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  • 1.
    Arnesén, Lisa
    University of Skövde, School of Bioscience.
    Vems landskap ska förändras för att öka den biologiska mångfalden?: En studie av skillnaderna i odlingslandskapets konnektivitet med avseende på två skyddsvärda arter med olika preferenser2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Organisms relevant for nature conservation dont follow administrative borders. Because of this there is a need for a landscape perspective within conservation and planning, and a need for the species of interest to have legal protection. Network analysis adapted for ecological purposes has grown to become a powerful tool for studying and communicating the relationships between species dispersion and access to habitat. In this study the following question is posed: How is the Osmoderma eremita and the Pernis apivorus dispersal possibilities in the small scale cultivated landscape of Borås affected by exploitation in respect to a) dispersal ability, b) habitat quality, c) position of habitat patches in a network? The analysis were based on municipal and regional nature conservation data, which in due to confidentiality is not accounted for in the report by maps, coordinates, etc. Several networks were established for both species to indicate how habitat patches are distributed today and how the species dispersal changes depending on which patches are excluded – this was done to imitate how exploitation can affect the species future survival and dispersion. The results showed that the O.e. is mainly inhibited by its poor dispersal abilities, followed by patch position, while the P.a. is the most affected by degrading habitat quality. The most important conclusions of the study were that the O.e. natural dispersal may be restricted but can be improved by linking small network components together and by maintaining the largest components. As for the P.a. it was concluded that a different type of analysis, focusing on its behaviour and need for different patches for different purposes, would generate more interesting results.

  • 2.
    Banks, H. T.
    et al.
    Center for Research in Scientific Computation North Carolina State University Raleigh, NC, USA.
    Banks, J. E.
    Undergraduate Research Opportunities Center (UROC) California State University, Monterey Bay Seaside, CA, USA.
    Bommarco, Riccardo
    Department of Ecology Swedish University of Agricultural Sciences Uppsala, Sweden.
    Curtsdotter, Alva
    Department of Ecology Swedish University of Agricultural Sciences Uppsala, Sweden.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology Swedish University of Agricultural Sciences Uppsala, Sweden.
    Laubmeier, A. N.
    Center for Research in Scientific Computation North Carolina State University Raleigh, NC, USA.
    Parameter estimation for an allometric food web model2017In: International journal of pure and applied mathematics, ISSN 1311-8080, E-ISSN 1314-3395, Vol. 114, no 1, p. 143-160Article in journal (Refereed)
    Abstract [en]

    The application of mechanistic models to natural systems is of interest to ecological researchers. We use the mechanistic Allometric Trophic Network (ATN) model, whichis well-studied for controlled and theoretical systems, to describe the dynamics of the aphidRhopalosiphum padi in an agricultural field. We diagnose problems that arise in a first attemptat a least squares parameter estimation on this system, including formulation of the modelfor the inverse problem and information content present in the data. We seek to establishwhether the field data, as it is currently collected, can support parameter estimation for theATN model.

  • 3.
    Berg, Sofia
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Physics, Chemistry and Biology, Div. of Theoretical Biology, Linköping Univ., Linköping, Sweden.
    Pimenov, Aexander
    Weierstrass Inst., Berlin, Germany / Environmental Research Inst., Univ. College Cork, Cork, Ireland.
    Palmer, Catherine
    Weierstrass Inst., Berlin, Germany.
    Emmerson, Mark
    School of Biological Sciences, Queen's Univ. Belfast, Belfast, United Kingdom.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Ecology, Swedish Univ. of Agricultural Sciences, Uppsala, Sweden.
    Ecological communities are vulnerable to realistic extinction sequences2015In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 124, no 4, p. 486-496Article in journal (Refereed)
  • 4.
    Bergman, Jimmy
    University of Skövde, School of Life Sciences.
    Cellulär automat simulerar utbredning av Taraxacum2012Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [sv]

    I detta arbete undersöks vilken grad av inomartskonkurrens som ger upphov till ett observerat utbredningsmönster av maskrosor (Taraxacum sect. Ruderalia). Maskrosor har både fröspridning och vegetativ förökning. Studien hypotiserar att utbredningen kan beskrivas utifrån enkla regler för spridning och konkurrens. Dessa används i simuleringar med en binär cellulär automat där utveckling sker i deterministiska tidssteg. Modellen består av ett rutnät där en tom cell antingen kan förbli tom eller koloniseras, medan en upptagen cell antingen kan överleva eller dö ut. Reglerna efterliknar situationer med hög respektive låg känslighet för inomartskonkurrens. De mått på jämförelse mellan observation och simulering som används är mönstrets fraktala dimension, mönstrets tendens att aggregera och storleken på den enklaste algoritm som beskriver datan. Två olika initialvillkor används för att testa modellens robusthet. Den observerade utbredningen kontrolleras även mot slumpmässig fördelning. Resultaten visar att den observerade utbredningen är klusterartad. Simulering med en högre inomartskonkurrens beskriver utbredningen väl sett till aggregering och fraktal dimension. Lägre inomartskonkurrens beskriver dock maskrosornas verkliga utbredning sett till algoritmisk komplexitet, vilket tolkas som att individer kan leva närmare inpå varandra än vad regeln om högre inomartskonkurrens förutsätter. För vald klusterstorlek är simuleringarna ej känsliga för initialvillkoren, men då hela fördelningen av antal celler per klusterstorlek i stickprov på ett tidssteg analyseras har initialvillkoren fakstiskt betydelse. Sett till fördelningen av cell per klusterstorlek liknar ingen simulering den observerade utbredningen. Därmed kan modellen tänkas inrymma den vegetativa förökningen medan fröspridningen, som är stokastisk, ej inryms på samma vis.

  • 5.
    Bergström, Lena
    et al.
    Swedish University of Agricultural Sciences, Department of Aquatic Resources, Öregrund, Sweden.
    Blenckner, Thorsten
    Stockholm Recilience Centre, Stockholm University, Stockholm, Sweden.
    Frelat, Romain
    University of Hamburg, Institute of Hydrobiology and Fishery Science, Hamburg, Germany.
    Grimvall, Anders
    Swedish Institute for the Marine Environment, Gothenburg, Sweden.
    Haapasaari, Päivi
    University of Helsinki, Department of Environmental Sciences, Helsinki, Finland.
    Haas, Bianca
    University of Hamburg, Institute of Hydrobiology and Fishery Science, Hamburg Germany.
    Heikinheimo, Outi
    Natural Resources Institute Finland, Helsinki, Finland.
    Jernberg, Susanna
    Finnish Environment Institute, Marine Research Centre, Helsinki, Finland.
    Large, Scott
    ICES, Copenhagen, Denmark.
    Lindegren, Martin
    Centre for Ocean Life, DTU-Aqua, Charlottenlund, Denmark.
    Levin, Phil
    Northwest Fisheries Science Center, Seattle, USA.
    Lehikoinen, Annukka
    Helsinki University, Kotka Maritime Research Centre, Kotka, Finland.
    Möllmann, Christian
    University of Hamburg, Institute of Hydrobiology and Fishery Science, Hamburg, Germany.
    Nordström, Marie
    Åbo Akademi University, Environmental and Marine Biology, Åbo, Finland.
    Norrström, Niclas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Otto, Saskia
    University of Hamburg, Institute of Hydrobiology and Fishery Science, Hamburg, Germany.
    Peltonen, Heikki
    Marine Research Centre, Finnish Environment Institute, Helsinki, Finland.
    Précuchét, Laurence
    Centre for Ocean Life, DTU-Aqua, Charlottenlund, Denmark.
    Putnis, Ivars
    Institute of Food Safety, Animal Health and Environment BIOR, Fish Resources Research Department, Riga, Latvia.
    Romakkaniemi, Atso
    Natural Resources Institute Finland, Oulun yliopisto, Finland.
    Suikkanen, Sanna
    Finnish Environment Institute, Marine Research Centre, Helsinki, Finland.
    Torres, Marian
    Swedish University of Agricultural Sciences, Department of Aquatic Resources, Öregrund, Sweden.
    Uusitalo, Laura
    Finnish Environment Institute, Marine Research Centre, Helsinki, Finland.
    Weigel, Benjamin
    Åbo Akademi University, Environmental and Marine Biology, Åbo, Finland.
    Wesslander, Karin
    Swedish Meteorological and Hydrological Institute, Marine Environment, Västra Frölunda, Sweden.
    Zagrodzka, Zuzanna
    University of Hamburg, Institute of Hydrobiology and Fishery Science, Hamburg, Germany.
    Interim Report of the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB): 18-22 April 2016 Helsinki, Finland2016Report (Other academic)
    Abstract [en]

