A systems approach reveals urban pollinator hotspots and conservation opportunities

Article metrics


Urban areas are often perceived to have lower biodiversity than the wider countryside, but a few small-scale studies suggest that some urban land uses can support substantial pollinator populations. We present a large-scale, well-replicated study of floral resources and pollinators in 360 sites incorporating all major land uses in four British cities. Using a systems approach, we developed Bayesian network models integrating pollinator dispersal and resource switching to estimate city-scale effects of management interventions on plant–pollinator community robustness to species loss. We show that residential gardens and allotments (community gardens) are pollinator ‘hotspots’: gardens due to their extensive area, and allotments due to their high pollinator diversity and leverage on city-scale plant–pollinator community robustness. Household income was positively associated with pollinator abundance in gardens, highlighting the influence of socioeconomic factors. Our results underpin urban planning recommendations to enhance pollinator conservation, using increasing city-scale community robustness as our measure of success.

Access options

Rent or Buy article

Get time limited or full article access on ReadCube.


All prices are NET prices.

Fig. 1: Pollinator abundance and richness for the nine urban land uses in four cities.
Fig. 2: Floral abundance and richness for the nine urban land uses in four cities.
Fig. 3: Land use proportions and estimated numbers of pollinators per land use at a city scale for four cities.
Fig. 4: Heat maps of estimated city-scale floral and pollinator abundances.
Fig. 5: Predicted increase in city-scale plant–pollinator network robustness for two management strategies.

Code availability

The modelling code used in the robustness models is available upon request from the corresponding author.

Data availability

The data that support the findings of this study are available within the article and Supplementary Information (see Supplementary Tables 19 and Supplementary Data 15). Supplementary Data 1 contains pollinator and floral abundance and richness data that support Figs. 1 and 2. Supplementary Data 2 contains data used in the socioeconomic analyses. The data used in the floral null model analyses are presented in Supplementary Data 3, and the model outputs are summarized in Supplementary Tables 7 and 8. Supplementary Data 4 contains data used in Figs. 3 and 4 as well as Supplementary Figs. 35. Supplementary Data 5 contains data used in the robustness models.


  1. 1.

    Dicks, L. V. et al. Ten policies for pollinators. Science 354, 975–976 (2016).

  2. 2.

    Potts, S. G. et al. Safeguarding pollinators and their values to human well-being. Nature 540, 220–229 (2016).

  3. 3.

    IPBES. The Assessment Report of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services on Pollinators, Pollination and Food Production. (eds Potts, S. G., Imperatriz-Fonseca, V. L. & Ngo, H. T.) (Secretariat of the Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services, Bonn, Germany, 2016).

  4. 4.

    Ollerton, J., Erenler, H., Edwards, M. & Crockett, R. Extinctions of aculeate pollinators in Britain and the role of large-scale agricultural changes. Science 346, 1360–1362 (2014).

  5. 5.

    Knop, E. et al. Artificial light as a new threat to pollination. Nature 548, 206–209 (2017).

  6. 6.

    Seto, K. C., Guneralp, B. & Hutyra, L. R. Global forecasts of urban expansion to 2030 and direct impacts on biodiversity and carbon pools. Proc. Natl Acad. Sci. USA 109, 16083–16088 (2012).

  7. 7.

    Aronson, M. F. J. et al. A global analysis of the impacts of urbanization on bird and plant diversity reveals key anthropogenic drivers. Proc. R. Soc. Lond. B 281, 20133330 (2014).

  8. 8.

    Fortel, L. et al. Decreasing abundance, increasing diversity and changing structure of the wild bee community (Hymenoptera: Anthophila) along an urbanization gradient. PLoS ONE 9, e104679 (2014).

  9. 9.

    Baldock, K. C. R. et al. Where is the UK’s pollinator biodiversity? The importance of urban areas for flower-visiting insects. Proc. R. Soc. Lond. B 282, 20142849 (2015).

  10. 10.

    Hall, D. M. et al. The city as a refuge for insect pollinators. Conserv. Biol. 31, 24–29 (2017).

  11. 11.

