are tree species of high economic and ecological value for European forestry. Both species coexist naturally in a large part of their distributions but there is a lack of knowledge on the ecological functioning of mixtures of these species and how to manage such stands. This paper analyses these species' intra- and inter-specific competition, including size-symmetric vs. size-asymmetric competition, and explore the effect of weather conditions on tree growth and competition. We studied basal area growth at tree level for Scots pine and Norway spruce in mixed versus pure stands in 22 triplets of fully-stocked plots along a broad range of ecological conditions across Europe. Stand inventory and increment cores provided insights into how species mixing modifies tree growth compared with neighbouring pure stands. Five different competition indices, weather variables and their interactions were included and checked in basal area growth models using a linear mixed model approach. Interspecific size-asymmetric competition strongly influenced growth for both tree species, and was modulated by weather conditions. However, species height stratification in mixed stands resulted in a greater tree basal area growth of Scots pine (10.5 em(2) year(-1)) than in pure stands (9.3 em(2) year(-1)), as this species occupies the upper canopy layer. Scots pine growth depended on temperature and drought, whereas Norway spruce growth was influenced only by drought. Interspecific site-asymmetric competition increased in cold winters for Scots pine, and decreased after a drought year for Norway spruce. Although mixtures of these species may reduce tree size for Norway spruce, our results suggest that this could be offset by faster growth in Scots pine. How inter-specific competition and weather conditions alter tree growth may have strong implications for the management of Scots pine-Norway spruce mixtures along the rotation period into the ongoing climate change scenario.

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  • 41.
    Aldea, Jorge
    et al.
    Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Lomma, Sweden.
    Ruiz-Peinado, Ricardo
    Forest Research Center, INIA, CSIC, Madrid, Spain; iuFOR, Sustainable Forest Management Research Institute, University of Valladolid & INIA, Valladolid, Spain.
    del Río, Miren
    Forest Research Center, INIA, CSIC, Madrid, Spain; iuFOR, Sustainable Forest Management Research Institute, University of Valladolid & INIA, Valladolid, Spain.
    Pretzsch, Hans
    Chair of Forest Growth and Yield Science, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany.
    Heym, Michael
    Chair of Forest Growth and Yield Science, School of Life Sciences Weihenstephan, Technical University of Munich, Freising, Germany.
    Brazaitis, Gediminas
    Department of Forest Science, Vytautas Magnus University, Kaunas, Lithuania.
    Jansons, Aris
    Latvian State Forest Research Institute Silava, Salaspils, Latvia.
    Metslaid, Marek
    Chair of Silviculture and Forest Ecology, Institute of Forestry and Rural Engineering, Estonian University of Life Sciences, Tartu, Estonia.
    Barbeito, Ignacio
    Department of Forest Resources Management, Faculty of Forestry, The University of British Columbia, BC, Vancouver, Canada.
    Bielak, Kamil
    Department of Silviculture, Institute of Forest Sciences, Warsaw University of Life Sciences, Warsaw, Poland.
    Hylen, Gro
    NIBIO, Norwegian Institute of Bioeconomy Research, Ås, Norway.
    Holm, Stig-Olof
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Nothdurft, Arne
    Department of Forest- and Soil Sciences, Institute of Forest Growth, BOKU, University of Natural Resources and Life Sciences Vienna, Vienna, Austria.
    Sitko, Roman
    Technical University in Zvolen, Faculty of Forestry, Department of Forest Resource Planning and Informatics, Zvolen, Slovakia.
    Löf, Magnus
    Southern Swedish Forest Research Centre, Swedish University of Agricultural Sciences, Lomma, Sweden.
    Timing and duration of drought modulate tree growth response in pure and mixed stands of Scots pine and Norway spruce2022Ingår i: Journal of Ecology, ISSN 0022-0477, E-ISSN 1365-2745, Vol. 110, nr 11, s. 2673-2683Artikel i tidskrift (Refereegranskat)
    Abstract [en]
    1. Climate change is increasing the severity and frequency of droughts around the globe, leading to tree mortality that reduces production and provision of other ecosystem services. Recent studies show that growth of mixed stands may be more resilient to drought than pure stands. The two most economically important and widely distributed tree species in Europe are Norway spruce (Picea abies (L.) Karst) and Scots pine (Pinus sylvestris L.), but little is known about their susceptibility to drought when coexist.
    2. This paper analyses the resilience (resistance, recovery rate and recovery time) at individual-tree level using a network of tree-ring collections from 22 sites along a climatic gradient from central Europe to Scandinavia. We aimed to identify differences in growth following drought between the two species and between mixed and pure stands, and how environmental variables (climate, topography and site location) and tree characteristics influence them.
    3. We found that both the timing and duration of drought drive the different responses between species and compositions. Norway spruce showed higher vulnerability to summer drought, with both lower resistance and a longer recovery time than Scots pine. Mixtures provided higher drought resistance for both species compared to pure stands, but the benefit decreases with the duration of the drought. Especially climate sensitive and old trees in climatically marginal sites were more affected by drought stress.
    4. Synthesis. Promoting Scots pine and mixed forests is a promising strategy for adapting European forests to climate change. However, if future droughts become longer, the advantage of mixed stands could disappear which would be especially negative for Norway spruce.
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  • 42.
    Alewell, C
    et al.
    Institute of Environmental Geosciences, University of Basel, Switzerland.
    Giesler, Reiner
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Leifeld, J
    Agroscope Reckenholz-Tanikon Research Station ART, Switzerland.
    Rollog, M
    Institute of Environmental Geosciences, University of Basel, Switzerland.
    Stable carbon isotopes as indicators for environmental change inpalsa peats2011Ingår i: Biogeosciences, ISSN 1726-4170, E-ISSN 1726-4189, Vol. 8, s. 1769-1778Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Palsa peats are unique northern ecosystems formed under an arctic climate and characterized by a high biodiversity and sensitive ecology. The stability of the palsas are seriously threatened by climate warming which will change the permafrost dynamic and induce a degradation of the mires.