    The ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) meeting was held in Helsinki (Finland), 18-22 April 2016. The meeting was attended by 26 participants from five countries and chaired by Laura Uusitalo, Fin-land, Saskia Otto, Germany, Martin Lindegren, Denmark, and Lena Bergström, Swe-den. This was the first year of the new three-year Terms of Reference (ToR) for WGIAB. The main working activities in 2016 were to A) develop the trait-based ap-proach of understanding the ecosystem function, and B) explore the social-ecological system, including indicator development, revising the conceptual model, and devel-oping case studies. As a primary outcome of the ToR A, we built on our previous work on integrated ecosystem assessments (IEAs) in the Baltic Sea, but extended it beyond considering changes in abundances of a few dominant species, to accounting for community-wide changes in a number of key traits across multiple trophic levels. These traits represent various ecosystem functions upon which we derive important ecosystem services. By investigating temporal changes in the community weighted mean traits of phyto-plankton, zooplankton, zoobenthos, and fish, we demonstrated whether trait reor-ganizations at the level of entire communities occurred in the Central Baltic Sea as a result of the 1980s regime shift. Using in total 29 traits combined for all groups we found indications of two breakpoints across all four taxonomic groups over the last decades, i.e. one around 1990 and one around 2000. Further work will focus on ex-ploring the nature of the changes in trait composition and on standardizing the num-ber of traits and data types (i.e. binary, continuous or categorical) across taxonomic group.In addition, we collected data on key functional groups and abiotic variables in all main sub-basins of the Baltic Sea, setting the stage for a cross-regional comparison of temporal patterns and trends in lower trophic level in the face of recent develop-ments in climate-related drivers.With reference to Tor B, to explore how social indicators could be used in parallel with biological indicators in an integrated assessment framework, we developed a conceptual model of interrelationships between ecosystem and society. We used the model as a basis for mapping factors to be accounted for in the ecosystem-based management using the Baltic salmon and clupeid species as case studies. The models depict 1) the structure of the foodweb relevant to the target species, 2) the key com-munity level and population traits that contribute to the state of the species, 3) main pressures affecting the foodweb and their effects on the species, 4) key management measures, and 5) benefits that the species can produce for society.To support the development of Ecosystem Overview the group members evaluated the probability of occurrence and the magnitude of the effect of 15 pressures occur-ring in the Baltic Sea. The top five pressures identified were input of nutrients, in-creased temperature, decreased salinity, input of hazardous substances, and input or spread of non-indigenous species.The work will continue intersessionally and the next meeting of WGIAB is planned to be held in Lisbon, Portugal, back-to-back with WGCOMEDA and WGEAWESS.

  • 6.
    Blomstrand, Johanna
    University of Skövde, School of Life Sciences.
    Studie av kantzoner i Valleområdet och Varaslätten: Inventering av invertebrater, träd, mossor och lavar2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Ecotones are areas where different ecosystems meet, and they vary in sharpness and range. The areas provide a great biological diversity since they are a mixture of the meeting areas and provide special microclimate. The biological diversity is affected by the width, length and structure of the ecotone and they have a biological significance in that they provide habitat, protection and food to many species. To demonstrate where in the landscape there are ecotones the tool GIS can be used. In this work GIS have been used to define which areas the work is concentrated on and to randomize out points for inventory in the ecotones in these areas. Inventory of the ecotones was made with the help of twenty 5x2 meters big inventory boxes, ten in the Valle area and ten on the Vara flat. Invertebrates, trees, mosses and lichens where inventoried in the boxes. The aim of this work was to see how the biological diversity in ecotones between forest and open land differ between the Valle area and the Vara flat. A study was also made to see whether the cardinal direction the ecotones lie in have an impact on the invertebrate fauna or not. None of the tests made showed any statistically significant difference between the Valle area and the Vara flat. Nor was there any statistically significant difference in invertebrate fauna depending on cardinal direction of the ecotone. Nevertheless, there are indications that the areas differ in invertebrate fauna and number of tree individuals. 

  • 7.
    Borrvall, Charlotta
    et al.
    Linköping University.
    Ebenman, Bo
    Linköping University.
    Jonsson, Tomas
    Linköping University.
    Biodiversity lessens the risk of cascading extinction in model food webs2000In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 3, p. 131-136Article in journal (Refereed)
  • 8.
    Carrelli, Tove
    University of Skövde, School of Life Sciences.
    FÖRSTUDIE OM RESTAURERING AV VÄNGA MOSSE2012Independent thesis Advanced level (degree of Master (One Year)), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Vänga bog is one of the six large peat bogs in the Borås municipality which all have high biodiversity. All of these bogs are threatened by encroachment of shrubs and trees. This report presents a study of how the shrubs and trees are invading Vänga bog, and what the possible causes might be.

    A comparison of vegetation via five aerial photos over Vänga bog from 1955, 1964, 1983, 1996 and 2007, was conducted using ArcGIS. Aerial photos are made up of pixels and the method used was to dived the pixels in two values (open ground and shrubs-trees) and then to calculate how the area of shrubs and trees has changed over time. The analysis shows that there was an increase in growth of 43.5% from 1955 to 2007 and that the annual growth varied considerably between the different periods.

    Four factors were examined to determine the possible cause of such changes, namely, temperature, precipitation, atmospheric nitrogen (nitrate and ammonium) and sulphur deposition. The analysis contained within this report shows that temperature, precipitation and nitrogen deposits have a positive correlation to the growth of shrubs and trees. However, sulphur deposition exhibited the strongest correlation, indicating an inhibiting effect on growth of shrubs and trees during the end of the last century. These are new results when sulphur deposition was assumed to be a potential cause of growth of shrubs and trees on bogs in southern Sweden.

  • 9.
    Cohen, Joel
    et al.
    The Rockefeller University and Columbia University, New York, USA.
    Jonsson, Tomas
    The Rockefeller University, New York, USA.
    Carpenter, Stephen R.
    Center for Limnology, University of Wisconsin, Madison, USA.
    Ecological community description using the food web, species abundance, and body size2003In: Proceedings of the National Academy of Sciences of the United States of America, ISSN 0027-8424, E-ISSN 1091-6490, Vol. 100, no 4, p. 1781-1786Article in journal (Refereed)
  • 10.
    Ebenman, Bo
    et al.
    Department of Biology, Linköping University, Linköping, Sweden.
    Johansson, Annie
    Department of Biology, Linköping University, Linköping, Sweden.
    Jonsson, Tomas
    Department of Biology, Linköping University, Linköping, Sweden.
    Wennergren, Uno
    Department of Biology, Linköping University, Linköping, Sweden.
    Evolution of stable population dynamics through natural selection1996In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 263, no 1374, p. 1145-1151Article in journal (Refereed)
  • 11.
    Fant, Sanna
    University of Skövde, School of Life Sciences.
    Uppföljning av hotade och sällsynta växtarter på och kring Mösseberg, Falköping2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Mösseberg is a plateau mountain with an interesting nature and with a great variety of habitats and plant species. In this project the inventory has been performed in meadows, dry grasslands, gullies, scree slopes, wetlands and broad-leaved deciduous forests. This project aims to perform an inventory of 25 threatened and rare plant species in the municipality of Falköping, because of a sub target in the conservation program of Falköping. It is also a follow-up of an honours thesis performed in 2008. The project also surveyed how the plant species status had changed from previous years, what the reason to the changes are and what management actions that can improve the species’ status in the future. Of the 25 focal species that were included in the inventory of 2011, 22 species were found. The highest species richness was found in habitat D, Bestorpskärret, with large amounts of the five focal species that grow here. The results of the inventory in 2011 are both positive and negative. Most focal species were found, some species have increased in number and a small number was not found at all. Some species occur in very small numbers.

    According to Västergötlands Flora (Bertilsson et al 2002) the greatest threats today are overgrowth, eutrophication, pesticides, draining and acidification. Examples of these have been seen during the inventory, especially over-growth due to un-managed meadows and eutrophication. Also, some of the populations are quite small. There are a number of problems with small populations, like decreased adaptability and survivability.

    The future of threatened vascular plant species in Falköping vary from habitat to habitat. Some areas are prioritized and managed very well while others are threatened by overgrowth. If management recommendations are followed, the probability for a positive change is quite high for several species. But some plant populations are so small that the future of these is critical even if management recommendations are followed. In Falköping, the economy and the distribution of resources is limiting for conservation and management actions. Management actions would also be better if the team carrying out the work had more knowledge about the nature and specific needs of the species. 

  • 12.
    Freij, Mathilda
    University of Skövde, School of Bioscience.
    Restaureringens roll gällande Hornborgasjöns förmåga till kväve- och fosforretention2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Today Lake Hornborga is one of Europe’s most important bird lakes but that has not always been the case. Before natural and cultural conservation interests were given credit the lake was drained in favor of agricultural purposes and left to overgrow. The lake was restored in the early 90’s which meant an increased area and higher water levels in the lake.

     

    The water quality of the lake has been regularly tested in both the inlets and the outlet. This report sought to use some of this data to examine the retention of nitrogen and phosphorus in the lake, as well as the changes in retention due to the restauration. This was made by using the mean differences between the inlets and the outlet. The mean difference will indicate if less content is pouring out of the lake than in to the lake.

     

    The analysis shows that the mean differences in total nitrogen between the inlets and the outlet have increased after the restauration. No distinction can be shown in most of the tests regarding the mean differences in total phosphorus. In fact one of the tests shows that the mean differences in total phosphorus between the inlets and the outlet have significantly decreased. These results indicates that the restauration of Lake Hornborga have increased its ability to reduce contents of nitrogen but not phosphorus. However, more comprehensive studies with more accurate methods are needed to prove these results.

