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Pollinators face multiple pressures and there is evidence of populations in decline. As demand for insect-pollinated crops increases, crop production is threatened by shortfalls in pollination services. Understanding the extent of current yield deficits due to pollination and identifying opportunities to protect or improve crop yield and quality through pollination management is therefore of international importance. To explore the extent of "pollination deficits," where maximum yield is not being achieved due to insufficient pollination, we used an extensive dataset on a globally important crop, apples. We quantified how these deficits vary between orchards and countries and we compared "pollinator dependence" across different apple varieties. We found evidence of pollination deficits and, in some cases, risks of overpollination were even apparent for which fruit quality could be reduced by too much pollination. In almost all regions studied we found some orchards performing significantly better than others in terms of avoiding a pollination deficit and crop yield shortfalls due to suboptimal pollination. This represents an opportunity to improve production through better pollinator and crop management. Our findings also demonstrated that pollinator dependence varies considerably between apple varieties in terms of fruit number and fruit quality. We propose that assessments of pollination service and deficits in crops can be used to quantify supply and demand for pollinators and help to target local management to address deficits although crop variety has a strong influence on the role of pollinators. ; This project was funded by the Sustainable Pollination in Europe Super-B COST Action (FA1307), Project Kennisimpuls Bestuivers (funded by the Dutch Ministry of Agriculture, Nature and Food Quality; BO-43-011.06-007), BBSRC, Defra, NERC, the Scottish Government and the Wellcome Trust, under the Insect Pollinators Initiative (BB/I000348/1), the "Sustainable Management of Orchard Pollination Services" Project (BB/P003664/1), the Stapledon Memorial Trust, the Volkswagen Foundation "Identifying functional pollinator biodiversity and threats to its decline in Georgia and Kyrgyzstan" (AZ: 86880), Georgian National Science Foundation "Functional pollinator biodiversity and their number, decline and threats in Georgia" (DO/372/10-101/14), the NKFIH project (FK123813), the Bolyai János Fellowship of the MTA, the ÚNKP-19-4-SZIE-3 New National Excellence Program of the Ministry for Innovation and Technology, the Hungarian Scientific Research Fund OTKA 101940, Northern Ireland Department of Agriculture and Rural Affairs, BiodivERsA/FACCE-JPI (agreement# BiodivERsA-FACCE2014-74) EcoFruit project, Swedish Research Council Formas (grant# 2014-1784), German Federal Ministry of Education and Research (PT-DLR/BMBF) (grant# 01LC1403), the Spanish Ministerio de Economía y Competitividad (MINECO) (project# PCIN-2014-145-C02), The Worshipful Company of Fruiterers, Natural Science and Engineering Research Council of Canada and the Fonds de recherche nature et technologies du Québec, Hort Innovation Pollination Fund project PH15001: Healthy bee populations for sustainable pollination in horticulture, Smith Lever and Hatch Funds administered by Cornell University Agricultural Experiment Station and by a USDA-AFRI grant (USDA 2010-03689, B.N. Danforth, PI), the Walloon Region (Belgium) Direction générale opérationnelle de l'Agriculture, des Ressources naturelles et de l'Environnement (DGO3) for the Modèle permaculturel project on biodiversity in micro-farms, FNRS/FWO joint program EOS—Excellence Of Science CliPS: Climate change and its impact on Pollination Services (project 30947854), MinECo and FEDER (INIA-RTA2013-00139-C03-01), Formas (grant #2014-1784), Sainsbury's Supermarkets Ltd (BB/K012843/1) and RR acknowledges the receipt of a fellowship from OECD Co-operative Research Programme: Biological Resource Management for Sustainable Agricultural Systems in 2016

In order to predict which ecosystem functions are most at risk from biodiversity loss, meta-analyses have generalised results from biodiversity experiments over different sites and ecosystem types. In contrast, comparing the strength of biodiversity effects across a large number of ecosystem processes measured in a single experiment permits more direct comparisons. Here, we present an analysis of 418 separate measures of 38 ecosystem processes. Overall, 45 % of processes were significantly affected by plant species richness, suggesting that, while diversity affects a large number of processes not all respond to biodiversity. We therefore compared the strength of plant diversity effects between different categories of ecosystem processes, grouping processes according to the year of measurement, their biogeochemical cycle, trophic level and compartment (above- or belowground) and according to whether they were measures of biodiversity or other ecosystem processes, biotic or abiotic and static or dynamic. Overall, and for several individual processes, we found that biodiversity effects became stronger over time. Measures of the carbon cycle were also affected more strongly by plant species richness than were the measures associated with the nitrogen cycle. Further, we found greater plant species richness effects on measures of biodiversity than on other processes. The differential effects of plant diversity on the various types of ecosystem processes indicate that future research and political effort should shift from a general debate about whether biodiversity loss impairs ecosystem functions to focussing on the specific functions of interest and ways to preserve them individually or in combination.