    We used stable carbon isotope depth profiles in two palsa mires of Northern Sweden to track environmental change during the formation of the mires. Soils dominated by aerobic degradation can be expected to have a clear increase of carbon isotopes (δ13C) with depth, due to preferential release of 12C during aerobic mineralization. In soils with suppressed degradation due to anoxic conditions, stable carbon isotope depth profiles are either more or less uniform indicating no or very low degradation or depth profiles turn to lighter values due to an enrichment of recalcitrant organic substances during anaerobic mineralisation which are depleted in 13C.

    The isotope depth profile of the peat in the water saturated depressions (hollows) at the yet undisturbed mire Storflaket indicated very low to no degradation but increased rates of anaerobic degradation at the Stordalen site. The latter might be induced by degradation of the permafrost cores in the uplifted areas (hummocks) and subsequent breaking and submerging of the hummock peat into the hollows due to climate warming. Carbon isotope depth profiles of hummocks indicated a turn from aerobic mineralisation to anaerobic degradation at a peat depth between 4 and 25 cm. The age of these turning points was 14C dated between 150 and 670 yr and could thus not be caused by anthropogenically induced climate change. We found the uplifting of the hummocks due to permafrost heave the most likely explanation for our findings. We thus concluded that differences in carbon isotope profiles of the hollows might point to the disturbance of the mires due to climate warming or due to differences in hydrology. The characteristic profiles of the hummocks are indicators for micro-geomorphic change during permafrost up heaving.

  • 43.
    Alewell, C
    et al.
    Institute of Environmental Geosciences, University of Basel, Switzerland.
    Giesler, Reiner
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Klaminder, Jonatan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Leifeld, J
    Agroscope Reckenholz-Tänikon Research Station ART, Switzerland.
    Rollog, M
    Institute of Environmental Geosciences, University of Basel, Switzerland.
    Stable carbon isotopes as indicators for micro-geomorphic changes in palsa peats2011Ingår i: Biogeosciences Discussions, ISSN 1810-6277, E-ISSN 1810-6285, Vol. 8, nr 1, s. 527-548Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Palsa peats are unique northern ecosystems formed under an arctic climate and characterizedby an unique biodiversity and ecology. The stability of the palsas are seriouslythreatened by climate warming which will change the permafrost dynamic and5 results in degradation of the mires. We used stable carbon isotope depth profiles intwo palsa mires of Northern Sweden to track environmental change during the formationof the mires. Carbon isotope (13C) depth profile of the yet undisturbed mireStorflaket indicated very low to no degradation of the peat in the water saturated depressions(hollows) but increased rates of anaerobic degradation at the Stordalen site.10 The latter might be induced by degradation of the permafrost cores in the uplifted areas(hummocks) and subsequent braking and submerging of the hummock peat intothe hollows due to climate warming. Carbon isotope depth profiles of hummocks indicateda turn from aerobic mineralisation to anaerobic degradation at a peat depthbetween 4 to 25 cm. The age of these turning point was 14C dated between 150 and15 670 years and could thus not be caused by anthropogenically induced climate change.We found the uplifting of the hummocks due to permafrost heave the most likely explanationfor our findings. We thus concluded that differences in carbon isotope profiles ofthe hollows might point to the disturbance of the mires due to climate warming or dueto differences in hydrology. The characteristic profiles of the hummocks are indicators20 for micro-geomorphic change during permafrost up heaving.

