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  • 201. Aronson, M.F.J.
    et al.
    La Sorte, F.A.
    Nilon, C.H.
    Katti, M.
    Goddard, M.A.
    Lepczyk, C.A.
    Warren, P.S.
    Williams, W.P.S.
    Cilliers, S.
    Clarkson, B.
    Dobbs, Cynnamon
    Dolan, R.
    Hedblom, M.
    Klotz, S.
    Louwe Kooijmans, Jip
    Kühn, I.
    MacGregor-Fors, I.
    McDonnell, Mark
    Mörtberg, Ulla
    KTH, Skolan för arkitektur och samhällsbyggnad (ABE), Hållbar utveckling, miljövetenskap och teknik, Mark- och vattenteknik.
    Pyšek, P.
    Siebert, S.
    Sushinsky, J.
    Werner, Peter
    Winter, M.
    A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers2014Ingår i: Proceedings of the Royal Society of London. Biological Sciences, ISSN 0962-8452, E-ISSN 1471-2954, Vol. 281, nr 1780, s. 20133330-Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Urbanization contributes to the loss of the world's biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the world's cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km2) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.

  • 202.
    Aronsson, Hanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    On Sexual Imprinting in Humans2011Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis I investigate whether human sexual preferences develop through sexual imprinting. Sexual imprinting is the acquisition of sexual preferences through non-rewarded experiences with parents and siblings during an early sensitive period and it is known to exist in many other animals. Learning is often sex specific so that males, for instance, learn to prefer as sexual partners individuals that look like their mother, and avoid individuals that look like their father. First, sexual imprinting in animals and humans is reviewed and compared to prevailing evolutionary views presupposing genetically determined sexual preferences. Further, by means of web surveys, I have explored the relationship between childhood exposure to parents with certain natural and cultural traits and sexual attraction to these traits in a partner. Cultural traits were included because it is unlikely that preferences for them are genetically determined adaptations. Parental effects varied between traits. For instance, in heterosexual males, a positive effect of mother was found on attraction to smoking, but not glasses, while a negative paternal effect was found on attraction to glasses, but not smoking. However, when maternal and paternal effects were investigated for a large number of artificial and natural traits, including smoking and glasses, an overall positive effect of opposite sex parent emerged in both heterosexual males and females. Additionally, in the last study we explored a sexual preference for pregnant and lactating women. Results suggest that exposure to a pregnant and lactating mother had an effect if it occurred when the respondent was between 1,5 and 5 years old. In conclusion, these results suggest that human sexual preferences are the result of sex specific learning during a sensitive period. Sexual imprinting should therefore be recognised as a plausible explanation to human sexual preferences that deserves further scientific investigation.

  • 203.
    Aronsson, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gamberale-Stille, Gabriella
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Domestic chicks primarily attend to colour, not pattern, when learning an aposematic coloration2008Ingår i: Animal Behaviour, ISSN 0003-3472, E-ISSN 1095-8282, Vol. 75, s. 417-423Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Aposematic conspicuous coloration consists of one or a few bright colours, often in combination with a black defined internal pattern. The function of conspicuousness in aposematism has been ascribed to signal efficacy, based on experimental evidence involving prey items with uniform colour that contrast with the background. Although there are several hypotheses about the existence of internal contrasts within warning coloration, little experimental evidence has been presented. Here we used domestic chicks, Gallus gallus domesticus, to investigate the relative importance of colour and pattern in avoidance learning. Birds in two groups were first trained to discriminate between a grey positive stimulus and a cyan negative stimulus with either black dots or stripes. Pieces of mealworms, untreated and palatable or made unpalatable by soaking in quinine were used as reinforcers. Secondly, to determine what birds had attended to when learning the discrimination, colour and/or pattern, we compared how they generalized their avoidance of the ‘training stimulus’ to either a ‘colour only’ or ‘pattern only’ stimulus. The chicks learned to avoid the unpalatable prey items but showed no difference in behaviour depending on the type of pattern presented. The generalization test showed that birds avoided the novel ‘colour only’ stimulus at least as much as the ‘training stimulus’, and did not generalize their avoidance to the ‘pattern only’ stimulus. We conclude that birds do not necessarily attend to complex patterns when learning a warning signal, and domestic chicks primarily learn a bright colour rather than an equally novel conspicuous black pattern.

  • 204.
    Aronsson, Marianne
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Gamberale-Stille, Gabriella
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Evidence of signaling benefits to contrasting internal color boundaries in warning coloration2013Ingår i: Behavioral Ecology, ISSN 1045-2249, E-ISSN 1465-7279, Vol. 24, nr 2, s. 349-354Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    It has been suggested that the common existence of regular patterning in aposematic prey animals makes them stand out from the background, improving detection and recognition. Another suggestion is that internal patterns could have a similar positive effect on predator aversion learning as prey-to-background contrast. We used wild caught blue tits (Cyanistes caeruleus) and artificial prey signals to investigate if internal color boundaries, pattern regularity and pattern symmetry affect learning. Birds in different treatments were trained, on a complex background, to discriminate between artificial prey with different nonrewarding color stimuli with a black pattern and rewarding stimuli without a black pattern, followed by a generalization test. This study provides evidence of learning benefits to internally contrasting patterns as the striped prey stimuli were learned faster than the unstriped. Also, we found no beneficial effects of pattern regularity and symmetry. The birds generalized more between prey with different black patterns than to the profitable prey, suggesting that color is of foremost importance. The generalization test also showed a greater avoidance of striped than that of unstriped prey, suggesting some attention on patterns. Thus, internal patterning may affect signal salience and in some circumstances benefit prey due to both a faster avoidance learning and generalization behavior.

  • 205.
    Arrhenius, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för systemekologi.
    Feeding ecology of Baltic Sea herring (Clupea harengus L.): field and model studies of a dominant zooplanktivor1995Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
  • 206.
    Arthington, Angela H
    et al.
    Australian Rivers Institute and eWater Co-operative Research Centre, Griffith University, Brisbane, Qld, Australia.
    Naiman, Robert J
    School of Aquatic & Fishery Sciences, University of Washington-355020, Seattle, WA, U.S.A..
    McClain, Michael E
    UNESCO-IHE Institute for Water Education, Delft, The Netherlands and Department of Earth and Environment, Florida International University, Miami, FL, U.S.A..
    Nilsson, Christer
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Preserving the biodiversity and ecological services of rivers: new challenges and research opportunities2010Ingår i: Freshwater Biology, ISSN 0046-5070, E-ISSN 1365-2427, Vol. 55, nr 1, s. 1-16Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Natural biogeochemical processes and diverse communities of aquatic biota regulate freshwater quantity and quality in ways that are not sufficiently acknowledged nor appreciated by the water resources management community. The establishment and enforcement of environmental flow requirements offer promising means to improve and care for these critical environmental services. This Special Issue provides new insights and novel techniques to determine, protect and restore ecologically and socially sustainable flow regimes, and thereby help achieve the water-related goals of the Millennium Ecosystem Assessment.

    Whilst alteration of flow, sediment, organic matter and thermal regimes interact to reduce biological diversity and the ecological integrity of freshwater ecosystems - and thereby degrade the properties and ecological services most valued by humans - ‘environmental flows' left in rivers, or restored to developed rivers, will sustain many ecological and societal values. The success of river protection and rehabilitation ⁄ restoration depends upon understanding and accurately modelling relationships between hydrological patterns, fluvial disturbance and ecological responses in rivers and floodplains.

    This Special Issue presents new analytical and modelling approaches to support the development of hydro-ecological models and environmental flow standards at multiple spatial scales - applicable to all rivers in any economic and societal setting. Examples include the new framework Ecological Limits of Hydrologic Alteration (ELOHA) founded on hydrological classification and gradient analysis; ecological trait analysis; Bayesian hierarchical modelling; Bayesian Decision Networks; and Integrated Basin Flow Assessment (IBFA).

    Advances in the allocation of flood flows along the River Murray in Australia, an Ecosystems Function Model (HEC-EFM) for the Bill Williams River restoration programme in Arizona (U.S.A), the European Water Framework Directive, and improved management of hydroelectric dams demonstrate the potential for significant ecological recovery following partial restoration of natural river flow regimes.

    Based on contributions to this Special Issue, the action agenda of the 2007 Brisbane Declaration on environmental flows and the wider literature, we propose an invigorated global research programme to construct and calibrate hydro-ecological models and to quantify the ecological goods and services provided by rivers in contrasting hydro-climatic settings across the globe. A major challenge will be to find acceptable ways to manage rivers for multiple uses. Climate change intensifies the urgency. Environmental flows help to preserve the innate resilience of aquatic ecosystems, and thereby offer the promise of improved sustainability and wellbeing for people as well as for ecosystems.

  • 207. Artioli, Yuri
    et al.
    Friedeich, Jana
    Gilbert, Alison J.
    McQuatters-Gollop, Abigail
    Mee, Laurence D.
    Vermaat, Jan E.
    Wulff, Fredrik
    Stockholms universitet, Naturvetenskapliga fakulteten, Systemekologiska institutionen.
    Humborg, Christoph
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Palmeri, Luca
    Pollehne, Falk
    Nutrient budgets for European seas: A measure of the effectiveness of nutrient reduction policies.2008Ingår i: Marine Pollution Bulletin, ISSN 0025-326X, E-ISSN 1879-3363, Vol. 56, nr 9, s. 1609-1617Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Socio-economic development in Europe has exerted increasing pressure on the marine environment. Eutrophication, caused by nutrient enrichment, is evident in regions of all European seas. Its severity varies but has, in places, adversely impacted socio-economic activities. This paper aims to evaluate the effectiveness of recently adopted policies to reduce anthropogenic nutrient inputs to European seas. Nitrogen and phosphorus budgets were constructed for three different periods (prior to severe eutrophication, during severe eutrophication and contemporary) to capture changes in the relative importance of different nutrient sources in four European seas suffering from eutrophication (Baltic Proper, coastal North Sea, Northern Adriatic and North-Western Black Sea Shelf). Policy success is evident for point sources, notably for P in the Baltic and North Seas, but reduction of diffuse sources has been more problematic.

  • 208.
    Arvanitis, Leena
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    Plant polyploidy and interactions with insect herbivores2007Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    Polyploidization has been suggested to be a common mechanism for plant speciation. Polyploidy is associated with changes in plant traits and altered habitat preference. Antagonistic and mutualistic animals are known to discriminate between plants based on variation in such plant traits, suggesting that interactions may have an important role in divergence of plant polyploids after the polyploidization. In this thesis, I investigated the effect of insect herbivores on divergence of plant polyploids in a system consisting of the predispersal seed predator butterfly Anthocharis cardamines, the bud gall forming midge Dasineura cardaminis, and tetraploids and octoploids of the herb Cardamine pratensis. Octoploid populations occurred more often in shaded and nongrazed habitats than tetraploids. Octoploid plants were larger and had fewer but larger flowers than tetraploids. Butterfly attack rates were higher in tetraploid than in octoploid populations, whereas the gall midge attacked only octoploids. These differences were associated with higher abundance of butterflies in sunny habitats and gall midges in shaded habitats. In contrast to the pattern at the population level, octoploid flower shoots were more likely to be attacked by the butterfly in sympatric populations. Also trait selection differed between ploidy levels, both in the absence and in the presence of herbivores. In a field experiment, butterfly preference did not alter the trait selection in tetraploids. In octoploids, the two herbivores did not change selection considered separately. However, their joint effect resulted in significant selection for smaller flower shoots and reduced selection on number of flowers. This thesis demonstrates that differences in habitat preference and phenotypic plant traits between polyploid cytotypes can lead to altered interactions with herbivores. Such differences in interactions with animals may alter not only the relative fitness of cytotypes but also trait selection within the respective ploidy type.