  • 13.
    Gagic, Vesna
    et al.
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Bartomeus, Ignasio
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden / Departamento de Ecología Integrativa, Estación Biológica de Doñana (EBD-CSIC), Sevilla, Spain.
    Jonsson, Tomas
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Taylor, Astrid
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Winqvist, Camilla
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Fischer, Christina
    Department of Ecology and Ecosystem Management, Technische Universität München, Restoration Ecology, Germany.
    Slade, Eleanor M.
    Department of Zoology, University of Oxford, Oxford, UK.
    Steffan-Dewenter, Ingolf
    Department of Animal Ecology and Tropical Biology, Biocentre, University of Würzburg, Würzburg, Germany.
    Emmerson, Mark
    School of Biological Sciences, Queen's University Belfast, Medical Biology Centre, Belfast, UK.
    Potts, Simon G.
    School of Agriculture, Policy and Development, Reading University, Reading, UK.
    Tscharntke, Teja
    Department of Agroecology, University of Göttingen, Göttingen, Germany.
    Weisser, Wolfgang
    Terrestrial Ecology Research Group, Department of Ecology and Ecosystem Management, Center for Food and Life Sciences Weihenstephan, Technische Universität München, Freising, Germany.
    Bommarco, Riccardo
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Functional identity and diversity of animals predict ecosystem functioning better than species-based indices2015In: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 282, no 1801, article id UNSP 20142620Article in journal (Refereed)
  • 14.
    Hedlin, Emelie
    University of Skövde, School of Life Sciences.
    Påverkan på stormusslors (Unionoida) miljö som kan motverka livskraftiga bestånd: En studie över redoxförhållanden och kantzoners sammansättning i fyra vattensystem i Västra Götalands län2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Freshwater mussels, who have a central role in aquatic ecosystems, are considered one of the most vulnerable and threatened freshwater organism groups. Sweden has nine species of large freshwater mussels, which of four are listed in the national Red List. Most studies and research have been focused on the freshwater pearl mussel (Margaritifera margaritifera) and its possible threats. Studies of more common species like the duck mussel (Anodonta anatina) and swollen river mussel (Unio tumidus) in Västra Götaland district, indicates severe difficulties of recruitment and viable populations. The most vulnerable phase in the life of freshwater mussels is considered to be the juvenile phase, when they are embedded in the sediment.

    The aim of this study has been to measure the quality of sediments at 12 of the earlier studied sites in Västra Götaland district. Redox potentials, which is a master variable in aquatic ecosystems and control parts of the chemistry in sediments, have been measured to analyze a possible correlation to the poor recruitment. The structure of the riparian buffer zones of the mussel’s unique catchment areas, have also been analyzed. The buffer zones are closely linked to the sediment ecosystems and have a fundamental role in the function of the ecosystems of streams.

    Analysis of regression trees indicated the most impacting factor on the mussel density, to be the difference of the mean redox value between the sediment surface and the depth of five centimeters. The variable with most impact on the recruitment was the proportion of area between catchment and lake. A none-parametric test showed a positive correlation between the proportion of marshes in the riparian buffer zone and the recruitment of A. anatina. A negative correlation existed between the proportion of young forests in the buffer zone and the recruitment of U. tumidus.

    More extended studies of redox potentials than was possible in this thesis, could contribute with valuable information of the quality of juvenile habitat. Further studies of the freshwater mussels could facilitate the evaluation of viable populations.

  • 15.
    Henriksson, Frida
    University of Skövde, School of Life Sciences.
    Ålder vid reproduktion hos den allmänna dammusslan (Anodonta anatina)2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Molluscs (Mollusca) belong to one of the most threatened taxonomic groups in the world and mussels (Bivalvia) have been observed to drastically decrease. The reduced growth of the mussel population may depend on factors such as decrease of the host fishes, acidification, invasive species, pollution and siltation of the seabed. All species of large mussels (Unionoida) are sensitive to eutrophication and physical changes in their habitat and can thus be used as indicators of territories with high conservation value or as an indicator of the chemical quality of the water. For a mussel population to be viable it requires a mean the proportion of juveniles (rejuvenation) in the population between 10 to 20 percentages. In Västra Götaland country only half of the previously 33 studied populations show satisfactory rejuvenation. When a mussel is considered to be a juvenile or adult is contentious. Today there are few studies on age at maturity of unionid mussels. Most often estimated values or knowledge of other species age at maturity is used. This work aims to investigate the growth of Anodonta anatina. Growth was measured as the differences in the distance between growth rings on each of the mussel individuals shell. With the annual growth rings an exponential growth rate was calculated that indicated the year in which most of the individuals slowed their growth. The breaking point was found using Von Bertalanffys growth model which indicates growths over time. Knowing the age at which most mussels slows their growth can give us a conclusion of possible age when sexual maturity occurs. The conclusion can be made upon the knowing that an individual starts to allocate the amount of energy available to more features than growth, where reproduction is the most likely. It is important to know the age at which spices reaches sexual maturity due to conservation purposes. A clam is considered very sensitive in its juvenile years. The result in this study shows that growth is slowing at the age of 4 years for one of the studied lakes. In the other two studied, the growth slowed before the mussel attained the age of 3 years. The age at which growth slows differ between lakes and may due to that natural conditions in lakes are various favorable.        

  • 16.
    Hinrichsen, Hans-Harald
    et al.
    Dept. Evolutionary Ecology, Kiel, Germany.
    Large, Scott
    International Council for the Exploration of the Sea (ICES), Copenhagen, Denmark.
    Möllmann, Christian
    University of Hamburg, Institute of Hydrobiology and Fishery Science, Hamburg, Germany.
    Müller-Karulis, Bärbel
    Stockholm University, Baltic Sea Centre, Stockholm, Sweden.
    Neuenfeldt, Stefan
    Technical University of Denmark, National Institute of Aquatic Resources, Section for Marine Ecology and Oceanography, Charlottenlund, Denmark.
    Norrström, Niclas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Schmidt, Jörn
    Christian-Albrechts-Universität zu Kiel, Department of Economics, Kiel, Germany.
    Sguotti, Camilla
    Institute for Hydrobiology and Fisheries Science, University of Hamburg, Hamburg, Germany.
    Tomczak, Maciej
    Stockholm University, Baltic Sea Centre, Stockholm, Sweden.
    Voss, Rudi
    Christian-Albrechts-Universität zu Kiel, Department of Economics, Kiel, Germany.
    Hamrén, Henrik
    Stockholm University, Baltic Sea Centre, Stockholm, Sweden.
    Report of the Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE): 18-21 April 2016 Helsinki, Finland2016Report (Other academic)
    Abstract [en]

    The first ICES Workshop on DEveloping Integrated AdviCE for Baltic Sea ecosystem-based fisheries management (WKDEICE) had the aim to start identifying and devel-oping ways to include environmental and economic considerations into ICES advice on Baltic Sea fish stocks. The WKDEICE meeting was held in Helsinki, Finland, on18–21 April 2016, with 12 participants from three countries and was chaired by Chris-tian Möllmann (Germany), Rudi Voss (Germany), and Maciej T. Tomczak (Sweden). Focusing on Eastern Baltic cod (subdivisions 25-32), WKDEICE addressed five main topics:

    1)developing a strategy for integrating environmental and economic infor-mation in fish stock advice;

    2)conducting an integrated environmental assessment;

    3)conducting a socio-economic assessment;

    4)conducting short-term projections informed by environmental and economic conditions; and

    5)communicating the approach and the results.

    Eastern Baltic cod has been selected as a case study. The exercise will likely be ex-tended to the baltic clupeid stocks of herring and sprat.

    A central point of the meeting was to discuss and design a concept of operationalized Integrated Ecosystem Assessment (IEA) including short-term predictions, to be used in advice on the main Baltic Sea fish stocks. The group developed an operational strategy, and started to quantify potentially useful environmental indicators, focusing on hydrographic conditions influencing cod recruitment. Economic short-term fore-casts were established to include the human dimension, and to provide additional quantitative information on fishing options. The suggested integrated advice frame-work will be further developed using simulation modelling during a next meeting in 2017. This meeting will be coordinated with the ICES/HELCOM Working Group on Integrated Assessments of the Baltic Sea (WGIAB) and the Baltic Fisheries Assess-ment Working Group (WGBFAS) to test concepts, apply Management Strategy Eval-uation (MSE) models, and have direct feedback for relevant ICES bodies. 

  • 17.
    Holmgren, Noél
    University of Skövde, School of Life Sciences.
    Coupled dynamics of lemmings and long-distance migratory birds2004In: Biological Resources and Migration / [ed] Dietrich Werner, Springer Berlin/Heidelberg, 2004, p. 219-228Conference paper (Refereed)
  • 18.
    Holmgren, Noél
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Norrström, Niclas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Aps, Robert
    University of Tartu, Estonia.
    Kuikka, Sakari
    University of Helsinki, Finland.
    A Concept of Bayesian Regulation in Fisheries Management2014In: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 9, no 11, article id e111614Article in journal (Refereed)
    Abstract [en]

    Stochastic variability of biological processes and uncertainty of stock properties compel fisheries managers to look for tools to improve control over the stock. Inspired by animals exploiting hidden prey, we have taken a biomimetic approach combining catch and effort in a concept of Bayesian regulation (BR). The BR provides a real-time Bayesian stock estimate, and can operate without separate stock assessment. We compared the performance of BR with catch-only regulation (CR), alternatively operating with N-target (the stock size giving maximum sustainable yield, MSY) and F-target (the fishing mortality giving MSY) on a stock model of Baltic Sea herring. N-targeted BR gave 3% higher yields than F-targeted BR and CR, and 7% higher yields than N-targeted CR. The BRs reduced coefficient of variance (CV) in fishing mortality compared to CR by 99.6% (from 25.2 to 0.1) when operated with F-target, and by about 80% (from 158.4 to 68.4/70.1 depending on how the prior is set) in stock size when operated with N-target. Even though F-targeted fishery reduced CV in pre-harvest stock size by 19–22%, it increased the dominant period length of population fluctuations from 20 to 60–80 years. In contrast, N-targeted BR made the periodic variation more similar to white noise. We discuss the conditions when BRs can be suitable tools to achieve sustainable yields while minimizing undesirable fluctuations in stock size or fishing effort.

