NERC GW4+ CASE - Urban buzz: quantifying and enhancing the resources available to pollinators in urban landscapes

Urban ecology is a research area of considerable current interest. Recent work from the University of Bristol has shown that cities can be remarkably good habitats for pollinators, with more bee species in cities than in the surrounding countryside (Baldock et al., 2015). Urban gardens provide forage for large numbers of pollinators and while it is not possible to increase the quantity of gardens in most cities, it is possible to increase their quality with respect to food resources for pollinators (Salisbury et al. 2015).

Currently many gardens have large areas of lawn, decking and hard standing, and contain flowers which provide little forage for pollinators (e.g. grasses, roses and many bedding plants). Ongoing analysis of the Urban Pollinators project (£1.3M consortium project funded by the Insect Pollinator Initiative and led by Memmott & Baldock at the University of Bristol) means that we can predict the effect of habitat management on the robustness of the urban pollinator communities. Robustness measures the response of a community to species loss, it is calculated using plant-pollinator network data (e.g. Memmott et al., 2004) and is often cited as one of the key targets in conservation projects. This is due to a more robust community being more likely to cope with environmental change.

The aim of this PhD project is to increase the value of urban habitats to pollinators, thereby increasing the robustness of urban pollinator communities. Urban areas are increasing worldwide and for pollinators at least, they can provide excellent habitat which is relatively free from the threats that exist in the countryside, for example, pesticides and a shortage of forage. We will work with the Royal Horticultural Society as a CASE partner and there are three objectives to the project:

1) To quantify nectar and pollen provided by UK gardens. The amount of nectar and pollen produced by 30 gardens in three socio-economic bands will be quantified in Bristol and Reading. Memmott’s group has quantified the amount of nectar produced in the British countryside, publishing this in Nature (Baude et al., 2016). Here we will use these methods to quantify forage for pollinators in gardens.
2) To increase the amount of nectar and pollen in the highly urbanized central zone of a city. Hanging baskets and planters are common in urbanized inner cities and a pilot project has shown that their nectar value can be increased. Here we will increase the amount of pollinator forage in baskets/planters in central Bristol and use community robustness models to predict the effect on pollinator communities across the city.
3) Use a large scale field experiment to increase the amount of nectar and pollen in gardens in replicate urban streets, comparing pollinator communities to unmanipulated controls. We will also investigate the effect on plant-pollinator community robustness and on garden owners’ wellbeing.