  • 209.
    Arvanitis, Leena
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen. Växtekologi.
    Wiklund, Christer
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen. Ekologi.
    Ehrlén, Johan
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen. Växtekologi.
    Butterfly seed predation: effects of landscape characteristics, plant ploidy level and population structure2007Ingår i: Oecologia, ISSN 0029-8549, Vol. 152, nr 2, s. 275-285Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Polyploidization has been suggested as one of the most common mechanisms for plant diversification. It is often associated with changes in several morphological, phenological and ecological plant traits, and therefore has the potential to alter insect–plant interactions. Nevertheless, studies evaluating the effect of plant polyploidy on interspecific interactions are still few. We investigated pre-dispersal seed predation by the butterfly Anthocharis cardamines in 195 populations of two ploidy levels of the herb Cardamine pratensis (tetraploid ssp. pratensis, 2n = 30 vs. octoploid ssp. paludosa, 2n = 56–64). We asked if differences in incidence and intensity of predation among populations were related to landscape characteristics, plant ploidy level and population structure. The incidence of the seed predator increased with increasing plant population size and decreasing distance to nearest population occupied by A. cardamines. The intensity of predation decreased with increasing plant population size and was not affected by isolation. Probability of attack decreased with increasing shading, and intensity of predation was higher in grazed than in non-grazed habitats. The attack intensity increased with increasing mean flower number of plant population, but was not affected by flowering phenology. Individuals in tetraploid populations suffered on average from higher levels of seed predation, had higher mean flower number, were less shaded and occurred more often in grazed habitats than octoploid populations. When accounting for differences in habitat preferences between ploidy levels there was no longer a difference in intensity of predation, suggesting that the observed differences in attack rates among populations of the two ploidy levels are mediated by the habitat. Overall, our results suggest that polyploidization is associated with differentiation in habitat preferences and phenotypic traits leading to differences in interspecific interaction among plant populations. This, in turn, may facilitate further divergence of ploidy levels.

  • 210.
    Arvidsson, Fredrik
    et al.
    Lund University.
    Jonsson, Lars J.
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man & Biosphere Health (MABH).
    Birkhofer, Klaus
    Lund University.
    Geographic location, not forest type, affects the diversity of spider communities sampled with malaise traps in Sweden2016Ingår i: Annales Zoologici Fennici, ISSN 0003-455X, E-ISSN 1797-2450, Vol. 53, nr 3-4, s. 215-227Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The latitudinal diversity gradient predicts higher species richness at lower latitudes. Here, we utilize the data from a long-term monitoring with malaise traps to analyse if spider communities in Sweden are affected by geographic gradients and if these effects hold independent of forest type. The species richness and the effective number of species in spider communities were not significantly related to the latitudinal gradient. The effective number of species and the taxonomic distinctness of spider communities were related to longitude, with a higher number, but fewer related species in western parts of Sweden. The species and family composition were significantly related to latitude independent of forest type, with a dominance of Linyphiidae individuals and species in the north. Our study demonstrates the suitability of malaise trap sampling to contribute to a better understanding of local spider communities, as several rare and locally new species were recorded in this study.

  • 211.
    Arzel, Céline
    et al.
    University of Turku.
    Dessborn, Lisa
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Pöysä, Hannu
    Joensuu Game and Fisheries Research.
    Elmberg, Johan
    Högskolan Kristianstad, Sektionen för lärande och miljö, Avdelningen för Naturvetenskap. Högskolan Kristianstad, Forskningsmiljön Man and Biosphere Health (MABH).
    Nummi, Petri
    University of Helsinki.
    Sjöberg, Kjell
    Swedish University of Agricultural Sciences, Umeå.
    Early springs and breeding performance in two sympatric duck species with different migration strategies2014Ingår i: Ibis, ISSN 0019-1019, E-ISSN 1474-919X, Vol. 156, nr 2, s. 288-298Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The capacity of migratory species to adapt to climate change may depend on their migratory and reproductive strategies. For example, reproductive output is likely to be influenced by how well migration and nesting are timed to temporal patterns of food abundance, or by temperature variations during the brood rearing phase. Based on two decades (1988–2009) of waterfowl counts from a boreal catchment in southern Finland we assessed how variation in ice break-up date affected nesting phenology and breeding success in two sympatric duck species, Mallard Anas platyrhynchos and Eurasian Teal Anas crecca. In Fennoscandia these species have similar breeding habitat requirements but differ in migration distance; Teal migrate roughly seven times as far as do Mallard. Annual ice break-up date was used as a proxy of spring ‘earliness’ to test the potential effect of climate change on hatching timing and breeding performance. Both species were capable of adapting their nesting phenology, and bred earlier in years when spring was early. However, the interval from ice break-up to hatching tended to be longer in early springs in both species, so that broods hatched relatively later than in late springs. Ice break-up date did not appear to influence annual number of broods per pair or annual mean brood size in either species. Our study therefore does not suggest that breeding performance in Teal and Mallard is negatively affected by advancement of ice break-up at the population level. However, both species showed a within-season decline in brood size with increasing interval between ice break-up and hatching. Our study therefore highlights a disparity between individuals in their capacity to adjust to ice break-up date, late breeders having a lower breeding success than early breeders. We speculate that breeding success of both species may therefore decline should a consistent trend towards earlier springs occur.

  • 212.
    Ashitani, T.
    et al.
    Yamagata Univ, Dept Bioenvirom, Fac Agr, Tsuruoka, Yamagata 9978555, Japan.;Royal Inst Technol, Sch Chem Sci & Engn, Ecol Chem Grp, Dept Chem, SE-10044 Stockholm, Sweden..
    Garboui, Samira Sadek
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Zooekologi.
    Schubert, F.
    Royal Inst Technol, Sch Chem Sci & Engn, Ecol Chem Grp, Dept Chem, SE-10044 Stockholm, Sweden..
    Vongsombath, C.
    Royal Inst Technol, Sch Chem Sci & Engn, Ecol Chem Grp, Dept Chem, SE-10044 Stockholm, Sweden.;Natl Univ Laos NOUL, Viangchan, Laos..
    Liblikas, I.
    Inst Technol, Sect Organ Chem, EE-50411 Tartu, Estonia..
    Palsson, K.
    Royal Inst Technol, Sch Chem Sci & Engn, Ecol Chem Grp, Dept Chem, SE-10044 Stockholm, Sweden..
    Borg-Karlson, A. -K
    Activity studies of sesquiterpene oxides and sulfides from the plant Hyptis suaveolens (Lamiaceae) and its repellency on Ixodes ricinus (Acari:Ixodidae)2015Ingår i: Experimental & applied acarology, ISSN 0168-8162, E-ISSN 1572-9702, Vol. 67, nr 4, s. 595-606Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Hyptis suaveolens (Lamiaceae), a plant traditionally used as a mosquito repellent, has been investigated for repellent properties against nymphs of the tick Ixodes ricinus. Essential oils and volatile compounds of fresh and dried leaves, from plants originating from Laos and Guinea-Bissau, were identified by GC-MS and tested in a tick repellency bioassay. All the essential oils were strongly repellent against the ticks, even though the main volatile constituents differed in their proportions of potentially tick repellent chemicals. (+)/(-)-sabinene were present in high amounts in all preparations, and dominated the emission from dry and fresh leaves together with 1,8-cineol and alpha-phellandrene. 1,8-Cineol and sabinene were major compounds in the essential oils from H. suaveolens from Laos. Main compounds in H. suaveolens from Guinea-Bissau were (-)-sabinene, limonene and terpinolene. Among the sesquiterpene hydrocarbons identified, alpha-humulene exhibited strong tick repellency (96.8 %). Structure activity studies of oxidation or sulfidation products of germacrene D, alpha-humulene and beta-caryophyllene, showed increased tick repellent activity: of mint sulfide (59.4 %), humulene-6,7-oxide (94.5 %) and caryophyllene-6,7-oxide (96.9 %). The substitution of oxygen with sulfur slightly lowered the repellency. The effects of the constituents in the oils can then be regarded as a trade off between the subsequently lower volatility of the sesquiterpene derivatives compared to the monoterpenes and may thus increase their potential usefulness as tick repellents.

  • 213.
    Ask, Jenny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Carbon metabolism in clear-water and brown-water lakes2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The trophic state of lakes is commonly defined by the concentration of nutrients in the water column. High nutrient concentrations generate high phytoplankton production, and lakes with low nutrient concentrations are considered low-productive. This simplified view of lake productivity ignores the fact that benthic primary producers and heterotrophic bacteria can be important basal producers in lake ecosystems.

    In this thesis I have studied clear-water and brown-water lakes with respect to primary production, respiration and bacterial production based on allochthonous organic carbon. These processes were quantified in pelagic and benthic habitats on temporal and spatial scales. I also calculated the net ecosystem production of the lakes, defined as the difference between gross primary production (GPP) and respiration (R). The net ecosystem production indicates whether a lake is net heterotrophic (GPP < R), net autotrophic (GPP > R) or in metabolic balance (GPP = R). Net heterotrophic lakes are sources of carbon dioxide (CO2) to the atmosphere since respiration in these lakes, by definition, is subsidized by an external organic carbon source. External organic carbon is transported to lakes from the terrestrial environment via inlets, and can serve as a carbon source for bacteria but it also limits light availability for primary producers by absorbing light.

    On a seasonal scale, four of the clear-water lakes studied in this thesis were dominated by primary production in the soft-bottom benthic habitat and by respiration in the pelagic habitat. Concentrations of dissolved organic carbon (DOC) were low in the lakes, but still high enough to cause the lakes to be net heterotrophic. However, the lakes were not low-productive due to the high production in the benthic habitat. One of the clear-water lakes was studied also during the winter and much of the respiration under ice was supported by the benthic primary production from the previous summer. This is in contrast to brown-water lakes where winter respiration is suggested to be supported by allochthonous organic carbon.

    By studying lakes in a DOC gradient (i.e. from clear-water to brown-water lakes) I could draw two major conclusions. The lakes became less productive since benthic primary production decreased with increasing light extinction, and the lakes became larger sources of CO2 to the atmosphere since pelagic respiration was subsidized by allochthonous organic carbon. Thus, lake carbon metabolism can have an important role in the global carbon cycle due to their processing of terrestrial organic carbon and to their possible feedback effects on the climate system.

  • 214.
    Ask, Jenny
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Rowe, Owen
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Brugel, Sonia
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Strömgren, Mårten
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Byström, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Andersson, Agneta
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap. Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Umeå marina forskningscentrum (UMF).
    Importance of coastal primary production in the northern Baltic Sea2016Ingår i: Ambio, ISSN 0044-7447, E-ISSN 1654-7209, Vol. 45, nr 6, s. 635-648Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In this study, we measured depth-dependent benthic microalgal primary production in a Bothnian Bay estuary to estimate the benthic contribution to total primary production. In addition, we compiled data on benthic microalgal primary production in the entire Baltic Sea. In the estuary, the benthic habitat contributed 17 % to the total annual primary production, and when upscaling our data to the entire Bothnian Bay, the corresponding value was 31 %. This estimated benthic share (31 %) is three times higher compared to past estimates of 10 %. The main reason for this discrepancy is the lack of data regarding benthic primary production in the northern Baltic Sea, but also that past studies overestimated the importance of pelagic primary production by not correcting for system-specific bathymetric variation. Our study thus highlights the importance of benthic communities for the northern Baltic Sea ecosystem in general and for future management strategies and ecosystem studies in particular.

