Classifying and valuing ecosystem services for urban planning
Highlights
► Urban ecosystems provide multiple ecosystem services for human well-being and can increase resilience to shocks. ► Loss of urban ecosystems involve long-term economic and insurance costs and can affect many social and cultural values. ► Valuation should not only take into account benefits from ecosystem services but also costs from ecosystem disservices. ► Economic and non-economic values of urban ecosystem services should be accounted for in urban decision-making and planning.
Introduction
More than half of the world's population lives in cities (Dye, 2008) and more than two thirds are expected to live in cities by 2050 (UN, United Nations, 2010). Concentration of population in cityscapes dominated by technology and built infrastructure has fostered the conception of an urban society that is increasingly decoupled and independent from ecosystems (Ausubel, 1996). However, demands on natural capital and ecosystems services keep increasing steadily in our urbanized planet (Ayres and van den Bergh, 2005, Guo et al., 2010, Krausmann et al., 2009). Furthermore, extensive research has shown that decoupling of cities from ecological systems can only occur locally and partially, thanks to the appropriation of vast areas of ecosystem services provision beyond the city boundaries (Folke et al., 1997, Rees, 1992, Rees and Wackernagel, 1996). Just as any other social–ecological system, cities depend on ecosystems and their components to sustain long-term conditions for life (Odum, 1989), health (Maas et al., 2006, Tzoulas et al., 2007), security (Costanza et al., 2006a, Dixon et al., 2006), good social relations (EEA, European Environmental Agency, 2011) and other important aspects of human well-being (TEEB, The Economics of Ecosystems and Biodiversity, 2011).
Urban ecosystems are still an open frontier in ecosystem service research. Since the seminal article by Bolund and Hunhammar (1999) was published in this journal, a mounting body of literature has strived to advance our understanding of urban ecosystem services in their biophysical (Escobedo et al., 2011, Pataki et al., 2011), economic (Jim et al., 2009, Sander et al., 2010), and socio-cultural dimensions (Chiesura, 2004, Andersson et al., 2007, Barthel et al., 2010). Ecosystem services provided in urban areas were addressed by major initiatives like the Millennium Ecosystem Assessment (McGranahan et al., 2005) and The Economics of Ecosystems and Biodiversity (TEEB, The Economics of Ecosystems and Biodiversity, 2011), and have received increasing attention as part of the policy debate on green infrastructure (DG Environment, 2012). Yet, as compared to other ecosystems like wetlands or forests, the attention given to urban ecosystems is relatively modest. Most studies on the topic have focused on single ecosystem services and/or value dimensions. For example, whereas monetary values have been broadly examined in the literature, description or measurement of symbolic, cultural, identity and other non-economic values remain largely unexplored (Chan et al., 2012). This is also the case for the ‘insurance value’ stemming from the contribution of urban ecosystems and green infrastructure to the resilience of cities. To our knowledge there is also little understanding of the additional challenges to the valuation in urban ecosystems, characterized by high complexity, heterogeneity, and fragmentation (Pickett et al., 2001.
In an attempt to address these knowledge gaps, this paper draws on recent developments in ecosystems service research to synthesize knowledge to classify and value ecosystem services for urban planning. Specifically, we i) categorize the most relevant ecosystem services and disservices provided in urban and peri‐urban areas, ii) identify economic and non-economic values associated to urban ecosystem services, and iii) examine challenges in measuring and articulating ecosystem service values in urban planning.
