title: A heterogeneous landscape does not guarantee high crop pollination.
abstract: The expansion of pollinator-dependent crops, especially in the developing world, together with reports of worldwide pollinator declines, raises concern of possible yield gaps. Farmers directly reliant on pollination services for food supply often live in regions where our knowledge of pollination services is poor. In a manipulative experiment replicated at 23 sites across an Ethiopian agricultural landscape, we found poor pollination services and severe pollen limitation in a common oil crop. With supplementary pollination, the yield increased on average by 91%. Despite the heterogeneous agricultural matrix, we found a low bee abundance, which may explain poor pollination services. The variation in pollen limitation was unrelated to surrounding forest cover, local bee richness and bee abundance. While practices that commonly increase pollinators (restricted pesticide use, flower strips) are an integral part of the landscape, these elements are apparently insufficient. Management to increase pollination services is therefore in need of urgent investigation.
authors.affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden Department of Biology, Lund University, Sölvegatan 37, 223 62 Lund, Sweden ulrika.samnegard@su.se ulrika.samnegard@biol.lu.se.
authors.forename: Ulrika
authors.identifier: 0000-0002-3791-4688
authors.initials: U
authors.lastname: Samnegård
authors.affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: Peter A
authors.initials: PA
authors.lastname: Hambäck
authors.affiliation: Ethiopian Biodiversity Institute, Forest and Range Land Plant Biodiversity Directorate, PO Box 30726, Addis Ababa, Ethiopia.
authors.forename: Debissa
authors.initials: D
authors.lastname: Lemessa
authors.affiliation: Department of Plant Biology and Biodiversity Management, Addis Ababa University, PO Box 3434, Addis Ababa, Ethiopia.
authors.forename: Sileshi
authors.initials: S
authors.lastname: Nemomissa
authors.affiliation: Department of Ecology, Environment and Plant Sciences, Stockholm University, 106 91 Stockholm, Sweden.
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Hylander
mesh_terms: D000383:Agriculture / Q000379:methods*; D000818:Animals; D001516:Bees; D018556:Crops, Agricultural; D005002:Ethiopia; D035264:Flowers; D011058:Pollen; D054817:Pollination
keywords: Brassica napus; forest cover; landscape composition; pollination services; sub-Saharan Africa; yield gaps