liu.seSearch for publications in DiVA
Endre søk
Begrens søket
3456 251 - 281 of 281
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf
Treff pr side
  • 5
  • 10
  • 20
  • 50
  • 100
  • 250
Sortering
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
  • Standard (Relevans)
  • Forfatter A-Ø
  • Forfatter Ø-A
  • Tittel A-Ø
  • Tittel Ø-A
  • Type publikasjon A-Ø
  • Type publikasjon Ø-A
  • Eldste først
  • Nyeste først
  • Skapad (Eldste først)
  • Skapad (Nyeste først)
  • Senast uppdaterad (Eldste først)
  • Senast uppdaterad (Nyeste først)
  • Disputationsdatum (tidligste først)
  • Disputationsdatum (siste først)
Merk
Maxantalet träffar du kan exportera från sökgränssnittet är 250. Vid större uttag använd dig av utsökningar.
  • 251.
    Svalberg, Andrea
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Estimating Detection Probability and Abundance for the Black Caiman (Melanosuchus niger) and the Yacare Caiman (Caiman yacare)2016Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The black caiman (Melanosuchus niger) and the yacare caiman (Caiman yacare) have in the past been exposed to overexploitation due to the economic profit for their hides, and therefore suffered from great declines in population sizes, especially black caimans. Legal regulation efforts made it possible for these two species to recover and today they are widely distributed in South America. Evaluation of protection and management of populations of top predators like these caimans depend on the ability to detect the animals. The probability of detecting a crocodile, or any animal, is affected by several factors such as habitat complexity and behaviour why it is of importance to acknowledge such matter in order to obtain reliable results for further implications. This study aims to investigate the detection probability and abundances in these two species as a contribution to the monitoring efforts at a local scale. Night counts were performed in Cedral lagoon located in the Beni region in Bolivia. By using the relation between marked animals and resightings of them, as well as the abundance estimate produced by the Lincoln-Petersen estimator, estimates of detection probabilities could be accounted for the total caiman population (black plus yacare caimans) and the black caiman population. Very low sighting probabilities (p = 0.03) were obtained when based on marked animals who tend to be more wary after a capture event. Those based on the L-P output were higher (total caiman population p = 0.15, black caimans p = 0.15). Population sizes were estimated to 25 ± 8.5 black caimans and 34 ± 12 caimans in total. The population size based on marked animals was 12 ± 25.4 caimans.

  • 252.
    Svennar, Erica
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet.
    Metoder för att undersöka effekterna av naturvårdshänsynen i skogsbruket efter den nya skogsvårdslagen2010Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    In 1994 a new Forestry Act was accepted in Sweden. One of its aims was to raise the consideration for preservation of biodiversity. Since this happened over 15 years ago there is now an interest in analyzing if the law has been effective in its purpose. In this study methods suitable for analysis are being investigated. The study contents a pilot study of methods for five parameters that can validate if the law has been followed. The fieldstudy were executed in Orsa, Dalarna, Sweden in a managed forest and where last clearcut was done after 1994. The work consisted of measuring the parameters in the field and to compare them with data from before 1994. The benefits of the parameters and the current and previous Forestry Act and their differences are discussed in the report. The parameters examined were the distribution of tree species, standing dead wood, smaller areas saved for preservation, big trees and trees with cavities/cavernous trees. All of these plus a few other variables favourable for the diversity of species in the forest are dealt with in the 30 § in the Forestry Act of 1994. The study implied that the variables reported to be favourable for biodiversity, and possible to investigate within the restrictions of this study, seemed to have increased. The results should however be interpreted with care since the study is small and the reference values sometimes were missing or covering larger areas than the field data.

  • 253.
    Svensson, Teresia
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Measurements and fluxes of volatile chlorinated organic compounds (VOCl) from natural terrestrial sources: Measurement techniques and spatio-temporal variability of flux estimates2019Rapport (Annet vitenskapelig)
    Abstract [no]

    Flyktiga organiska föreningar (VOC) och i synnerhet klorerade VOCs (VOCls) betraktas som miljö­farliga ämnen i vattenmiljöer på grund av sina toxiska egenskaper, men även i atmosfären eftersom de har en stor inverkan på atmosfärskemin, t ex genom att påverka ozonskiktet. Ett antal studier har hittat flera naturliga källor för VOCl och därmed förändrat synen på VOCls som endast producerade av människor. Trots det så saknas kunskaperna fortfarande om utsläpp de naturliga flödena av VOCls, särskilt när det gäller variation i tid och rum från terrestra miljöer. I kärnkraftsindustrin är Cl­36 en dosdominerande radionuklid för en del avfallströmmar. Därför behövs en bättre förståelse för omsättningen av klor i ytnära ekosystem.

    Klormetan är den mest studerade av VOCl och den näst mest studerade är kloroform. Några andra studier har uppskattat flöde av andra VOCl som tetraklormetan (CCl4), metylkloroform (CH3CCl3), tetrakloretan (C2H2Cl4), freoner (CFC), kloretan (C2H5Cl), bromodiklormetan (CHBrCl2). Studier genomfördes i klimat och markbaserade ekosystem som sträcker sig från arktisk tundra till tropisk regnskog, men de flesta studier fokuserar på tempererat klimatområde. Våtmarker och kustsystem är de studerande dominerande ekosystemen. Kammare är den vanligaste metoden för att uppskatta flöden av av VOCls, men det finns också några studier med koncentrationsgradienter i markprofiler, och en form av mikrometeorologimetodik. De metodologiska osäkerheterna som diskuteras kretsar i första hand kring kontamination, få replikat, design av fältmätningar och fältmätningarnas påverkan på markprocesser och därmed indirekt på flödena. Trots de många utmaningarna för att mäta VOCls och uppskatta flödena är det klart att flödet av klor till atmosfären är ett viktigt flöde i klors biogeo­kemiska cykel i terrestra ekosystem. Skogsekosystem kan avge så mycket som 0.1 g m–2, vilket är 40 % av våtdepositionen av klorid och det finns studier som tyder på att våtmarker är en långt mycket större källa till klor i atmosfären än man tidigare trott.

  • 254.
    Säterberg, Torbjörn
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Functional Extinctions of Species in Ecological Networks2016Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Current rates of extinctions are estimated to be around 1000 times higher than background rates that would occur without anthropogenic impacts. These extinction rates refer to the traditional view of extinctions, i.e. numerical extinctions. This thesis is about another type of extinctions: functional extinctions. Those occur when the abundance of a species is too small to uphold the species’ ecologically interactive role. I have taken a theoretical approach and used dynamical models to investigate functional extinctions and threshold values for species’ mortality rates in ecological networks. More specifically, I have derived threshold values for focal species mortality rates at which another species or the focal species itself goes numerically extinct (Paper I-II), or transgresses some predefined threshold abundance (Paper III). If an increased mortality rate of a focal species causes another species to go numerically extinct, the focal species can be regarded as functionally extinct, since its abundance is no longer large enough to uphold its ecologically interactive role. Such functional extinctions are investigated in the first papers (Paper I-II). In the following paper, limits for both increased and decreased mortality rates of species are explored (Paper III). Paper III also extends the basic theoretical idea developed in paper I-II into a more applied setting. In this paper I develop a time series approach aimed at estimating fishing mortalities associated with a low risk that any species in a community transgresses some predefined critical abundance threshold. In the last paper (Paper IV) the community wide effect of changes in the abundance of species is investigated.

    In the first paper (Paper I) I investigate threshold levels for the mortality rate of species in ecological networks. When an increased mortality rate of a focal species causes another species to go extinct, the focal species can be characterized as functional extinct, even though it still exists. Such functional extinctions have been observed in a few systems, but their frequency and general patterns have been unexplored. Using a new analytical method the patterns and frequency of functional extinctions in theoretical and empirical ecological networks are explored. It is found that the species most likely to be the first to go extinct is not the species whose mortality rate is increased, but instead another species in the network. The species which goes extinct is often not even directly linked to the species whose mortality rate is increased, but instead indirectly linked. Further, it is found that large-bodied species at the top of food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than the mere persistence of species.

    In Paper II I use the approach developed in Paper I to explore the frequency and patterns of functional extinctions in ecological networks with varying proportions of mutualistic and antagonistic (predator-prey) interactions. The general results from Paper I are also found in Paper II; that is, an increased mortality rate of one focal species often first leads to an extinction of another species rather than to an extinction of the focal species itself.

    Further, the frequency of functional extinctions is higher in networks containing a mixture of interaction types than in networks with only antagonistic interactions. Overall, this study generalize the findings of paper I for networks containing a variety of interaction types.

