| 1. |
- Bergman, Karl-Olof, et al.
(författare)
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Clear-cuts are temporary habitats, not matrix, for endangered grassland burnet moths (Zygaena spp.)
- 2020
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Ingår i: Journal of Insect Conservation. - : Springer Science and Business Media LLC. - 1366-638X .- 1572-9753. ; 24:2, s. 269-277
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Tidskriftsartikel (refereegranskat)abstract
- Burnet moths (Zygaena spp.) are day-flying Lepidoptera considered indicative of species-rich grasslands. In the present study, our aim was to clarify whether clear-cuts are habitat, supporting habitat or matrix for three species of Zygaena. We did so by sampling these species with sex pheromones on 48 clear-cuts, varying in amount of host and nectar plants, in southern Sweden. To compare the efficiency of such sampling, we also conducted transect walks on these clearcuts. Overall, host-plants on clear-cuts best explained the abundance of Zygaena spp. recorded, better than nectar-plants or connectivity with nearby grasslands. These results indicate that clear-cuts with an abundance of host plants are used as a fully functional habitat, and not a supporting habitat in the sense of only providing nectar. There is no support in these results for considering clear-cuts as an inert matrix. With about half the work-effort, pheromone traps recorded 100 times more Zygaena spp. as transect walks. The poor correspondence between observations during transects walks and pheromone trap catches suggest Zygaena spp. being difficult to monitor by transect walks. In contrast to grasslands, clear-cuts are short-term in nature requiring repeated recolonization, indicating the importance of permanent grasslands. However, clear-cuts are important temporary insect habitats due to their great acreage, and suitable management can increase the time they remain a habitat.
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| 2. |
- Blixt, Torbjörn, et al.
(författare)
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Clear-cuts in production forests: From matrix to neo-habitat forbutterflies
- 2015
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Ingår i: Acta Oecologica. - : Elsevier. - 1146-609X .- 1873-6238. ; 69, s. 71-77
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Tidskriftsartikel (refereegranskat)abstract
- Butterfly conservation in Europe is mainly focused on well-defined grassland habitat patches. Such anapproach ignores the impact of the surrounding landscape, which may contain complementary resourcesand facilitate dispersal. Here, we investigated butterfly species richness and abundance in a habitatnormally regarded as unsuitable matrix: production forestry clear-cuts. Butterflies were recorded in 48clear-cuts in southern Sweden differing with regards to the time since clear-cutting and land-use history(meadow or forest based on historical maps from the 1870s). All clear-cuts had been managed as productionforests for at least 80e120 years. A total of 39 species were found in clear-cuts of both land-usehistories, but clear-cuts with a history as meadow had on average 34% higher species richness and 19%higher abundance than did clear-cuts with a history as forest. No effect of the time since clear-cuttingwas found, irrespective of land-use history, which was likely due to the narrow timespan sampled (<8years). The absence of temporal effect suggests that clear-cuts may provide butterflies with valuableresources for 10e15 years. Assuming a 100 year forest rotational cycle, this means that 10e15% of thetotal forested area are made up by clear-cuts valuable to butterflies, which corresponds to an area aboutfour times as large as that of species-rich semi-natural grasslands. The study illustrates the importance ofconsidering land-use legacies in ecological research and question the landscape-ecological view thatclear-cuts make up an unsuitable matrix for butterflies. Moreover, forest conservation management withspecial attention to land-use history may increase the quality of the landscape, thus facilitating butterflymetapopulation persistence. Given their large area and assets of nectar and host plant resources, clearcutsmust be considered as a butterfly habitat in its own right. Being a man-made environment withshort history, we might call it a neo-habitat.
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| 3. |
- Jonason, Dennis, et al.