  • 215.
    Ask, Per
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Invasion of top and intermediate consumers in a size structured fish community2010Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    In this thesis I have investigated the effects of invading top and intermediate consumers in a size-structured fish community, using a combination of field studies, a lake invasion experiment and smaller scale pond and aquaria experiments.

    The lake invasion experiment was based on introductions of an intermediate consumer, ninespine stickleback (Pungitius pungitius L.), in to allopatric populations of an omnivorous top predator, Arctic char (Salvelinus alpinus L.). The invasion experiment was performed in two tundra lakes and in two birch forest lakes to investigate the effect of climate on the invasion success. I found that the effect of sticklebacks on char was size dependent. Small char suffered reduced growth from resource competition with sticklebacks whereas the maximum size of adult char increased from the addition of a larger prey resource, stickleback. The negative effect of sticklebacks on the growth of small char suggests that sticklebacks may be a better resource competitor than char, which was also supported by the pond and aquaria experiments. The pond experiments also suggested that char were more efficient cannibals than interspecific predators on sticklebacks. Cannibalism in char may limit the recruitment of char and decrease both their predatory and competitive effect on coexisting species and thereby also promote the coexistence of char and sticklebacks. The successful invasion by sticklebacks and their subsequent increases in density suggest that the absence of sticklebacks in char lakes in this region is not caused by biotic interactions with char. Instead, it may be suggested that co-occurrence of sticklebacks and char in the region is limited by dispersal.

    The char – stickleback system resembles an intraguild predation system with char as the top consumer and stickleback as the intermediate consumer. The effects of the stickleback invasion is also contrasted with a field study of a northern pike (Esox lucius L.) invasion into a system with coexisting char and stickleback, where pike can be viewed as the top consumer and char as the intermediate consumer both feeding on sticklebacks. In this case pike excluded char. The identity of the invading species and the relative strength of the predatory and competitive interactions in the two contrasting systems are discussed in relation to coexistence in intraguild predation systems. I found that the identity of the invading species is of crucial importance for the response at the ecosystem level, and that the inherent size dependency of competitive and predatory interactions in fish communities is important for attaining a mechanistical understanding of the effects of invasive species in lake ecosystems.

  • 216.
    Ask, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ask, Jenny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Byström, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Persson, Lennart
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Competition mediated coexistence of invading intermediate consumer, ninespine stickleback, and a resident omnivorous top predator, Arctic charManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    Climate change results in changes in the geographical distribution of species. Species invasion success into a new area is dependent both on the dispersal ability of species as well as the strength and identity of biotic interactions between resident and invading species. Coexistence in intraguild predation (IGP) systems depends on the relative strength of predation and competition interactions which in turn are temperature dependent. We investigated the effects of introducing an intermediate consumer, ninespine stickleback (Pungitius pungitius), into allopatric populations of the omnivorous top predator Arctic char (Salvelinus alpinus). Introductions were performed in lakes with different climate regimes, two tundra lakes and two forest lakes that differed in average summer temperatures with 1.4 ± 0.5 ºC (average ± 1SD). We found that sticklebacks were able to invade and increase in density in both tundra and forest lakes. Sticklebacks had strong negative effects on resource densities which also was reflected in a decreased growth of small char. Increasing stickleback density had a positive effect on growth of large adults and on the maximum size of char. We conclude that stickleback presence is not limited by biological interactions in these systems but rather by dispersion ability. We suggest that the size dependency in the response of char to the invasion of sticklebacks is fundamental for the successful invasion of sticklebacks, and that size dependent interactions including cannibalism play important roles for coexistence in natural IGP-systems.

  • 217.
    Ask, Per
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Ask, Jenny
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Byström, Pär
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Jansson, Mats
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Karlsson, Jan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Persson, Lennart
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Temperature mediated effects on top consumer populations in subarctic lakesManuskript (preprint) (Övrigt vetenskapligt)
    Abstract [en]

    The effects of temperature on top consumer populations in subarctic lake communities were studied by contrasting two lake pairs in different climate regimes: one pair on the low alpine tundra and one pair in the subalpine birch forest. We measured zooplankton and macroinvertebrate biomasses over the season and estimated population density and size structure of the top consumer Arctic char (Salvelinus alpinus). Furthermore, we modelled char growth using literature data on temperature dependent search rate, handling time and metabolic demands. The forest lakes were warmer than the tundra lakes. Char in the forest lakes were larger and had a higher individual growth compared to char in the tundra lakes, while population density and biomasses of char were not different between the forest and the tundra lakes. There were no differences in macroinvertebrate and zooplankton resource levels available for char between lake pairs. Our modeling of char growth revealed that higher temperature increased growth of char at the observed resource densities, suggesting that the higher temperature in the forest lakes was primarily the cause of the higher growth of char in these lakes. We suggest that cannibalism in char may regulate char recruitment and thereby population density and biomass of char leading to effects of increasing temperature on consumer biomass and consumer individual growth different from what is expected in pure consumer-resource systems. Our results emphasize the importance of feedbacks within ecosystems when addressing effects of climate change and increasing temperature on lake communities.

  • 218.
    Aspenberg, Per
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Ingen trutdöd i Gävlebukten sommaren 20092010Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Massdöd hos gråtrutar, kopplad till karaktäristiska förlamningssymptom, upptäcktes år 2000 i

    södra Sveriges kusttrakter. Denna onormala sjöfågeldöd med oklar orsak har varit föremål för

    flera speciella studier i landet. För Gävleborgs läns del har fältstudier gjorts under alla år från

    och med 2002. Detta år dog så mycket som ca 35% av de adulta gråtrutarna vid södra delen av

    länets kust. Fortsatta kontroller har visat att andelen döda gråtrutar vid gästrikekusten under

    åren 2003-2006 minskade till en lägre nivå på ca 7-8%. Denna andel klingade av ytterligare

    till nära 0% under åren 2007-2008 och har hållit sig kvar på denna harmlösa nivå även

    sistlidna sommar 2009.

     

    Efter utbrottet 2002 minskade antalet häckande par gråtrut efter gästrikekusten påtagligt

    (antalet kolonihäckande minskade från uppskattningsvis 715 par till 595 par år 2003). Denna

    nedgång fortsatte ytterligare till sommaren 2004 (då 483 par räknades in). Därefter har de

    skattade totalerna från räkningar i kolonierna pendlat i storleksordningen 500 till 600 par.

    Båda åren 2007 och 2008 låg siffran på runt 550 par, men 2009 hade den sjunkit med ca 40

    par. En generell minskning av den lokala gråtrutstammen har alltså nu kunnat dokumenteras.

    Trutsjukans roll i dessa sammanhang är svår att bedöma. Populationsutvecklingen bestäms

    naturligtvis också av många andra faktorer, som t ex tillgången till föda, inte minst under höst

    och vinter i övervintringsområdena i södra Östersjön, vilket i sin tur är kopplat till samhällets

    avfallshantering samt omfattningen av yrkesfiske.

     

    Liksom 2008 hittades inte en enda förlamad (levande) trut under sommarens fältarbete 2009.

    Ett i sammanhanget obetydligt antal om två sedan länge döda adulta gråtrutar påträffades

    under alla besök i kolonierna. Någon hypotes beträffande dödsorsak var inte möjlig att ange

    för dessa fåglar. Därmed måste man sammanfatta läget med att den observerade dödligheten i

    trutsjukan stannade på i princip 0% av den häckande populationen.

     

    Tre nyligen döda fåglar av andra arter (en vardera av havstrut, grågås och knölsvan) verkade

    emellertid ha kunnat drabbats av trutsjukan. Den slutsatsen var näraliggande genom att de var

    nersmetade med rester av gulgrön spillning runt kloaköppningen.

  • 219.
    Aspenberg, Per
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Minimal trutdöd i Gävlebukten sommaren 20102010Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Flera kustfågelarter har under 2000-talet drabbats av vad som betraktas som överdödlighet

    under normal häckningstid. En art som särskilt uppmärksammats i detta avseende är gråtruten.

    Stora mängder av gråtrutar har hittats döda vid häckplats och många har påträffats i

    förlamningstillstånd. Sedan 2002 har gråtrutarna årligen undersökts i Gävlebukten. Efter

    konstaterad massdöd i detta område 2002 avklingade andelen döda adulta åren 2003-2006 för

    att 2007-2009 hamna nära noll.

     

    Uppföljningarna har gjorts på så sätt att samtliga kända kolonier i Gävlebukten har besökts

    först i ett tidigt skede för att bedöma antalet par gråtrut som inleder häckning. Vid ett senare

    besök i slutfasen av häckningscykeln har eventuella döda fåglar räknats. Med tillgång till

    detta material kan dels totalpopulationen kolonihäckande bestämmas och dels även andelen

    av de adulta fåglarna som drabbats av ”trutdöden”.

     

    Från alla besök 2010 har endast registrerats tre döda gamla gråtrutar där man kan

    misstänka den tidigare grasserande trutsjukan som orsak. Detta motsvarar en obetydlig

    andel på ca 0,3% av de häckande adulta. En summering av totalpopulationen i

    undersökningsområdet hamnar på 529 par jämfört med 512 par 2009. I stort sett låg

    populationen alltså på oförändrad nivå.

     

    Man kan dock se tendenser till en liten men mer tydlig ökning i kolonierna i söder (+13%)

    och en tydlig minskning i de nordliga kolonierna (-20%). Materialet är litet men inbjuder ändå

    till spekulationer om att mink kan förklara en del geografisk omfördelning. De nordliga

    kolonierna ligger nämligen på minkbesökta skär och flera av de sydliga på minkfria öar.

  • 220.
    Aspenberg, Per
    et al.
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Axbrink, Mats
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Kustfåglar i Gävleborg 20072009Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Det främsta syftet med inventeringen 2007 var att kartlägga förekomsten av häckande

    kustfåglar detta år, för att genom jämförelse med motsvarande siffror från tidigare

    inventeringar få en uppfattning om populationsutvecklingen. Andra syften var att samla in

    data om onormal fågeldöd och om olika aspekter på skötsel av skyddade områden, t ex status

    för skyltning.

     

    De kustfåglar som inventerats är främst fågelarter som är knutna till vattenmiljön, dvs

    sjöfåglar, måsar, tärnor och vadare. Därutöver inkluderades andra arter utanför dessa

    kategorier som har sin regionala utbredning begränsad till just skärgårdsmiljö (t ex

    skärpiplärka) samt gråhäger och ängspiplärka som är relativt lättinventerade arter med en

    faunistiskt intressant förekomst i skärgården.

     

    För storskarv och häger skedde (liksom 1997) en systematisk boräkning. I övrigt användes

    antalet närvarande fåglar som underlag för uppskattningar av antalet häckande par.