  • 19.
    Howell, Daniel
    et al.
    Institute of Marine Research, Nordnes, Norway.
    Kempf, Alexander
    Thuenen Institute of Sea Fisheries, Hamburg, Germany.
    Bauer, Barbara
    Baltic Sea Centre, Stockholm, Sweden.
    Belgrano, Andrea
    Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
    Thorpe, Robert
    Centre for Environment, Fisheries and Aquaculture Science (CEFAS), Suffolk, United Kingdom.
    Vinther, Morten
    DTU-Aqua, Charlottenlund, Denmark.
    Bartolino, Valerio
    Swedish University of Agricultural Sciences, Department of Aquatic Resources, Lysekil, Sweden.
    Pope, John
    NRC (Europe) Ltd.
    Lehuta, Sigrid
    French Institute of Research for the Exploitation of the sea (Ifremer), Nantes, France.
    Gaichas, Sarah
    NOAA Northeast Fisheries Science Center, Woods Hole, USA.
    Lucey, Sean
    Dept. of Commerce/NOAA/NMFS Northeast Fisheries Science Center, Woods Hole, USA.
    Norrström, Niclas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Spence, Michael
    Department of Animal and Plant Sciences, Sheffield, United Kingdom.
    Holmgren, Noél
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Villanueva, Ching
    French Institute of Research for the Exploitation of the Sea (Ifremer), Nantes, France.
    Poos, Jan Jaap
    Wageningen Marine Research, Ijmuiden, the Netherlands.
    Kulatska, Nataliia
    Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
    Report of the Working Group on Multispecies Assessment Methods (WGSAM), 10-14 October 2016, Reykjavik, Iceland2017Report (Other academic)
    Abstract [en]

    The Working Group on Multispecies Assessment Methods (WGSAM) met in Reykjavik, Iceland, 10–14 October 2016. In this tenth report of the pan-regional WGSAM, work focused on four (B, E, F, G) of the multi-annual ToRs.

    Based on their knowledge, participants provided an updated inventory of progress of multispecies models in ICES Ecoregions (ToR A), noting those regions where no information was available. Reporting on ToR A was scarce compared to previous years, partly because recent relevant work was reported against ToR E and G instead.

    A Key Run (ToR B) of the Baltic Sea Ecopath with Ecosim (NS-EwE) model was presented and reviewed in detail by 4 WGSAM experts, and approved by the group following implementation of changes agreed in plenary at the meeting and verified by the 4 experts in January. The Key Run is documented in a detail in Annex 3, with key outputs summarised in Section 3 and data files made available on the WGSAM webpage). WGSAM also conducted an informal review of the LeMans modelling framework for potential application in the Irish Sea, and recommended adjustments to the framework for further review. Because the LeMans framework is a within-model ensemble addressing parameter uncertainty, this review also related to ToR D.

    Multispecies model skill assessment (ToR C) and multi-model ensemble methods (ToR D) were not emphasized this year. However, plans were made to coordinate future work for ToR C, and one ToR D presentation reviewed the utility of a dynamic multimodel ensemble for making inferences about the real world. This method can infer results for individual components of aggregate groups; the ensemble model uses correlations in other ecosystem models to determine what the models that group species would have predicted for individual species. A proof of concept for the North Sea was presented.

    Ecosystem indicator analyses (ToR E) were presented from a wide range of ecosystems. A theoretical analysis comparing results from the Celtic and North Seas with 4 “idealized” fleets was presented to analyse the performance of selected indicators in a multispecies mixed fishery. Four indicators including the Large Fish Indicator (LFI) were examined, and shown to have mixed utility in measuring the impact of different fleet sectors, with the best indicator varying by ecosystem. A multivariate analysis of ecosystem responses to multiple drivers was conducted for four US ecosystems using gradient forest method to identify potential ecosystem thresholds. Other multivariate methods were reviewed that draw on the strengths of multiple indicators for the Northeast US shelf ecosystem. A food web based biodiversity indicator was presented with an application for the Baltic Sea. This could be extended to any ecosystem with an EwE or similar model. A community status indicator relating a species-area relationship to the LFI and mean trophic levels was presented for the Swedish west coast.

    Impacts of apex predators on fisheries (ToR F) were examined with one presentation and a group discussion planning further work. A multipecies production model was parameterized to simulate interactions between three fish guilds, fisheries, and one marine mammal guild, concluding that fish reference points and trajectories change with marine mammal interactions. Fishery management was also important to reduce vessel interactions with and ensure prey supply to marine mammals. 4 | ICES WGSAM REPORT 2016 Exploration of practical advice for fisheries management incorporating multispecies, mixed fishery, and environmental factors (ToR G) was evident across regions. Two approaches for incorporating species, fleet, environmental, and other interactions are in progress in the Northeast US. One presentation outlined the New England approach, and another outlined the Mid-Atlantic approach. In New England, a management strategy evaluation is in progress to evaluate harvest control rules that consider herring's role as forage in the ecosystem. The modelling framework and stakeholder workshops were discussed. In the Baltic, a Nash Equilibrium optimisation approach incorporating environmental factors was presented for the cod-herring-sprat fishery to attempt to identify a solution that would give good yield for all species simultaneously. In the North Sea a theoretical analysis using 4 “idealized” fleets was presented to analyse the potential implications of "Pretty Good Yield" ranges around MSY. The model examined the likelihood of the fishery being precautionary for the different species given the uncertainties involved, and concluded that the upper ends of MSY ranges would not guarantee precautionarity.

  • 20.
    Höglind, Linnéa
    University of Skövde, School of Bioscience.
    Grönfläckig padda - Tillväxt och metamorfos hos yngel2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    In this work a hypothesis was tested that says tadpoles of green toad (Bufo viridis) may secrete a certain chemical substance in the water to inhibit the growth of other tadpoles. The hypothesis was based on an Australian study by Crossland & Shine (2012). They did a study on tadpoles of cane toads (Rhinella marina) where they discovered that the tadpoles produce a waterborne chemical in the water that inhibits growth. The idea of using a group with only siblings and a group of tadpoles from several females came from the knowledge that there is something called ”kin recognition" , which tests have shown that there are species with pheromones that can recognize closely related individuals ( Devall et al. 1986). By comparing the two groups of tadpoles where one group lived with only their siblings and the other group lived with tadpoles from all the females in the experiment, we were able to compare the growth in length and weight between the groups. After ten weeks, statistical analyses were done on the results. Before the tadpoles had gone through metamorphosis the tadpole’s length was measured and after metamorphosis the tadpoles instead was weighed. The results showed that there were differences in length but no significant differences in weight between the groups. The group with only siblings showed better growth in length and that could be because they can afford to spend energy on becoming longer and thus have advantage during metamorphosis. The group that lived with tadpoles from all the females perhaps adds more energy to grow in weight and thus have an advantage during metamorphosis.

  • 21.
    Iinatti, Sara
    University of Skövde, School of Bioscience.
    En modell som förutsäger naturlig skogstyp utifrån geografik information2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Sweden is covered by 60 % forestland, and most of it is used in forestry. There is a debate about the forestry methods in Sweden, where clear felling is the most commonly used practice, and alternate methods are being developed. Some of these methods, for example the Lübeck model, is focused on producing the best suited forest for a site, based on the environmental conditions. That forest would probably be of the natural forest type of that location.

    With this study a model is developed to predict natural forest types based on easily available GIS-data and without using remote sensing. Remote sensing is not considered to be useful in this particular case, since only the already existing vegetation can be analyzed using that method. Existing forests are likely to have been planted, and does not necessarily correspond to the type of vegetation that would develop, were there no human impact.

    The study was conducted by using forested areas that could be assumed to be natural (within nature reserves and other protected areas) in Askersund municipality, Örebro county, Sweden. An additive Generalized Linear Model (GZLM) has been used, and the prediction is based on soil, bedrock, elevation data and ground water data.

    The results from the first test, based on the training points on which the model was built, and the validation based on new, independent points from different forest areas, differ. The first test indicate that prediction works well for several of the forest types, while the validation gives the opposite results and shows that the prediction does not actually work.

    If the model was further developed and would become a working tool, it could make forest management easier and more effective, for example when continuous forestry is carried out. Field work could be concentrated to areas where the forest has been predicted to be of desired type.