    Turrini, T. & Knop, E. A landscape ecology approach identifies important drivers of urban biodiversity. Glob. Change Biol. 21, 1652–1667 (2015).

  12. 12.

    Grimm, N. B. et al. Global change and the ecology of cities. Science 319, 756–760 (2008).

  13. 13.

    Matteson, K. C., Ascher, J. S. & Langellotto, G. A. Bee richness and abundance in New York city urban gardens. Ann. Entomol. Soc. Am. 101, 140–150 (2008).

  14. 14.

    Ahrne, K., Bengtsson, J. & Elmqvist, T. Bumble bees (Bombus spp) along a gradient of increasing urbanization. PLoS ONE 4, e5574 (2009).

  15. 15.

    Foster, G., Bennett, J. & Sparks, T. An assessment of bumblebee (Bombus spp) land use and floral preference in UK gardens and allotments cultivated for food. Urban Ecosyst. 20, 425–434 (2017).

  16. 16.

    Bates, A. J. et al. Changing bee and hoverfly pollinator assemblages along an urban–rural gradient. PLoS ONE 6, e23459 (2011).

  17. 17.

    Normandin, E., Vereecken, N. J., Buddle, C. M. & Fournier, V. Taxonomic and functional trait diversity of wild bees in different urban settings. PeerJ 5, e3051 (2017).

  18. 18.

    Garbuzov, M., Fensome, K. A. & Ratnieks, F. L. W. Public approval plus more wildlife: twin benefits of reduced mowing of amenity grass in a suburban public park in Saltdean, UK. Insect Conserv. Divers. 8, 107–119 (2015).

  19. 19.

    Geslin, B., Le Féon, V., Kuhlmann, M., Vaissière, B. E. & Dajoz, I. The bee fauna of large parks in downtown Paris, France. Ann. Soc. Entomol. Fr. 51, 487–493 (2016).

  20. 20.

    Banaszak-Cibicka, W., Ratyńska, H. & Dylewski, Ł. Features of urban green space favourable for large and diverse bee populations (Hymenoptera: Apoidea: Apiformes). Urban For. Urban Green. 20, 448–452 (2016).

  21. 21.

    Pauw, A. & Louw, K. Urbanization drives a reduction in functional diversity in a guild of nectar-feeding birds. Ecol. Soc. 17, 27 (2012).

  22. 22.

    Chong, K. Y. et al. Not all green is as good: different effects of the natural and cultivated components of urban vegetation on bird and butterfly diversity. Biol. Conserv. 171, 299–309 (2014).

  23. 23.

    Mace, G. M. Whose conservation? Science 345, 1558–1560 (2014).

  24. 24.

    Oliver, T. H. et al. Biodiversity and resilience of ecosystem functions. Trends Ecol. Evol. 30, 673–684 (2015).

  25. 25.

    De Visser, S. N., Freymann, B. P. & Olff, H. The Serengeti food web: empirical quantification and analysis of topological changes under increasing human impact. J. Anim. Ecol. 80, 484–494 (2011).

  26. 26.

    Dunne, J. A., Williams, R. J. & Martinez, N. D. Network structure and biodiversity loss in food webs: robustness increases with connectance. Ecol. Lett. 5, 558–567 (2002).

  27. 27.

    Kaiser-Bunbury, C. N., Muff, S., Memmott, J., Muller, C. B. & Caflisch, A. The robustness of pollination networks to the loss of species and interactions: a quantitative approach incorporating pollinator behaviour. Ecol. Lett. 13, 442–452 (2010).

  28. 28.

    Staniczenko, P. P. A., Lewis, O. T., Jones, N. S. & Reed-Tsochas, F. Structural dynamics and robustness of food webs. Ecol. Lett. 13, 891–899 (2010).

  29. 29.

    Aronson, M. F. J. et al. Hierarchical filters determine community assembly of urban species pools. Ecology 97, 2952–2963 (2016).

  30. 30.

    Hope, D. et al. Socioeconomics drive urban plant diversity. Proc. Natl Acad. Sci. USA 100, 8788–8792 (2003).

  31. 31.