  • 44.
    Alfredsson, Hilda
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Soil Organic Carbon in Boreal Agricultural Soil: Tillage interruption and its effect on Soil Organic Carbon2023Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Farmers have been disrupting the carbon cycle ever since humans started converting forests to agricultural lands. But are there farming practices that can be applied to increase the carbon storage in the soil and subsequently counteract increasing carbon dioxide levels in the atmosphere? In this study I investigate if soil organic matter (SOM) and soil organic carbon (SOC) change with longer interruption between tillage events. The study was conducted by studying SOM concentrations and SOC pools in eight fields with different time since tillage (1 to 14 years). I found that SOM concentrations increased in the O horizon of the studied soil in response to increased time since tillage. Here, SOM concentrations were on average around 13 % one year after tillage, while fourteen-year-old farmland had a concentration around 15 %. In similar, SOC pool increased from around 0.1 kg C m-2 in the O horizon of 1 year old soil to 0.33 kg C m-2 14 years after tillage. While both SOM concentrations and SOC pools increased in the O horizon over time since tillage, the SOM concentration and SOC pools decreased in the subsoil. I found no net sequestering of SOC in response to less frequent tillage in comparison to more frequency tillage. My conclusion is that limiting tillage to 14-year cycles is not enough to increase carbon sequestration. 

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  • 45.
    Alftberg Melin, Mattias
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Change in growth and overall condition in populations of anadromous burbot (Lota lota) in the Gulf of Bothnia2019Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    Many populations of burbot (Lota lota)around the world have been extirpated, are endangered or are in serious decline both regarding numbers but also in size. The aim of this study was to investigate if growth and overall condition in populations of anadromous burbot in the Gulf of Bothnia has changed over time and if so, discuss potential causes behind. This was done by comparing size at age and individual level condition indices of the two populations of anadromous burbot in Sävarån and Rickleån to previous studies from the same rivers. The results showed thatgrowth of young burbot has increased between the time period 2001-2014 to 2019in Sävarånand also a change towards a higher frequency of young individuals and a lack of older ones. Furthermore, an increase over time in condition was observed in Sävarån. In Rickleån the growth at the age of 3 had increased from both 1969-1971 and 2001-2014 to 2019. At the age of 4 to 9 a decrease in growth was shown from the time period 1969-1971 to 2001-2014 in Rickleån. A shift towards warmer water temperatures due to climate change might be an explanation in the observed change in both growth and condition in the population of burbots in Sävarån and Rickleån. Furthermore, the observed change in age frequency in Sävarån could also be a result of an increase in water temperature but could also be an effect of restoration and the control of pH in Sävarån.