  • 22.
    Jacob, Ute
    et al.
    Institute for Hydrobiology and Fisheries Science, University of Hamburg, Hamburg, Germany.
    Jonsson, Tomas
    Population Ecology Unit, Institute for Ecology, Uppsala, Sweden.
    Berg, Sofia
    EnviroPlanning AB, Göteborg, Sweden.
    Brey, Thomas
    Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.
    Eklöf, Anna
    Department of Physics, Chemistry and Biology (IFM), Linköping University, Linköping, Sweden.
    Mintenbeck, Katja
    Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany.
    Möllmann, Christian
    Institute for Hydrobiology and Fisheries Science, University of Hamburg, Hamburg, Germany.
    Morissette, Lyne
    M-Expertise Marine, Sainte-Luce, Canada.
    Rau, Andrea
    Johann Heinrich von Thünen Institute for Baltic Sea Fisheries, Rostock, Germany.
    Petchey, Owen
    Institute of Evolutionary Biology and Environmental Studies, University of Zurich, Zurich, Switzerland.
    Valuing biodiversity and ecosystem services in a complex marine ecosystem2015In: Aquatic Functional Biodiversity: An Ecological and Evolutionary Perspective / [ed] Andrea Belgrano, Guy Woodward & Ute Jacob, London: Academic Press, 2015, p. 189-207Chapter in book (Refereed)
  • 23.
    Jacob, Ute
    et al.
    University of Hamburg, Inst Hydrobiol & Fisheries Sci, Hamburg, Germany.
    Thierry, Aaron
    University of Sheffield, Dept Anim & Plant Sci, Western Bank, Sheffield S10 2TN, S Yorkshire, England / Microsoft Res, Cambridge, England.
    Brose, Ulrich
    Georg-August University Göttingen JF Blumenbach Inst Zool & Anthropol, Syst Conservat Biol Grp, Göttingen, Germany.
    Arntz, Wofe E.
    Alfred Wegener Inst Polar & Marine Res, Bremerhaven, Germany.
    Berg, Sofia
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Brey, Thomas
    Alfred Wegener Institute for Polar and Marine Research.
    Fetzer, Ingo
    UFZ Helmholtz Ctr Environm Res, Dept Environm Microbiol, Leipzig, Germany.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Mintenbeck, Katja
    Alfred Wegener Inst Polar & Marine Res, Bremerhaven, Germany.
    Möllmann, Christian
    Univ Hamburg, Inst Hydrobiol & Fisheries Sci, Hamburg, Germany.
    Petchey, Owen
    Univ Zurich, Inst Evolutionary Biol & Environm Studies, Zurich, Switzerland.
    Riede, Jens O.
    Univ Gottingen, JF Blumenbach Inst Zool & Anthropol, Syst Conservat Biol Grp, Gottingen, Germany.
    Dunne, Jennifer A.
    Santa Fe Inst, Santa Fe, NM 87501 USA / Pacific Ecoinformat & Computat Ecol Lab, Berkeley, CA USA.
    The Role of Body Size in Complex Food Webs: A Cold Case2011In: Advances in Ecological Research, ISSN 0065-2504, E-ISSN 2163-582X, Vol. 45, p. 181-223Article in journal (Refereed)
    Abstract [en]

    Human-induced habitat destruction, overexploitation, introduction of alien species and climate change are causing species to go extinct at unprecedented rates, from local to global scales. There are growing concerns that these kinds of disturbances alter important functions of ecosystems. Our current understanding is that key parameters of a community (e.g. its functional diversity, species composition, and presence/absence of vulnerable species) reflect an ecological network’s ability to resist or rebound from change in response to pressures and disturbances, such as species loss. If the food web structure is relatively simple, we can analyse the roles of different species interactions in determining how environmental impacts translate into species loss. However, when ecosystems harbour species-rich communities, as is the case in most natural systems, then the complex network of ecological interactions makes it a far more challenging task to perceive how species’ functional roles influence the consequences of species loss. One approach to deal with such complexity is to focus on the functional traits of species in order to identify their respective roles: for instance, large species seem to be more susceptible to extinction than smaller species. Here, we introduce and analyse the marine food web from the high Antarctic Weddell Sea Shelf to illustrate the role of species traits in relation to network robustness of this complex food web. Our approach was threefold: firstly, we applied a new classification system to all species, grouping them by traits other than body size; secondly, we tested the relationship between body size and food web parameters within and across these groups and finally, we calculated food web robustness. We addressed questions regarding (i) patterns of species functional/trophic roles, (ii) relationships between species functional roles and body size and (iii) the role of species body size in terms of network robustness. Our results show that when analyzing relationships between trophic structure, body size and network structure, the diversity of predatory species types needs to be considered in future studies.

  • 24.
    Johansson, Hanna
    University of Skövde, School of Life Sciences.
    Inplantering av fisk och dess påverkan på biologisk mångfald i Hökensåsområdet: En jämförelse av invertebratfauna mellan sjöar2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Pisciculture has been shown to affect biodiversity negatively, e.g. owing to increased nutrient loading and modified genetic set by breeding at other qualities then what is advantageous in in the wild. The purpose of this study was to investigate which impact stocked fish has on the invertebrate fauna and thereby biodiversity. The study is performed at Hökensås area in Västra Götalands län, where there are about 20 lakes included in a sport fishing business. There are seven lakes included in the study; four which yearly became stocked with fish and three non-stocked. By bottom fauna samples invertebrate fauna has been collected, identified, counted and measured. No significant differences have been detected between the lake groups considering diversity index, number of taxa or size of taxa. Nor has significant correlation between amount stocked fish/year- and (a) diversity index, (b) number of taxa been shown. A possible factor that may have affected the result is, from a statistical point of view, the low number of lakes, the varying qualities of the lakes and that the collecting of invertebrate fauna was performed too early in the year than optimal. Strong correlation between number of taxa and grade of acidification was detected.

  • 25.
    Jonsson, Annie
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Bertilsson, Ann
    Örnborg Kyrkander Biologi och Miljö AB.
    Ökad biologisk mångfald och renare vatten med livskraftiga stormusselbestånd i Göta älvs vattensystem: Dagens situation och åtgärder för att minska vattenkraftens negativa påverkan2016Report (Other academic)
    Abstract [sv]

    Göta älv är Sveriges största vattendrag. Älven används av många olika intressen. Människan utnyttjande av älven påverkar dock vattenekosystemen negativt. Sötvattenslevande stormusslor har drabbats hårt av människans exploatering av vattendrag och mark kring vattendrag. De är betydelsefulla organismer som tillhandahåller flera ekosystemtjänster.

    Projektets första mål har varit att samla in kunskap om alla de stora sötvattensmusselarternas förekomster i Göta älvs vattensystem (biflöden) från Vänern till havet. Det finns stora kunskapsluckor över musslornas förekomster i Sverige, särskilt de mer vanligt förekommande arterna. Projektets andra mål har varit att samla in miljödata och analysera vilka eventuella miljöproblem som påverkar musselförekomsterna i de olika delarna av vattensystemet. Utifrån resultaten har vi diskuterat olika åtgärder och prioriteringar i generella drag och även kort för respektive biflödessystem.

    Resultatet visar att musselförekomsterna är få och svaga. Musslor har påträffats i knappt en tredjedel av de undersökta 201 lokalerna. Musslor har bara påträffats i 10 av de 25 undersökta biflödessystemen. Positivt är dock att fynd har gjorts av alla de fem arterna allmän dammussla, större dammussla, flat dammussla, spetsig målarmussla och flodpärlmussla. Föryngring har också förekommit någonstans i systemet av dessa arter. Alltså har vi möjlighet att handla!

    Projektet har finasierats av Naturskyddsföreningen och Göta älvs vattenvårdsförbund.

  • 26.
    Jonsson, Annie
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Toräng, Per
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Utvärdering av Hornborgasjöns restaurering: måluppfyllelse och effekter på biologisk mångfald med fokus på vegetation och fågelfauna2017Report (Other academic)
    Abstract [sv]

    Hornborgasjön räknas idag som en av Sveriges rikaste fågelsjöar och är internationellt utpekad som en av Sveriges värdefullaste våtmarker. Sjön har stor betydelse som både rast- och häckplats för en mängd fågelarter. Området är också av stort intresse för friluftslivet och som ett levande kulturlandskap. Under de senaste 150 åren har Hornborgasjön genomgått stora förändringar. En serie av sjösänkningar under 1800 och 1900-talen ledde till kraftig igenväxning och följdes av ett storskaligt restaureringsprojekt i senare tid. Syftet med Hornborgasjöns restaurering var att säkerställa Hornborgasjöns framtid som fågelsjö. Restaureringen är ett av Sveriges största naturvårdsprojekt. I denna rapport har vi utvärderat hur Hornborgasjöns restaurering påverkat vegetation och fågelfauna. Syftet var att analysera om och till vilken grad de biologiska målen med restaureringen uppnåtts.För att utvärdera måluppfyllelsen har vi i första hand jämfört olika naturtypers utbredning mellan åren 1905 och 2010 samt förändringar i fågelfaunan under flera tidsperioder. Analyser av vegetationskartor visar att vass- och buskområden kraftigt reducerats och att en stor öppen vattenspegel och omgivande mader återskapats. Våtmarksfåglarnas numerär har generellt sett återhämtat sig från igenväxningsperioden och är för vissa arter till och med större än vid förra sekelskiftet. För vissa naturtyper och fågelarter, som till exempel vassområden och häckande vadare, är dagens situation dock inte i linje med målen. Det står ändå klart att det övergripande målet och många av de mer specifika delmålen har uppfyllts så att Hornborgasjön idag är en levande våtmark med stort antal häckande och rastande fågelarter.I analyser av fågeldata från senare tid finns indikationer på negativa trender som man behöver vara observant på för att för framtiden säkra en biologiskt rik Hornborgasjö. En utmaning för denna utvärdering har dock varit bristen på högkvalitativa och jämförbara data att basera analyserna på. Vi belyser därför vikten av att ha ett fungerande övervakningssystem som kontinuerligt följer upp statusen i ekosystemet.

