| 1. |
- Herbertsson, Lina, et al.
(författare)
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Bees increase seed set of wild plants while the proportion of arable land has a variable effect on pollination in European agricultural landscapes
- 2021
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Ingår i: Plant Ecology and Evolution. - : Societe Royale de Botanique de Belgique. - 2032-3913 .- 2032-3921. ; 154:3, s. 341-350
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Tidskriftsartikel (refereegranskat)abstract
- Background and aims: Agricultural intensification and loss of farmland heterogeneity have contributed to population declines of wild bees and other pollinators, which may have caused subsequent declines in insect-pollinated wild plants.Material and methods: Using data from 37 studies on 22 pollinator-dependent wild plant species across Europe, we investigated whether flower visitation and seed set of insect-pollinated plants decline with an increasing proportion of arable land within 1 km.Key results: Seed set increased with increasing flower visitation by bees, most of which were wild bees, but not with increasing flower visitation by other insects. Increasing proportion of arable land had a strongly variable effect on seed set and flower visitation by bees across studies.Conclusion:Factors such as landscape configuration, local habitat quality, and temporally changing resource availability (e.g. due to mass-flowering crops or honey bee hives) could have modified the effect of arable land on pollination. While our results highlight that the persistence of wild bees is crucial to maintain plant diversity, we also show that pollen limitation due to declining bee populations in homogenized agricultural landscapes is not a universal driver causing parallel losses of bees and insect-pollinated plants.
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| 2. |
- Senapathi, Deepa, et al.
(författare)
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Wild insect diversity increases inter-annual stability in global crop pollinator communities
- 2021
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Ingår i: Royal Society of London. Proceedings B. Biological Sciences. - : The Royal Society. - 1471-2954 .- 0962-8452. ; 288:1947
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Tidskriftsartikel (refereegranskat)abstract
- While an increasing number of studies indicate that the range, diversity and abundance of many wild pollinators has declined, the global area of pollinator-dependent crops has significantly increased over the last few decades. Crop pollination studies to date have mainly focused on either identifying different guilds pollinating various crops, or on factors driving spatial changes and turnover observed in these communities. The mechanisms driving temporal stability for ecosystem functioning and services, however, remain poorly understood. Our study quantifies temporal variability observed in crop pollinators in 21 different crops across multiple years at a global scale. Using data from 43 studies from six continents, we show that (i) higher pollinator diversity confers greater inter-annual stability in pollinator communities, (ii) temporal variation observed in pollinator abundance is primarily driven by the three-most dominant species, and (iii) crops in tropical regions demonstrate higher inter-annual variability in pollinator species richness than crops in temperate regions. We highlight the importance of recognizing wild pollinator diversity in agricultural landscapes to stabilize pollinator persistence across years to protect both biodiversity and crop pollination services. Short-term agricultural management practices aimed at dominant species for stabilizing pollination services need to be considered alongside longer term conservation goals focussed on maintaining and facilitating biodiversity to confer ecological stability.
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| 3. |
- Blasi, Maria, et al.
(författare)
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Evaluating predictive performance of statistical models explaining wild bee abundance in a mass-flowering crop
- 2021
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Ingår i: Ecography. - : Wiley. - 0906-7590 .- 1600-0587. ; 44:4, s. 525-536
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Tidskriftsartikel (refereegranskat)abstract
- Wild bee populations are threatened by current agricultural practices in many parts of the world, which may put pollination services and crop yields at risk. Loss of pollination services can potentially be predicted by models that link bee abundances with landscape-scale land-use, but there is little knowledge on the degree to which these statistical models are transferable across time and space. This study assesses the transferability of models for wild bee abundance in a mass-flowering crop across space (from one region to another) and across time (from one year to another). The models used existing data on bumblebee and solitary bee abundance in winter oilseed rape fields, together with high-resolution land-use crop-cover and semi-natural habitats data, from studies conducted in five different regions located in four countries (Sweden, Germany, Netherlands and the UK), in three different years (2011, 2012, 2013). We developed a hierarchical model combining all studies and evaluated the transferability using cross-validation. We found that both the landscape-scale cover of mass-flowering crops and permanent semi-natural habitats, including grasslands and forests, are important drivers of wild bee abundance in all regions. However, while the negative effect of increasing mass-flowering crops on the density of the pollinators is consistent between studies, the direction of the effect of semi-natural habitat is variable between studies. The transferability of these statistical models is limited, especially across regions, but also across time. Our study demonstrates the limits of using statistical models in conjunction with widely available land-use crop-cover classes for extrapolating pollinator density across years and regions, likely in part because input variables such as cover of semi-natural habitats poorly capture variability in pollinator resources between regions and years.
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| 4. |
- Sidemo-Holm, William, et al.
(författare)
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Reduced crop density increases floral resources to pollinators without affecting crop yield in organic and conventional fields
- 2021
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Ingår i: Journal of Applied Ecology. - : Wiley. - 0021-8901 .- 1365-2664. ; 58:7, s. 1421-1430
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Tidskriftsartikel (refereegranskat)abstract
- Effective weed control in agricultural crop fields increases yields, but simultaneously reduces floral resources for pollinators because many weed species provide pollen and nectar. Consequently, efforts to enhance crop yields on organic farms by using effective weed control methods risk compromising positive effects of organic farming on pollinating insects. Thus, it is important to find management strategies that alleviate the trade-off between crop yields and flowering weeds on organic farms. We investigated the relationship between cereal yields, flowering weeds and bumblebees on organic and conventional arable land. We also investigated the potential of adjusting crop sowing density to benefit flowering weed species richness and floral resources to bumblebees without affecting crop yield. Floral resources and species richness of flowering weeds were higher in organic compared to conventional fields and were negatively related to crop yield in organic but not conventional fields (where the variation of floral resources and flowering weed species richness was comparatively low). Bumblebee species richness was higher in organic compared to conventional fields, and abundance was twice as high in organic as in conventional fields, but not significantly so. Yields in organic fields were two thirds of those in conventional fields. When simultaneously testing the effect of farming type (organic vs. conventional), crop yield and floral resources, only floral resources were related significantly to bumblebee abundance and species richness. A lower sowing density of the crop increased floral resources without negatively affecting crop yield. Synthesis and applications. We show that organic farming practices in cereals benefit bumblebees by allowing more flowering weeds, but at a cost in terms of lower yields. However, adjusting crop sowing density provides an opportunity to attain increased floral resources without negatively affecting crop yields. Thus, by increasing floral resources, adjusting crop sowing density may contribute to supporting high bumblebee densities, which in turn sustain pollination services to wild plants and insect-pollinated crops, such as oilseed rape and field beans, in agricultural landscapes. We suggest that sowing strategies have the potential to contribute to ecological intensification by supporting organisms that provide ecosystem services to agriculture.
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