Thursday, October 15, 2009

Urban green space as provisioning and regulating ecosystem services - thoughts on escaping the "Cultural services" catch-all

Ecosystem service provision is a rapidly growing field of inquiry and policy making.  In urban social-ecological systems, ecosystem services are an important way of placing additional focus and value on “green infrastructure.”  Unfortunately, current understanding of urban natural resources and their subsequent valuing in ecosystem services terms does not optimize awareness or prioritization of these features and functions of the urban landscape.  This is a result of how urban natural resources are often categorized, as primarily cultural service providers as opposed to regulatory or provisioning services.  This paper explores a critical argument that urban natural resources, for example trees, community gardens, and other green space are sometimes misplaced in the “cultural services” category, especially when urban trees and other urban natural resources are considered as only or exclusively providing cultural (aesthetic, spiritual, or recreational)  ecosystem services.  Further, by drawing on the horticultural therapy and other “nature contact” literatures, this paper makes the argument that one could (perhaps should) consider trees and greenspaces as producing provisioning and regulating services rather than just cultural services.    This paper contributes to a much-needed synthesis of the human health benefits of green space to the ecosystem services and resilience discourse, but also points out that some cultural ecological services provided by the presence of certain “green infrastructure” might be in conflict with efforts to manage for other regulatory ecosystem services in the same SES (narrow scale), as in the case of a gardener growing an invasive species in an urban community garden, for example.

Currently, Pickett’s diagram describes “cultural” ecosystem services as “aesthetic, spiritual, or recreational,”  “provisioning” ecosystem services as “food, fiber, fuel,” and “regulating” ecosystem services as nutrient filtration and retention, carbon sequestration, and pest and disease suppression.  Cultural ecosystem services are the third category, indicating recognition of them, but ranking them (intentionally or not) as least important.  Provisioning services are second. Regulating are first.  I don’t take issue with that ordering.  What I DO take issue with is that some ecologists often place urban trees, or urban green space into the cultural category.  They argue that the trees in Manhattan, for example, serve mostly aesthetic purposes.  I agree that they do serve aesthetic purposes, but this neglects an important point, which is that they may not serve exclusively cultural services.

Focusing on “provisioning services” for a moment, I argue that these things can generically be considered provision of basic needs for humans to thrive.  Now, if one considers the copious literature on the benefits of green space, trees, etc on both physical and mental health in urban contexts, then urban green space is contributing far more than just cultural ecosystem services.  If one considers the health benefits of green space, trees, etc in urban areas, then these green spaces are AT LEAST contributing  “provisioning services.” 

Focusing now on “regulating services,” it is does not appear to be difficult to link all the aforementioned peer-reviewed literature on physical and mental health benefits of green space to the notion of pest and disease suppression among humans and other species of concern within the SES of interest.  It just hasn't been done yet to my knowledge.  If it HAS been done in the ecosystem services literature, I am pretty sure it hasn't been done in the resilience framework.  Stay tuned.