    To make the theoretical approaches developed in paper I-II operational in a management setting I develop a time series approach aimed at estimating ecologically sustainable fishing mortalities in a multispecies fisheries context (Paper III). An ecologically sustainable fishing mortality is here defined as a long-term fishing mortality associated with a multispecies objective which infers a low risk that any species, either the focal species itself or another species, in a community transgresses a critical biomass limit, below which the risk of recruitment failure is high. The approach is exemplified using a statistical food web model of the dominating fish stocks in the Baltic Sea. For the most abundant fish stock a counterintuitive result is found; it is more likely that the multispecies objective is met if its mortality caused by fishing is increased compared to if it is decreased. Further, simultaneous changes of the fishing mortality of a number of interacting species in the food web model shows a much narrower region of possible sustainable fishing mortalities than a single species approach, something that is not captured by current stock assessment models. Altogether these results are governed by indirect effects propagating in the community and pinpoints the need to adopt community dynamical approaches in fisheries management.

    The population sizes of many species in the world are declining. Negative population trends are particular pronounced in large-bodied herbivores and carnivores, species known to play important regulatory roles in many ecosystems. Although this indicates that the ecological consequence of declining populations of species might be profound, its impact on ecosystem stability remains largely unexplored. In paper IV it is therefore explored how declining populations of rare and common species affects the resilience – recovery rate – of ecological networks. An analytical approximation shows that network resilience is a function of the harmonic mean of the species’ abundances. This means that network resilience is especially sensitive to declining abundances of rare species. Consistent with this analytically derived result, a clear and positive relationship between resilience and the abundance of the rarest species in a broad spectrum of dynamical models of ecological networks is found. Together these results illustrate the potentially negative consequences of declining populations of rare species for the stability of the ecological systems in which they are embedded, and provide ecological arguments for the protection and management of rare species.

    Delarbeid
    1. High frequency of functional extinctions in ecological networks
    Åpne denne publikasjonen i ny fane eller vindu >>High frequency of functional extinctions in ecological networks
    2013 (engelsk)Inngår i: Nature, ISSN 0028-0836, E-ISSN 1476-4687, Vol. 499, nr 7459, s. 468-+Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Intensified exploitation of natural populations and habitats has led to increased mortality rates and decreased abundances of many species(1,2). There is a growing concern that this might cause critical abundance thresholds of species to be crossed(1,3-5), with extinction cascades and state shifts in ecosystems as a consequence(4,6,7). When increased mortality rate and decreased abundance of a given species lead to extinction of other species, this species can be characterized as functionally extinct even though it still exists. Although such functional extinctions have been observed in some ecosystems(3,4,8), their frequency is largely unknown. Here we use a new modelling approach to explore the frequency and pattern of functional extinctions in ecological networks. Specifically, we analytically derive critical abundance thresholds of species by increasing their mortality rates until an extinction occurs in the network. Applying this approach on natural and theoretical food webs, we show that the species most likely to go extinct first is not the one whose mortality rate is increased but instead another species. Indeed, up to 80% of all first extinctions are of another species, suggesting that a species ecological functionality is often lost before its own existence is threatened. Furthermore, we find that large-bodied species at the top of the food chains can only be exposed to small increases in mortality rate and small decreases in abundance before going functionally extinct compared to small-bodied species lower in the food chains. These results illustrate the potential importance of functional extinctions in ecological networks and lend strong support to arguments advocating a more community-oriented approach in conservation biology, with target levels for populations based on ecological functionality rather than on mere persistence(8-11).

    sted, utgiver, år, opplag, sider
    Nature Publishing Group, 2013
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-96709 (URN)10.1038/nature12277 (DOI)000322157900038 ()
    Merknad

    Funding Agencies|Linkoping University||

    Tilgjengelig fra: 2013-08-23 Laget: 2013-08-23 Sist oppdatert: 2018-02-18
    2. Pattern of functional extinctions in ecological networks with a variety of interaction types
    Åpne denne publikasjonen i ny fane eller vindu >>Pattern of functional extinctions in ecological networks with a variety of interaction types
    2016 (engelsk)Inngår i: Theoretical Ecology, ISSN 1874-1738, E-ISSN 1874-1746, Vol. 9, nr 1, s. 83-94Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    There is a strong trend of declining populations in many species of both animals and plants. Dwindling numbers of species can eventually lead to their functional extinction. Functional, or ecological, extinction occurs when a species becomes too rare to fulfill its ecological, interactive role in the ecosystem, leading to true (numerical) extinction of other depending species. Recent theoretical work on food webs suggests that the frequency of functional extinction might be surprisingly high. However, little is known about the risk of functional species extinctions in networks with other types of interactions than trophic ones. Here, we explore the frequency of functional extinctions in model ecological networks having different proportions of antagonistic and mutualistic links. Furthermore, we investigate the topological relationship between functionally and numerically extinct species. We find that (1) the frequency of functional extinctions is higher in networks containing a mixture of antagonistic and mutualistic interactions than in networks with only one type of interaction, (2) increased mortality rate of species having both mutualistic and antagonistic links is more likely to lead to extinction of another species than to extinction of the species itself compared to species having only mutualistic or antagonistic links, and (3) trophic distance (shortest path) between functionally and numerically extinct species is, on average, longer than one, indicating the importance of indirect effects. These results generalize the findings of an earlier study on food webs, demonstrating the potential importance of functional extinction in a variety of ecological network types.

    sted, utgiver, år, opplag, sider
    Springer Netherlands, 2016
    Emneord
    Functional extinction, Declining populations, Interaction type, Interaction strength, Ecological network
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-121570 (URN)10.1007/s12080-015-0275-7 (DOI)000373308600009 ()
    Merknad

    Funding agencies: Linkoping University

    Tilgjengelig fra: 2015-09-25 Laget: 2015-09-25 Sist oppdatert: 2018-02-18bibliografisk kontrollert
  • 255.
    Säterberg, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Swedish Univ Agr Sci, Sweden.
    Casini, Michele
    Swedish Univ Agr Sci, Sweden.
    Gardmark, Anna
    Swedish Univ Agr Sci, Sweden.
    Ecologically Sustainable Exploitation Rates-A multispecies approach for fisheries management2019Inngår i: Fish and Fisheries, ISSN 1467-2960, E-ISSN 1467-2979Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fisheries management is slowly evolving from its traditional single-species focus to a more holistic ecosystem-based approach. Yet, limits for exploitation are almost always set based on single-species models, treating species as isolated entities. This is problematic since the sustainability of a fishery hinges on its effects on the exploited community as a whole. Here, we develop a novel analytical approach of estimating exploitation rates that are sustainable with respect to the state of whole fish communities. Our approach simultaneously addresses species interactions, environmental covariates and natural variability of population sizes, yet it is framed around a simple and accessible objective. We derive Ecologically Sustainable Exploitation Rates, that is exploitation rates associated with a maximum acceptable probability (determined by management) that any interacting species decreases to an unacceptably low population size. Using models fitted to an exploited fish community, we show how accounting for species interactions constrains the possibilities for ecologically sustainable exploitation. The conventional omission of species interactions may thus result in overestimated exploitation limits. Moreover, our application rendered a counterintuitive result: it suggests that the exploitation of one species should increase, as compared to mean historical levels, for the purpose of conservation of the community as a whole. Such insights could impossibly be gained using single-species approaches, illustrating the need to adopt multispecies models in fisheries management. Analytical derivation of Ecologically Sustainable Exploitation Rates offers a mean to do so.

  • 256.
    Säterberg, Torbjörn
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska fakulteten. Swedish Univ Agr Sci, Sweden.
    Jonsson, Tomas
    Swedish Univ Agr Sci, Sweden; Skovde Univ, Sweden.
    Yearsley, Jon
    Univ Coll Dublin, Ireland; UCD Earth Inst, Ireland.
    Berg, Sofia
    Skovde Univ, Sweden.
    Ebenman, Bo
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. Stockholm Univ, Sweden.
    A potential role for rare species in ecosystem dynamics2019Inngår i: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 9, artikkel-id 11107Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The ecological importance of common species for many ecosystem processes and functions is unquestionably due to their high a bundance.Yet, the importance of rare species is much less understood. Here we take a theoretical approach, exposing dynamical models of ecological networks to small perturbations, to explore the dynamical importance of rare and common species. We find that both species types contribute to the recovery of communities following generic perturbations (i.e. perturbations affecting all species).Yet, when perturbations are selective (i.e. affects only one species), perturbations to rare species have the most pronounced effect on community stability. We show that this is due to the strong indirect effects induced by perturbations to rare species. Because indirect effects typically set in at longer timescales, our results indicate that the importance of rare species may be easily overlooked and thus underrated. Hence, our study provides a potential ecological motive for the management and protection of rare species.

