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- Schäfer, Martina, et al.
(författare)
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Influence of landscape structure on mosquitoes (Diptera : Culicidae) and dytiscids (Coleoptera
- 2006
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Ingår i: Wetlands (Wilmington, N.C.). - 0277-5212 .- 1943-6246. ; 26:1, s. 57-68
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Patterns of species diversity and community structure depend on scales larger than just a single habitat and might be influenced by the surrounding landscape. We studied the response of two insect families, mosquitoes (Diptera: Culicidae) and dytiscids (Coleoptera: Dytiscidae), to landscape variables at five spatial scales. We studied adult mosquito and dytiscid abundance, diversity, and species assemblages in relation to water permanence (area of permanent water bodies versus temporary wetlands) and forest cover (area covered by forest versus open land) within nested circles of 100 to 3000 m around trap sites in four wetlands in southern Sweden and in five wetlands in central Sweden. We found that mosquito abundance was greatest in areas with plentiful forest cover and a high proportion of temporary water, while most dytiscids favored open areas with a high proportion of permanent wetlands. However, diversity of both mosquitoes and dytiscids was positively correlated with high permanence and little forest cover. Mosquito species assemblages were mainly influenced by forest cover at a large spatial scale, whereas permanence was more important at local scales. Dytiscid species assemblages were mainly influenced by water permanence, especially at intermediate spatial scales. These results can be explained by the flight capability and dispersal behavior of mosquito and dytiscid species. The observed landscape associations of mosquitoes and dytiscids could be useful when creating new wetlands. Mosquito colonization could be reduced by creating permanent wetlands in an open landscape, which would favor colonization by dytiscids, a potential predator of mosquito larvae, while also supporting the diversity of both taxa.
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| 5. |
- Bergman, Karl-Olof, 1965-, et al.
(författare)
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Distribution of occupied and vacant sites and migration of Lopinga achine (Nymphalidae : Satyrinae) in a fragmented landscape
- 2001
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Ingår i: Biological Conservation. - 0006-3207 .- 1873-2917. ; 102:2, s. 183-190
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Tidskriftsartikel (refereegranskat)abstract
- The distribution of occupied and vacant sites and migration of the threatened butterfly Lopinga achine were studied in the province of ╓sterg÷tland, Sweden. The probability of occupation increased with increasing patch area and decreasing distance to the nearest occupied patch, presumably due to different probabilities of colonisation and survival of the populations inhabiting the patches. Probability of female emigration from and immigration to a patch increased with decreasing area. Middle-sized patches produced the largest number of female migrants, although the highest fraction was noted for the smallest patches, and the greatest number of females was marked in the largest patch. The fraction of resident females, but not males, increased with increasing area. The observed occupancy and migration pattern have important conservation implications: all but two populations comprising three or more individuals were within 740 m of the nearest neighbour, indicating the need for networks of suitable, closely situated patches. ⌐ 2001 Elsevier Science Ltd. All rights reserved.
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| 6. |
- Bergman, Karl-Olof, 1965-, et al.
(författare)
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Population structure and movements of a threatened butterfly (Lopinga achine) in a fragmented landscape in Sweden
- 2002
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Ingår i: Biological Conservation. - 0006-3207 .- 1873-2917. ; 108:3, s. 361-369
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Tidskriftsartikel (refereegranskat)abstract
- The red-listed butterfly Lopinga achine was studied by mark-recapture methods in southern Sweden for three seasons. We examined movement within and between populations and egg production in relation to age. The majority of the movements were small with mean movements between recaptures of 45-54 m for males and 94-116 m for females. There were few movements between sites, 20 of 996 recaptured males moved and 36 of 391 recaptured females, even though the distance to other sites was in many cases < 100 m. The distance moved and the number of females moving between sites increased with increasing age. On average, a female that moves does so after laying two-thirds of its eggs in its natal site. It is therefore important to take account of the proportion of reproductive effort involved in dispersal when estimating colonisation ability. The males did not move more with increasing age. Female behaviour can be seen as a "spread-the-risk" strategy, an adaptation to the successional habitat of L. achine, whose natal site sooner or later will deteriorate. Butterflies like L. achine living in successional habitats may exhibit mobility that is intermediate between butterflies living in ephemeral habitats (very mobile) and in long-lived habitats (sedentary). ⌐ 2002 Elsevier Science Ltd. All rights reserved.
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| 9. |
- Lundkvist, Elisabeth, 1970-, et al.
(författare)
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Diving beetle (Dytiscidae) assemblages along environmental gradients in an agricultural landscape in Southeastern Sweden
- 2001
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Ingår i: Wetlands (Wilmington, N.C.). - : Wiley. - 0277-5212 .- 1943-6246. ; 21:1, s. 48-58
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Tidskriftsartikel (refereegranskat)abstract
- We investigated diving beetle (Dytiscidae) assemblages in twelve wetlands in an agricultural landscape in southeastern Sweden. Beetles were trapped in wetlands that varied in permanence (temporary or permanent), area (25 to 4,800 m2), age (11 to >50 yr), and shading (open to wooded surroundings). Our objective was to determine if those environmental factors are important in structuring the local assemblages of diving beetles and how the combination of different types of wetlands influence the diversity of diving beetles in a landscape. Generally, species-area relationships were weak, and shaded wetlands, both permanent and temporary, of intermediate size (240-1,100 m2) had the highest richness after a rarefaction analysis. It was not possible to discern a certain type of wetland where diversity was highest (measured by index a and Shannon-Wiener's index), although, again, intermediate sized wetlands did tend to be more diverse than others. Similarities in species compositions were highest among environmentally similar wetlands, and assemblage structure differed substantially between different types of wetlands. Results of ordination (CCA) and variance partitioning revealed that permanence and degree of shading were the most important factors in structuring assemblages. Our findings imply that high diversity of the diving beetles depends on the number of wetland types represented in a landscape. It is possible to achieve high diversity in a small area by combining permanent and temporary wetlands, as well as many age and successional stages, located in wooded and open environments.
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