(författare)
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Assessing the effect of the time since transition to organic farming on plants and butterflies
- 2011
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Ingår i: Journal of Applied Ecology. - : Wiley. - 1365-2664 .- 0021-8901. ; 48:3, s. 543-550
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Tidskriftsartikel (refereegranskat)abstract
- P>1. Environmental changes may not always result in rapid changes in species distributions, abundances or diversity. In order to estimate the effects of, for example, land-use changes caused by agri-environment schemes (AES) on biodiversity and ecosystem services, information on the time-lag between the application of the scheme and the responses of organisms is essential. 2. We examined the effects of time since transition (TST) to organic farming on plant species richness and butterfly species richness and abundance. Surveys were conducted in cereal fields and adjacent field margins on 60 farms, 20 conventional and 40 organic, in two regions in Sweden. The organic farms were transferred from conventional management between 1 and 25 years before the survey took place. The farms were selected along a gradient of landscape complexity, indicated by the proportion of arable land, so that farms with similar TST were represented in all landscape types. Organism responses were assessed using model averaging. 3. Plant and butterfly species richness was c. 20% higher on organic farms and butterfly abundance was about 60% higher, compared with conventional farms. Time since transition affected butterfly abundance gradually over the 25-year period, resulting in a 100% increase. In contrast, no TST effect on plant or butterfly species richness was found, indicating that the main effect took place immediately after the transition to organic farming. 4. Increasing landscape complexity had a positive effect on butterfly species richness, but not on butterfly abundance or plant species richness. There was no indication that the speed of response to organic farming was affected by landscape complexity. 5. Synthesis and applications. The effect of organic farming on diversity was rapid for plant and butterfly species richness, whereas butterfly abundance increased gradually with time since transition. If time-lags in responses to AESs turn out to be common, long-term effects would need to be included in management recommendations and policy to capture the full potential of such schemes.
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| 4. |
- Jonason, Dennis, et al.
(författare)
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Field scale organic farming does not counteract landscape effects on butterfly trait composition
- 2012
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Ingår i: Agriculture, Ecosystems & Environment. - : Elsevier BV. - 1873-2305 .- 0167-8809. ; 158, s. 66-71
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Tidskriftsartikel (refereegranskat)abstract
- We tested how dispersal capacity, host plant specificity and reproductive rate influenced the effects of farming system and landscape composition on butterfly species richness and abundance. In no case did variation in these traits explain species responses to organic farming, indicating that all species benefit equally. In contrast, butterflies with high mobility and reproductive rate were disproportionally more abundant in landscapes dominated by arable land, and the species richness of butterflies with low mobility tended to decrease with increasing proportion of arable land whereas those of high mobility remained fairly constant. Hence, although organic farming increased biodiversity, it did not counteract landscape effects on butterfly trait composition. As a trait dependent loss of biodiversity may result in a larger decline of functional trait diversity compared to species diversity, these results imply that organic farming may not increase or restore functional agro-ecosystem diversity. Information provided by species traits, rather than biodiversity per se, may provide important information for successful revisions of future agri-environment schemes.
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| 5. |
- Jonason, Dennis, et al.
(författare)
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Land-use history exerts long-term effects on the clear-cut flora in boreonemoral Sweden
- 2016
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Ingår i: Applied Vegetation Science. - : WILEY-BLACKWELL. - 1402-2001 .- 1654-109X. ; 19:4, s. 634-643
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Tidskriftsartikel (refereegranskat)abstract
- QuestionsCan signs of 19th century grassland management, which can be observed in the flora immediately (2-4yrs) after clear-cutting in boreonemoral Sweden, still remain 4yrs later? Do the effects from the time since clear-cutting differ between forest and grassland plant species? LocationProvince of ostergotland, southern Sweden. MethodsTwelve contemporary clear-cut areas that were once meadows and 12 that were once forests were selected using land-use maps from the 1870s. Grasses and herbaceous plants were surveyed twice, once in 2009 and once in 2013 (2-4 and 6-8yrs after clear-cutting, respectively). Plant presence was recorded within 100 circular sample plots (radius 1m) placed evenly throughout each respective clear-cut area along transects spaced 25-m apart. The number of sample plots in which a species was present was taken as a measure of that species frequency. Random effects meta-analysis, odds ratios and ANCOVA were used to analyse species responses to clear-cutting over time. ResultsA total of 170 plant species were found in the study, of which 33 were classified as grassland indicator species and 31 as plants primarily confined to forests. Clear-cut areas with a history as meadowland had, on average, up to 64% higher total species richness and 110% more grassland indicator species than did clear-cut areas with a history as forest. The time since clear-cutting had no effect on total species richness. However, the odds of finding a grassland indicator species decreased with the time since clear-cutting, whereas the odds of finding a forest species increased. ConclusionsWe concluded that land-use history plays an important role in explaining the flora found in Swedish clear-cuts, and that its effects on species richness remain for a minimum of 8yrs after harvest (conservative estimate). This phenomenon highlights the importance of acknowledging land-use legacies in ecological research and conservation. Future studies should investigate various options for the promotion of grassland plants in clear-cuts with a history of grassland management while also acknowledging the potential conflicts between conservation and production. The results may pertain to other countries with similar land-use histories.