  • 257.
    Tarasova, Yana
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Effects of local habitat characteristics and landscape composition on the occurrence of burnet moths.2016Independent thesis Advanced level (degree of Master (Two Years)), 20 poäng / 30 hpOppgave
    Abstract [en]

    A decline in biodiversity in agricultural landscapes has been reported for decades. One of the most important habitats for biodiversity in agricultural landscapes is semi-natural grasslands. To preserve species-rich semi-natural grasslands, research need to focus both on local habitat quality and on landscape composition at various scales. In the current study I examined how nectar sources, host plants and other environmental parameters affected the occurrence of adults of four burnet moth species, residents of semi-natural grasslands. Also, I investigated the effects of landscape composition at 34 spatial scales. The results in general showed positive effects of host plants cover, nectar sources abundance, dry soil, sun exposure, tall sward height, small herb and grass cover. At the landscape level all the species responded negatively to the amount of arable land and positively to the amount of forests at scales up to 10000 m. Two species were negatively affected by the amount of artificial surfaces and pasture at some scales. Though the amount of semi-natural grasslands and patch area did not affect the occurrence of the species, at the local scale semi-natural grasslands were still important for the species. Thus, my results suggest that management should be focused both on local and landscape levels. Focus should be to preserve sunny and open areas of high-quality semi-natural grasslands rich in burnet moths’ host plants and especially nectar sources that seem to be more important than host plants for adults. Semi-natural grasslands should be preferably adjacent to forests and not arable land.

  • 258.
    Thörnow, Johan
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Effekter av urbanisering på grönalgen trädgröna i Linköpings stad med omnejd.: Biologiundervisning i närmiljön2013Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Urbanization has for a long time been a threat to our biodiversity. Epiphytic organisms such as lichens have been negative affected by traffic pollution and the new urban environment surrounding their old habitat (van Her 2001). Another epiphytic organism is the green algae Desmococcus olivaceus. Unlike lichens the green algae is favoured by polluted areas. The aim of this study was to investigate if time in urban environments affected the cover of the green algae on old oaks. 91 oaks were investigated in urban and rural environments in and around Linköping city, Sweden. Data were collected on cover from green algae, lichens and mosses and analysed with regard to the time in urban environment. There were no correlation between time in urban environments and the cover of the green algae, however, the presence of green algae on an oak increased by the time in urban environment. The results also indicated that green algae were distributed on the northwest side of the trunk, whereas lichens were distributed on the northeast side. This could be due to competition between the epiphytic groups. The study also contains findings of four exercises of outdoor education in the field of ecology for high school students.

  • 259.
    Tyler, Torbjörn
    et al.
    Biological Museums, Dept of Biology, Lund Univ., Lund, Sweden.
    Karlsson, Thomas
    Swedish Museum of Natural History, Stockholm, Sweden.
    Milberg, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Sahlin, Ullrika
    Centre of Environmental and Climate Research, Lund Univ., Lund, Sweden.
    Sundberg, Sebastian
    The Swedish Species Information Centre, Swedish Univ. of Agricultural Sciences, Uppsala, Sweden.
    Invasive plant species in the Swedish flora: Developing criteria and definitions, and assessing the invasiveness of individual taxa2015Inngår i: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 33, nr 3, s. 300-317Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In a north European context, identifying invasive species is far from trivial because the vegetation has been influenced by human activities for thousands of years. New species have immigrated continuously since the end of the last glaciation, both spontaneously and through direct or indirect help by man. Still, newly immigrated species may be problematic in a nature conservation context and may harm biodiversity, and cause changes in ecosystem services. In this study, all 721 presently established vascular plant and bryophyte taxa known to have been introduced to, or to have immigrated to, Sweden since the year 1700 are assessed for their invasive potential. The assessment is based on six components considered relevant for their invasiveness: 1) ability to compete in natural vegetation, 2) ability to form dense populations, 3) realized dispersal ability, 4) gene flow to native relatives, 5) time since immigration and 6) distance to their native range. Although the relative importance of these components is context dependent, a compound general index of invasive concern is proposed and calculated for all taxa. The index of invasive concern is validated by comparing it to assessments by a Bayesian Belief Network in which the influences of the same six components are assigned by expert opinions. In addition, rough estimates of the present-day abundance of each taxon in Sweden are presented. The origin, biology and possible impact of the 150 taxa with the highest index values are discussed. Based on the index of invasive concern, Campylopus introflexus, Epilobium adenocaulon, E. ciliatum, Rosa rugosa, Lamiastrum galeobdolon subsp. argentatum, Orthodontium lineare, Solidago canadensis, Calystegia sepium subsp. spectabilis, Rubus armeniacus and Prunus serotina are identified as the ten most problematic alien vascular plant and bryophyte taxa in Sweden.

  • 260.
    Tälle, Malin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Conservation of semi-natural grasslands: Effects of different management methods on biodiversity2018Doktoravhandling, med artikler (Annet vitenskapelig)
    Abstract [en]

    Species-rich semi-natural grassland are valuable habitats in the agricultural landscape as they may contain a high diversity of both plant and animal species, as well as provide essential ecosystem services like pollination. To keep these habitats open and to maintain the biodiversity in them, management like grazing or mowing is necessary. Due to changed agricultural practices many semi-natural grasslands have been lost, e.g. due to secondary succession after abandonment or use of more intense management practices. As limited resources are available for the management and restoration of semi-natural grasslands, research is needed to find the best available management method that maintains biodiversity at a low cost. Therefore, the overall aim of this thesis was to use existing data to compare effects of different management methods and explore their effect on the biodiversity of semi-natural grasslands. More specifically, effects of grazing vs. mowing, different mowing frequencies and different mowing techniques were investigated using data from Swedish, European and global studies, with the aim of using the results to formulate management recommendations.

    Paper I investigated the effect of mowing using a sickle bar mower or a grass trimmer at a 5-cm or 0-cm cutting height on plant indicator species of good management for species richness, poor management and excess nitrogen. Analyses of data from a Swedish 11-year field experiment revealed that over time, there was no difference in the odds of finding indicators of any type for any of the mowing techniques. This suggest that there is a similar effect of mowing using a sickle bar mower and a grass trimmer on the floristic composition of semi-natural grasslands.

    Paper II and III investigated effects of different management methods using a Swedish long-term, multi-site field experiment. Paper II compared effects of grazing vs. mowing and paper III compared effects of annual mowing and mowing every third year. Both papers used meta-analyses to compare effect on plant indicator species of good management for species richness and poor management. Additionally, paper II examined effects of indicators of excess nitrogen, while paper III also examined effects on plant species richness and diversity and species-wise responses. For paper II, analyses revealed an increase in the odds of finding indicators of good management for species richness in mowed plots and increased odds of finding indicators of excess nitrogen in grazed plots. For paper III, meta-analyses revealed a small drop in plant species richness and diversity, and an increase in woody and tall-grown species, when mowing every third year. However, there were no difference in the odds of finding indicators of good management for species richness or poor management between mowing frequencies. These results suggest that mowing is a better long-term management method compared to grazing in seminatural grasslands in southern Sweden, while annual mowing have a slightly more positive effect compared to mowing every third year.

    Paper IV and V investigated management effects on a larger scale, by systematically reviewing studies comparing effects of grazing vs. mowing or different mowing frequencies on grassland flora and fauna, and analysing the data using meta-analysis. The included mowing frequencies were annual mowing vs. mowing every fifth, third or second year, or mowing two, three or four times a year. Paper IV analysed data from 35 studies from across the globe, and revealed a slightly more positive effect of grazing on the biodiversity of seminatural grasslands. However, results differed for different grassland characteristics like e.g. geography, grassland type and previous management. Paper V analysed data from 29 European studies, and revealed a more positive effect of mowing more frequently than once per year. However, the differences were small and varied for different grassland characteristics. For example, a higher mowing frequency was better in more productive grasslands. These results suggest that grazing is slightly better than mowing and that mowing less frequently, e.g. every other year, can be a viable management method in less productive grasslands, as a way of using limited funds more efficiently.

    The results from the papers included in this thesis suggest that different management methods have different effects on the biodiversity of semi-natural grasslands. However, in many cases these differences are relatively small. Thus, to a certain extent one of the most important factors for semi-natural grassland biodiversity seems to be the fact that management occurs at all, while the actual management methods is of less importance. Hence, choosing the most suitable management method for a certain situation should be based on conservation aims, grassland conditions, the previous management practice used, the cost of management, the availability of different management methods and previous research. 