     

    För att tillfredsställa möjligheterna till goda jämförelser tio år bakåt i tiden användes nu,

    liksom 1997, en metodik innebärande tre räkningstillfällen. Den första räkningen var inriktad

    på sjöfåglar (men noteringar gjordes för alla observerade fåglar) och genomfördes

    tidsperioden 28 april – 13 maj. Den andra räkningen genomfördes i huvudsak 31 maj – 16

    juni. Vid båda dessa taxeringsomgångar genomkorsades länets skärgård av de två författarna

    tillsammans i en öppen båt från länsgränsen mot Uppland i söder till gränsen mot Medelpad i

    norr. Den tredje taxeringsomgången genomfördes under perioden 18 juni – 22 juli. Vid denna

    omgång, som huvudsakligen syftade till att studera reproduktion, minkpredation och onormal

    sjöfågeldöd, arbetade författarna parallellt på olika håll.

     

    En jämförelse av resultatet för 2007 med tidigare inventeringar visar exempel på arter med en

    uppseendeväckande populationsökning såväl som arter med en lika kraftig minskning inom

    länets gränser.

     

    Populationsökningarna kan bero på en ökad födotillgång till följd av eutrofiering. Även en

    förbättrad miljögiftssituation och minskad jakt kan spela in. Minskningar av populationer

    beror sannolikt på predation från framför allt mink.

     

    Resultatet kan sammanfattas i nedanstående tabell, där förändringar mellan 1997 och 2007

    samt möjliga orsaker till dessa redovisas för olika artgrupper.

     

    Artgrupp

    Trend

    Möjlig orsak

    Doppingar

    Stark ökning

    Eutrofiering

    Storskarv

    Explosionsartad ökning

    Minskad jakt, ökad   födotillgång

     

    Svanar & gäss

    Ökning

    Minskad jakt

    Simänder

    Ökning

    Eutrofiering

     

    Dykänder

    Splittrad bild

    Olika påverkan av mink

    Vadare

    Minskning (dock ej f.

    strandskata

    Eutrofiering? Mink?   Flyttning – övervintring?

    Labb

    Viss ökning

    Fler tärnor

    Skrattmås

    Ökning

    Omflyttning från   insjöar till skärgård,

    eutrofiering

    Övriga måsfåglar

    Tämligen oförändrat

     

    Fisk- och silvertärna

    Ökning

    Ökad födotillgång

    Alkfåglar

    Ökad födotillgång

    Predation från mink   och ökad födotillgång

     

    Återgivning av tabell 2 från avsnitt 6.1.2 i rapporten.

     

    Ett intryck som förstärktes under fältarbetet våren-sommaren 2007 var skillnaden mellan

    fågelrika och fågelfattiga skärgårdsavsnitt. I stort sett tycks samma geografiska skillnader som

    noterades under inventeringen 1997-1998 kvarstå.

    Resultaten visar att onormal sjöfågeldöd betingat av sjukdom och/eller toxiner endast

    förekom i mycket ringa omfattning denna sommar. Betydande ungförluster förorsakade av

    mink kunde dock dokumenteras för de markhäckande kustfåglarna och det kan konstateras att

    problemet kvarstår i tämligen oförminskad omfattning.

     

    Förslag på åtgärder för att minska hoten mot kustfåglarna inkluderar fortsatt övervakning av

    skärgårdens toppkonsumenter och miljögifter, skapa säkrare farleder och navigationssystem

    för att minska risken för oljeolyckor, fortsatt uppföljning av trutsjukan samt stimulera

    decimeringen av mink. Även hänsyn vid planering och exploatering längs kusten anses

    angeläget, liksom aktiva åtgärder för att minska igenväxningen av öppna strandängar och

    vissa fågelskär utan högre vegetation. Slutligen bör häckfågellivet i skärgårdarna undersökas

    även framöver med tanke på den förväntade klimatförändringen.

  • 221.
    Aspenberg, Per
    et al.
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Keller, Olle
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Metodjämförelse av undersökningstyper för kustfåglar2009Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Sommaren 2008 genomfördes jämförande studier mellan två olika inventeringsmetoder för

    kustfågeltaxering. Fältarbetet skedde efter en elva kilometer lång skärgårdssträcka i södra

    Gävleborgs län. Syftet med studien var att studera skillnaden i utfall med att taxera kustfåglar

    genom dels den s.k. Anderssons metod och dels en senare av länsstyrelsen i Gävleborg

    beskriven förenklad metod. Båda metoderna innehåller en tidig andfågelräkning som inte

    behandlades. Jämförelsen skedde bara mellan metodernas utfall i den senare inventeringsfasen,vilket för Anderssons metod innebar två inventeringstillfällen och för den nya metoden ett samlat inventeringstillfälle.

     

    De arter som var föremål för räkning i Anderssons första inventeringstillfälle fick sammantaget en högre numerär där än i den nya metoden med en enda integrerad räkning (ca 25 % högre). Hela skillnaden kunde förklaras av en stor diskrepans för småskrak. De arter som var föremål för räkning i Anderssons andra inventeringstillfälle fick omvänt en högre sammanlagd numerär i den nya metoden (också ca 25 % skillnad).

     

    Studien var upplagd med jämförande taxeringar med ganska stora tidsmellanrum. Det bedöms

    som att båda de ovan beskrivna skillnaderna huvudsakligen kunde förklaras av säsongsmässiga

    skillnader. Tidpunkten för inventeringen skulle alltså vara viktigare än vilken av de

    två metoderna som väljs.

     

    Även behovet av landstigning undersöktes genom jämförelser mellan observationer från båt

    före landstigning på ön och efter landstigning. De arter som då främst studerades var

    måsfåglar, tärnor och vadare. För samtliga dessa grupper gav landstigning inte oväntat något

    högre numerärer än räkningar från båt. För måsfåglar och tärnor sågs dock från närgången båt

    så mycket som 80-90% av antalet inräknade efter landstigning. För vadare indikerade

    undersökningen ett lägre utfall från båt på runt 60%.

  • 222.
    Aspenberg, Per
    et al.
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Kellner, Olle
    Utförare miljöövervakning, Länsstyrelser, lst, Länsstyrelsen Gävleborg.
    Metodstudie Kustfågelinventering 20072009Rapport (Övrigt vetenskapligt)
    Abstract [sv]

    Vid kustfågelinventering kan ingen inventerare se alla häckande fåglar vid ett enda besök.

    Den andel av de häckande fåglarna som en viss inventerare noterar vid ett visst tillfälle kan

    kallas inventeringseffektivitet. Inventeringseffektiviteten skiljer sig mellan olika inventerare

    och varierar under säsongen och mellan arter. Dessutom finns ett inslag av slumpmässiga

    faktorer som tillfällig frånvaro av fåglar, inventerarens ”dagsform”, väder m.m.

     

    Inventeringseffektiviteten undersöktes våren-sommaren 2007 genom en serie inventeringsbesök av sju olika observatörer vid tre fågelöar i Gävlebukten, huvudsakligen under perioden 23 maj – 2 juli. Sex av observatörerna saknade direkt erfarenhet av kustfågelinventering men hade alla mycket stora erfarenheter av fältornitologi och var därmed genomgående skickliga på artbestämning.

     

    Rent generellt kan man säga att ca 70 % var ett vanligt värde på inventeringseffektiviteten.

    För de mest lättinventerade arterna (t.ex. knölsvan, roskarl, rödbena) nåddes regelmässigt ca

    90 % inventeringseffektivitet, medan det för svårinventerade arter (t.ex. gräsand, drillsnäppa)

    snarare låg på 20-30 %.

     

    Inventeringseffektiviteten minskade under studieperioden, särskilt mot slutet. Dessutom var

    det en påtaglig slumpmässig variation mellan olika inventeringsdagar under samma vecka,

    särskilt för kolonihäckande fåglar som kunde variera 10-20 procentenheter inom några dagar,

    för de tre öarna i testet. Man kan dock anta att denna korttidsvariation spelar mindre roll i en

    större inventering som sträcker sig över flera inventeringsdagar.

     

    Skillnaderna mellan de olika inventerarna var som regel 5-10 procentenheter. När det fanns

    risk för sammanblandning av arter var dock skillnaden större, särskilt för blandade fisksilvertärnekolonier. Även för änderna som är generellt svårinventerade blev det stora

    personskillnader. Skillnaderna var också mycket större för en ”ringrostig” inventerare som

    varit mindre aktiv under några år. Personskillnaderna var delvis systematiska. Det beror

    troligen dels på ovana att räkna kolonihäckande fåglar (systematisk underskattning) samt

    skillnader i bedömning av fåglarnas uppträdande (häckar anden här eller är den bara tillfällig

    gäst vid ön). Dessa skillnader accentuerar värdet av att:

     

    • använda samma inventerare helt eller delvis i manskapet mellan olika år
    • introducera nya inventerare i problematiken med att särskilja förväxlingsarter
    • koncentrera sig på ett urval av vissa arter vid ett inventeringsbesök
    • använda fotografering som dokumentationsmetod vid större vitfågelkolonier
    • styra upp fältanteckningarna med t ex strikt användning av protokoll

    Slutsatser:

    • Inventeringsresultat underskattar de verkliga populationsstorlekarna
    • Det är viktigt att inventerarna är tränade i just kustfågelinventering, och nya

    inventerare bör samkalibrera sig med mer erfarna.

    • Även med tränad personal kommer ett visst fel att kvarstå, och små

    populationsförändringar (10-20 %) är mycket svåra att säkert skilja från metodfel. För

    svårinventerade arter är metodfelet ofta avsevärt större.

  • 223. Assefa, Anteneh T.
    et al.
    Sobek, Anna
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Sundqvist, Kristina L.
    Cato, Ingemar
    Jonsson, Per
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för tillämpad miljövetenskap (ITM).
    Tysklind, Mats
    Wiberg, Karin
    Temporal Trends of PCDD/Fs in Baltic Sea Sediment Cores Covering the 20th Century2014Ingår i: Environmental Science and Technology, ISSN 0013-936X, E-ISSN 1520-5851, Vol. 48, nr 2, s. 947-953Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    The pollution trend of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) in the Baltic Sea region was studied based on depth profiles of PCDD/Fs in sediment cores collected from six-offshore areas, eight coastal sites impacted by industrial/urban emissions, and one coastal reference site. A general trend was observed for the offshore and coastal reference sites with substantial increase in PCDD/F concentrations in the mid-late 1970s and peak levels during 1985-2002. The overall peak year for PCDD/Fs in Baltic Sea offshore areas was estimated (using spline-fit modeling) to 1994 +/- 5 years, and a half-life in sediments was estimated at 29 +/- 11 years. For the industrial/urban impacted coastal sites, the temporal trend was more variable with peak years occurring 1-2 decades earlier compared to offshore areas. The substantial reductions from peak levels (38 +/- 11% and 81 +/- 12% in offshore and coastal areas, respectively) reflect domestic and international actions taken for reduction of the release of PCDD/Fs to the environment. The modeled overall half-life and reductions of PCDD/Fs in offshore Baltic Sea sediment correspond well to both PCDD/F trends in European lakes without any known direct. PCDD/F sources (half-lives 30 and 32 years), and previously modeled reduction in atmospheric deposition of,PCDD/Fs to the Baltic Sea since 1990. These observations support previous findings of a common diffuse source, such as long-range air transport of atmospheric emissions, as the prime source of PCDD/Fs to the Baltic Sea region. The half-life of PCDD/Fs in Baltic Sea offshore sediments was estimated to be approximately 2 and 4-6 times longer than in semirural and urban European air, respectively. This study highlights the need for further international actions to reduce the levels of PCDD/Fs in Baltic Sea air specifically and in European air in general.

