| 1. |
- Carrié, Romain, et al.
(author)
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Bee diversity in crop fields is influenced by remotely-sensed nesting resources in surrounding permanent grasslands
- 2018
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In: Ecological Indicators. - : Elsevier BV. - 1470-160X. ; 90, s. 606-614
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Journal article (peer-reviewed)abstract
- Landscape heterogeneity is an important driver of biodiversity in agroecosystems. However, the functional heterogeneity of agricultural landscapes, taking into account the different resources that habitat patches can provide to species, has rarely been studied. In this study, we explored the effect of landscape-scale nest availability provided by permanent grasslands on wild bee communities. Wild bees were sampled in 43 cereal fields in south-western France differing in the surrounding proportion of permanent grasslands. Using remote sensing tools, we measured two parameters of grassland structure known to locally influence bee nest density (slope and proportion of sparse vegetation). We found that mean slope of surrounding grasslands was the factor that most positively influenced bee richness, abundance and trait distribution in bee communities. We also found that mean slope of surrounding grasslands had a better predictive power of bee community structure than the proportion of permanent grasslands. Ground-nesting species, species with high dispersal capacities and species with a generalist diet were positively affected by the availability of sloped ground in the surrounding permanent grasslands. Only bee species with specialized flower requirements responded positively to the proportion of sparse vegetation in grasslands. Our results suggest that landscape-scale availability of nesting resources provided by grasslands affects bee communities in agricultural landscapes and can help sustain functionally diverse bee assemblages. Using simple remote sensing tools, this study highlights the importance of considering nesting resources in agricultural landscapes to maintain wild bee diversity in farmlands.
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| 2. |
- Rivers-Moore, Justine, et al.
(author)
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Contrasting effects of wooded and herbaceous semi-natural habitats on supporting wild bee diversity
- 2023
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In: Agriculture, Ecosystems and Environment. - 0167-8809. ; 356
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Journal article (peer-reviewed)abstract
- The use of pesticides and the lack of resources caused by the simplification of landscapes are often cited as the main drivers of the loss of wild bees. Landscape complexity has been shown to interact with local pesticide use in studies of the effect of these factors on the abundance and diversity of insects. But, to date, few studies have simultaneously investigated local and landscape effects on wild bees using more precise descriptors of the landscape and of farming practices. The aim of the present study was thus to disentangle the effects of landscape composition and farming practices on the taxonomic and functional diversity of wild bees and their possible consequences for pollination potential. We analysed a dataset of 107 crops at whose edges wild bees were captured between 2013 and 2019. Pesticide treatments of each crop were recorded throughout the year. At the landscape level, the proportions of different types of land use were calculated in a circle with a radius of 500 m. We caught 1536 wild bees belonging to 86 species and, using generalized mixed modelling, found that the number of insecticide applications had a negative effect on wild bee abundance and richness, while forest cover within a 500-m radius had a positive effect on wild bees whatever the farming practices. However, we also showed that the effect of the proportion of permanent grasslands on taxonomic and functional diversity of wild bees differed depending on the use of fungicides in the field. Finally, we found a negative effect of the number of herbicide applications on pollination potential. This study advances our understanding of the contrasting but complementary roles of diverse semi-natural habitats in agricultural landscapes in supporting wild bee diversity and which, under certain conditions, may buffer the detrimental consequences of pesticide use.
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| 3. |
- Sirami, Clélia, et al.
(author)
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Increasing crop heterogeneity enhances multitrophic diversity across agricultural regions
- 2019
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In: Proceedings of the National Academy of Sciences of the United States of America. - : Proceedings of the National Academy of Sciences. - 0027-8424 .- 1091-6490. ; 116:33, s. 16442-16447
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Journal article (peer-reviewed)abstract
- Agricultural landscape homogenization has detrimental effects on biodiversity and key ecosystem services. Increasing agricultural landscape heterogeneity by increasing seminatural cover can help to mitigate biodiversity loss. However, the amount of seminatural cover is generally low and difficult to increase in many intensively managed agricultural landscapes. We hypothesized that increasing the heterogeneity of the crop mosaic itself (hereafter “crop heterogeneity”) can also have positive effects on biodiversity. In 8 contrasting regions of Europe and North America, we selected 435 landscapes along independent gradients of crop diversity and mean field size. Within each landscape, we selected 3 sampling sites in 1, 2, or 3 crop types. We sampled 7 taxa (plants, bees, butterflies, hoverflies, carabids, spiders, and birds) and calculated a synthetic index of multitrophic diversity at the landscape level. Increasing crop heterogeneity was more beneficial for multitrophic diversity than increasing seminatural cover. For instance, the effect of decreasing mean field size from 5 to 2.8 ha was as strong as the effect of increasing seminatural cover from 0.5 to 11%. Decreasing mean field size benefited multitrophic diversity even in the absence of seminatural vegetation between fields. Increasing the number of crop types sampled had a positive effect on landscape-level multitrophic diversity. However, the effect of increasing crop diversity in the landscape surrounding fields sampled depended on the amount of seminatural cover. Our study provides large-scale, multitrophic, cross-regional evidence that increasing crop heterogeneity can be an effective way to increase biodiversity in agricultural landscapes without taking land out of agricultural production.
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