The role of socio-economic factors in planning and managing urban ecosystem services

How green spaces in cities benefit urban residents depends critically on the interaction between biophysical and socio-economic factors. Urban ecosystem services are affected by both ecosystem characteristics and the social and economic attributes of city dwellers. Yet, there remains little synthesis of the interactions between ecosystem services, urban green spaces, and socio-economic factors. Articulating these linkages is key to their incorporation into ecosystem service planning andmanagement in cities and to ensuring equitable outcomes for city inhabitants. We present a conceptual model of these linkages, describe threemajor interaction pathways, and explore how to operationalize themodel. First, socio-economic factors shape the quantity and quality of green spaces and their ability to supply services by influencing management and planning decisions. Second, variation in socio-economic factors across a city alters people’s desires and needs and thus demands for different ecosystem services. Third, socio-economic factors alter the type and amount of benefit for human wellbeing that a service provides. Integrating these concepts into green space policy, planning, andmanagementwouldbe a considerable improvement on ‘standards-based’ urban green space planning. We highlight the implications of this for facilitating tailored planning solutions to improve ecosystem service benefits across the socio-economic spectrum in cities. 2018 Elsevier B.V. All rights reserved.


Introduction
Green spaces in urban areas, such as gardens, parks, street trees, and other 'natural' features, provide vital ecosystem services that contribute to the wellbeing and health of city residents (Elmqvist et al., 2013) (Table 1). This includes basic resources such as fresh water and food, as well as life-improving benefits such as opportunities for recreation, local climate regulation, and improvements in air quality (MA, 2005;TEEB, 2010). Given the projected dramatic increase in urbanization around the world (Seto et al., 2012), managing and optimizing urban ecosystem services is critical for social and ecological sustainability. Incorporating specific goals for managing and improving ecosystem services into urban planning and management has therefore been strongly endorsed (Bolund and Hunhammar, 1999;Niemelä et al., 2010;Gómez-Baggethun and Barton, 2013) and is increasingly explored in theory and practice (Tratalos et al., 2007;Cowling et al., 2008;TEEB, 2010;Elmqvist et al., 2013;Lovell and Taylor, 2013). However, empirical research on urban ecosystem services has generally neglected clear, contextual links between ecosystems and the benefits people derive from them (Luederitz et al., 2015).
In seeking to address this research gap, some scholars have highlighted the importance of the socio-economic circumstances of urban residents for determining benefits received from urban green space (e.g. Lin et al., 2014, Shanahan et al., 2014. However, why, when, and how socio-economic factors mediate ecosystem service has been poorly synthesized to date (Carpenter et al., 2009). The paucity of usable models and tools presents an even more immediate challenge for real-world application to guide the inclusion of these considerations into urban planning and management. In this paper, we use the ecosystem service supply chain framework to synthesize how socio-economic factors influence those services for people living in cities, crafting a conceptual model as a decision aid. We  The supply of and demand for ecosystem services is not homogeneous across any individual city. Importantly, ecosystem service demand is determined by the needs and desires of people and is influenced by socio-economic factors such as income, wealth, education, and ethnicity (MEA, 2005;Rounsevell et al., 2010;Ernston, 2013). Socio-economic factors can also influence green space management and planning decisions, leading to uneven supply of green spaces across cities (Pham et al., 2012). Thus, spatiotemporal variation in socio-economic factors within cities can lead to significant variability in the supply and demand of ecosystem services derived from green spaces (McDonald, 2009;Escobedo et al., 2011). This means that the relationships between socio-economic factors and ecosystem services should be a key planning and management consideration (Cowling et al., 2008;Lyytimaki and Sipila, 2009;Gómez-Baggethun and Barton, 2013), despite rarely being addressed in urban planning policy or scholarship.
Three key insights about the role of socio-economics in urban ecosystem services are currently evident from the literature and all hinge on 'differences': (1) green spaces are perceived and used differently by different demographic groups (e.g., Madge, 1997;Tinsley et al., 2010), (2) there are often inequalities in green space provision along socio-economic gradients (e.g., Pedlowski et al., 2002;Pickett et al., 2008), and (3) the types and importance of ecosystem services to urban residents can differ along socioeconomic gradients (e.g., Tratalos et al., 2007;Lubbe et al., 2010;Cilliers et al., 2013). Importantly, recent research has started to reveal the potential mechanisms by which socio-economic factors can influence ecosystem service benefits. For example, Shanahan et al. (2015) showed that higher formal education levels and greater neighborhood socio-economic advantage are associated with the use of local parks that incorporate native remnant ecosystems. Additionally, Peterson et al. (2008) showed that residents choosing to live in more natural areas were older, better educated, and more environmentally-oriented than those choosing residential areas with less green space.
With such evidence accumulating, there is an urgent need to bring these threads together to improve the conceptual understanding of how socio-economic factors influence ecosystem services in cities that can then be operationalized for urban planning. Such a model could then directly improve ecosystem service management by delineating and linking ecosystems service components such that urban policy-makers, planners, and managers can more clearly consider critical contextual factors in their focal areas (Cowling et al., 2008;Luederitz et al., 2015). Without this, there is the risk that planning initiatives to improve the quantity or quality of green space across cities will result in fewer or less equitable benefits for city inhabitants. We note here that, while some decision-making factors for private spaces differ from those for public spaces, planners and managers must influence both for equitable ecosystem service provision (Aronson et al., 2017). Many cities have simple prescriptive targets for green space quantity and spacing that are intended to provide equal access (Heynen et al., 2006), but these well-meaning targets may need to be reconsidered in the context of varying socio-economic contexts from city to city and within any given city.
Here, we first identify and conceptualize how socio-economic factors influence the supply, demand, and benefit of ecosystem services to people in cities. By framing this around the ecosystem service supply chain framework (also known as the 'ecosystem service cascade'), we distinguish between the biophysical supply of a service, the demand for it, and the benefit it gives people (Potschin and Haines-Young, 2011). In turn, we focus on how socioeconomic factors influence the links in the supply chain and illustrate this via three urban ecosystem service/disservice examples: moderation of temperature extremes, urban gardening, and fear and stress reactions. We then outline ways forward for planners and managers to apply this understanding by providing specific suggestions about how to use these concepts and the model to deliver better urban ecosystem service outcomes.

