| 1. |
- 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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| 2. |
- 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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| 3. |
- 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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