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  • 46.
    Algesten, Grete
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Brydsten, Lars
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jonsson, Per
    Institute of Applied Environmental Research, Stockholm University, Stockholm, Sweden.
    Kortelainen, Pirkko
    Finnish Environment Institute, P.O. Box 140, FIN-00251, Helsinki, Finland.
    Löfgren, Stefan
    Department of Environmental Assessment, SLU, P.O. Box 7050, Uppsala, Sweden.
    Rahm, Lars
    Department of Water and Environmental Studies, Linköping University, SE-58183 Linköping, Sweden.
    Räike, Antti
    Finnish Environment Institute, P.O. Box 140, FIN-00251, Helsinki, Finland.
    Sobek, Sebastian
    Institute for Aquatic Sciences and Water Pollution Control, Swiss Federal Institute of Technology Zurich (ETH), Universitätsstr. 16, CH-8092 Zurich, Switzerland.
    Tranvik, Lars
    Department of Ecology and Evolution, EBC, Uppsala University, SE-752 36 Uppsala, Sweden.
    Wikner, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Jansson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Organic carbon budget for the Gulf of Bothnia2006Ingår i: Journal of Marine Systems, ISSN 0924-7963, E-ISSN 1879-1573, Vol. 63, nr 3-4, s. 155-161Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We calculated input of organic carbon to the unproductive, brackish water basin of the Gulf of Bothnia from rivers, point sources and the atmosphere. We also calculated the net exchange of organic carbon between the Gulf of Bothnia and the adjacent marine system, the Baltic Proper. We compared the input with sinks for organic carbon; permanent incorporation in sediments and mineralization and subsequent evasion of CO2 to the atmosphere. The major fluxes were riverine input (1500 Gg C year− 1), exchange with the Baltic Proper (depending on which of several possible DOC concentration differences between the basins that was used in the calculation, the flux varied between an outflow of 466 and an input of 950 Gg C year 1), sediment burial (1100 Gg C year− 1) and evasion to the atmosphere (3610 Gg C year− 1). The largest single net flux was the emission of CO2 to the atmosphere, mainly caused by bacterial mineralization of organic carbon. Input and output did not match in our budget which we ascribe uncertainties in the calculation of the exchange of organic carbon between the Gulf of Bothnia and the Baltic Proper, and the fact that CO2 emission, which in our calculation represented 1 year (2002) may have been overestimated in comparison with long-term means. We conclude that net heterotrophy of the Gulf of Bothnia was due to input of organic carbon from both the catchment and from the Baltic Proper and that the future degree of net heterotrophy will be sensible to both catchment export of organic carbon and to the ongoing eutrophication of the Baltic Proper.

  • 47.
    Algesten, Grete
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Sobek, Sebastian
    Bergström, Ann-Kristin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jonsson, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Tranvik, Lars J
    Jansson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Contribution of sediment respiration to summer CO2 emission from boreal and subarctic lakes2005Ingår i: Microbial Ecology, ISSN 0095-3628, E-ISSN 1432-184X, Vol. 50, nr 4, s. 529-535Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We measured sediment production of carbon dioxide (CO(2)) and methane (CH(4)) and the net flux of CO(2) across the surfaces of 15 boreal and subarctic lakes of different humic contents. Sediment respiration measurements were made in situ under ambient light conditions. The flux of CO(2) between sediment and water varied between an uptake of 53 and an efflux of 182 mg C m(-2) day(-1) from the sediments. The mean respiration rate for sediments in contact with the upper mixed layer (SedR) was positively correlated to dissolved organic carbon (DOC) concentration in the water (r(2) = 0.61). The net flux of CO(2) across the lake surface [net ecosystem exchange (NEE)] was also closely correlated to DOC concentration in the upper mixed layer (r(2) = 0.73). The respiration in the water column was generally 10-fold higher per unit lake area compared to sediment respiration. Lakes with DOC concentrations <5.6 mg L(-1) had net consumption of CO(2) in the sediments, which we ascribe to benthic primary production. Only lakes with very low DOC concentrations were net autotrophic (<2.6 mg L(-1)) due to the dominance of dissolved allochthonous organic carbon in the water as an energy source for aquatic organisms. In addition to previous findings of allochthonous organic matter as an important driver of heterotrophic metabolism in the water column of lakes, this study suggests that sediment metabolism is also highly dependent on allochthonous carbon sources.

  • 48.
    Algesten, Grete
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Ekologi och geovetenskap.
    Sobek, Sebastian
    Bergström, Ann-Kristin
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ågren, Anneli
    Tranvik, Lars J
    Jansson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Role of lakes for organic carbon cycling in the boreal zone2004Ingår i: Global Change Biology, ISSN 1354-1013, E-ISSN 1365-2486, Vol. 10, nr 1, s. 141-147Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    We calculated the carbon loss (mineralization plus sedimentation) and net CO2 escape to the atmosphere for 79 536 lakes and total running water in 21 major Scandinavian catchments (size range 437–48 263 km2). Between 30% and 80% of the total organic carbon that entered the freshwater ecosystems was lost in lakes. Mineralization in lakes and subsequent CO2 emission to the atmosphere was by far the most important carbon loss process. The withdrawal capacity of lakes on the catchment scale was closely correlated to the mean residence time of surface water in the catchment, and to some extent to the annual mean temperature represented by latitude. This result implies that variation of the hydrology can be a more important determinant of CO2 emission from lakes than temperature fluctuations. Mineralization of terrestrially derived organic carbon in lakes is an important regulator of organic carbon export to the sea and may affect the net exchange of CO2 between the atmosphere and the boreal landscape.

