Impacts of simulated warming on plant-pollinator interactions and ecosystem services in agro-ecosystems

Abstract

Agro-ecosystems are complex environments that provide a range of ecosystem services, many of which are delivered by biodiversity. Climate change represents a threat to the stability and functioning of agro-ecosystems through the effect it will have on these organisms. This thesis examines the impacts of climate change upon biodiversity in UK agroecosystems using both a multidisciplinary framework and a field experiment. The Driver-Pressure-State-Impact-Response (DPSIR) framework is a problem structuring tool; here it was employed to collate evidence of the impacts of all aspects of climate change on three groups of service providing organisms (pollinators, pest regulators and mycorrhizal fungi) in UK agro-ecosystems, along with evidence linking these effects to societal impacts. Further development of the framework demonstrated downward trends in biodiversity and ecosystem services due to climate change and exposed the lack of evidence examining the effects on species interactions for the three groups. Climate warming was simulated in a replicated open-air field experiment on an arable farm, where the impacts upon pollinators and wildflowers were investigated. Simulated warming reduced floral abundance by nearly 40% and nectar volumes for two species by over 60%. It also significantly increased the frequency of insect visits to flowers and the complexity of flower-visitor interaction networks. Four of the five wildflower species produced significantly fewer and/or lighter seeds under simulated warming. Experimental data were collected throughout two growing seasons allowing investigation of both the temporal dynamics of the system and how this responds to simulated warming. Treatment effects on floral abundance, species interactions, and community composition were highly variable throughout the seasons and between years. Overall, these results suggest that climate change will negatively impact ecosystem service provision in UK agro-ecosystems. More specifically, these findings illustrate the adverse effects that climate change could have upon arable wildflowers and the pollinators that feed upon them