    Leong, M., Dunn, R. R. & Trautwein, M. D. Biodiversity and socioeconomics in the city: a review of the luxury effect. Biol. Lett. 14, 20180082 (2018).

  32. 32.

    Vaughan, I. P. et al. econullnetr: an R package using null models to analyse the structure of ecological networks and identify resource selection. Methods Ecol. Evol. 9, 728–733 (2018).

  33. 33.

    Baude, M. et al. Historical nectar assessment reveals the fall and rise of floral resources in Britain. Nature 530, 85–88 (2016).

  34. 34.

    Hicks, D. M. et al. Food for pollinators: quantifying the nectar and pollen resources of urban flower meadows. PLoS ONE 11, e0158117 (2016).

  35. 35.

    Eklöf, A., Tang, S. & Allesina, S. Secondary extinctions in food webs: a Bayesian network approach. Methods Ecol. Evol. 4, 760–770 (2013).

  36. 36.

    Wood, C. J., Pretty, J. & Griffin, M. A case–control study of the health and well-being benefits of allotment gardening. J. Public Health 38, e336–e344 (2016).

  37. 37.

    Salisbury, A. et al. Enhancing gardens as habitats for flower-visiting aerial insects (pollinators): should we plant native or exotic species? J. Appl. Ecol. 52, 1156–1164 (2015).

  38. 38.

    Stott, I., Soga, M., Inger, I. & Gaston, K. J. Land sparing is crucial for urban ecosystem services. Front. Ecol. Environ. 13, 387–393 (2015).

  39. 39.

    Soga, M., Yamaura, Y., Koike, S. & Gaston, K. J. Land sharing vs. land sparing: does the compact city reconcile urban development and biodiversity conservation? J. App. Ecol. 51, 1378–1386 (2014).

  40. 40.

    Pocock, M. J. O., Evans, D. M. & Memmott, J. The robustness and restoration of a network of ecological networks. Science 335, 973–977 (2012).

  41. 41.

    Orsini, F., Kahane, R., Nono-Womdim, R. & Gianquinto, G. Urban agriculture in the developing world: a review. Agron. Sustain. Dev. 33, 695–720 (2013).

  42. 42.

    Lepczek, C. A. et al. Biodiversity in the city: fundamental questions for understanding the ecology of urban green spaces for biodiversity conservation. Bioscience 67, 799–807 (2017).

  43. 43.

    United Nations, Department of Economic and Social Affairs, Population Division. World Urbanization Prospects: The 2014 Revision, Highlights (ST/ESA/SER.A/352) (2014).

  44. 44.

    Aronson, M. F. J. et al. Biodiversity in the city: key challenges for urban green space management. Front. Ecol. Environ. 15, 189–196 (2017).

  45. 45.

    Willmer, P. G. & Stone, G. N. Behavioral, ecological, and physiological determinants of the activity patterns of bees. Adv. Stud. Behav. 34, 347–466 (2004).

  46. 46.

    R Development Core Team. R: a Language and Environment for Statistical Computing (R Foundation for Statistical Computing, 2014).

  47. 47.

    Bates, D., Maechler, M. & Bolker, B. lme4: Linear Mixed-Effects Models Using S4 Classes R package version 0.999999–2 http://CRAN.R-project.org/package=lme4 (2013).

  48. 48.

    Hothorn, T., Bretz, F. & Westfall, P. Simultaneous inference in general parametric models. Biometrical J. 50, 346–363 (2008).

  49. 49.

    Zuur, A. F., Ieno, E. N., Walker, N. J., Saveliev, A. A. & Smith, G. Mixed Effects Models and Extensions in Ecology with R (Springer, New York, 2009).

  50. 50.

    Orford, K. A., Vaughan, I. P. & Memmott, J. The forgotten flies: the importance of non-syrphid Diptera as pollinators. Proc. R. Soc. Lond. B 282, 20142934 (2015).

  51. 51.

    Rader, R. et al. Non-bee insects are important contributors to global crop pollination. Proc. Natl Acad. Sci. USA 113, 146–151 (2016).

  52. 52.

    Willmer, P. G. Pollination and Floral Ecology (Princeton Univ. Press, Princeton and Oxford, 2011).

