Integrating Designed Experiments into Urban Planning

If you had paid a plumber to fix a leaky pipe, you would be understandably upset if you discovered that water was still flooding your basement. Most likely, you would demand your money back or ask the plumber to return and fix the problem. Yet, as part owners of the cities in which we live, the purported ecological “fixes” of the expensive green infrastructure projects emerging in urban areas across the world come with no such moneyback guarantee. In fact, large-scale urban sustainability projects—such as tree-planting initiatives in New York, London, and Auckland and constructed wetlands, urban hydrology, and bioretention projects in Australia, the United Kingdom, Canada, and the United States—are designed and implemented in the face of considerable uncertainty and significant gaps in scientific knowledge. Although such projects are often informed by rapid ecological assessments and the best available knowledge, the wisdom of this emerging field—the melding of many disciplines, including ecology, Earth sciences, engineering, and architecture—is incomplete. The biological assumptions underlying green infrastructure design, such as the provision of ecosystem services including flood control, pollution mitigation, and carbon storage, are often extrapolated from very different contexts—from “natural” rather than urban habitats. The validity of such juxtaposition is rarely empirically tested. After construction, there may be no monitoring of how effective infrastructural elements are at attaining the ecosystem services that they were designed to achieve. Therein lies an expensive and risky problem. Can we justify spending millions of dollars on innovative infrastructure that we hope but do not know will work? One possible solution calls not the plumber but the experimental ecologist to the rescue. Adaptive management— the process of learning by doing and then monitoring and tweaking as you go along—is a well-established approach (at least in theory, if not often in practice) in areas of applied biology such as forestry and fisheries. “It’s the idea of treating actions as hypotheses,” explains ecologist Jill Baron, codirector of the John Wesley Powell Center for Analysis and