    Delarbeid
    1. Mowing for biodiversity: grass trimmer and knife mower perform equally well
    Åpne denne publikasjonen i ny fane eller vindu >>Mowing for biodiversity: grass trimmer and knife mower perform equally well
    Vise andre…
    2014 (engelsk)Inngår i: Biodiversity and Conservation, ISSN 0960-3115, E-ISSN 1572-9710, Vol. 23, nr 12, s. 3073-3089Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Mowing of semi-natural grasslands is an important management method to maintain the conservation value and species-richness of this habitat. Mowing using cutting instruments, e.g. sickle bar mowers, is thought to be superior by practitioners compared with other mechanical instruments that tears off the plant material, e.g. grass trimmers. However, almost no studies exist that supports this assumption. We analysed a 12-year field trial in a semi-natural grassland in south-eastern Sweden, with the aim of determining which mowing technique best maintains the conservation value of semi-natural grasslands. Two mowing techniques were compared: mowing using a hand-pushed sickle bar mower (a type of knife mower), or mowing using a grass trimmer at a 5-cm or 0-cm cutting height. The odds that a recorded species belongs to a group of indicator species were calculated for sample plots, and odds ratios were calculated contrasting treatments. Three types of indicator species classification systems were used: (i) indicators of management for species richness, (ii) indicators of excess nitrogen and (iii) indicators of lack of management. The odds ratios were calculated for years 1–5, 7 and 12 of the trial. In addition, Principal Response Curve analysis was performed to analyse the change in vegetation composition over time and ANOVA for plant species richness in plots. The results showed that over time there were no differences in the odds of finding indicators of any of the three types, for any of the mowing techniques. Furthermore, there were no apparent change in vegetation composition and only a small effect on richness. These results suggest that mowing using a sickle bar mower or a grass trimmer had the same effect on the floristic composition of grasslands, and both techniques can be recommended for use in semi-natural grasslands.

    sted, utgiver, år, opplag, sider
    Springer Publishing Company, 2014
    Emneord
    Indicators, Management, Meta-analysis, Mowing techniques, Odds ratio, Semi-natural grassland, Sweden
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-111926 (URN)10.1007/s10531-014-0765-8 (DOI)000343908600010 ()
    Tilgjengelig fra: 2014-11-10 Laget: 2014-11-10 Sist oppdatert: 2018-10-02bibliografisk kontrollert
    2. The conservation benefit of mowing vs grazing for management ofspecies-rich grasslands: a multi-site, multi-year field experiment
    Åpne denne publikasjonen i ny fane eller vindu >>The conservation benefit of mowing vs grazing for management ofspecies-rich grasslands: a multi-site, multi-year field experiment
    2015 (engelsk)Inngår i: Nordic Journal of Botany, ISSN 0107-055X, E-ISSN 1756-1051, Vol. 33, nr 6, s. 761-768Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Species-rich semi-natural grasslands in Europe are becoming more fragmented and many species that depend on thishabitat type are rare and threatened today. Management methods like mowing and grazing are needed to preserve remaininggrasslands. Because management is costly it is important to use the most cost-effective as well as the most beneficialmanagement method, but few studies have compared mowing and grazing. We investigated the effect of mowing andgrazing on grassland vegetation using data from 11 long-term field trials situated in southern Sweden. We calculated thechange in the odds of finding species belonging to three different groups of indicators at the start of the treatment and after8 and 14 years. The used indicator groups were indicators of good management, excess nitrogen and poor management.The results revealed an increase in the odds of finding indicators of good management in mowed plots and an increasein finding indicators of excess nitrogen in grazed plots. The odds of finding indicators of poor management remainedunchanged. Results from sub-analysis of the grazing intensity showed a more negative effect from grazing with low grazingintensity than normal/high grazing intensity. Therefore, mowing is the best long-term management method for seminaturalgrasslands in Sweden and grazing using a low grazing intensity should be avoided.

    sted, utgiver, år, opplag, sider
    Nordic Society Oikos, 2015
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-123378 (URN)10.1111/njb.00966 (DOI)000368428700017 ()
    Merknad

    Funding agencies: Swedish Board of Agriculture; Stiftelsen Oscar och Lili Lamms minne

    Tilgjengelig fra: 2015-12-14 Laget: 2015-12-14 Sist oppdatert: 2018-01-30
    3. The biodiversity cost of reducing management intensity in species-rich grasslands: Mowing annually vs. every third year
    Åpne denne publikasjonen i ny fane eller vindu >>The biodiversity cost of reducing management intensity in species-rich grasslands: Mowing annually vs. every third year
    2017 (engelsk)Inngår i: Basic and Applied Ecology, ISSN 1439-1791, E-ISSN 1618-0089, Vol. 22, s. 61-74Artikkel i tidsskrift (Fagfellevurdert) Published
    Abstract [en]

    Mowing is an important management method for species-rich semi-natural grasslands in Europe. Since mowing is costly, it is important to find a balance between mowing frequency and conservation benefits. We compared vegetation data from eleven field trials situated in southern Sweden that involved two mowing regimes, annually and every third year, as well as a no-management control. After approximately 14 years, mowing every third year showed (i) a drop in species richness and Shannon and GiniSimpson diversity indices, (ii) an increase in woody species, and (iii) increases in tall-grown species. However, there were no apparent changes in (iv) species that were indicative of poor management, nor (v) those indicating good management. For one of the trials, data after 38 years were also evaluated. Compared with annual mowing, there were strong negative changes in the number of species in the untreated control, while the results were conflicting for mowing every third year. In conclusion, the expected loss of conservation values from reduced mowing intensity was 5060% of the loss after abandonment. The outcomes, however, varied among the eleven sites. (C) 2017 Gesellschaft fur Okologie. Published by Elsevier GmbH. All rights reserved.

    sted, utgiver, år, opplag, sider
    ELSEVIER GMBH, URBAN & FISCHER VERLAG, 2017
    Emneord
    Cutting; Indicators; Meta-analysis; Mowing; Odds ratio; Response ratio; Semi-natural grassland; Sweden
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-141735 (URN)10.1016/j.baae.2017.07.004 (DOI)000409994800007 ()
    Merknad

    Funding Agencies|Swedish Board of Agriculture

    Tilgjengelig fra: 2017-10-05 Laget: 2017-10-05 Sist oppdatert: 2018-01-30
    4. Grazing vs. mowing: A meta-analysis of biodiversity benefits forgrassland management
    Åpne denne publikasjonen i ny fane eller vindu >>Grazing vs. mowing: A meta-analysis of biodiversity benefits forgrassland management
    Vise andre…
    2016 (engelsk)Inngår i: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 222, s. 200-212Artikkel, forskningsoversikt (Fagfellevurdert) Published
    Abstract [en]

    To maintain the high biodiversity of semi-natural grasslands, management by grazing or mowing isneeded. Given the limited resources and few remaining areas, the best management method should beused. However, only a few studies comparing the effects of mowing and grazing on grassland biodiversityexists. Therefore, the goal of the present review was to extract as much data as possible from theliterature and evaluate them using a meta-analysis approach. We searched scientific and grey literaturefor studies comparing the effects of grazing and annual mowing on outcomes relevant for biodiversityconservation. We identified 35 relevant studies on grazing and annual mowing that provided datasuitable for the meta-analysis. We found that grazing generally had a more positive effect on theconservation value of semi-natural grasslands compared to mowing, but effect sizes were generally smallto moderate for most contrasts. Furthermore, effects varied across some grassland characteristics e.g. fordifferent grassland types, with grazing and mowing having a similar effect or mowing having a morepositive effect in certain cases. Our results suggest, that in most cases grazing should be the preferredmanagement method when managing for grassland conservation.

    sted, utgiver, år, opplag, sider
    Elsevier, 2016
    Emneord
    Conservation management Cutting Evidence-based Livestock grazing Meadow Pasture Semi-natural grassland
    HSV kategori
    Identifikatorer
    urn:nbn:se:liu:diva-125592 (URN)10.1016/j.agee.2016.02.008 (DOI)000384383600021 ()
    Merknad

    Funding agencies: Swedish Board of Agriculture

    Tilgjengelig fra: 2016-02-26 Laget: 2016-02-26 Sist oppdatert: 2018-02-21
  • 261.
    Tälle, Malin
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Effekterna av urbanisering, barksprickedjup och solexponering på lavfloran i sydöstra Sverige2011Independent thesis Basic level (degree of Bachelor), 10 poäng / 15 hpOppgave
    Abstract [en]