  • 27.
    Jonsson, Annie
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Wennergren, Uno
    Linköping University, Linköpings Universitet.
    Approximations of population growth in a noisy environment: on the dichotomy of non-age and age structure2019In: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 12, no 1, p. 99-110Article in journal (Refereed)
  • 28.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Conditions for Eltonian Pyramids in Lotka-Volterra Food Chains2017In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 7, article id 10912Article in journal (Refereed)
    Abstract [en]

    In ecological communities consumers (excluding parasites and parasitoids) are in general larger and less numerous than their resource. This results in a well-known observation known as 'Eltonian pyramids' or the ` pyramid of numbers', and metabolic arguments suggest that this pattern is independent of the number of trophic levels in a system. At the same time, Lotka-Volterra (LV) consumer-resource models are a frequently used tool to study many questions in community ecology, but their capacity to produce Eltonian pyramids has not been formally analysed. Here, I address this knowledge gap by investigating if and when LV food chain models give rise to Eltonian pyramids. I show that Eltonian pyramids are difficult to reproduce without density-dependent mortality in the consumers, unless biologically plausible relationships between mortality rate and interaction strength are taken into account.

  • 29.
    Jonsson, Tomas
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Metabolic theory predicts animal self-thinning2017In: Journal of Animal Ecology, ISSN 0021-8790, E-ISSN 1365-2656, Vol. 86, no 3, p. 645-653Article in journal (Refereed)
    Abstract [en]
    1. The metabolic theory of ecology (MTE) predicts observed patterns in ecology based on metabolic rates of individuals. The theory is influential but also criticized for a lack of firm empirical evidence confirming MTE's quantitative predictions of processes, e.g. outcome of competition, at population or community level.
    2. Self-thinning is a well-known population level phenomenon among plants, but a much less studied phenomenon in animal populations and no consensus exists on what a universal thinning slope for animal populations might be, or if it exists.
    3. The goal of this study was to use animal self-thinning as a tool to test population-level predictions from MTE, by analysing (i) if self-thinning can be induced in populations of house crickets (Acheta domesticus) and (ii) if the resulting thinning trajectories can be predicted from metabolic theory, using estimates of the species-specific metabolic rate of A. domesticus.
    4. I performed a laboratory study where the growth of A. domesticus was followed, from hatching until emergence as adults, in 71 cohorts of five different starting densities.
    5. Ninety-six per cent of all cohorts in the three highest starting densities showed evidence of self-thinning, with estimated thinning slopes in general being remarkably close to that expected under metabolic constraints: A cross-sectional analysis of all data showing evidence of self-thinning produced an ordinary least square (OLS) slope of −1·11, exactly that predicted from specific metabolic allometry of A. domesticus. This result is furthermore supported by longitudinal analyses, allowing for independent responses within cohorts, producing a mean OLS slope across cohorts of −1·13 and a fixed effect linear mixed effects models slope of −1·09. Sensitivity analysis showed that these results are robust to how the criterion for on-going self-thinning was defined. Finally, also as predicted by metabolic theory, temperature had a negative effect on the thinning intercept, producing an estimate of the activation energy identical to that suggested by MTE.
    6. This study demonstrates a direct link between the metabolic rate of individuals and a population-level ecological process and as such provides strong support for research that aims to integrate body mass, via its effect on metabolism, consumption and competition, into models of populations and communities.
  • 30.
    Jonsson, Tomas
    Swedish University of Agricultural Sciences.
    Trophic links and the relationship between predator and prey body sizes in food webs2014In: Community Ecology, ISSN 1585-8553, Vol. 15, p. 54-64Article in journal (Refereed)
  • 31.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Berg, Sofia
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Physics, Chemistry and Biology, Division of Theoretical Biology, Linköping University, Linköping, Sweden.
    Emmerson, Mark
    School of Biological Sciences, Queen's University Belfast, Belfast, UK.
    Pimenov, Alexander
    Environmental Research Institute, University College Cork, Lee Road, Cork, Ireland / Weierstrass Institute, Berlin, Germany.
    The context dependency of species keystone status during food web disassembly2015In: Food Webs, ISSN 2352-2496, Vol. 5, p. 1-10Article in journal (Refereed)
  • 32.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Ecology, Swedish Univ. of Agricultural Sciences, Uppsala, Sweden.
    Berg, Sofia
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Dept of Physics, Chemistry and Biology, Div. of Theoretical Biology, Linköping Univ., Linköping, Sweden.
    Pimenov, Alexander
    Environmental Res. Inst., Univ. College Cork, Cork, Ireland / Weierstrass Inst., Berlin, Germany.
    Palmer, Catherine
    Environmental Res. Inst., Univ. College Cork, Cork, Ireland.
    Emmerson, Mark
    School of Biological Sciences, Queen's Univ. Belfast, Belfast, United Kingdom.
    The reliability of R50 as a measure of vulnerability of food webs to sequential species deletions2015In: Oikos, ISSN 0030-1299, E-ISSN 1600-0706, Vol. 124, no 4, p. 446-457Article in journal (Refereed)
  • 33.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Life Sciences.
    Cohen, Joel E.
    Carpenter, Stephen R.
    Food webs, body size, and species abundance in ecological community description2005In: Advances in Ecological Research, ISSN 0065-2504, E-ISSN 2163-582X, Vol. 36, p. 1-83Article in journal (Refereed)
  • 34.
    Jonsson, Tomas
    et al.
    Department of Biology, Linköping University, Linköping, Sweden.
    Ebenman, Bo
    Department of Biology, Linköping University, Linköping, Sweden.
    Effects of predator-prey body size ratios on the stability of food chains1998In: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 193, no 3, p. 407-417Article in journal (Refereed)
  • 35.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Kaartinen, Riikka
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Jonsson, Mattias
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Bommarco, Riccardo
    Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Predictive power of food web models based on body size decreases with trophic complexity2018In: Ecology Letters, ISSN 1461-023X, E-ISSN 1461-0248, Vol. 21, no 5, p. 702-712Article in journal (Refereed)
    Abstract [en]

    Food web models parameterised using body size show promise to predict trophic interaction strengths (IS) and abundance dynamics. However, this remains to be rigorously tested in food webs beyond simple trophic modules, where indirect and intraguild interactions could be important and driven by traits other than body size. We systematically varied predator body size, guild composition and richness in microcosm insect webs and compared experimental outcomes with predictions of IS from models with allometrically scaled parameters. Body size was a strong predictor of IS in simple modules (r(2)=0.92), but with increasing complexity the predictive power decreased, with model IS being consistently overestimated. We quantify the strength of observed trophic interaction modifications, partition this into density-mediated vs. behaviour-mediated indirect effects and show that model shortcomings in predicting IS is related to the size of behaviour-mediated effects. Our findings encourage development of dynamical food web models explicitly including and exploring indirect mechanisms.

  • 36.
    Jonsson, Tomas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre. Department of Ecology, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Setzer, Malin
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    A freshwater predator hit twice by effects of warming across trophic levels2015In: Nature Communications, ISSN 2041-1723, E-ISSN 2041-1723, Vol. 6, article id 5992Article in journal (Refereed)
  • 37.
    Karlsson, David
    University of Skövde, School of Bioscience.
    Uppskattning av nätselektivitet och populationsstruktur av sik (Coregonus spp) i Vättern2016Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 38.
    Karlsson, Susanna
    University of Skövde, School of Life Sciences.
    HARR (THYMALLUS THYMALLUS) I VÄTTERBÄCKARNA: En studie om samband mellan bottenfauna och harrens förekomst2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
  • 39.
    Kollberg, Ida
    et al.
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Bylund, H.
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Jonsson, Tomas
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Schmidt, A.
    Max Planck Institute for Chemical Ecology, Department of Biochemistry, Jena, Germany.
    Gershenzon, J.
    Max Planck Institute for Chemical Ecology, Department of Biochemistry, Jena, Germany.
    Björkman, C.
    Swedish University of Agricultural Sciences, Department of Ecology, Uppsala, Sweden.
    Temperature affects insect outbreak risk through tritrophic interactions mediated by plant secondary compounds2015In: Ecosphere, ISSN 2150-8925, E-ISSN 2150-8925, Vol. 6, no 6, article id 102Article in journal (Refereed)
  • 40.
    Kotta, Jonne
    et al.
    Estonian Marine Institute, University of Tartu, Tallinn, Estonia.
    Vanhatalo, Jarno
    Department of Mathematics and Statistics and Organismal and Evolutionary Biology Research Program, University of Helsinki, Helsinki, Finland.
    Jänes, Holger
    Estonian Marine Institute, University of Tartu, Tallinn, Estonia / Centre for Integrative Ecology, Deakin University, Melbourne, Victoria, Australia.
    Orav-Kotta, Helen
    Estonian Marine Institute, University of Tartu, Tallinn, Estonia.
    Rugiu, Luca
    Department of Biology, University of Turku, Turku, Finland.
    Jormalainen, Veijo
    Department of Biology, University of Turku, Turku, Finland.
    Bobsien, Ivo
    GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel, Germany.
    Viitasalo, Markku
    Finnish Environment Institute, Helsinki, Finland.
    Virtanen, Elina
    Finnish Environment Institute, Helsinki, Finland.
    Nyström Sandman, Antonia
    AquaBiota Water Research, Stockholm, Sweden.
    Isaeus, Martin
    AquaBiota Water Research, Stockholm, Sweden.
    Leidenberger, Sonja
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Jonsson, Per R.
    Department of Marine Sciences – Tjärnö, University of Gothenburg, Tjärnö, Strömstad, Sweden.
    Johannesson, Kerstin
    Department of Marine Sciences – Tjärnö, University of Gothenburg, Tjärnö, Strömstad, Sweden.
    Integrating experimental and distribution data to predict future species patterns2019In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, article id 1821Article in journal (Refereed)
    Abstract [en]