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| 6. |
- Jonason, Dennis, et al.
(författare)
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Landscape simplification promotes weed seed predation by carabid beetles (Coleoptera: Carabidae)
- 2013
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Ingår i: Landscape Ecology. - : Springer Science and Business Media LLC. - 1572-9761 .- 0921-2973. ; 28:3, s. 487-494
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Tidskriftsartikel (refereegranskat)abstract
- Weeds constitute major constraints for farmers by reducing crop yield and quality. However, weeds are managed effectively using herbicides, but this may cause harmful effects on human health and the environment. In an experiment on weed seed predation, we tested the biological control potential of carabid beetles to combat weeds in the absence of herbicides. Seeds from three common weed species were placed in cereal fields on conventional and organic farms located along a landscape complexity gradient (area annual crops within 1 km) in two distinct regions in Sweden. Carabid beetles were sampled in the same fields using pitfall traps. Neither carabid species richness nor seed removal was related to organic farming. Seed removal was significantly related to carabid species richness and both carabid species richness and seed removal was higher in landscapes with large total area of annual crops, although the evenness of the carabid communities was lower. The carabid genera with strongest positive relationship to seed removal differed between regions (Trechus in Uppland and Pterostichus in Scania), as did the preference for the different weed seed species. This study concludes that carabid species richness contributes to weed seed predation and that large scale landscape context explains more variation in the carabids' responses than local farming practices.
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| 7. |
- Jonason, Dennis
(författare)
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Monitoring of butterflies within a landscape context
- 2007
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Rapport (övrigt vetenskapligt/konstnärligt)abstract
- Monitoring of butterflies is most often only directed towards the grassland fauna. Species associated with other vegetation types, as well as the impact of the surrounding landscape, often become neglected. The aim with this study was, in contrast, to perform a novel landscape-based monitoring method for butterflies in diverse vegetation types and more specifically(i) evaluate the impact of environmental variables on butterfly abundance, (ii) compare the distribution of butterflies in different vegetation types and (iii) analyse and improve the monitoring method. Eight randomly placed study sites (750 m x 750 m) located in south eastern Sweden were used. The vegetation composition inside the squares had been assessed using aerial photos. Tree cover had largest impact on butterfly abundance with a negative linear relationship between abundance and increasing tree cover. Clear-cuts were the vegetation type harbouring the overall highest abundance and diversity of butterflies. In semi-natural grasslands, where the nationally-based monitoring of butterflies in Sweden currently is being performed, only 42% of the species were found, indicating a bias directed towards only a part of the species pool. The novel kind of monitoring presented here, using a landscape context, can, if performed regularly, increase our knowledge of how structural changes at landscape level affect butterflies and thereby improve the conservation efforts.
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| 8. |
- Jonason, Dennis, et al.