    Studies have shown that air pollution, as well as bark fissure depth and sun exposure of a tree can have an effect on lichen growth as well as abundance of lichen species. The aim of this study was to find out the relative importance of these factors. 211 oaks in south eastern Sweden were surveyed for presence of 17 lichen species, as well as the total number of lichen species. Half of the trees were situated in urban areas and half in the countryside. For each tree the bark fissure depth was measured and the sun exposure of the trunk was estimated. The results showed a significant negative effect on a majority of lichens growing in an urban environment and a significant positive effect on a majority of lichens growing on trees with deep bark fissures. The sun exposure was a less important factor but could not be excluded as a factor affecting lichen occurrence. These results show the negative effect urbanization can have on rare lichen species, as well as be used in the development and maintenance for the nature reserves containing them

  • 262.
    Tälle, Malin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet, Tekniska högskolan.
    Management of semi-natural grassland vegetation: long-term effects of grazing, mowing and different mowing techniques2013Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Semi-natural grasslands are species-rich and one of the most threatened habitats in Europe, since land-use changes have led to reduced area of grassland. Appropriate management practices like grazing or mowing is needed to maintain the conservation values and species-richness of semi-natural grasslands. However, few studies have investigated which of grazing or mowing is most appropriate. Furthermore, almost no studies have investigated which mowing technique is best for the conservation value of grassland flora. The aim of this study was to determine which management practice of grazing and mowing, and which mowing technique, has the most positive effect on grassland flora. Data from two long-term trials were evaluated: one compared the effect of grazing and mowing in eleven sites in southern Sweden during at least twelve years; the other compared the effect of the knife mower and grass trimmer at different cutting heights in one site during twelve years. Meta-analysis was used, based on the odds for a plant record being an indicator species, using eight different indicator systems of classification of grassland plants. Over time, results show increasing odds of finding indicators of good management and no change in odds of finding indicators of lack of management in mowed compared to grazed plots. There were no differences in the odds of finding any indicator species for any of the mowing techniques. Hence, to maintain the conservation values of semi-natural grasslands, mowing is the better management practice compared to grazing. Mowing using a knife mower or grass trimmer has similar effects, and can both be recommended.

  • 263.
    Tälle, Malin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Deák, Balázs
    MTA-DE Biodiversity and Ecosystem Services Research Group, Egytem tér 1, Debrecen H-4032, Hungary.
    Poschlod, Peter
    Ecology and Conservation Biology, Institute of Plant Sciences, University of Regensburg, D-93040 Regensburg, Germany.
    Valkó, Orsolya
    University of Debrecen, Department of Ecology, P.O. Box 71, Debrecen H-4010, Hungary.
    Westerberg, Lars
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Milberg, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Grazing vs. mowing: A meta-analysis of biodiversity benefits forgrassland management2016Inngår i: Agriculture, Ecosystems & Environment, ISSN 0167-8809, E-ISSN 1873-2305, Vol. 222, s. 200-212Artikkel, forskningsoversikt (Fagfellevurdert)
    Abstract [en]

    To maintain the high biodiversity of semi-natural grasslands, management by grazing or mowing isneeded. Given the limited resources and few remaining areas, the best management method should beused. However, only a few studies comparing the effects of mowing and grazing on grassland biodiversityexists. Therefore, the goal of the present review was to extract as much data as possible from theliterature and evaluate them using a meta-analysis approach. We searched scientific and grey literaturefor studies comparing the effects of grazing and annual mowing on outcomes relevant for biodiversityconservation. We identified 35 relevant studies on grazing and annual mowing that provided datasuitable for the meta-analysis. We found that grazing generally had a more positive effect on theconservation value of semi-natural grasslands compared to mowing, but effect sizes were generally smallto moderate for most contrasts. Furthermore, effects varied across some grassland characteristics e.g. fordifferent grassland types, with grazing and mowing having a similar effect or mowing having a morepositive effect in certain cases. Our results suggest, that in most cases grazing should be the preferredmanagement method when managing for grassland conservation.

  • 264.
    Tälle, Malin
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Wissman, Jörgen
    Milberg, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Gräsröjaren: ett skötselalternativ i artrika gräsmarker.2015Inngår i: Svensk Botanisk Tidskrift, ISSN 0039-646X, Vol. 108, s. 254-259Artikkel i tidsskrift (Fagfellevurdert)
  • 265.
    Törnqvist, Lina
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Lövskogens förändring i eklandskapet söder om Linköping: 1927 jämfört med 20132013Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The forests of Sweden are constantly changing. Map studies indicate that the amount of deciduous trees in Sweden has decreased in recent years in favor of the coniferous trees. The National Forest Inventory has since the early 1920s monitored the Swedish forests and in recent years has made the old data digitally available. In the present project, we have investigated how the numbers of stems in different diameter classes have changed for birch and other deciduous trees. The inventory was conducted in the same manner as in the first forest inventory. Ten meters wide transects, each two kilometers long, were inventoried from west to east in oak woodland south of Linköping. All trees breast-height diameter were measured in the transect and placed in nine diameter classes. The total number of stems per hectare for both birch and other deciduous trees had increased in area. The results of the inventory also show that the proportion of deciduous trees against conifers had increased by about ten percent for all diameter classes. The increased stem number, here documented in a small spatial scale, is in accordance with previous studies in Sweden. However, the other result differs from the hypothesis that deciduous trees should have decreased and pine trees increased. Based on previous studies in Sweden, conifers and especially spruce has increased. The increase of deciduous trees may be due to the investigation area that has historically been characterized by large areas of meadows and pastures. In the study area, there are a small number of landowners with large estates, who have been able to preserve the deciduous forest.

  • 266.
    van Aswegen, JD
    et al.
    North West University, South Africa.
    Nel, L
    North West University, South Africa.
    Strydom, NA
    Nelson Mandela University, South Africa.
    Minnaar, Karen
    North West University, South Africa.
    Kylin, Henrik
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Filosofiska fakulteten.
    Comparing the metallic elemental compositions of Kelp Gull Larus dominicanus eggs and eggshells from the Swartkops Estuary, Port Elizabeth, South Africa2019Inngår i: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 221, s. 533-542Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metals attributed to pollution may increase their concentrations above the geological background and pose toxic challenges towards humans and biota. We analysed sixteen Kelp Gull eggs and eggshells for 30 metallic elements from the Swartkops Estuary (SE), an important recreational, industrial, and ecological asset for Port Elizabeth, the region, and South Africa. Mean concentrations for eggshell and egg content for Hg was 0.02 and 0.4 mg/kg dm, Cr was 4 and 18 mg/kg dm (the highest yet recorded for any gull or tern egg), for Zn 2.1 and 62 mg/kg dm, for Sr 880 and 12 mg/kg dm, for V 170 and 1.3 mg/kg dm, and for Co 1.7 and 0.002 mg/kg dm, respectively. Zink, Se, and Hg, increased on a dry-mass basis from sediment via small fish to gull egg content, indicating bioaccumulation. No effect on eggshell thickness was seen. We also determined that eggshell concentrations cannot be used as a proxy for egg content concentrations. Mercury, Cr, V, Co, and Zn were elements we identified as potentially problematic that require source identification and mitigation. Further research into other high-trophic animals such as herons, egrets, cormorants, and otters in the SE system is proposed.

    Fulltekst tilgjengelig fra 2021-01-07 12:13
  • 267.
    Vogels, Chantal B. F.
    et al.
    University of Wageningen and Research Centre, Netherlands.
    Möhlmann, Tim
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten. University of Wageningen and Research Centre, Netherlands.
    Melsen, Diede
    University of Wageningen and Research Centre, Netherlands.
    Favia, Guido
    University of Camerino, Italy.
    Wennergren, Uno
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Koenraadt, Constantianus J. M.
    University of Wageningen and Research Centre, Netherlands.
    Latitudinal Diversity of Culex pipiens Biotypes and Hybrids in Farm, Peri-Urban, and Wetland Habitats in Europe2016Inngår i: PLoS ONE, ISSN 1932-6203, E-ISSN 1932-6203, Vol. 11, nr 11, artikkel-id e0166959Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Despite the presence of Culex (Cx.) pipiens mosquitoes and circulation of West Nile virus (WNV), WNV outbreaks have so far not occurred in northern Europe. The species Cx. pipiens consists of two morphologically identical biotypes, pipiens and molestus, which can form hybrids. Until now, population dynamic studies of Cx. pipiens have not differentiated between biotypes and hybrids at the European scale, nor have they used comparative surveillance approaches. We therefore aimed to elucidate the relative abundance of Cx. pipiens biotypes and hybrids in three habitat types at different latitudes across Europe, using two different surveillance traps. BG-Sentinel and Mosquito-Magnet Liberty Plus traps were placed in three habitat types (farms, peri-urban, wetlands), in three European countries (Sweden, The Netherlands, Italy). Collected Cx. pipiens mosquitoes were identified to biotype with real-time PCR. Both trap types collected equal ratios of the biotypes and their hybrids. From northern to southern latitudes there was a significant decrease of pipiens and an increase of molestus. Habitat types influenced the relative ratios of biotypes and hybrids, but results were not consistent across latitudes. Our results emphasize the need to differentiate Cx. pipiens to the biotype level, especially for proper future WNV risk assessments for Europe.