Ecosystem services are defined as benefits that humans obtain from ecosystem functions (De Groot et al., 2002, MA (Millennium Ecosystem Assessment), 2005), or as direct and indirect contributions from ecosystems to human well-being (TEEB, The Economics of Ecosystems and Biodiversity, 2010). The range of our inquiry is restricted to ‘urban ecosystem services’, defined here as those provided by urban ecosystems and their components. Urban ecosystems are those where the built infrastructure covers a large proportion of the land surface, or those in which people live at high densities (Pickett et al., 2001). They include all ‘green and blue spaces’ in urban areas, including parks, cemeteries, yards and gardens, urban allotments, urban forests, wetlands, rivers, lakes, and ponds. Definitions of urban areas and their boundaries vary between countries and regions, depending on land use type, total population, population density, distance between dwellings, and percentage employment outside the primary sector. Given that many ecological fluxes and interactions extend well beyond the urban boundaries defined by political or biophysical reasons, urban ecosystems are defined here in the broader sense that comprises the hinterlands directly managed or affected by the energy and material flows from the urban core and suburban lands, including city catchments, and peri-urban forests and cultivated fields (see Pickett et al., 2001, p.129). Because in the urban context ecosystems are by definition highly modified and fragmented, our analysis is not restricted to ecosystems as such, but also includes specific ecosystem components involved in the delivery of services such as individual trees, water surfaces, and soil surfaces (Nowak and Crane, 2002).
In public policy discourse, urban ecosystems are often portrayed as ‘green infrastructure’ (EEA, European Environmental Agency, 2011; DG Environment, 2012). This metaphor captures the role that water and vegetation in or near the built environment play in delivering ecosystem services at different spatial scales (building, street, neighborhood, region). Urban ecosystems may be seen as a broader concept in the sense that they can also include community-driven forest or river/lake areas close or within the city boundaries as well as private gardens not directly subjected to public urban planning.
The paper is structured in four main sections. Section 2 classifies and describes ecosystem services and disservices provided in urban areas. Section 3 discusses the range of economic and non-economic values associated to urban ecosystem services provided and identifies methods and tools by which such values may be elicited and quantified. Section 4 discusses the scope and limits of valuation methods in urban planning and identifies additional challenges for valuation in urban ecosystems. Section 5 synthesizes our main findings and points out priorities for the research agenda in urban ecosystem assessments.
Section snippets
Classifying Ecosystem Services Provided in Urban Areas
Building on previous categorizations of ecosystem services (Daily, 1997, De Groot et al., 2002, MA (Millennium Ecosystem Assessment), 2005) the TEEB report identifies 22 types of ecosystem services grouped in four categories: provisioning, regulating, habitat, and cultural and amenity services (TEEB, The Economics of Ecosystems and Biodiversity, 2010). Because different habitats provide different types of ecosystem services, general classifications need to be adapted to specific types of
Valuing Ecosystem Services in Urban Areas
Classifications of ecosystem service values can vary greatly depending on the axiological, ontological, and epistemological positions adopted at the outset (Gómez-Baggethun and de Groot, 2010, TEEB (The Economics of Ecosystems and Biodiversity), 2010). Here we endorse a ‘value pluralism’ perspective, which maintains that valuation processes in social-ecological systems involve dealing with multiple and often conflicting valuation languages, whereby values may be combined to inform decisions but
Informing Urban Planning Through Ecosystem Services Valuation
Decision contexts in which valuation of ecosystem services can inform urban planning include awareness raising, economic accounting, priority-setting, incentive design, and litigation (TEEB, The Economics of Ecosystems and Biodiversity, 2010; Barton et al., 2012) (Fig. 1).
Economic valuation of ecosystem services increases in cost with increases in the spatial scale and resolution at which biophysical quantification is required, and with the policy requirements for accuracy and reliability. The
Conclusions
We synthesized concepts, methods, and tools to classify and value ecosystem services delivered in urban areas to support decision-making, e.g. by reshaping municipal budgets and guiding land-use planning. Three main insights can be extracted from our review. First, in line with previous literature on the topic, our research shows that there is growing evidence on the positive impacts of urban ecosystem services on quality of life in cities. Regulating and cultural services, including air
Acknowledgments
We thank two anonymous reviewers for useful comments to a previous draft of this paper. This research was funded by the ERA-Net BiodivERsA through the Spanish Ministry of Science and Education project ‘Urban Biodiversity and Ecosystem Services’ (URBES) (PRI-PIMBDV-2011-1179).
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