    Predictive species distribution models are mostly based on statistical dependence between environmental and distributional data and therefore may fail to account for physiological limits and biological interactions that are fundamental when modelling species distributions under future climate conditions. Here, we developed a state-of-the-art method integrating biological theory with survey and experimental data in a way that allows us to explicitly model both physical tolerance limits of species and inherent natural variability in regional conditions and thereby improve the reliability of species distribution predictions under future climate conditions. By using a macroalga-herbivore association (Fucus vesiculosus - Idotea balthica) as a case study, we illustrated how salinity reduction and temperature increase under future climate conditions may significantly reduce the occurrence and biomass of these important coastal species. Moreover, we showed that the reduction of herbivore occurrence is linked to reduction of their host macroalgae. Spatial predictive modelling and experimental biology have been traditionally seen as separate fields but stronger interlinkages between these disciplines can improve species distribution projections under climate change. Experiments enable qualitative prior knowledge to be defined and identify cause-effect relationships, and thereby better foresee alterations in ecosystem structure and functioning under future climate conditions that are not necessarily seen in projections based on non-causal statistical relationships alone.

  • 41.
    Larsson, Maria
    University of Skövde, School of Life Sciences.
    Finns det något samband mellan stormusslors (unionoida) föryngring och utsläpp i närheten av dess levnadsmiljö?: en jämförelse mellan vattendrag i Västra Götaland2008Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Common species of freshwater mussels may, like the freshwater pearl mussel (Margaritifera margaritifera) have a drastic decline in number and there is several reasons, like sedimentation, a decline of host fishes, introduction of alien species, nutrition leakages from agriculture and pollutants of medic drugs and poison. Ann Gustavsson made in the year of 2007 a study over rejuventation of freshwater great mussels in nine watersystems and considered that the rejuventation within the populations were all along the line poor. This study orients from her work and points to determine if there is a connection between the poor juventation and pollution of nitrogen and phosphorous from industries and private sanitations. The study was performed with the software program ArcGIS9.2 to take out drainage areas for the concerned habitats and contact was made with the concerned authoritys. When it comes to supervision of private sanitations is it the countys and for industries is it the county administrative board. Most of the countys had a very difficult way to reach their data of the private sanitations and those who had data had great holes in their knowledge in them. The greatest emission of nitrogen was without doubt the industries, but a more even allocation could be seen in the pollution of phosphourus, where the industries and the private sanitations stood for about fifty- fifty of the pollution. The greatest emission of nitrogen and phosphourus happened in Viskan, in the drainage area for Lekvad,there it was a lack of mussels. The species of Anodonta anatina showed a strong positive correlation between emission of nitrogen and phosphourus with the way of juvenile mussels in the population. More studies is need to do in these areas, both when it comes to continuing mapping of rejuventation within the freshwater great mussels in several waters and template value for pollution of nitrogen and phosphourus, that is very doubtful today. Even studies concerning other factors, like predation, host fishes and the influence of poison and medic drugs is needing to do, as it is few studies concerning this today.

  • 42.
    Leickt, Evelina
    University of Skövde, School of Life Sciences.
    Bäverhyddors påverkan på vattenlevande evertebrater2013Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The activity of beavers creates productive wetlands with high biodiversity. A previous study found that dam constructions of beavers contribute to a higher number of aquatic invertebrate species compared to upstream and downstream sites. In some cases beavers build their hut along the shore without damming up the water flow (Törnblom & Henrikson 2011). This report is intended to determine how the beaver hut affects the abundance of water living invertebrates.Sampling at the beaver hut, upstream and downstream, of water living invertebrates was performed. To determine differences in individual number, species number and diversity index between the sites statistical calculation was performed. The results show a difference in individual numbers between beaver huts and downstream and upstream sites and the individual number was higher at the beaver hut than the two other sites. No difference in number of species or diversity index was found. The higher temperature of the water and more nutrition is two aspects that are discussed as contributing factor to the higher number of individuals near the hut. The difference in species and species number between a beaver dam and a beaver hut build long side the shore is also discussed.

  • 43.
    Leverin, Malin
    University of Skövde, School of Bioscience.
    Skogsbrukets påverkan på artmångfalden hos mossor och lavar: Är artmångfalden större i en skog vid kontinuitetsskogsbruk än vid trakthyggesbruk?2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    The most common forestry model in Sweden, the clear cutting forestry, has caused problems for the biodiversity in the forests. In 2010, Sweden had 319 different bryophytes and lichens in the Red List that were connected to the forest. Some of which are dependant of forest continuity, old decaying wood, forest fire or other natural phenomenon found only in more or less undisturbed forests. The alternative to this forestry model is the continuous cover forestry as was common in the past, before forestry became an industry. At the time when the farmers themselves plucked out the wood they needed for they own survival, the forests could still function as an ecosystem. This report aims to compare and account for possible differences in species diversity between the tree forest type natural forest, continuous cover managed and clear-cutting managed forest. This study was based on four different continuous cover managed forests in Skåne, Västra Götaland and Östergötland County. Based on these forests prerequisites, natural forests and clear-cutting managed forests have been selected in acceptable closeness. The results of the survey show that the clear-cutting managed forests differ significant in biodiversity from the other forest types. Natural forests and continuous cover managed forests are richer in biodiversity and have more congruent values, however the presence of epiphytes is higher in natural forests. The result also shows that the presence of indicator species is higher in a continuous cover managed forest than in a clear-cutting managed forest.

  • 44.
    Lindén, Linda
    University of Skövde, School of Life Sciences.
    Floran i Blüchers park; Genarp2011Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Lund has since a few years back made some inventories of different fauna groups in different natural areas in Genarp; a small community located about 25 kilometers to the southeast of Lund. During those summers (2007-2010) nine red-listed insect species was found and registered in Blüchers Park, a nature area with a mosaic of different habitats on sand ground. Blüchers Park is approximately 2.7 acres and is located in the eastern part of Genarp. The purpose of this work is partly to seek understanding of why the found vascular plants in Blüchers Park grow where they grow, partly to find out which management actions that might be appropriate in the area, that is how the presence of the found red-listed insect species may benefit from different management measures.

    During June-August 2011, 175 different plant species were found in Blüchers Park. Of these, nine so-called liaison plants (five species and four species groups) were of special interest to benefit. This because they are plants on which red-listed insect species, found in earlier surveys, rely for their survival.

    To promote the liaison plants and the diversity of other plant species and endangered insect species in Blüchers Park, it requires a change in the flora management in the park. To clarify which type or types of flora management actions that would be appropriate in Blüchers Park, the facts and data about the liaison plants and the pros and cons of the various management actions such as burning, grazing, mowing and soil mixing were analyzed and discussed.

    Mowing was shown to be the best flora management action for most of Blüchers Park although several of the liaison species in the park are more directly favored by grazing than by mowing (Ekstam 1997). Burning of all or part of subarea 4 to promote the heath and to implement a land agitation in parts of the park to facilitate ground nesting insects, is also relevant. Seed dispersal, planting of more liaison plants and clearing around the light demanding trees and shrubs are additional measures that might benefit biodiversity in the area.

    In summary Blüchers park exhibits a flora- and faunadiversity that is worth preserving and developing. This study contributes to knowledge base for this work.

  • 45.
    Lund, Mikael
    University of Skövde, School of Bioscience.
    Släktskapets påverkan på tillväxt, storlek, mortalitet och defekter hos yngel vid uppfödning hos Grönfläckig padda (Bufo viridis).2014Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    This work aims to respond to the hypothesis that says that there are differences in growth, size, mortality and deformation in the kin of green toad (Bufo viridis) between unrelated egg and later on juveniles when breeding. A previous Australian studie demonstrates that chemical substances that the toads themselves secrete affect growth and survival. It also appears that the siblings chemically recognize and favours each other, and thus competition for food between siblings is not as strong. Eggs and later on juveniles of five different females have been divided into groups and placed in aquariumtanks. Either with related individuals from a single female or mixed. The juveniles reared together with their siblings had on average larger bodies than juveniles reared with unrelated brood. There were no difference in growth over time between the different rearing methods. There where, however, differences in growth during the first measurements, which indicates that the mechanisms that differentiates the growth is strongest in an early stage of development. Mortality from egg to juvenile where larger in the unrelated individuals than within the siblings. Previous Swedish study show similar results and these contradicts result from Australian studies. Overall, it gives an indication that the mechanism that affect size, growth and mortality is more complex than what transpired in the previous work. The result points to differences that may form the basis for the development of new methods for the breeding of European Green Toad, and which can also help in the preservation of the Swedish population.

