Urban green infrastructure: optimising local food and fuel production for regional sustainability and resilience

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More than half of the worlds' population now live in urban areas. Consequently, urban areas are key drivers of global change and are responsible for >70% of carbon emissions. The UK government has committed to reduce CO2 emissions by 80% on 1990 values by 2050. Maximising local energy and food production could provide a key mechanism to achieve this goal. Urban green infrastructure (UGI) (e.g. parks, gardens, wasteland, allotments) represents a substantial component, typically >50%, of UK cities. However, there has been no quantitative evaluation of the potential for UGI to support sustainable local food and biofuel production.Research has demonstrated the potential of UGI to provide many key ecosystems services to urban inhabitants, e.g. flood mitigation, pollutant infiltration, carbon storage. Soils are the foundation of terrestrial ecosystems, and soil organic carbon (OC) is crucial to their ability to support ecosystem services. However, until recently urban soils were assumed to be of poor quality and unable to contribute significantly to ecosystem service provision. My research has been transformative in revealing nationally important OC stocks in urban soils.In the UGI of North East England I found that 35% of soil OC was black carbon (BC) - the product of the incomplete combustion of fossil fuels and biomass, which includes a range of molecules from charred biomass to soots. The high soil BC concentrations measured are attributable to fossil fuel emissions and are often positively associated with heavy metal (HM) pollutants. Using UGI for own-growing could provide a tool to increase food security, but, there are potential risks to health associated with own-growing due to the accumulation of HM in urban soils. The components of soils that control HM movement in the own-grown food chain are undetermined, but recent research suggests that BC may reduce uptake by plants.My research revealed that soils within UGI are typically of higher quality than agricultural soils, revealing potential for sustainable food and fuel production. In Leicester, I found that allotments make a significant contribution to local food security, covering only 1.5% of the city they feed approx. 4,500 people on their '5 a day' diet. Crucially, own-growing has been recognised by policy makers as key contributor to local food security. In contrast, the guidelines for biofuel production using short rotation coppice (SRC) focus exclusively on agricultural land, but, these guidelines do not preclude urban areas. Indeed the urban fringe has been identified as being suited to SRC. We demonstrated that 8% of Leicester was suitable for SRC. This could supply energy to >1560 homes, whilst simultaneously producing biochar which can enhance soil quality and potentially reduce pollutant availability to plants. Despite this evidence there have been no systematic UK scale assessments of how UGI could contribute to local food and biofuel production.This fellowship will provide the first estimate of current national own-grown food production. The novel approach used in this research program, will combine high-resolution geographic information systems datasets, and geospatially referenced soil chemical analysis for BC and HM at a UK scale, modelled historic and current emissions data, together with soil-to-plant growth experiments to understand the mechanisms driving HM uptake from soil by food and biofuel crops. When combined these techniques will provide a powerful tool to determine the ability of UGI to provide food and biofuel at a national scale. Potential own-grown crop production estimates will be modelled under a range of uptake scenarios. Potential UK biofuel and biochar production in UGI will be modelled and the contribution to renewable energy targets estimated. Trade-offs between use of UGI for food and biofuel production and effects on ecosystem services will be assessed, and potential to relieve pressure on agricultural land quantified.