  • 268.
    Walck, Jeffery L.
    et al.
    Department of Biology, Middle Tennessee State University, USA.
    Karlsson, Laila M.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet, Tekniska högskolan.
    Milberg, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Ekologi. Linköpings universitet, Tekniska högskolan.
    Hidayati, Siti N.
    Department of Biology, Middle Tennessee State University, USA.
    Kondo, Tetsuya
    Graduate School of Agriculture, Hokkaido University, Japan.
    Seed germination and seedling development ecology in world-wide populations of a circumboreal Tertiary relict2012Inngår i: AoB Plants, ISSN 2041-2851, s. pls007-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Background and aims Temperate forests are disjunct in the Northern Hemisphere, having become fragmented from the earlier widespread (Tertiary) boreotropical forest. We asked ‘What are the contemporary patterns of population variation in ecological traits of a Tertiary relict in a macroecological context?’. This issue underpins our understanding of variation in populations occurring in the same biome but on different continents.

    Methodology We examined characters associated with root and shoot emergences among populations of Viburnum opulus in temperate forests of Asia, North America and Europe. This species has complex seedling emergence extending over several years and requiring various temperature cues.

    Principal results Populations varied in germination responses and clustered into groups that were only partly related to varietal status. Whereas roots (at warm temperatures) and shoots (following a cold period) simultaneously emerged from seeds of all populations when simulated dispersal occurred in winter, they were delayed in some populations when dispersal occurred in summer.

    Conclusions Viburnum opulus populations, some separated by 10 300 km, showed high similarity in seedling development and in germination phenology, and we suggest that stabilizing selection has played a key role in maintaining similar dormancy mechanisms. Nevertheless, there was some degree of variation in other germination characters, suggesting local adaptation.

  • 269.
    Walett, Emma
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Foraging and exploratory behaviour in Red Junglefowl (Gallus gallus) selected for fear of humans2010Independent thesis Advanced level (degree of Master (Two Years)), 40 poäng / 60 hpOppgave
    Abstract [en]

    Domestication is a process in which animals become adapted to a life among humans by means of selection. A reduced fear of humans is probably one of the first aims of selection, intentionally or unintentionally. Animals that have undergone the process of domestication have a different appearance than animals in the wild (domestic phenotype) and behave in a different way towards humans. In this study I have looked at foraging and explorative behaviours in an unselected parental generation of red junglefowl and their offspring. The parental generation were bred in three lines, a high line, with birds displaying a strong fear of humans, an intermediate line, birds showing a modest fear, and one low line, with birds performing a more tame behaviour towards humans. I presented the birds with three different feeding alternatives, familiar chicken food, meal worms camouflaged with wood shavings and just wood shavings. I counted number of pecks in the different food options, number of changes between sites and how many sites a bird visited. The results show that females of both generations were more explorative than males, by pecking more in cups of meal worms hidden in wood shavings whereas the males pecked more in cups containing chicken food. Females also moved around more in the arena. Results from the first selected generation show significant differences between the selection lines among the females, with females from the high and low groups being the most explorative.

  • 270.
    Wedel, Elsa
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Biology in Swedish Upper Secondary School: Does it Contribute to Ecocentrism?2019Independent thesis Advanced level (degree of Master (Two Years)), 10 poäng / 15 hpOppgave
    Abstract [en]

    Environmental issues are increasingly on the agenda and education is recognised as an important part in turning the negative trend. Originally formulated in 1976, the intent of environmental education was toprotect the nature from human impact and to induce in students a sense of the natural worlds’ own values.However, this has come to change during the years and the focus now lies on the values that nature possess for humans, in the shape of education for sustainable development. Though creating a concern for the environmental issues, critics point out that the anthropocentric attitude is not as strongly committed to protecting the nature as the ecocentric attitudes are, and therefore suggest that ecocentrism should be included in the curriculums. Assuming that biology in Swedish upper secondary school is the only subject where such values may be considered this study examines whether there is a significant difference between students who undergo these classes and students who do not, in terms of their attitudes. The study was divided in two parts, where firstly a content analysis was performed to confirm that biology was indeed the only subject to include ecocentric values, and secondly a comparative study was performed with students (n=82) taking biology and students not taking biology in Swedish upper secondary school. The results imply that biology is unique in including ecocentric attitudes, however, not to the extent that was expected. Furthermore, the results reveal that there is no significant difference between students taking the biology classes and students who do not, implying that the subject biology is not successful in increasing students ecocentric attitudes.

  • 271.
    Weisner, Angelica
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Does Asellus aquaticus change its pigmentation when given different types of food?2019Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    When an animal’s pigmentation matches the background across various types of environments, it is potentially an example of cryptic pigmentation, most likely as a response to natural selection by visually oriented predators. One example of cryptic pigmentation is phenotypic plasticity, meaning that an organism can exhibit different phenotypes in different environments. The freshwater isopod Asellus aquaticusliving in stands of reeds tends to have darker pigmentation than individuals living amongst lighter-coloured stoneworts, which has been suggested to result from visual predation. A recent study showed, however, that pigmentation in A. aquaticus is partly plastic, influenced by the nutritional composition in their diet. Here, I performed a laboratory experiment on A. aquaticusto see if the nutritional composition in stoneworts decreases pigmentation. Isopods were provided with a diet of either decaying leaves or stoneworts. The experiment took place over four weeks and pigmentation and growth were analysed at 0, 15 and 31 days. I found that pigmentation in A. aquaticusincreased significantly on both diets. And, there was no difference between both diets in amount of change in pigmentation. The fact that isopods that were feeding on stoneworts did not become lighter to match their background colour preferably depend on a high nutritional composition in the provided food, considering they also more than doubled their weight. In other words, phenotypic plasticity due to different diets between habitats is not the explanation to lighter coloured isopods living amongst stoneworts. However, these results do not exclude that differences can arise over a longer time or differs between different species of stoneworts. 

  • 272.
    Westerberg, Lars
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Haider Muhammadi, Usman
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Bergman, Karl-Olof
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Milberg, Per
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Spatial pattern of occurrence of epiphytic lichens on oaks in a heterogeneous landscape2017Inngår i: Acta Oecologica, ISSN 1146-609X, E-ISSN 1873-6238, Vol. 84, s. 64-71Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Quercus robur (oaks) provides an important substrate for many epiphytic lichens, and with increasing age the bark becomes suitable for some rare species. These species may respond to environmental and landscape factors differently, and at different spatial scales. We tested the effect of factors related to the individual tree and the surrounding landscape on the occurrence and richness patterns of lichens species. The study system consisted of 213 oaks selected in a grid system within a 400 km(2) heterogeneous oak-rich area in south-eastern Sweden. Oaks had been selected to be relatively uniform in size (circumference 3.1-4.1 m), and as uniformly distributed as possible in the study area. Landscape factors were calculated for various spatial scales (circles with radius ranging from 28 to 1225 m from a studied oak). One of the landscape factors stands out as of general importance oak density in the surrounding while the others (amount of forest, water, houses and arable field) had no effects, or weak effects on only some species. Among the tree specific variables, circumference was consistently important (despite ranging from only 3.1-4.1 m) while inconsistent effects were seen by sun exposure of oak trunk (Chaenotheca phaeocephala, Ramalina baltica) and density of shrubs and trees near the tree (Ch. phaeocephala). The occurrence patterns of Cliostomum corrugatum, Ch. phaeocephala, R. baltica and richness (number of eleven target lichens) were best explained by the density of oaks within radii of 401, 199, 199 and 303 m, respectively. In conclusion, our study highlighted the importance of spatial scale for understanding the occurrence of epiphytic lichens and suggests spatial scales and oak densities that could be targeted for landscape and conservation planning. (C) 2017 Elsevier Masson SAS. All rights reserved.