  • 46.
    Mauritsson, Karl
    University of Skövde, School of Bioscience.
    Ecological and Edaphic Correlations of Soil Invertebrate Community Structure in Dry Upland Forests of Eastern Africa2018Independent thesis Basic level (degree of Bachelor), 20 credits / 30 HE creditsStudent thesis
    Abstract [en]

    Natural forests are characterised by great vegetation diversity and create habitats for a major part of Earth’s terrestrial organisms. Plantation forests, which are mainly composed of a few genera of fast-growing trees, constitute an increasing fraction of global forests, but they only partly compensate for loss of area, habitat and ecological functions in natural forests. Plantation forests established near natural forests can be expected to serve as buffers, but they seem to be relatively poor in invertebrate species and it is not clear why. This bachelor’s degree project aimed at establishing the ecological and edaphic factors that correlate with soil invertebrate diversity in dry upland forests and surrounding plantation forests in eastern Africa. Some aspects of the above-ground vegetation heterogeneity were investigated since this was assumed to influence the heterogeneity of the soil environment, which is considered as critical for soil biodiversity. The obtained knowledge may be valuable in conservation activities in East African forests, which are threatened by destruction, fragmentation and exotic species.

    The study area was Karura Forest, a dry upland forest in Nairobi, Kenya. Three different sites were investigated; a natural forest site characterized by the indigenous tree species Brachylaena huillensis and Croton megalocarpus, and two different plantation forest sites, characterized by the exotic species Cupressus lusitanica and Eucalyptus paniculata, respectively. For each forest type, six plots were visited. Soil invertebrates were extracted from collected soil and litter samples by sieving and Berlese-Tullgren funnels. The invertebrates were identified, and the taxonomic diversity calculated at the order level. The ecological and edaphic factors, measured or calculated for each plot, were tree species diversity, ratio of exotic tree species, vertical structure of trees, vegetation cover, vegetation density, litter quality, soil pH, soil temperature and soil moisture.

    One-way ANOVA was used to compare soil invertebrate diversity and other variables between different forest types. Akaike’s Information Criterion and Multiple Linear Regression were used to establish linear models with variables that could explain measured variations of the diversity.

    There was some evidence for higher soil invertebrate diversity in natural forests than in surrounding plantation forests. The abundance of soil invertebrates was also clearly higher in natural forests, which indicates that natural forests are more important than plantation forests for conservation of soil invertebrate populations. Soil invertebrate diversity (in terms of number of orders present) was found to be influenced by forest type and litter quality. The diversity was higher at places with high amounts of coarse litter, which here is considered as more heterogenous than fine litter. The dependence on forest type was partly a consequence of differences in soil pH since Eucalyptus trees lower soil pH and thereby also soil biodiversity. No relation to heterogeneity of above-ground vegetation was found.

    For future conservation activities in Karura Forest Reserve it is recommended to continue removing exotic plant species and replanting indigenous trees, to prioritize the removal of Eucalyptus trees before Cypress trees, to only remove a few trees at a time and to establish ground vegetation when doing so.

  • 47.
    Neubert, Michael G.
    et al.
    Biology Department, Woods Hole Oceanographic Institution, Woods Hole, MA, United States.
    Blumenshine, Steven C.
    Department of Biological Sciences, Arkansas State University, State University, United States.
    Duplisea, Daniel E.
    CEFAS Lowestoft Laboratory, Lowestoft, Suffolk, United Kingdom.
    Jonsson, Tomas
    Department of Biology, Linköping University, Linköping, Sweden / Rockefeller University, New York, NY, United States.
    Rashleigh, Brenda
    EPA Ecosystems Assessment Branch, Athens, GA, United States.
    Body size and food web structure: testing the equiprobability assumption of the cascade model2000In: Oecologia, ISSN 0029-8549, E-ISSN 1432-1939, Vol. 123, no 2, p. 241-251Article in journal (Refereed)
  • 48.
    Niemer, Jessica
    University of Skövde, School of Bioscience.
    Omgivande markslags påverkan på förekomst av bibagge Apalus bimaculatus i sand- och grustäkter i Västra Götalands län2014Independent thesis Basic level (degree of Bachelor), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Apalus bimaculatus is a red-listed beetle that occurs in open sandy habitats and is strongly tied to its host species, Colletes cunicularius, since it parasites on its nest. Inventories of secondary habitats in the form of sand and gravel pits have been performed in Västra Götaland County in early spring 2009 and 2010. Data from this survey have been used in this study to examine if surrounding habitat types influence the occurrence of A. bimaculatus in gravel- and sandpits. Within the sand and gravel pits the surveyors registered different patches where A. bimaculatus or C. cunicularius where found. If none of the species where found the patch which was considered to be most suitable for one or both species where registered. A buffer zone was created around the patches in ArcGis with a radius of 541 meters, which is based on the measured maximum flight distance of C. cunicularius during search for food, 350 meters, together with the average size of sand and gravel pits in Västra Götaland County, 191 meters. The radius is also based on an assumption that the gravel- and sandpits has the shape of a circle. The buffer zones were then analyzed to see how big area each habitat type represented around each respective patch with and without findings of A. bimaculatus and C.

    cunicularius. T-tests was performed to see if the area of various habitat types differed around patches with and without findings of A. bimaculatus and C. cunicularius. Regression analysis was performed for the natural logarithm of the number of A. bimaculatus and C. cunicularius at patches and the area of respective surrounding habitat types. The t-test for mean deciduous forest area within the buffer zones surrounding patches with and without A. bimaculatus is the only one that show a statistically significant difference (t = 2.36, d.f.=184, p = 0.02). A statistically significant negative relationship was found with the regression analyzes for the natural logarithm of the number of A. bimaculatus and the area of cropland in the buffer zone (r2 = 0.38, d.f. =14, p = 0.01). A positive relationship that was statistically significant was found for the natural logarithm of the number of A. bimaculatus and area of coniferous and mixed forest in the buffer zone (r2 = 0.46, d.f. =14, p = 0.004). The results are very interesting, especially when they are obtained by using rough habitat type analysis in GIS.

  • 49.
    Norrström, Niclas
    et al.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Casini, Michele
    Swedish University of Agricultural Sciences, Department of Aquatic Resources, Institute of Marine Research, Lysekil, Sweden.
    Holmgren, Noél M. A.
    University of Skövde, School of Bioscience. University of Skövde, The Systems Biology Research Centre.
    Nash equilibrium can resolve conflicting maximum sustainable yields in multi-species fisheries management2017In: ICES Journal of Marine Science, ISSN 1054-3139, E-ISSN 1095-9289, Vol. 74, no 1, p. 78-90Article in journal (Refereed)
    Abstract [en]

    The current fisheries management goals set by the European Commission states that fish stocks should be harvested to deliver maximum sustainable yields (MSY) and simultaneously, management should take ecosystem considerations into account. This creates unsolved trade-offs for the management of the stocks. We suggest a definition of a multi-species-MSY (MS-MSY) where no alternative fishing mortality (F) can increase yield (long term) for any ecologically interacting stock, given that the other stocks are fished at constant efforts (Fs). Such a MS-MSY can be solved through the game theoretic concept of a Nash equilibrium and here we explore two solutions to this conflict in the Baltic Sea. We maximize the sustainable yield of each stock under two constraints: first, we harvest the other stocks at a fixed F (FNE); second, we keep the spawning stock biomasses of the other stocks fixed [biomass Nash equilibrium (BNE)]. As a case study, we have developed a multi-species interaction stochastic operative model (MSI-SOM), which contains a SOM for each of the three dominant species of the Baltic Sea, the predator cod (Gadus morhua), and its prey herring (Clupea harengus), and sprat (Sprattus sprattus). For our Baltic Sea case, MS-MSYs exist under both the FNE and the BNE, but there is no guarantee that point solutions exists. We found that the prey species’ spawning stock biomasses are additive in the cod growth function, which allowed for a point solution in BNE. In the FNE, the herring MSY was found to be relatively insensitive to the other species’ fishing mortalities (F), which facilitated a point solution. The MSY targets of the BNE and the FNE differ slightly where the BNE gives higher predator yields and lower prey yields.

  • 50.
    Nyberg, Per
    et al.
    Fiskeriverkets Sötvattenslaboratorium (nuvarande Institutionen för akvatiska resurser, SLU).
    Degerman, Erik
    Fiskeriverkets Sötvattenslaboratorium (nuvarande Institutionen för akvatiska resurser, SLU).
    Setzer, Malin
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre.
    Norrgård, Johnny
    Vätternvårdsförbundet.
    Jonsson, Tomas
    University of Skövde, School of Life Sciences. University of Skövde, The Systems Biology Research Centre. School of Bioscience, University of Skövde.
    Predation av fisk och signalkräfta på rödingrom - resultat från en fältstudie i Vättern2012Report (Other academic)
    Abstract [sv]

    Vätterns unika bestånd av storröding har minskat kraftigt de senaste decennierna och orsakerna till minskningen diskuteras livligt. Bland föreslagna orsaker nämns exvis konkurrens från inplanterad lax, överexploatering och klimatförändringar. Därutöver befaras även signalkräftan, via predation på rödingrom kunna ha en negativ inverkan på rödingens reproduktion. För att undersöka predationen på rödingrom från såväl fisk som signalkräfta utfördes 2009 ett fältförsök vid en känd lekplats i norra Vättern. I de använda försöksburarna var den uppskattade mortaliteten av ägg till följd av kräftpredation 5 gånger högre än den till följd av fiskpredation. Resultaten indikerar därmed att predationen på rödingrom från signalkräfta kan vara kraftigt underskattad och att den kan ha påverkat rödingbeståndets återhämtning i Vättern negativt.

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