Background

1. The provision of urban ecosystem services along a rural-urban gradient: A case study of Greater Manchester Kathleen G. Radford and Philip James Research Centre For Urban Change, School of Environment and Life Sciences University of Salford Email: k.g.radford@edu.salford.ac.uk Background Since the publication of the Millennium Ecosystem Assessment (2005), the importance of ecosystem services in providing healthy and sustainable communities, and the degradation of services as a result of human actions, has been highlighted within policy and planning procedures (Fisher et al., 2009). The quality of ecosystem services (the benefits human populations derive from an ecosystem function (Contanza et al., 1997)) is negatively correlated with urbanisation (Fu et al., 2009) at local and global scales (Alberti, 2005). The ecosystem services which stand the greatest risk of degradation as a result of urbanisation include: • Aesthetic, recreation and spiritual values; • Biodiversity/genetic conservation and pollination services; • Water quality and flow control; • Noise buffering and nutrient cycling; • Air quality and climate control. (Haines-Young and Potschin, 2008). One of the main issues surrounding combating the loss of ecosystem services is that of finding a common method of quantification and assessment. Currently, most methods focus on the economic benefits of services, such as the travel-cost, hedonic pricing and direct market value methods. Economic assessment allows for the comparison of services through a common metric (MEA, 2005). However, this method remains weak for non-marketable services (Zheng et al., 2009) such as spiritual and aesthetic services and also faces many other criticisms as it relies largely on assumption. This research aims to measure a number of ecosystem services important to urban areas using non-economic methods. The quality of these services will be measured along a rural-urban gradient (based on the percentage of impermeable landscape) to allow for a better understanding of the provision of ecosystem services along the gradient. Synergies or trade-offs between different ecosystem services will be analysed. For example, can high quality recreational services exist in the same area as high quality biodiversity conservation? Methods The data collection process was split into two parts; a desktop survey (using ArcView 9.2) and a field survey. Air quality control / carbon sequestration (desktop survey): The tree cover for each site was digitised from aerial photographs and total cover calculated. Based on methods used by Tratalos et al. (2007), tonnes of carbon sequestration hectare-1 year-1 = 0.00335 (% tree cover). Climate control (desktop survey): Using a model derived from Whitford et al. (2001), the maximum temperature was calculated using the equation: proportion of land classified as ‘impervious’ + proportion of gardens which have sealed surfaces x the proportion of land covered by gardens. The climatic inputs used by Whitford et al. (2001) were used. Water flow regulation (desktop survey): Based on studies by the Soil Conservation Service (1972), surface runoff was calculated as: Pe = (P – 0.2S)2/(P – 0.8S) where Pe is the surface runoff, P precipitation and S the maximum potential rainfall retention of the catchment. S = 2540/CN – 25.4, where CN is the curve number calculated by the Soil Conservation Service. Biodiversity potential (desktop survey): Based on a model used by Pauleit et al. (2005), biodiversity potential = proportional area of green space (Pt) x structural diversity. Structural diversity was measured using the following equation: where p1 = proportion of bare ground and turf grass; p2 = proportion of rough grassland and herbs; p3 = proportion of shrubs; p4 = proportion of trees; and p5 = proportion of built up land. The proportions of these habitats were calculated by digitising the respective areas from aerial photographs. Recreation potential (desktop and field survey): The true recreational potential of any given area involves both public and privately owned areas. To measure the number of recreational opportunities within public areas, a simple count was done whilst walking through each site. As visual access cannot always be obtained within privately owned areas, aerial photographs were studied to gain this access. For each recreational opportunity, a score of 1 or 2 was ascribed, with 1 = poor quality or scarce and 2 = of good quality and adequate provision. Aesthetic and spiritual values (field survey): Currently, no methods exist to measure aesthetic and spiritual ecosystem services. Therefore, in order to measures these, criteria used within the Residential Environment Assessment Tool (Dunstan et al., 2005), a tool which measures the quality of the urban environment, were applied, where applicable. The tool did not adequately reflect the importance of urban green space, so therefore criteria from Green Flag Award, which assesses the quality of green space, were also incorporated. Climate change adaptation, noise buffering and pollination potential (field survey): The quality of these services were measured were assessed on criteria obtained from a literature review. Aims • To create a methodology to allow researchers to measure the quality of a selection of ecosystem services at the neighbourhood scale. • To measure the quality of a selection of ecosystem services along a rural-urban gradient within the Greater Manchester conurbation. • To map the provision and quality of ecosystem services within the Greater Manchester conurbation and identify any synergies and tradeoffs between services and quality criteria to allow for sustainable and healthy communities. Results Study area All sites have been selected within Greater Manchester (53°30N’, 2°15’W), a city born of the industrial revolution, as the conurbation adequately represents different levels of urbanisation as well as contrasting soil types and a full range of neighbourhood and land use types (Gill et al., 2008). Greater Manchester covers an area of 1276km2 and is located within the north west region of England. Approximately 42% of the conurbation can be classified as ‘built up’ (Lindley and Walsh, 2005). The conurbation was divided into 4 different categories of urbanisation, based on data provided by Manchester University, thereby creating an rural-urban gradient. This gradient was based on the percentage of impermeable landscape. In total 69 sites were studied: 30 rural; 6 peri-urban; 22 suburban and 11 urban. Each site was 0.25km2. Figure 2 Effects of urbanisation on biodiversity potential, pollination potential and carbon sequestration along a rural-urban gradient. Figure 3 Effects of urbanisation on noise buffering, climate change adaptation and water flow regulation along a rural-urban gradient. Figures 2 – 4 show the results obtained from the pilot study. Each shows the differences in quality of the selected ecosystem services provided within each category of urbanisation. Figure 4 Effects of urbanisation on aesthetic, spiritual and recreation services along a rural-urban gradient. Conclusions The data obtained from this study is in line with what would generally be expected. Firstly, aesthetic and spiritual functions were of the greatest quality within rural and peri-urban areas. This is because larger and more diverse green spaces exist within these categories, providing contact with nature and safe, calm and secure surroundings. Recreational potential was greatest within suburban areas, possibly as these areas have the highest concentration of residential properties, as apposed to urban sites which are largely industrial and commercial, and rural areas which are largely agricultural. Climate change adaptation was highest in the urban and suburban categories. It is thought that this is a result of greater concentrations of people, industry and commerce and, therefore, more responsibility for implementing such measures. Pollination and biodiversity potential services were of lowest quality in urban areas, as would be expected, as these areas have the lowest provision of green space. Carbon sequestration was greatest in peri-urban areas, probably due to a higher proportion of trees compared to rural and urban areas. Finally, water flow regulation is, as one would expect, negatively correlated with the amount of impermeable land cover, and therefore levels of increasing urbanisation. Following these initial findings, further research will be carried out to establish any synergies or trade-offs between services. It will also investigate any criteria attributing itself significantly to a poor or high quality ecosystem service. These conclusions can then hopefully feed into planning procedures for improving the sustainability of urban environments and improving the health and wellbeing of urban inhabitants. Figure 1 Rural-urban gradient of Greater Manchester References Alberti, M., 2005. 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