  • 224. Atkinson, Lindsey J
    et al.
    Campbell, Catherine D
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Zaragoza-Castells, Joana
    Hurry, Vaughan
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för fysiologisk botanik.
    Atkin, Owen K
    Impact of growth temperature on scaling relationships linking photosynthetic metabolism to leaf functional traits2010Ingår i: Functional Ecology, ISSN 0269-8463, E-ISSN 1365-2435, Vol. 24, nr 6, s. 1181-1191Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. Scaling relationships linking photosynthesis (A) to leaf traits are important for predicting vegetation patterns and plant-atmosphere carbon fluxes. Here, we investigated the impact of growth temperature on such scaling relationships.

    2. We assessed whether changes in growth temperature systematically altered the slope and/or intercepts of log-log plots of A vs leaf mass per unit leaf area (LMA), nitrogen and phosphorus concentrations for 19 contrasting plant species grown hydroponically at four temperatures (7, 14, 21 and 28 degrees C) in controlled environment cabinets. Responses of 21 degrees C-grown pre-existing (PE) leaves experiencing a 10 day growth temperature (7, 14, 21 and 28 degrees C) treatment, and newly-developed (ND) leaves formed at each of the four new growth temperatures, were quantified. Irrespective of the growth temperature treatment, rates of light-saturated photosynthesis (A) were measured at 21 degrees C.

    3. Changes in growth temperature altered the scaling between A and leaf traits in pre-existing (PE) leaves, with thermal history accounting for up to 17% and 31% of the variation on a mass and area basis, respectively. However, growth temperature played almost no role in accounting for scatter when comparisons were made of newly-developed (ND) leaves that form at each growth temperature.

    4. Photosynthetic nitrogen and phosphorus use efficiency (PNUE and PPUE, respectively) decreased with increasing LMA. No systematic differences in temperature-mediated reductions in PNUE or PPUE of PE leaves were found among species.

    5. Overall, these results highlight the importance of leaf development in determining the effects of sustained changes in growth temperature on scaling relationships linking photosynthesis to other leaf traits.

  • 225.
    Attermeyer, Katrin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Leibniz Inst Freshwater Ecol & Inland Fisheries C, Muggelseedamm 310, D-12587 Berlin, Germany..
    Flury, S.
    Leibniz Inst Freshwater Ecol & Inland Fisheries C, Muggelseedamm 310, D-12587 Berlin, Germany.;Univ Geneva, Fac Sci, Blvd Carl Vogt 66, CH-1211 Geneva, Switzerland..
    Jayakumar, R.
    IITM, IGCS, Madras 600036, Tamil Nadu, India.;IITM, Environm & Water Resources Engn Div, Dept Civil Engn, Madras 600036, Tamil Nadu, India..
    Fiener, P.
    Univ Augsburg, Dept Geog, Alter Postweg 118, D-86159 Augsburg, Germany..
    Steger, K.
    IITM, IGCS, Madras 600036, Tamil Nadu, India..
    Arya, V.
    IITM, Environm & Water Resources Engn Div, Dept Civil Engn, Madras 600036, Tamil Nadu, India..
    Wilken, F.
    Univ Augsburg, Dept Geog, Alter Postweg 118, D-86159 Augsburg, Germany.;BTU, Chair Soil Protect & Recultivat, Konrad Wachsmann Allee 6, D-03013 Cottbus, Germany..
    van Geldern, R.
    Univ Erlangen Nurnberg, GeoZentrum Nordbayern, Schlossgarten 5, D-91054 Erlangen, Germany..
    Premke, K.
    Leibniz Inst Freshwater Ecol & Inland Fisheries C, Muggelseedamm 310, D-12587 Berlin, Germany.;Leibniz Ctr Agr Landscape Res ZALF, Inst Landscape Biogeochem, Eberswalder Str 84, D-15374 Muncheberg, Germany..
    Invasive floating macrophytes reduce greenhouse gas emissions from a small tropical lake2016Ingår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 6, artikel-id 20424Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Floating macrophytes, including water hyacinth (Eichhornia crassipes), are dominant invasive organisms in tropical aquatic systems, and they may play an important role in modifying the gas exchange between water and the atmosphere. However, these systems are underrepresented in global datasets of greenhouse gas (GHG) emissions. This study investigated the carbon (C) turnover and GHG emissions from a small (0.6 km(2)) water-harvesting lake in South India and analysed the effect of floating macrophytes on these emissions. We measured carbon dioxide (CO2) and methane (CH4) emissions with gas chambers in the field as well as water C mineralization rates and physicochemical variables in both the open water and in water within stands of water hyacinths. The CO2 and CH4 emissions from areas covered by water hyacinths were reduced by 57% compared with that of open water. However, the C mineralization rates were not significantly different in the water between the two areas. We conclude that the increased invasion of water hyacinths and other floating macrophytes has the potential to change GHG emissions, a process that might be relevant in regional C budgets.

  • 226.
    Attermeyer, Katrin
    et al.
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Limnologi. Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Chemical Analytics and Biogeochemistry, Germany.
    Grossart, Hans-Peter
    Leibniz-Institute of Freshwater Ecology and InlandFisheries, Experimental Limnology, Germany; Institute for Biochemistry and Biology, Potsdam University, Germany.
    Flury, Sabine
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Chemical Analytics and Biogeochemistry, Germany; Faculty of Science, University of Geneva, Switzerland.
    Premke, Katrin
    Leibniz-Institute of Freshwater Ecology and Inland Fisheries, Chemical Analytics and Biogeochemistry, Germany; Leibniz Centre for Agricultural Landscape Research (ZALF), Institute for Landscape Biogeochemistry, Germany.
    Bacterial processes and biogeochemical changes in the water body of kettle holes: mainly driven by autochthonous organic matter?2017Ingår i: Aquatic Sciences, ISSN 1015-1621, E-ISSN 1420-9055, Vol. 79, nr 3, s. 675-687Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Kettle holes are small inland waters formed from glacially-created depressions often situated in agricultural landscapes. Due to their high perimeter-to-area ratio facilitating a high aquatic-terrestrial coupling, kettle holes can accumulate high concentrations of organic carbon and nutrients, fueling microbial activities and turnover rates. Thus, they represent hotspots of carbon turnover in the landscape, but their bacterial activities and controlling factors have not been well investigated. Therefore, we aimed to assess the relative importance of various environmental factors on bacterial and biogeochemical processes in the water column of kettle holes and to disentangle their variations. In the water body of ten kettle holes in north-eastern Germany, we measured several physico-chemical and biological parameters such as carbon quantity and quality, as well as bacterial protein production (BP) and community respiration (CR) in spring, early summer and autumn 2014. Particulate organic matter served as an indicator of autochthonous production and represented an important parameter to explain variations in BP and CR. This notion is supported by qualitative absorbance indices of dissolved molecules in water samples and C:N ratios of the sediments, which demonstrate high fractions of autochthonous organic matter (OM) in the studied kettle holes. In contrast, dissolved chemical parameters were less important for bacterial activities although they revealed strong differences throughout the growing season. Pelagic bacterial activities and dynamics might thus be regulated by autochthonous OM in kettle holes implying a control of important biogeochemical processes by internal primary production rather than facilitated exchange with the terrestrial surrounding due to a high perimeter-to-area ratio.

  • 227.
    Audusseau, Helene
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Nylin, Sören
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Janz, Niklas
    Stockholms universitet, Naturvetenskapliga fakulteten, Zoologiska institutionen.
    Implications of a temperature increase for host plant range: predictions for a butterfly2013Ingår i: Ecology and Evolution, ISSN 2045-7758, E-ISSN 2045-7758, Vol. 3, nr 9, s. 3021-3029Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Although changes in phenology and species associations are relatively well-documented responses to global warming, the potential interactions between these phenomena are less well understood. In this study, we investigate the interactions between temperature, phenology (in terms of seasonal timing of larval growth) and host plant use in the polyphagous butterfly Polygonia c-album. We found that the hierarchy of larval performance on three natural host plants was not modified by a temperature increase as such. However, larval performance on each host plant and temperature treatment was affected by rearing season. Even though larvae performed better at the higher temperature regardless of the time of the rearing, relative differences between host plants changed with the season. For larvae reared late in the season, performance was always better on the herbaceous plant than on the woody plants. In this species, it is likely that a prolonged warming will lead to a shift from univoltinism to bivoltinism. The demonstrated interaction between host plant suitability and season means that such a shift is likely to lead to a shift in selective regime, favoring specialization on the herbaceous host. Based on our result, we suggest that host range evolution in response to temperature increase would in this species be highly contingent on whether the population undergoes a predicted shift from one to two generations. We discuss the effect of global warming on species associations and the outcome of asynchrony in rates of phenological change.

  • 228.
    Auffret, Alistair
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Cousins, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Can motor vehicles substitute the movement of livestock for effective seed dispersal in the modern rural landscape?2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    Before agricultural industrialisation, the dispersal of plant species through the rurallandscape was largely mediated by the movement of livestock. Today, species-rich,semi-natural grasslands exist as only small, isolated fragments, and livestock aregenerally kept within the same pasture throughout the grazing season. On the otherhand, the introduction of motor vehicles has provided a potential vector for seeddispersal through the landscape, and farming machinery, which is not confined toroads, can pick up and deposit a great deal of material. Our aim was to explore thepotential for motor vehicles to maintain the functional connectivity of the landscape inthe absence of free-ranging livestock. We collected manure samples from grazers onsemi-natural grassland pastures, and mud from the cars and tractors of five farmsduring the outdoor grazing season in a 10 km 2 landscape in southern Sweden, andgrew them in a greenhouse to assess their seed content. 31 713 seedlings of 109species emerged from 31 manure samples, while 12 675 seedlings of 111 speciesemerged from 49 samples of mud removed from motor vehicles. Both sets ofsamples were dominated by the genera Agrostis and Poa, which together stood for43% and 77% of the seedlings emerging from motor vehicle and manure samplesrespectively. Otherwise, manure samples contained several grassland specialists,whereas, despite the occasional grassland species, widespread ruderal speciesmade up the majority of the rest of the seeds dispersed by motor vehicles. Ourresults indicate that motor vehicles do not provide an effective link for the dispersal ofgrassland species through the rural landscape, and that the movement of grazersbetween fragmented grasslands should be encouraged to improve functionalconnectivity and biodiversity in the rural landscape.

  • 229.
    Auffret, Alistair G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Can seed dispersal by human activity play a useful role for the conservation of European grasslands?2011Ingår i: Applied Vegetation Science, ISSN 1402-2001, E-ISSN 1654-109X, Vol. 14, nr 3, s. 291-303Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Objective: To review the recent research into human-mediated dispersal (HMD) in the European rural landscape, and explore the potential positive aspect of HMD for grassland conservation, in contrast to it's common association with the spread of invasive species. Methods: A literature search was undertaken to identify HMD vectors in the rural landscape for discussion regarding dispersal potential past and present, implications for management, and the identification of future research needs. Results: Grazing animals are important propagule dispersers, but the reduced movement of livestock through the landscape has also meant a reduction in seeds dispersed in this way. Other, non-standard human-mediated dispersal vectors such as clothing and motor vehicles can also transport seeds of many species, and HMD vectors often transport seeds with a variety of dispersal specialisations. Recommendations: There should be a greater movement of grazing animals throughout the landscape, either within larger grazing areas or between existing grasslands. Where this is not possible, other, more directed dispersal of propagules from species-rich communities to target sites should be considered. The potential of non-standard HMD vectors to make a positive contribution to biodiversity should be considered, but more research into all types of HMD vectors is important if we are to fully understand their role in the dispersal of plant species in fragmented landscapes.