  • 273.
    Westling, Fred
    et al.
    Univ Sydney, Australia.
    Underwood, James
    Univ Sydney, Australia.
    Örn, Samuel
    Linköpings universitet.
    Light interception modelling using unstructured LiDAR data in avocado orchards2018Inngår i: Computers and Electronics in Agriculture, ISSN 0168-1699, E-ISSN 1872-7107, Vol. 153, s. 177-187Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In commercial fruit farming, managing the light distribution through canopies is important because the amount and distribution of solar energy that is harvested by each tree impacts the production of fruit quantity and quality. It is therefore an important characteristic to measure and ultimately to control with pruning. We present a solar-geometric model to estimate light interception in individual avocado (Persea americana Mill.) trees, that is designed to scale to whole-orchard scanning, ultimately to inform pruning decisions. The geometry of individual trees was measured using handheld mobile LiDAR and represented by point clouds. A discrete energy distribution model of the hemispherical sky was synthesised using public weather records. The light from each sky node was then ray traced, applying a radiation absorption model where rays pass the point cloud representation of the tree. The model was validated using ceptometer energy measurements at the canopy floor, and model parameters were optimised by analysing the error between modelled and measured energies. The model was shown to perform well qualitatively through visual comparison with tree shadows in photographs, and quantitatively well with R-2 = 0.854, suggesting it is suitable to use in the context of agricultural decision support systems, in future work.

  • 274.
    Wohlfarth Hasle, Inger-Marie
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi.
    Tranors förekomst på fält kring Tåkern påverkas av vägar, vatten, byggnader, träd och buskage2016Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Every year the Eurasian crane travel from northern Africa to northern Europe and Asia. On their migration route they need to rest and often choose places around shallow lakes in agriculture landscapes. During their time in these resting sites the cranes forage in agriculture fields surrounding the lakes, which often cause crop-damage and thereof also financial loses. The last 30 years the population has increased radically, resulting in more extensive crop-damage. This study was set out to gain a better understanding how these migrating cranes choose sites to forage, based on four environment factors: roads, water, buildings, trees and shrub. A study-area in north of Lake Tåkern was selected and during six days in the spring all the cranes in the area were counted and marked on a map. The results showed that the factors affected the occurrence of cranes in the fields. They wanted to be close to shallow water and keep a distance to buildings, roads, trees and shrub. The cranes often spend the night in shallow water and search for food in the area close by to not lose too much energy, which probably was the main reason for the birds to stay close to the water. The distance to buildings and roads suggests that the cranes want to avoid interference from humans and the distance to trees and shrub that they want to have a good awareness of their surroundings. Through this understanding, areas with higher risk to attract groups of cranes can more easily be identified.

  • 275.
    Ziels, Ryan
    et al.
    Linköpings universitet, Biogas Research Center. Civil and Environmental Engineering, University of Washington, WA, USA.
    Karlsson, Anna
    Linköpings universitet, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Beck, David A.C.
    Science Institute, University of Washington, WA, USA.
    Ejlertsson, Jörgen
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Biogas Research Center. Linköpings universitet, Filosofiska fakulteten. Scandinavian Biogas Fuels AB, Sweden.
    Shakeri Yekta, Sepehr
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Biogas Research Center. Linköpings universitet, Filosofiska fakulteten.
    Björn, Annika
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Biogas Research Center. Linköpings universitet, Filosofiska fakulteten.
    Stensel, H. David
    Civil and Environmental Engineering, University of Washington, WA, USA.
    Svensson, Bo H.
    Linköpings universitet, Institutionen för tema, Tema Miljöförändring. Linköpings universitet, Biogas Research Center. Linköpings universitet, Filosofiska fakulteten.
    Microbial community adaptation influences long-chain fatty acidconversion during anaerobic codigestion of fats, oils, and grease withmunicipal sludge2016Inngår i: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 103, s. 372-382Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Codigesting fats, oils, and greases with municipal wastewater sludge can greatly improve biomethanerecovery at wastewater treatment facilities. Process loading rates of fats, oils, and greases have beenpreviously tested with little knowledge of the digester microbial community structure, and high transientfat loadings have led to long chain fatty acid (LCFA) accumulation and digester upsets. This studyutilized recently-developed quantitative PCR assays for syntrophic LCFA-degrading bacteria along with16S amplicon sequencing to relate changes in microbial community structure to LCFA accumulationduring transient loading increases to an anaerobic codigester receiving waste restaurant oil andmunicipal wastewater sludge. The 16S rRNA gene concentration of the syntrophic b-oxidizing genusSyntrophomonas increased to ~15% of the Bacteria community in the codigester, but stayed below 3% inthe control digester that was fed only wastewater sludge. Methanosaeta and Methanospirillum were thedominant methanogenic genera enriched in the codigester, and together comprised over 80% of theArchaea community by the end of the experimental period. Constrained ordination showed that changesin the codigester Bacteria and Archaea community structures were related to measures of digester performance.Notably, the effluent LCFA concentration in the codigester was positively correlated to thespecific loading rate of waste oil normalized to the Syntrophomonas 16S rRNA concentration. Specificloading rates of 0e1.5 1012 g VS oil/16S gene copies-day resulted in LCFA concentrations below 30 mg/g TS, whereas LCFA accumulated up to 104 mg/g TS at higher transient loading rates. Based on thecommunity-dependent loading limitations found, enhanced biomethane production from high loadingsof fats, oils and greases can be achieved by promoting a higher biomass of slow-growing syntrophicconsortia, such as with longer digester solids retention times. This work also demonstrates the potentialfor controlling the loading rate of fats, oils, and greases based on the analysis of the codigester communitystructure, such as with quantitative PCR measurements of syntrophic LCFA-degrading bacteriaabundance.

  • 276.
    Zook, Alexander E
    et al.
    Department of Ecology and Evolution, University of Chicago, United States.
    Eklöf, Anna
    Department of Ecology and Evolution, University of Chicago, United States.
    Jacob, Ute
    Institute for Hydrobiologie and Fisheries Science, University Hamburg, Germany.
    Allesina, Stefano
    Department of Ecology and Evolution, University of Chicago, United States; Computation Institute, University of Chicago, United States.
    Food webs: ordering species according to body size yields high degree of intervality2011Inngår i: Journal of Theoretical Biology, ISSN 0022-5193, E-ISSN 1095-8541, Vol. 271, nr 1, s. 106-113Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Food webs, the networks describing "who eats whom" in an ecosystem, are nearly interval, i.e. there is a way to order the species so that almost all the resources of each consumer are adjacent in the ordering. This feature has important consequences, as it means that the structure of food webs can be described using a single (or few) species' traits. Moreover, exploiting the quasi-intervality found in empirical webs can help build better models for food web structure. Here we investigate which species trait is a good proxy for ordering the species to produce quasi-interval orderings. We find that body size produces a significant degree of intervality in almost all food webs analyzed, although it does not match the maximum intervality for the networks. There is also a great variability between webs. Other orderings based on trophic levels produce a lower level of intervality. Finally, we extend the concept of intervality from predator-centered (in which resources are in intervals) to prey-centered (in which consumers are in intervals). In this case as well we find that body size yields a significant, but not maximal, level of intervality. These results show that body size is an important, although not perfect, trait that shapes species interactions in food webs. This has important implications for the formulation of simple models used to construct realistic representations of food webs.