  53. 53.

    Hill, M. O., Preston, C. D. & Roy, D. B. PLANTATT—Attributes of British and Irish Plants: Status, Size, Life History, Geography and Habitats (Centre for Ecology and Hydrology, 2004).

  54. 54.

    Venables, W. N. & Ripley, B. D. Modern Applied Statistics with S 4th edn (Springer, New York, 2002).

Download references


This research was supported by the UK Insect Pollinators Initiative, funded by the BBSRC, Defra, the NERC, the Scottish Government and the Wellcome Trust under the auspices of the Living with Environmental Change partnership: grant BB/I00047X/1 (www.urbanpollinators.org). We thank M. Pavett, J. Deeming, B. Levey, M. Wilson, R. Morris and R. Barnett for taxonomic expertise, and land owners and managers for access to sites. We thank S. Bettoni, P. Cannard, S. Cartwright, R. Comont, E. Elliot, C. Grey, P. Harris, R. Harris, B. Jarrett, K. Mikolajczak, V. Miravent, H. Morse, E. Moss, P. Ouvrard, L. Riggi, V. Radhakrishnan, D. Roumpeka, F. Sinclair, M. Stone and V. Williams for assistance with field data collection. This work is based on data provided through Ordnance Survey, the Office for National Statistics, the UK Data Service (EDINA UKBORDERS and Casweb MIMAS), Natural England, the Countryside Council for Wales and Scottish Natural Heritage, and uses boundary material which is copyright of the Crown. Census output is Crown copyright and is reproduced with the permission of the Controller of HMSO and Queen’s Printer for Scotland.

Author information

The study was conceived by J.M. and designed with input from all authors. Fieldwork was carried out by K.C.R.B., M.A.G., D.M.H., N.M., H.M., L.M.O. and K.M.R., with local teams supervised by J.M., G.N.S., S.G.P. and W.E.K. K.C.R.B., I.P.V. and P.P.A.S. carried out the analyses. K.C.R.B. and J.M. led the writing of the manuscript. All authors contributed to drafts of the manuscript and gave final approval for publication.

Correspondence to Katherine C. R. Baldock.

Ethics declarations

Competing interests

The authors declare no competing interests.

Additional information

Publisher’s note: Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Supplementary information

Supplementary Information

Supplementary Methods, Supplementary Figures 1, 2 and 5, Supplementary Tables 1–6, 9 and 10, and Supplementary References

Reporting Summary

Supplementary Figure 3

Heat maps of estimated city-scale floral abundances. High-resolution file of Fig. 4a–d. Crown copyright and database rights 2018 Ordnance Survey (100025252)

Supplementary Figure 4

Heat maps of estimated city-scale pollinator abundances. High resolution file of Fig. 4e–h. Crown copyright and database rights 2018 Ordnance Survey (100025252)

Supplementary Table 7

Null model results for all plant taxa in all four cities

Supplementary Table 8

Null model standardised effect sizes (SES) for all plant taxa by city

Supplementary Data 1

Data set on pollinator and floral abundance and richness that supports analyses in Results section ‘Abundance, occurrence and richness of pollinating insects and plants’ and used to create Figs. 1 and 2 and Supplementary Fig. 5

Supplementary Data 2

Data set on pollinator and floral abundance and richness in gardens that supports analyses in Results section ‘Household income level’

Supplementary Data 3

Data sets used for null model analyses in Results section ‘Plant selection by pollinating insects’

Supplementary Data 4

Data set used to calculate values used in Results section ‘Scaling to the city level’ and for Figs. 3 and 4, and Supplementary Figs. 3–5

Supplementary Data 5

Data sets used in robustness models in Results section ‘Network models and management strategies’

Rights and permissions

Reprints and Permissions

About this article

Verify currency and authenticity via CrossMark

Cite this article

Baldock, K.C.R., Goddard, M.A., Hicks, D.M. et al. A systems approach reveals urban pollinator hotspots and conservation opportunities. Nat Ecol Evol 3, 363–373 (2019) doi:10.1038/s41559-018-0769-y

Download citation

Further reading