  • 230.
    Auffret, Alistair G.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Seed mobility and connectivity in changing rural landscapes2013Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The success or failure of many organisms to respond to the challenges of habitat destruction and a warming climate lies in the ability of plant species to disperse between isolated habitats or to migrate to new ranges. European semi-natural grasslands represent one of the world's most species-rich habitats at small scales, but agricultural intensification during the 20th century has meant that many plant species are left only on small fragments of former habitat. It is important that these plants can disperse, both for the maintenance of existing populations, and for the colonisation of target species to restored grasslands. This thesis investigates the ecological, geographical and historical influences on seed dispersal and connectivity in semi-natural grasslands, and the mobility of plants through time and space. Seed dispersal by human activity has played a large role in the build-up of plant communities in rural landscapes, but patterns have shifted. Livestock are the most traditional, and probably the most capable seed dispersal vector in the landscape, but other dispersal methods may also be effective. Motor vehicles disperse seeds with similar traits to those dispersed by livestock, while 39% of valuable grasslands in southern Sweden are connected by the road network. Humans are found to disperse around one-third of available grassland species, including several protected and red-listed species, indicating that humans may have been valuable seed dispersers in the past when rural populations were larger. Past activities can also affect seed mobility in time through the seed bank, as seeds of grassland plant species are shown to remain in the soil even after the grassland had been abandoned. Today however, low seed rain in intensively grazed semi-natural grasslands indicates that seed production may be a limiting factor in allowing seeds to be dispersed in space through the landscape.

  • 231.
    Auffret, Alistair G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Berg, Johan
    Stockholms universitet, Samhällsvetenskapliga fakulteten, Kulturgeografiska institutionen.
    Cousins, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Dispersal geography: a new concept for managing seed dispersal in rural landscapesManuskript (preprint) (Övrigt vetenskapligt)
  • 232.
    Auffret, Alistair G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Cousins, Sara A.O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Grassland connectivity by motor vehicles and grazing livestock2013Ingår i: Ecography, ISSN 0906-7590, E-ISSN 1600-0587, Vol. 36, nr 10, s. 1150-1157Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In addition to habitat loss and fragmentation, agricultural change has led to a change in seed dispersal processes in therural landscape through a loss of structural and functional connectivity. Here, human-mediated dispersal vectors areprevalent, and we explored whether the loss of connectivity via free-ranging livestock could be mitigated by the increasein roads and motor vehicles. We found that structurally, 39% of all valuable semi-natural grassland habitats in southernSweden are adjacent to public road verges, which in the rural landscape are often considered to be suitable habitat forgrassland species. Additionally, by collecting mud attached to cars and farming machinery and manure from livestock(cattle, horse, sheep) grazing semi-natural grassland pasture, we found that motor vehicles are also capable seed dispers-ers. A similar number of species were dispersed by both vectors, although the composition of samples was quite different.Motor vehicles dispersed more grassland specialists than invasive species, although in much lower abundances than didgrazing livestock. Despite these differences, motor vehicles were found to be able to disperse species with the same kindsof dispersal traits as livestock. A high number of seeds, species and specialists in manure samples means that greater move-ment of livestock is desirable to increase functional grassland connectivity. However, effective management could improvethe suitability of roadsides as grassland corridors and increase the availability of seeds for long-distance human-mediateddispersal via cars and tractors. Our results suggest that in many rural landscapes, connectivity by road networks couldhelp mediate habitat loss and fragmentation of grasslands. However, such effects can be context dependent, and the con-nectivity provided by roads could have serious negative consequences in other regions.

  • 233.
    Auffret, Alistair G.
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Schmucki, Reto
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Reimark, Josefin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Cousins, Sara A. O.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Grazing networks provide useful functional connectivity for plants in fragmented systems2012Ingår i: Journal of Vegetation Science, ISSN 1100-9233, E-ISSN 1654-1103, Vol. 23, nr 5, s. 970-977Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Question To what extent does the movement of animals between fragmented habitat patches provide functional connectivity via endozoochorous seed dispersal? Location The Stockholm archipelago, Sweden. Methods We followed all movements of livestock between islands during one grazing season. After each movement, manure was collected and its seed content assessed through seedling emergence. Seedling data were then compared to vegetation surveys from the grazed islands with regard to functional traits. Results Light- and nitrogen-demanding locally abundant species, and those with relatively small and persistent seeds were more likely to be moved between islands. For quantitative traits, only a subset of the available trait ranges were dispersed, with extreme values left behind. Species apparently specialized to other means of dispersal emerged from the manure samples. Neither dispersed traits nor seed density changed with timing of movement, but seed richness and diversity both increased throughout the season. The subsets of endozoochorously-dispersed species in the established vegetation were more similar than non-dispersed subsets between islands linked by livestock. Conclusions Grazing networks contribute to the connectivity of the core species in the system, and could provide useful tools for grassland management in fragmented landscapes.

  • 234.
    Auffret, Alistair
    et al.
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Schmucki, Reto
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Reimark, Josefin
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    Cousins, Sara
    Stockholms universitet, Naturvetenskapliga fakulteten, Institutionen för naturgeografi och kvartärgeologi (INK).
    A trait-based analysis of the functional connectivity provided by mobile grazers in an island grazing system2011Ingår i: 8th IALE World Congress, Beijing 18-21 August 2011: Landscape Ecology for Sustainable Environment and Culture, 2011Konferensbidrag (Refereegranskat)
    Abstract [en]

    The area of species-rich semi-natural grassland in Europe has declined dramatically duringthe past two centuries. The Stockholm archipelago was once a vibrant agricultural landscape,with the movement of livestock between islands forming an extensive grazing network. Likein much of Europe, agricultural industrialisation led to most grasslands either beingabandoned to become scrub or woodland, or converted to arable fields and subsequentlyreverted to relatively species-poor pasture. The restoration of these habitats to species-richgrassland communities has been a major goal, but restoration success has often been found tobe seed or dispersal limited. In island systems, the hostility of the matrix exacerbates thisproblem, but also provides an ideal study system for investigating the dispersal of plantspecies between fragmented habitats. One management strategy has been to restart smallgrazing networks to improve connectivity in the landscape, and in the summer of 2009, wecollected fresh manure samples from grazing cattle and sheep after movement by boatbetween islands. These were then grown in a greenhouse, and 5915 seedlings of 74 speciesemerged from the 18 samples, corresponding to 18 movements within the grazing network.Comparing the species dispersed with the vegetation communities in the donor and receiverislands, we assess the subset of species and species traits which were transported. We can thusexamine the extent of the functional connectivity provided by these mobile grazers, and theeffect that timing of movement has on the range of species and traits dispersed.

  • 235.
    Aunapuu, Maano
    Umeå universitet, Teknisk-naturvetenskaplig fakultet, Ekologi och geovetenskap.
    Predators in low arctic tundra and their impact on community structure and dynamics2004Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The abundance of predators and their impact on ecosystem dynamics is a vividly discussed topic in current ecology. In my studies, incorporating field observations, field experiments and theoretical modeling, I explored the importance of predators and predation in a low arctic tundra ecosystem in northern Norway. This involved observing the abundance and spatial activity of predators (raptors and small mustelids); manipulating the abundance of predators (spiders and birds) in an arthropod community; and exploring the theoretical consequences of intraguild predation on the coexistence among predators.

    The results show that predation is important both in the arthropod assemblage and, depending on the productivity of the community, in the vertebrate assemblage. In arthropod communities predators are at least as abundant as their prey, whereas in the vertebrate part of ecosystem, predators are substantially less abundant than their prey. Still, in both cases predators had strong impact on their prey, influencing the abundance of prey and the species composition of prey assemblages. The impact of predation cascaded to the plant community both in the reticulate and complex arthropod food web and in the linear food chain-like vertebrate community. In the vertebrate-based community we could even observe the long time scale effect on plant community composition.

    Within the predator community, exploitation competition and intraguild predation were the structuring forces. As the arthropod communities consist of predators with different sizes, intraguild predation is an energetically important interaction for top predators. As a consequence, they reduce the abundance of intermediate predators and the impact of intermediate predators on other prey groups. Moreover, being supported by intermediate predators, top predators can have stronger impact themselves on other prey groups.

    In vertebrate communities, intraguild predation seems to be unimportant as energetic link, instead it manifests as an extreme version of interference competition. Therefore intraguild predation reduces the likelihood of coexistence, as it is due limited prey diversity and intense exploitative competition already precarious in the low arctic tundra.

    In conclusion, predators have strong impact on their prey, especially in the more productive parts of the low arctic tundra. This applies even to the food webs with complex and reticulate structure, and these effects carry through the community both in the short time scale of population growth and on the long time scale of population generations.

  • 236.
    Aunapuu, Maano
    et al.
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Oksanen, Lauri
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland; Department of Natural Sciences, Finnmark University College, Alta, Norway.
    Oksanen, Tarja
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Korpimaki, Erkki
    Department of Biology, Section of Ecology, University of Turku, Turku, Finland.
    Intraguild predation and interspecific co-existence between predatory endotherms2010Ingår i: Evolutionary Ecology Research, ISSN 1522-0613, E-ISSN 1937-3791, Vol. 12, nr 2, s. 151-168Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: According to the current predominant view, intraguild predation leads to the replacement of intermediate predators from highly productive habitats, whereas top predators and intermediate predators can co-exist in habitats with intermediate primary productivity. These predictions are contradicted by the observed abundance of intermediate predators in productive environments. But the predictions are derived by modelling interactions in food chains where the top predator is primarily adapted to exploit intermediate predators but also has some capacity to exploit the resources of the intermediate predators. We call this 'food chain omnivory'. In contrast, 'genuine intraguild predation' is the case where the two predators have shared tactics of resource acquisition, resulting in broadly overlapping prey preferences that is, the interacting predators belong to the same guild as defined by Root (1967).

    Questions: What are the effects of productivity on genuine intraguild predation? Do the predictions for food chain omnivory apply also to genuine intraguild predation'?

    Methods: We modelled genuine intraguild predation by using parameter values such that the intermediate predator and the basal prey were equally valuable to the top predator. We assumed that the basal prey was a herbivore, with a carrying capacity directly proportional to primary productivity and a habitat-specific intrinsic rate of population growth that increases asymptotically in response to increasing primary productivity.

    Results: With the above premises, intermediate predators can prevail even in highly productive habitat. Also, a priority effect is possible. Predictable replacement of intermediate predators by top predators requires that intermediate predators are much easier to find than basal prey. Stable co-existence requires biologically implausible parameter values.

    Conclusions: Genuine intraguild predation is a destabilizing force in food webs. The dynamics of genuine intraguild predation systems differ from those in food chain omnivory systems where the intermediate and top predators have different feeding tactics and, therefore, different prey preferences.