(författare)
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Monitoring of butterflies within a landscape context in south-eastern Sweden
- 2010
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Ingår i: JOURNAL FOR NATURE CONSERVATION. - : Elsevier Science B.V., Amsterdam. - 1617-1381. ; 18:1, s. 22-33
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Tidskriftsartikel (refereegranskat)abstract
- Monitoring of butterflies is often directed only towards grassland fauna. Species associated with other habitats, as well as the impact of the surrounding landscape, are often neglected. The aim with this study was, in contrast, to perform and evaluate a landscape-based monitoring method for butterflies in diverse habitats and more specifically to (i) evaluate the impact of environmental variables on butterfly abundance; (ii) compare the distribution of butterflies in different habitats; and (iii) analyse data from the study with the aim of improving the method. Eight randomly placed study sites (750 m x 750 m) located in south-eastern Sweden were used. The vegetation composition (tree cover, percentage of coniferous and deciduous forest, shrubs, dry, mesic, damp and wet land) inside the squares was analysed using aerial photos and habitats along transects were categorised in the field. The butterfly composition varied depending on the landscape composition. Tree cover had the largest impact on butterfly abundance with a negative relationship between abundance and increasing tree cover. The most species-rich habitats were other grasslands (abandoned fields and fallows), clear-cuts, semi-natural grasslands, and bogs, each habitat also harbouring unique species. Clear-cut was the habitat harbouring the highest abundance and other grasslands the highest diversity of butterflies. Semi-natural grasslands, where the nationally based monitoring of butterflies in Sweden currently is being performed, constitutes andlt;1% of the total land area in Sweden, indicating a current bias in monitoring directed towards only a part of the species pool. The landscape-based form of monitoring presented here can, if performed regularly, increase our knowledge of how structural changes of landscape affect butterflies and thereby improve conservation efforts.
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| 9. |
- Jonason, Dennis, et al.
(författare)
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Surveying Moths Using Light Traps: Effects of Weather and Time of Year
- 2014
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Ingår i: PLOS ONE. - : Public Library of Science. - 1932-6203. ; 9:3, s. 0092453-
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Tidskriftsartikel (refereegranskat)abstract
- Light trapping is an ideal method for surveying nocturnal moths, but in the absence of standardised survey methods effects of confounding factors may impede interpretation of the acquired data. We explored the influence of weather, time of year, and light source on nightly catches of macro moths in light traps, and compared four strategies for sampling by estimating observed species richness using rarefaction. We operated two traps with different light sources for 225 consecutive nights from mid-March to the end of October in eastern Germany in 2011. In total, 49 472 individuals of 372 species were recorded. Species richness and abundance per night were mainly influenced by night temperature, humidity and lamp type. With a limited sample size (less than10 nights) it was slightly better to concentrate sampling on the warmest summer nights, but with more sampling nights it was slightly better to sample during the warmest nights in each month (March to October). By exploiting the higher moth activity during warm nights and an understanding of the species phenology, it is possible to increase the number of species caught and reduce effects of confounding abiotic factors.
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| 10. |
- Jonason, Dennis
(författare)
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Temporal effects of organic farming on biodiversity and ecosystem services
- 2012
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Agricultural intensification has caused a dramatic decline of global biodiversity and associated ecosystem services. Organic farming has been shown to partially counteract agricultural intensification by applying environmentally friendly and resource efficient farming practices, but opportunities to improve in efficiency still remain. This thesis investigates the contribution of organic farming to biodiversity and ecosystem services with focus on the effect of the time since transition (TST) to organic farming methods. Surveys on butterflies, plants, moths, carabid beetles and an experimental study on weed seed predation were performed on conventional and organic farms situated in landscapes differing in landscape complexity. The organic farms had been under organic management between 1 and 25 years before surveys. This design allowed for analyzes of the effect of organic farming while accounting for the time since transition and landscape composition. The overall effect of organic farming was small. Only butterflies and plants (in one out of two studies) had higher species richness and abundance on organic compared to conventional farms. However, analyses of the time since transition to organic farming revealed novel facts: butterfly abundance increased gradually by 100% over 25 years, whereas butterfly and plant species richness increased rapidly at the transition and then remained fairly constant. The moths that initially did not appear to increase in the organic farming system showed a clear positive response to newly transitioned farms (TST≤6 years), whereas conventional and old organic farms (TST≥15 years) had similar diversity. Two plant species occurred more frequently on new organic farms and two species on old organic farms. Neither carabids nor seed predation showed any temporal responses to organic farming. This thesis shows that explicitly addressing temporal effects of organic farming may result in novel and unexpected findings. Control for temporal effects opens up for better understanding of the complexities between organic farming, biodiversity and ecosystem services over time. Future evaluations need to address this factor for high credibility and usefulness in the development of improved policies for organic farming.
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