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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Tillväxttakt hos sydsvenska populationer av trollsländor (Odonata) i ett varmare klimat - en pilotstudie.

Ceder, Patric, Jönsson, Christopher January 2017 (has links)
In order to gain better understanding of climate change effects on ecosystems, it is necessary to study the response of different species to predicted climate change. Dragonflies are, due to their ecology, a suitable organism group for conducting such studies. In this pilot study we examined the response in growth- and mortality rate to increased ambient temperatures in an experimental set-up of three temperature levels (20°C, 22°C och 24°C) in larvae of three species from the Aeshnidae family (Aeshna grandis, Aeshna cyanea and Anax imperator). A. imperator were, due to insufficient number of collected specimens, excluded in the 22°C temperature regime. The studied species are reproducing in Sweden, but A. grandis and A. cyanea are native, whereas A. imperator is considered newly established since it was first discovered in Sweden in the early 2000’s. Our results show that A. grandis and A. cyanea reacted positively to an increased ambient temperature, in terms of growth rates. However, the response to increased temperatures differed between the two species as A. grandis showed both higher growth- and mortality rate, compared to A. cyanea. Thus, we assume that both species are likely to benefit from the ongoing climate change, but that interactions between them may change. Further studies are required to elucidate how the two species will be affected in presence of newly established species, such as A. imperator. Although, based on our results, the competitiveness of both native species might increase with rising temperatures - which should be considered in future conservation planning.
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2

Aeshna viridis distribution and habitat choices in South and Central Sweden and the possibility to use a database as a tool in monitoring a threatened species

Andersen, Emelie January 2014 (has links)
Aeshna viridis, a dragonfly generally considered to be a specialist as it in most cases choosesStratiotes aloides as its habitat, have suffered badly from habitat loss and fragmentationsthroughout Europe under the last century as the human demand of land use have grown. It´sthereby considered near threatened on EU red list and is included in the Habitat Directive.This means that it is protected by EU law as all EU Member States is committed to protect,monitor and report back to EU the status of the species. Several European countries havedesigned protection plans for S. aloides to improve the preservation of A. viridis. My study inSouth and Central Sweden shows that the strong connection between A. viridis and S. aloidesmay not be consistent all over the distribution range of A. viridis, as my survey showed thatlarvae occur among other water plants when S. aloides is not present. Another aim in thisstudy was to evaluate the possibility to use occurrence data on A. viridis and S. aloides fromthe Species Observations System to monitor A. viridis distribution and dispersal. My studyimplies uncertainties of how well the datasets reflects reality and more research is necessarybefore clarifying if datasets could be a possible tool in conservation management of A. viridis.
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3

Sukzession, Struktur und Dynamik von Libellenpopulationen an Kleingewässern, unter besonderer Berücksichtigung der Ökologie von Aeshna cyanea (Müller, 1764) /

Inden-Lohmar, Christoph. January 1997 (has links)
Thesis (doctoral)--Rheinische Friedrich-Wilhelms-Universität zu Bonn, 1997.

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