  • 237. Aune, Karin
    et al.
    Jonsson, Bengt-Gunnar
    Mittuniversitetet, Fakulteten för naturvetenskap, teknik och medier, Institutionen för naturvetenskap.
    Moen, Jon
    Isolation and edge effects among woodland key habitats in Sweden: making fragmentation into forest policy?2005Ingår i: Biological Conservation, ISSN 0006-3207, E-ISSN 1873-2917, Vol. 124, nr 1, s. 89-95Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Fragmentation of natural forests is a major threat to forest biodiversity. In areas with a long history of forestry, the remaining patches of old forests constitute only a minor part of the landscape. In such situations small stands may be valuable and important for conservation. However, as they may suffer from strong edge effects and isolation, their value may be lower than anticipated. In Sweden a national inventory of woodland key habitats (WKHs) has identified about 1% of the forest landscape as sites where red-listed species occur or may occur. Most are small (national median 1.4 ha) and isolated stands within an intensively managed landscape. The present analyses calculate WKH core area based on a range of depths of edge influence, and isolation based on both distance to nearest WKH and a weighted isolation measure that includes all neighboring WKHs and protected forest. These analyses are done on the WKHs in Norrbotten County in northern Sweden and include almost 5000 stands. The actual core area in the WKHs is about 30% given a 50 m edge influence. The degree of isolation is species dependent but the results indicate that only species with high dispersal abilities may effectively utilize the network of WKHs. For species with effective dispersal distances of less than 2 km the network is probably insufficient. The results emphasize the need to create buffer zones, to increase reserve areas and to manage the matrix so that species dispersal is promoted. This likely includes a necessity to aggregate biodiversity efforts on the landscape scale.

  • 238. Aura, Christopher
    et al.
    Raburu, Philip
    Herrmann, Jan
    Linnéuniversitetet, Fakultetsnämnden för naturvetenskap och teknik, Institutionen för naturvetenskap, NV.
    Macroinvertebrates’ community structure in Rivers Kipkaren and Sosiani, River Nzoia basin, Kenya2011Ingår i: Journal of Ecology and the Natural Environment, ISSN 2006-9847, E-ISSN 2006-9847, Vol. 3, nr 2, s. 39-46Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Benthic macroinvertebrates from Rivers Kipkaren and Sosiani in the upper reaches of River Nzoiabasin, Kenya, were sampled semi-quantitatively monthly from December 2006 to May 2007 using a0.5 mm mesh size scoop net in the riffles, pools and runs. Seven sampling sites were selected on theareas of the rivers along a longitudinal gradient in relation to anthropogenic impact. Physicochemicalparameters were measured in situ, while specific chemical parameters were determinedcalometrically in the laboratory using standard methods. Habitat and land use characteristics werealso recorded. A total of 1499 macroinvertebrates belonging to 13 orders, 28 families and 31 generawere collected. The orders Ephemeroptera, Hemiptera and Coleoptera were taxonomically richest.Overall, a total of 31 genera for River Kipkaren dominated by the EPT and 19 macroinvertebrategenera for the lower River Sosiani dominated by dipterans were recorded. Conductivity, oxygen andtotal nitrogen varied significantly (p < 0.05) between sampled sites, but not temporally. The results ofredundancy analysis using 9 dominant macroinvertebrate genera revealed a distinction betweenimpacted and the less impacted sites and the physico-chemical parameters associated with thisdistinction.

  • 239.
    Averhed, Björn
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet.
    Kan förändringar i bottenfaunan påvisas två år efter en bäckrestaurering?2010Självständigt arbete på grundnivå (kandidatexamen), 10 poäng / 15 hpStudentuppsats (Examensarbete)
    Abstract [en]

    The aim of this work is to analyze if a change in the benthic community can be detected two years after a restoration of a small stream. The samples were taken in a small stream at Tinnerö Eklandskap just south of Linköping. In addition to the restored area, two reference sites upstream and downstream of the restored area were sampled to compare to the restored site. The method used for sampling of benthic fauna in the stream was kick sampling. ASPT, Berger-Parker and Renkonen-indices were used to find out if there was any difference between the reference areas and the restored area. In addition to indices, rank-abundance curves and species lists were made to see if there was any trend difference between the different areas. The only index that showed a difference between the different areas was Berger-Parker diversity index. The reason why there were no greater differences between the areas may be due to the fact that two years is too short to allow time for the benthos to re-colonize the restored area.

  • 240. Avia, Komlan
    et al.
    Karkkainen, Katri
    Lagercrantz, Ulf
    Uppsala universitet, Teknisk-naturvetenskapliga vetenskapsområdet, Biologiska sektionen, Institutionen för ekologi och genetik, Växtekologi och evolution.
    Savolainen, Outi
    Association of FLOWERING LOCUS T/TERMINAL FLOWER 1-like gene FTL2 expression with growth rhythm in Scots pine (Pinus sylvestris)2014Ingår i: New Phytologist, ISSN 0028-646X, E-ISSN 1469-8137, Vol. 204, nr 1, s. 159-170Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Understanding the genetic basis of the timing of bud set, an important trait in conifers, is relevant for adaptation and forestry practice. In common garden experiments, both Scots pine (Pinus sylvestris) and Norway spruce (Picea abies) show a latitudinal cline in the trait. We compared the regulation of their bud set biology by examining the expression of PsFTL2, a Pinus sylvestris homolog to PaFTL2, a FLOWERING LOCUS T/TERMINAL FLOWER 1 (FT/TFL1)-like gene, the expression levels of which have been found previously to be associated with the timing of bud set in Norway spruce. In a common garden study, we analyzed the relationship of bud phenology under natural and artificial photoperiods and the expression of PsFTL2 in a set of Scots pine populations from different latitudes. The expression of PsFTL2 increased in the needles preceding bud set and decreased during bud burst. In the northernmost population, even short night periods were efficient to trigger this expression, which also increased earlier under all photoperiodic regimes compared with the southern populations. Despite the different biology, with few limitations, the two conifers that diverged 140 million yr ago probably share an association of FTL2 with bud set, pointing to a common mechanism for the timing of growth cessation in conifers.

  • 241.
    Avril, Alexis
    et al.
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Grosbois, Vladimir
    CIRAD, France.
    Latorre-Margalef, Neus
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM). Univ Georgia, USA.
    Gaidet, Nicolas
    CIRAD, France.
    Tolf, Conny
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Olsen, Björn
    Uppsala University.
    Waldenström, Jonas
    Linnéuniversitetet, Fakulteten för Hälso- och livsvetenskap (FHL), Institutionen för biologi och miljö (BOM).
    Capturing individual-level parameters of influenza A virus dynamics in wild ducks using multistate models2016Ingår i: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 53, nr 4, s. 1289-1297Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Disease prevalence in wildlife is governed by epidemiological parameters (infection and recovery rates) and response to infection, both of which vary within and among individual hosts. Studies quantifying these individual-scale parameters and documenting their source of variation in wild hosts are fundamental for predicting disease dynamics. Such studies do not exist for the influenza A virus (IAV), despite its strong impact on the global economy and public health. Using capture-recaptures of 3500 individual mallards Anas platyrhynchos during seven migration seasons at a stopover site in southern Sweden, we provide the first empirical description of the individual-based mechanisms of IAV dynamics in a wild reservoir host. For most years, prevalence and risk of IAV infection peaked at a single time during the autumn migration season, but the timing, shape and intensity of the infection curve showed strong annual heterogeneity. In contrast, the seasonal pattern of recovery rate only varied in intensity across years. Adults and juveniles displayed similar seasonal patterns of infection and recovery each year. However, compared to adults, juveniles experienced twice the risk of becoming infected, whereas recovery rates were similar across age categories. Finally, we did not find evidence that infection influenced the timing of emigration.Synthesis and applications. Our study provides robust empirical estimates of epidemiological parameters for predicting influenza A virus (IAV) dynamics. However, the strong annual variation in infection curves makes forecasting difficult. Prevalence data can provide reliable surveillance indicators as long as they catch the variation in infection risk. However, individual-based monitoring of infection is required to verify this assumption in areas where surveillance occurs. In this context, monitoring of captive sentinel birds kept in close contact with wild birds is useful. The fact that infection does not impact the timing of migration underpins the potential for mallards to spread viruses rapidly over large geographical scales. Hence, we strongly encourage IAV surveillance with a multistate capture-recapture approach along the entire migratory flyway of mallards.

  • 242.
    Avril, Alexis
    et al.
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, SE-39182 Kalmar, Sweden..
    Grosbois, Vladimir
    CIRAD, Campus Int Baillarguet, F-34398 Montpellier, France..
    Latorre-Margalef, Neus
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, SE-39182 Kalmar, Sweden.;Univ Georgia, Southeeastern Cooperat Wildlife Dis Study, Coll Vet Med, Dept Populat Hlth, Athens, GA 30602 USA..
    Gaidet, Nicolas
    CIRAD, Campus Int Baillarguet, F-34398 Montpellier, France..
    Tolf, Conny
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, SE-39182 Kalmar, Sweden..
    Olsen, Björn
    Uppsala universitet, Medicinska och farmaceutiska vetenskapsområdet, Medicinska fakulteten, Institutionen för medicinsk biokemi och mikrobiologi.
    Waldenström, Jonas
    Linnaeus Univ, Ctr Ecol & Evolut Microbial Model Syst EEMiS, SE-39182 Kalmar, Sweden..
    Capturing individual-level parameters of influenza A virus dynamics in wild ducks using multistate models2016Ingår i: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 53, nr 4, s. 1289-1297Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Disease prevalence in wildlife is governed by epidemiological parameters (infection and recovery rates) and response to infection, both of which vary within and among individual hosts. Studies quantifying these individual-scale parameters and documenting their source of variation in wild hosts are fundamental for predicting disease dynamics. Such studies do not exist for the influenza A virus (IAV), despite its strong impact on the global economy and public health. Using capture-recaptures of 3500 individual mallards Anas platyrhynchos during seven migration seasons at a stopover site in southern Sweden, we provide the first empirical description of the individual-based mechanisms of IAV dynamics in a wild reservoir host. For most years, prevalence and risk of IAV infection peaked at a single time during the autumn migration season, but the timing, shape and intensity of the infection curve showed strong annual heterogeneity. In contrast, the seasonal pattern of recovery rate only varied in intensity across years. Adults and juveniles displayed similar seasonal patterns of infection and recovery each year. However, compared to adults, juveniles experienced twice the risk of becoming infected, whereas recovery rates were similar across age categories. Finally, we did not find evidence that infection influenced the timing of emigration.Synthesis and applications. Our study provides robust empirical estimates of epidemiological parameters for predicting influenza A virus (IAV) dynamics. However, the strong annual variation in infection curves makes forecasting difficult. Prevalence data can provide reliable surveillance indicators as long as they catch the variation in infection risk. However, individual-based monitoring of infection is required to verify this assumption in areas where surveillance occurs. In this context, monitoring of captive sentinel birds kept in close contact with wild birds is useful. The fact that infection does not impact the timing of migration underpins the potential for mallards to spread viruses rapidly over large geographical scales. Hence, we strongly encourage IAV surveillance with a multistate capture-recapture approach along the entire migratory flyway of mallards.