Linking socio-economic factors to ecosystem services
Our conceptual model distinguishes between the biophysical supply of an ecosystem service, the demand for it by people, and the benefit that people receive from a service that contributes to their well-being (Potschin and Haines-Young, 2011;Tallis et al., 2012;TEEB, 2010; Fig. 1). Urban ecosystems provide biodiversity and ecosystem processes that can potentially provide ecosystem services to people (i.e. ecosystem service supply). Socio-economic factors in cities affect ecosystem services through two distinct and interrelated direct pathways: (1) by influencing the management of urban green space and in turn ecosystem service supply, and (2) by altering human needs and activities and therefore people's demand for specific ecosystem services. For certain services, there is an (3) indirect pathway whereby a resident's socio-economic status can influence how the provision of an ecosystem service affects their wellbeing (i.e., their physical or psychological health). Along each of these pathways, ecosystem services can also feed-back to influence socio-economics (e.g., Wolch et al., 2014) although we do not focus on that bidirectionality here. Our model emphasizes the need to understand these multiple pathways through which socio-economic variables influence both the biophysical and social aspects of urban ecosystem service provision (Bagstad et al. 2013).

Socio-economic factors influence the supply of services
Changes to the amount and characteristics of urban green space affect the presence and abundance of species, the structure of vegetation, the ability of urban residents to access green space, and, subsequently, the ability of urban green spaces to actually supply ecosystem services (Gaston et al., 2013;Caynes et al., 2016). Socioeconomic factors influence the ecosystem services supplied by green spaces by altering how much green space is present in cities and how it is managed (Fig. 1). For example, city regulations, zoning