The potential contribution of brownfield ecosystem services to urban resilience

Preston, Paul David (2021) The potential contribution of brownfield ecosystem services to urban resilience. Doctoral thesis (PhD), Manchester Metropolitan University.

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Abstract

Urbanisation processes result in land cover changes which can modify the biological, chemical, and geological characteristics of the urban environment. As a result, cities face increased exposure to environmental hazards, placing individuals and communities at risk. While the role of urban green space in mitigating these hazards and enhancing urban resilience is widely recognised, brownfield land has been largely overlooked, with a paucity of research investigating the contribution of brownfield ecosystem services to urban resilience. Brownfield land is experiencing rapid land cover changes in urban areas due to brownfield-first approaches to development. Brownfield is disproportionately located in densely built urban areas, characterised by high levels of socio-economic deprivation, low amounts of green space, and increased exposure to environmental hazards. As the developmental pressure on brownfield increases, and the importance of urban resilience intensifies, it is important to understand the potential impacts of brownfield loss before they are redeveloped. It is important to understand the potential impacts of urban redevelopment processes utilising brownfield before they are redeveloped. Thus, this research explored how brownfield ecosystem services may contribute to building resilience to environmental hazards in urban areas. This research applies new approaches to the characterisation of brownfield, the quantification of their ecosystem services, comparison to existing green infrastructure, their relationship to environmental hazards and those who are most at risk in Greater Manchester, UK. Findings show that brownfield is widely distributed, disproportionately concentrated in urban areas, providing highly vegetated (51%) and pervious (58%) space. A novel typology developed utilising land cover analysis, landscape metric analysis and cluster analysis identified 26 distinct types which vary in terms of physical and ecological characteristics and impacts upon ecosystem services provision. In total, brownfield provided an estimated 52 kt of carbon storage, annual carbon sequestration of 2kt, removed 305t of air pollution, and avoided 133,000m3 of surface water runoff. Several types of brownfield (irregular shaped and vegetated, densely vegetated, vegetated with water body, and uneven and vegetated), provide more regulating ecosystem services than many types of park. In densely built urban areas, brownfield provides five times more regulating ecosystem services than parks, where scenario analysis indicated that interventions like extensive tree planting could deliver an 8-fold increase in benefits. Hotspots where high social vulnerability and exposure to environmental hazards intersected with increased brownfield were identified in urban regions. Brownfield is 8 times more prevalent in acute socially vulnerable areas than areas of low social vulnerability. Recommendations for strategic greening opportunities, the removal of impervious surfaces, enabling public access and redevelopment avoidance are made. The findings demonstrate several types of brownfield can provide significant regulating ecosystem services, are a valuable component of a city’s green infrastructure in densely built urban areas and have scope to be managed or modified to maintain or increase urban resilience. The abundance of brownfield, with both high and low ecosystem service provision, in socially vulnerable neighbourhoods, suggest that brownfield could provide additional open green space and reduce exposure to environmental hazards. Strategic redevelopment of brownfield should be employed contingent on their location, distribution, and characteristics, and it is recommended that a rapid ecosystem service assessment tool is developed to support practice.