  • 243.
    Avril, Alexis
    et al.
    ONCFS, France.
    Letty, Jerome
    ONCFS, Direct Etud & Rech, F-34990 Juvignac, France.
    Leonard, Yves
    ONCFS, F-45370 Dry, France.
    Pontier, Dominique
    Univ Lyon .
    Exploration forays in juvenile European hares (Lepus europaeus): dispersal preludes or hunting-induced troubles?2014Ingår i: BMC Ecology, ISSN 1472-6785, E-ISSN 1472-6785, Vol. 14, artikel-id 6Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Background: Movements of animals have important consequences, at both the individual and population levels. Due to its important implications in the evolutionary dynamics of populations, dispersal is one of the most studied types of movement. In contrast, non-permanent extra home-range movements are often paid less attention. However, these movements may occur in response to important biological processes such as mating or predation avoidance. In addition, these forays are often preludes to permanent dispersal, because they may help individuals gain cues about their surroundings prior to settlement in a new place. In the European hare, exploration forays occur predominantly in juveniles, the time at which most hares disperse. In France, the timing of dispersal also overlaps with the hare hunting period. However, the determinants of such behaviour have not yet been studied. Herein, we investigate whether these non-permanent explorations are dispersal attempts/preludes or, in contrast, whether they are triggered by other factors such as disturbances related to hunting. Results: Contrary to natal dispersal, we did not find strong male-bias in the propensity to engage in explorations. Exploration forays occurred less in juveniles than in adults and later in the season than natal dispersal. This was the case both for philopatric movements and for movements occurring after dispersal and settlement. These movements were also more likely to occur during the hare hunting period and the mating season. Conclusions: We suggest that explorations in hares are triggered by factors other than dispersal and that hares may respond to hunting disturbances. Overall, we emphasize the need to account for human-related predation risk as a factor driving space-use in harvested species.

  • 244. Axelsson, E. Petter
    et al.
    Hjalten, Joakim
    LeRoy, Carri J.
    Whitham, Thomas G.
    Julkunen-Tiitto, Riitta
    Wennström, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Leaf litter from insect-resistant transgenic trees causes changes in aquatic insect community composition2011Ingår i: Journal of Applied Ecology, ISSN 0021-8901, E-ISSN 1365-2664, Vol. 48, nr 6, s. 1472-1479Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    1. Recent research has addressed how transgenic residues fromarable crops may influence adjacent waterways, aquatic consumers and important ecosystem processes such as litter breakdown rates. With future applications of transgenic plants in forestry, such concerns may apply to forest stream ecosystems. Before any large-scale release of genetically modified (GM) trees, it is therefore imperative to evaluate the effects of genetic modifications in trees on such ecosystems. 2. We conducted decomposition experiments under natural stream conditions using leaf litter from greenhouse grown GM trees (Populus tremula x Populus tremuloides) that express Bacillus thuringiensis (Bt) toxins (cry3Aa; targeting coleopteran leaf-feeding beetles) to examine the hypothesis that GM trees would affect litter decomposition rates and/or the aquatic arthropod community that colonizes and feeds on leaf litter in streams. 3. We show that two independent transformations of isogenic Populus trees to express Bt toxins caused similar changes to the composition of aquatic insects colonizing the leaf litter, ultimately manifested in a 25% and 33% increases in average insect abundance. 4. Measurements of 24 phenolic compounds as well as nitrogen (N) and carbon (C) in the litter did not significantly differ among modified and wild-type trees and were thus not sufficient to explain these differences in the insect assemblage. 5. Decomposition rates were comparable among litter treatments suggesting that the normal suite of leaf traits influencing decomposition was similar among litter treatments and that the shredding functions of the community were maintained despite the changes in insect community composition. 6. Synthesis and applications. We report that leaf litter from GM trees affected the composition of aquatic insect communities that colonized litter under natural stream conditions. This suggests that forest management using GM trees may affect adjacent waterways in unanticipated ways, which should be considered in future commercial applications of GM trees. We also argue that studies at different scales (e.g. species, communities and ecosystems) will be needed for a full understanding of the environmental effects of Bt plants.

  • 245. Axelsson, E. Petter
    et al.
    Hjalten, Joakim
    Whitham, Thomas G.
    Julkunen-Tiitto, Riitta
    Pilate, Gilles
    Wennström, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Leaf ontogeny interacts with Bt modification to affect innate resistance in GM aspens2011Ingår i: Chemoecology, ISSN 0937-7409, E-ISSN 1423-0445, Vol. 21, nr 3, s. 161-169Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    Bioassays with a non-target slug (Deroceras spp.) and chemical analyses were conducted using leaf tissue from already existing genetically modified insect-resistant aspen trees to examine whether genetic modifications to produce Bacillus thuringiensis (Bt) toxins could affect plant phytochemistry, which in turn might influence plant-herbivore interactions. Three major patterns emerged. First, two independent modifications for Bt resistance affected the phytochemical profiles of leaves such that both were different from the isogenic wild-type (Wt) control leaves, but also different from each other. Among the contributors to these differences are substances with a presumed involvement in resistance, such as salicortin and soluble condensed tannins. Second, bioassays with one Bt line suggest that the modification somehow affected innate resistance ("Innate" is used here in opposition to the "acquired" Bt resistance) in ways such that slugs preferred Bt over Wt leaves. Third, the preference test suggests that the innate resistance in Bt relative to Wt plants may not be uniformly expressed throughout the whole plant and that leaf ontogeny interacts with the modification to affect resistance. This was manifested through an ontogenetic determined increase in leaf consumption that was more than four times higher in Bt compared to Wt leaves. Our result are of principal importance, as these indicate that genetic modifications can affect innate resistance and thus non-target herbivores in ways that may have commercial and/or environmental consequences. The finding of a modification-ontogeny interaction effect on innate resistance may be especially important in assessments of GM plants with a long lifespan such as trees.

  • 246. Axelsson, E Petter
    et al.
    Hjältén, Joakim
    LeRoy, Carri J
    Julkunen-Tiitto, Riitta
    Wennström, Anders
    Umeå universitet, Teknisk-naturvetenskapliga fakulteten, Institutionen för ekologi, miljö och geovetenskap.
    Pilate, Gilles
    Can leaf litter from genetically modified trees affect aquatic ecosystems?2010Ingår i: Ecosystems (New York. Print), ISSN 1432-9840, E-ISSN 1435-0629, Vol. 13, nr 7, s. 1049-1059Artikel i tidskrift (Refereegranskat)
    Abstract [en]

    In addition to potential benefits, biotechnology in silviculture may also be associated with environmental considerations, including effects on organisms associated with the living tree and on ecosystems and processes dependent on tree residue. We examined whether genetic modification of lignin characteristics (CAD and COMT) in Populus sp. affected leaf litter quality, the decomposition of leaf litter, and the assemblages of aquatic insects colonizing the litter in three natural streams. The decomposition of leaf litter from one of the genetically modified (GM) lines (CAD) was affected in ways that were comparable over streams and harvest dates. After 84 days in streams, CAD-litter had lost approximately 6.1% less mass than the non-GM litter. Genetic modification also affected the concentration of phenolics and carbon in the litter but this only partially explained the decomposition differences, suggesting that other factors were also involved. Insect community analyses comparing GM and non-GM litter showed no significant differences, and the two GM litters showed differences only in the 84-day litterbags. The total abundance and species richness of insects were also similar on GM and non-GM litter. The results presented here suggest that genetic modifications in trees can influence litter quality and thus have a potential to generate effects that can cross ecosystem boundaries and influence ecosystem processes not directly associated with the tree. Overall, the realized ecological effects of the GM tree varieties used here were nevertheless shown to be relatively small.

  • 247.
    Axelsson, Karolin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Chemical signals in interactions between Hylobius abietis and associated bacteria2016Doktorsavhandling, sammanläggning (Övrigt vetenskapligt)
    Abstract [en]

    The pine weevil (Hylobius abietis L.) is one of the two topmost economically important insect pests in Swedish conifer forests. The damage increase in areas were the silvicultural practice is to use clear cuttings were the insects gather and breed. During egglaying the female protects her offspring by creating a cave in roots and stumps were she puts her egg and covers it with frass, a mixture of weevil feces and chewed bark. Adult pine weevils have been observed to feed on the other side of the egg laying site and antifeedant substance has been discovered in the feces of the pine weevil. We think it is possible that microorganisms present in the frass contribute with antifeedant/repellent substances. Little is known about the pine weevils associated bacteria community and their symbiotic functions. In this thesis the bacterial community is characterized in gut and frass both from pine weevils in different populations across Europe as well as after a 28 day long diet regime on Scots pine, silver birch or bilberry. Volatile substances produced by isolated bacteria as well as from a consortium of microorganisms were collected with solid phase micro extraction (SPME) and analyzed with GC-MS. The main volatiles were tested against pine weevils using a two-choice test. Wolbachia, Rahnella aquatilis, Serratia and Pseudomonas syringae was commonly associated with the pine weevil. 2-Methoxyphenol, 2-phenylethanol, 3-methyl-1-butanol were found in the headspace from Rahnella aquatilis when grown in substrate containing pine bark. 2-Methoxyphenol and 3-methyl-1-butanol, phenol and methyl salicylate were found in pine feces. Birch and bilberry feces emitted mainly linalool oxides and bilberry emitted also small amounts of 2-phenylethanol.

    A second part of the thesis discusses the role of fungi in forest insect interactions and the production of oxygenated monoterpenes as possible antifeedants. Spruce bark beetles (Ips typhographus L.) aggregate with the help of pheromones and with collected forces they kill weakened adult trees as a result of associated fungi growth and larval development. A fungi associated with the bark beetle, Grosmannia europhoides, was shown to produce de novo 2-methyl-3-buten-2-ol, the major component of the spruce bark beetle aggregation pheromone. Chemical defense responses against Endoconidiophora polonica and Heterobasidion parviporum were investigated using four clones of Norway spruce with different susceptibility to Heterobasidion sp. Clone specific differences were found in induced mono-, sesqui and diterpenes. A number of oxygenated monoterpenes which are known antifeedants for the pine weevil were produced in the infested areas.

  • 248.
    Axelsson, Karolin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Nilsson, Louise
    Nordlander, Göran
    Dep. of Ecology, SLU.
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Terenius, Olle
    Dep of Ecology, SLU.
    Do pine weevil microbiota and corresponding volatiles change due to selective feeding?Manuskript (preprint) (Övrigt vetenskapligt)
  • 249.
    Axelsson, Karolin
    et al.
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zendegi-Shiraz, Amene
    Swedjemark, Gunilla
    Borg-Karlson, Anna-Karin
    KTH, Skolan för kemivetenskap (CHE), Kemi, Organisk kemi.
    Zhao, Tao
    KTH, Skolan för kemivetenskap (CHE), Kemi.
    Clone specific chemical defense responses in Norway spruce to infestations by two pathogenic fungi2016Ingår i: Forest Pathology, ISSN 1437-4781, E-ISSN 1439-0329Artikel i tidskrift (Övrigt vetenskapligt)
    Abstract [en]

    Heterobasidion parviporum (Hp) were investigated using four clones of Norway spruce (Picea abies) with different susceptibility to Heterobasidion sp. Eight year old trees were inoculated with Ep and Hp to minimize the variation due to environment. After three weeks the bark tissue at the upper border of the inoculation hole were extracted with hexane and analyzed by GC-MS. Both treatment and clonal differences were found based on induced mono-, sesqui- and diterpenes. In addition, the Hp produced toxin, fomanoxin, was identified in lowest amount in the most Hp susceptible clone. The clonal trees seem to use different defense strategies towards the two fungi. One of the clones was able to induce strong chemical defense against both fungi, one clone induced chemical defense only against Ep and the most susceptible clone exhibited the least capacity to produce an effective defense against Ep and Hp. Two diterpenes were found to be distinctly different between clones with different susceptibilities, which can be used as chemical indication of Norway spruce resistance against fungi.

  • 250.
    Axemar, Hanna
    Stockholms universitet, Naturvetenskapliga fakulteten, Botaniska institutionen.
    An experimental study of plant habitat choices by macroinvertebrates in brackish soft-bottom bays2007Bok (Övrigt vetenskapligt)
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