  • 277.
    Zupan, Manja
    et al.
    Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Box 7068, Uppsala, SE-750 07, Uppsala, Sweden.
    Buskas, Julia
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Altimiras, Jordi
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska fakulteten.
    Keeling, Linda J.
    Swedish University of Agricultural Sciences, Department of Animal Environment and Health, Box 7068, Uppsala, SE-750 07, Uppsala, Sweden.
    Assessing positive emotional states in dogs using heart rate and heartrate variability2016Inngår i: Physiology and Behavior, ISSN 0031-9384, E-ISSN 1873-507X, Vol. 155, s. 102-111Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Since most animal species have been recognized as sentient beings, emotional state may be a good indicator ofwelfare in animals. The goal of this study was to manipulate the environment of nine beagle research dogs tohighlight physiological responses indicative of different emotional experiences. Stimuli were selected to be amore or a less positive food (meatball or food pellet) or social reward (familiar person or less familiar person).That all the stimuli were positive and of different reward value was confirmed in a runway motivation test.Dogs were tested individually while standing facing a display theatre where the different stimuli could beshown by lifting a shutter. The dogs approached and remained voluntarily in the test system. They were testedin four sessions (of 20 s each) for each of the four stimuli. A test session consisted of four presentation phases(1st exposure to stimulus, post exposure, 2nd exposure, and access to reward). Heart rate (HR) and heart ratevariability (HRV) responses were recorded during testing in the experimental room and also when lying restingin a quiet familiar room. A newmethod of ‘stitching’ short periods of HRV data together was used in the analysis.When testing different stimuli, no significant differenceswere observed in HR and LF:HF ratio (relative power inlow frequency (LF) and the high-frequency (HF) range), implying that the sympathetic tone was activated similarlyfor all the stimuli and may suggest that dogs were in a state of positive arousal. A decrease of HF was associatedwith the meatball stimulus compared to the food pellet and the reward phase (interacting with the personor eating the food) was associated with a decrease in HF and RMSSD (root mean square of successive differencesof inter-beat intervals) compared to the preceding phase (looking at the person or food). This suggests that parasympatheticdeactivation is associated with a more positive emotional state in the dog. A similar reduction in HFandRMSSDwas found in the test situation compared to the resting situation. This is congruentwith the expectedautonomic effects related to postural shift i.e. sympathetic activation and parasympathetic withdrawal, duringstanding versus lying, but it cannot explain the parasympathetic deactivation in response to the more positivestimuli since the dogs were always standing in the test situation.Wediscuss the systematic pattern of responses,which support that increased HRand LF:HF ratio are associatedwithemotional arousal, but add the newproposalthat a combined decrease inRMSSD and HFmay reflect a more positively valencedemotional state evenwhen anindividual is already in a positive psychological state.

  • 278.
    Åberg, Elin
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Biologi. Linköpings universitet, Tekniska högskolan.
    Turbiditet som ersättningsmått för totalfosforhalt i kustmynnande vattendrag i Östergötland2014Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    Eutrophication is a major problem in the Baltic Sea, as a result of increased loading of nitrogen and phosphorus. In the coastal parts of Östergötland the soil largely consists of clay and contains high levels of phosphorus bound to clay particles. Erosion of the soil in agricultural areas makes the water turbid and transports phosphorus to the Baltic Sea. The aim of this project was to examine the relationship between phosphorus and turbidity in the coastal streams of Östergötland. The aim was also to evaluate the possibility to use turbidity as a surrogate measure for phosphorus. Water samples from 41 streams along the coast of Östergötland were collected once from each location 7 – 11 of April 2014. Variables examined were turbidity, total phosphorus, molybdate reactive phosphorus and water color (absorbance 420 nm). On average, particulate phosphorus made up 80 % of total phosphorus. The study showed a significant correlation between total phosphorus and turbidity (R2adj=0.879, P<0.01, linear regression). Water color was not correlated with total phosphorus. A multiple regression with turbidity and water color as independent variables resulted in a slightly improved model (R2adj = 0,886), but was regarded as not meaningful considering the additional efforts. The conclusion of the project is that is it possible to use turbidity as a surrogate measure in these streams. 

  • 279.
    Årevall, Jonatan
    Linköpings universitet, Institutionen för fysik, kemi och biologi.
    Klimatinducerade fenologiförändringar och dess effekter i näringsväven2011Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [en]

    The climate affects animal populations through several processes. These processes includereproduction, phenology and the success of hunting. By influencing the phenology of species theclimate also affects the way species interact. If a climate-induced phenology change promotes abasal species to bud earlier in the spring for example, this will affect the links to other species inthe food web due to a time lag in the tropic levels above. This dependence, that a predator has tobeing synchronous to its prey, is called the match/mismatch hypothesis (MMH). Studies haveindicated that species higher up in the food web adapt slower than species lower in the food webwith shorter generation times (which creates a temporal mismatch).A climate-induced phenology change in basal species could therefore be expected to affect thedensities and extinction rates of species higher up in the food web.In this study a declining conversion efficiency for predators was used to model the effects ofclimate change on triangular food webs with three trophic levels. This was done by using ageneralized Lotka-Volterra model. The results indicate that, in a food web with three trophiclevels, the densities of herbivores and carnivores drops in response to an increased change ofclimate. The extinction rates of carnivores also increase rapidly in response to an increasedclimate change.

  • 280.
    Årevall, Jonatan
    et al.
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Early, Regan
    Univ Exeter Penryn Campus, England.
    Estrada, Alba
    Oviedo Univ Campus Mieres, Spain.
    Wennergren, Uno
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Eklöf, Anna
    Linköpings universitet, Institutionen för fysik, kemi och biologi, Teoretisk Biologi. Linköpings universitet, Tekniska fakulteten.
    Conditions for successful range shifts under climate change: The role of species dispersal and landscape configuration2018Inngår i: Diversity & distributions: A journal of biological invasions and biodiversity, ISSN 1366-9516, E-ISSN 1472-4642, Vol. 24, nr 11, s. 1598-1611Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Aim: Ongoing climate change is currently modifying the geographical location of areas that are climatically suitable for species. Understanding a species ability to successfully shift its geographical range would allow us to assess extinction risks and predict future community compositions. We investigate how habitat configuration impedes or promotes climate-driven range shifts, given different speeds of climate change and dispersal abilities. Location: Theoretical, but illustrated with European examples. Methods: We model how a species ability to track a directional shift in climatic conditions is affected by (a) species dispersal abilities; (b) speed of climatic shift; and (c) spatial arrangement of the habitat. Our modelling framework includes within-and between-patch population dynamics and uses ecologically realistic habitat distributions and dispersal scenarios (verified with data from a set of European mammal species) and, as such, is an improvement of classical range shift models. Result: In landscapes with a homogeneous distribution of suitable habitats, all but the least dispersive species will be able to range shift. However, species with high dispersal ability will have lower population densities after range shift. In heterogeneous landscapes species ability to range shift is far more variable and heavily dependent on the habitat configuration. This means that landscape configuration in combination with the speed of climate change and species dispersal abilities give rise to nonlinear effects on population sizes and survival after a climatic shift. Main conclusions: Our analyses point out the importance of accounting for the interplay of species dispersal and the landscape configuration when estimating future climate impact on species. These results link ecologically important attributes of both species and their landscapes to outcomes of species range shift, and thereby long-term persistence of ecological communities.

  • 281.
    Åström, Therese
    Linköpings universitet, Institutionen för fysik, kemi och biologi. Linköpings universitet, Tekniska högskolan.
    Betydelsen av skogskontinuitet och egenskaper hos gran för förekomst av Lecanactis abietina2013Independent thesis Basic level (degree of Bachelor), 10,5 poäng / 16 hpOppgave
    Abstract [sv]

    Skyddandet av gamla skogar med höga naturvärden är en viktig del i bevarandet av den biologiska mångfalden. För att kunna lokalisera och kvalitetsbedöma skogar med höga naturvärden används signalarter. En av dessa signalarter är Lecanactis abietina, gammelgranslav. Syftet med denna studie är att identifiera vilka faktorer som påverkar förekomst av signalarten L. abietina och täckningsgraden av apothecier. Studien utfördes i Ycke, Ullstämma och Säby Västerskog, vilka är naturreservat av olika ålder i Linköpings kommun, Östergötlands län. I de studerade områdena undersöktes samtliga granar med en diameter över 5 cm. Granarnas diameter och skuggning mättes, vid förekomst av L. abietina undersöktes förekomsten av apothecier, lavens täckningsgrad, maxhöjd och i vilka väderstreck laven förekom. Ett mindre urval av granarna borrades och ålderbestämdes. Resultatet visar att faktorerna som påverkar förekomst av L. abietina och täckningsgraden av apothecier främst är, skoglig kontinuitet i området, samt granarnas diameter och ålder. Resultaten från denna studie styrker användandet av L. abietina som lämplig indikatorart i Östergötland då lavens förekomst och spridning tydligt  speglade skogens kontinuitet (störst förekomst i de äldsta reservaten) och trädens egenskaper. Studien visar även att enbart förekomst inte räcker för att påvisa skog med höga naturvärden, utan de viktigaste faktorerna var förekomst av fertil lav, lavens täckningsgrad och frekvens på granar. Studien visar även att bevarandet av skogar med lång kontinuitet och förekomst av stora och gamla träd är viktigt för förekomsten av L. abietina.

3456 251 - 281 of 281
RefereraExporteraLink til resultatlisten
Permanent link
Referera
Referensformat
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Annet format
Fler format
Språk
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Annet språk
Fler språk
Utmatningsformat
  • html
  • text
  • asciidoc
  • rtf