Pollination ecosystem services and the urban environment

Insect pollination is a vital ecosystem service, essential for both wild and domesticated plants, yet to-date there are no standardised national schemes to monitor its status. Thus this PhD focused on assessment of pollination provision in UK urban green spaces, using a combination of citizen science and field/laboratory methods. Each of the following thesis chapters considers a specific pollination-related theme: The need for pollination. Demonstrating how much gardeners need insect pollination is important to underpin public support for pollinator conservation. During 2014-2015, online questionnaires were used to collect information about the crops grown in domestic green spaces and gardening practices used. Participants highly valued ‘growing their own’, and three of five crops grown by the majority (tomatoes, apples, strawberries) have high requirements for insect pollination. A ‘garden shop calculator’ spreadsheet was also tested (positively) as a quick way to calculate the equivalent bought-value of garden crops and the proportion directly attributable to insect actions. Assessment of pollination provision. Citizen science volunteers undertook a simple direct pollination experiment (exclusion, hand pollination, local), requiring treatment randomisation and accurate yield recording. The main ‘Bees ‘n Beans’ projects used Vicia faba to monitor bumblebee pollination, detecting no national deficit during 2014-2016. This suggests that the domestic pollination needs of V. faba are currently met, and that urban populations of long-tongued bumblebees are sufficient to provide it. The potential of using other plants to cover wider pollinator populations was also explored, identifying Allium hollandicum as suitable. The effects of companion planting. Using tomato plants to examine whether co-planting crops with flowering plants boosts pollination provision (‘magnet species’ effects), or distracts insects. Provided plants were hosted in volunteered gardens and school grounds in Brighton in 2015 & 2016. No effect (improved or detrimental) of co-flowering plants was found on tomato yields at either site type. Using citizen science to monitor pollination services. This chapter combined findings from other chapters and a final questionnaire, which focused on participants’ motivations and willingness to make behavioural changes after taking part. It concludes that the projects have demonstrated volunteers’ ability and willingness to follow experimental protocols under guidance, to collect meaningful data at otherwise-impractical geographical scales. Suggested protocol. This details the finalised Bees ‘n Beans approach and how it relates to other potential pollination monitoring methods. I propose that this style of project is suitable for incorporation into national monitoring scheme development.