| 1. |
- Andersson, Petter, et al.
(författare)
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Roads may act as barriers to flying insects : Species composition of bees and wasps differs on two sides of a large highway
- 2017
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Ingår i: Nature Conservation. - : Pensoft Publishers. - 1314-6947 .- 1314-3301. ; 18, s. 47-59
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Tidskriftsartikel (refereegranskat)abstract
- Roads may act as barriers to animal movements, but direct barrier effects on insects have rarely been studied. In this study we collected data on bees and wasps along two sides of a large road in Sweden using yellow pan traps. We then analyzed if the species composition differed between the two sides of the road; first for the whole community, and then only for the smallest species (which typically are poorer dispersers). As a complement, we analyzed if different vegetation variables differed between the two sides of the road, as this may also affect differences in species composition. Finally, we analyzed if species richness and abundance in general differed between the two sides and how these two response variables were explained by the vegetation variables. There was a significant difference in species composition between the eastern and the western side of the road when analyzing the whole community, and this relationship became even stronger when the largest species were excluded. The vegetation variables did not strongly differ between the two sides, and there was no difference in species richness and abundance of bees and wasps either. Abundance was, however, explained by the number of flowering plants in the surroundings of the trap. Even though using a rather limited data set, our results indicate that large roads may act as barriers on the movement of bees and wasps, especially for small species with poor dispersal ability. On the other hand, road verges may be important habitat for many species, which leads to a potential conflict that is important to consider in the planning of green infrastructure.
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| 2. |
- Johansson, Victor, et al.
(författare)
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Estimates of accessible food resources for pollinators in urban landscapes should take landscape friction into account
- 2018
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Ingår i: Ecosphere. - : John Wiley & Sons. - 2150-8925 .- 2150-8925. ; 9:10
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Tidskriftsartikel (refereegranskat)abstract
- Maintaining biodiversity in urban landscapes requires a well-functioning green infrastructure for the landscape to remain ecologically functional. However, city planners often lack knowledge to identify how well different parts of the green infrastructure are connected, and tools to estimate the accessibility to important habitats for different species in urban areas are strongly needed. We compared the ability of three measures of available food resources, with increasing complexity, for explaining species richness and abundance of bees and wasps at 23 locations in an urban landscape in Sweden. Specifically, we tested (1) the summed amount of food habitat within a buffer circle, (2) the amount of food habitat weighted by distance, and (3) the summed amount of food habitat within an area created by cost-weighted distance based on the surrounding landscape friction. We tested two spatial scales (200 and 400 m). The results show that both the summed (1) and the weighted measures (2) were very poor in explaining species richness and abundance regardless of spatial scale, while we found significant relationships for both species richness and abundance with the friction-based measure (3) at both scales. For the friction-based measure, the relationships with both response variables were strongest at the smallest spatial scale (200 m). We conclude that bees and wasps are sensitive to barriers such as large roads and built-up areas when foraging in urban environments. This is important to consider when assessing the functionality of urban green infrastructure in order to not overestimate the available amount of habitat and how well different parts of the landscape are connected for these important pollinators.
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| 3. |
- Tibell, Leif, et al.
(författare)
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Chaenotheca nitidula, a New Species of Calicioid Lichen from North America
- 2002
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Ingår i: The Bryologist. - 0007-2745 .- 1938-4378. ; 105:3, s. 353-357
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Tidskriftsartikel (refereegranskat)abstract
- Chaenotheca nitidula is described as a new species from northeastern North America. It is characterized by long, shining stalks; rather small, spheric, non-pruinose capitul; immersed thallus; and its association with Stichococcus as photobiont. In a phylogenetic analysis based on rDNA ITS1-5.8S-ITS2 sequences, C. nitidula was most closely related to Chaenotheca gracilenta and C. gracillima. It occurs on wood of conifers in old woodlands and has so far been recorded from Maine and New Brunswick.
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