  • 49.
    Algesten, Grete
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Wikner, Johan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Sobek, Sobek
    Department of Limnology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden .
    Tranvik, Lars T.
    Department of Limnology, Evolutionary Biology Centre, Uppsala University, Uppsala, Sweden .
    Jansson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Seasonal variation of CO2 saturation in the Gulf of Bothnia: Indications of marine net heterotrophy2004Ingår i: Global Biogeochemical Cycles, ISSN 0886-6236, E-ISSN 1944-9224, Vol. 18, s. 4021-4028Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Seasonal variation of pCO2 and primary and bacterioplankton production were measured in the Gulf of Bothnia during an annual cycle. Surface water was supersaturated with CO2 on an annual basis, indicating net heterotrophy and a source of CO2 to the atmosphere. However, the Gulf of Bothnia oscillated between being a sink and a source of CO2 over the studied period, largely decided by temporal variation in bacterial respiration (BR) and primary production (PP) in the water column above the pycnocline. The calculated annual respiration-production balance (BR-PP) was very similar to the estimated CO2 emission from the Gulf of Bothnia, which indicates that these processes were major determinants of the exchange of CO2 between water and atmosphere. The southern basin (the Bothnian Sea) had a lower net release of CO2 to the atmosphere than the northern Bothnian Bay (7.1 and 9.7 mmol C m−2 d−1, respectively), due to higher primary production, which to a larger extent balanced respiration in this basin.

  • 50.
    Al-Hayali, Abdullah
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    DO BUMBLEBEES PARTITION AN ELEVATIONAL GRADIENT BY BODY SIZE?2022Självständigt arbete på avancerad nivå (masterexamen), 40 poäng / 60 hpStudentuppsats (Examensarbete)
    Abstract [en]

    As the climate warms, Arctic bumblebee species face the loss of habitat and must deal with increased competition from southern species tracking their thermal and habitat niches north, for example Bombus terrestris. Previous studies demonstrate that bumblebees follow Bergmann’s rule, i.e., larger body sizes at higher latitudes, despite bumblebees not being considered truly ectothermic, as they can generate heat through muscular activity (i.e., beating their wings). This study seeks to confirm and understand the relationship between body size and temperature using an elevational gradient as a proxy for climate. In this study, I examined 13 plots (420-1164 m.a.s.l.) set along the 3.4 km transect up the slope of Mt. Nuolja in Abisko National Park, Sweden. For body size, I chose to use the commonly accepted proxy distance between the base of the wings (i.e., intertegular distance). For temperature, I chose the mean temperature at time of visitation. Results show that climate is a significant explanatory variable for bumblebee body size, with an overall increasing body size with increasing elevation (i.e., colder climate), although most of the variance is explained by caste, i.e., queens having a larger body size than workers. Body size also shows some correlation with day of capture, which can be explained by changes in environmental conditions (e.g., temperature, flowering plant species) during the growing season experienced by the different emerging times for the castes. Given that caste was the most useful explanatory variable for body size, future studies could look at a larger environmental gradient, for example, by sampling at multiple locations along the entire Scandes mountain range to see if the effects found are localized. Further, specific habitat and specific traits of preferred plants may also help to elucidate body-size differences between species and castes. For example, many bumblebee species’ castes emerge at a specific time of year when only certain flowering plant species in specific habitats are available. This important research would also help to illuminate whether bumblebees and the species of plants they pollinate remain synchronous as climate warming accelerates. Nevertheless, my results show an overall positive relationship between bumblebee body size and elevation, indicating that a warming climate will result in reduced body sizes among bumble bee species. Future studies will have to investigate what consequences this will have for Arctic bumblebee populations – and for the plants that rely on bumblebee visits for their pollination.

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