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 money-back 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? Alexander J. Felson and the Urban Ecology and Design Lab construct a bioretention green infrastructure research tool and public park for coastal adaptation in a highly urbanized housing development in Bridgeport, with participation from The Nature Conservancy and the local community. Photograph: Adam Whelchel, The Nature Conservancy. 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 Synthesis at the US Geological Survey, senior research ecologist at Colorado State University, and president of the Ecological Society of America (ESA). Such an approach is warranted in applied fields because decisions and policies are made in the face of uncertainty. In urban planning, however, the idea of incorporating experiments into design is relatively new. In the construction industry, the traditional mentality has been that “we build it the way we've always built it,” says Alexander J. Felson, director of the Urban Ecology and Design Laboratory ( www.uedlab.yale.edu ) at Yale University. Trained as a landscape architect before embarking on a PhD in ecology, Felson is intimately familiar with urban development practices. Typically, urban planning is “precedent driven rather than science driven,” says Felson, so “there is very little ecological or scientific information informing green infrastructure design.” That is a reality that Felson is determined to alter, as a pioneer of the idea of incorporating “designed experiments” and data collection opportunities into urban design projects. This embryonic approach challenges the mantra in design to reduce complexity, stick to what is known, and find ways of reducing maintenance and management needs. “When you get into this realm of innovation and adaptation, you increase the potential for failure,” Felson acknowledges. Consequently, “designed experiments” in urban planning are unusual. Felson hopes to make them mainstream (see the Overview and Professional Biologist articles that begin on p. 854 and p. 882 of this issue). Cities are home to “an increasing fraction of humanity,” and the urban landscape has “a disproportionate impact on regional and global systems,” as was outlined by Pickett and colleagues in BioScience in 2008 (doi:10.1641/B580208). What they proposed is a new framework for urban ecology, involving integrated studies of large urban areas as biophysical—social complexes. “Probably the great frontier in environmental science now is to make humans a part of the system,” says Peter Groffman of the Cary Institute of Ecosystem Studies, adding that, although that idea is both difficult and exciting, the place to sort it out is urban areas. Findings from the Baltimore Ecosystem Study (BES), for which Groffman is a lead scientist, suggest a rethinking of our ecological assumptions about cities. BES data from Baltimore and five surrounding counties showed, for example, that urban biodiversity may be greater than we thought. Within Baltimore City, the BES researchers found new species of invertebrates, rare plants, and about one-third of the regionally present native bird species. Urban soils are more complex and variable than was predicted, as is the ability of these soils to store organic carbon. The BES is a working example of how ecological experiments can replace urban legends with solid scientific knowledge. Designed experiments can help answer important questions in urban ecology, yielding unexpected findings. Felson and his colleagues outline in this issue of BioScience both how such experimental integration into the design and planning process can be achieved and why such experimentation is necessary. Cities worldwide are developing and investing in strategies to improve sustainability and adapt to a changing climate. Urban design that embeds rigorous data collection and monitoring with feedbacks into management, design, and construction makes both ecological and economic sense. “To include this type of rigorous ecological assessment of the consequences of their actions is a logical way for many practical disciplines to go,” says Baron. She is delighted to see this new approach move into urban planning and landscape architecture. Although she has not conducted research in the urban context, she is happy to be a “cheerleader” and the glue adhering the right people together to make it happen. “This is exactly the kind of activity that will promote ESA's Earth Stewardship Initiative,” Baron says. The Earth Stewardship Initiative is the ESA's formalized acknowledgment of global responsibility to share ecological knowledge and move toward sustainability. The initiative recognizes that cities provide unprecedented stewardship challenges and opportunities. Engaging strategic stakeholders, one of the strategies identified by the initiative, is precisely the mechanism that Felson and his colleagues are using as their fulcrum to initiate the shift from precedent-based to dynamic, adaptive, experimental urban design. The recipe for such a shift is also outlined in Felson's recent article (doi:10.1890/130061) entitled “Promoting Earth stewardship through urban design experiments” in Frontiers in Ecology and the Environment . Judy Layzer, a political scientist and professor in the Department of Urban Studies and Planning at the Massachusetts Institute of Technology, points out that the concept of adaptive management, although it is endorsed in theory, is rarely successfully implemented in practice in other fields. In a recent review in Biological Conservation (doi:10.1016/j.biocon.2012.08.016), Westgate and his colleagues discussed these challenges, analyzing professed examples in detail, and concluded that there are actually “surprisingly few practical, on-the-ground examples of adaptive management.” One of the key failings of adaptive management as it has been applied to the biological sciences, explains Layzer, is in monitoring. Not only “expensive and unglamorous,” monitoring often falls short in actually collecting data relevant for informing management. One of a number of stumbling blocks is the difficulty of running experiments in areas in which the public is very attached to the status quo or has a preservationist ethic, she explains. “Experiments to [discover] and reduce uncertainty sound like a great idea but are very hard to run in the context of places like the Chesapeake Bay, the California Bay Delta, or the Everglades,” where people are very attached to the land as it is or to certain fishing practices, for example. Another hurdle, she explains, is the persistently poor communication and interaction and the lack of shared goals in many agencies between scientists and managers. Will such problems be more or less severe if adaptive management is applied to the urban ecology context? It's difficult to predict, says Layzer, but she's hopeful that, in urban areas that are already altered—not pristine—people may be more tolerant of experimentation, especially if its purpose is explained. She's optimistic about the prospects of embedding ecological research into urban design. “[It] doesn't have the win—lose feeling that adaptive management in other sectors can have… It's a question of good, better, best,” she explains. “It feels less risky because you are restoring and building. You are certainly not going to make anything worse.” Whether monitoring will be as challenging in the urban context as it is in other settings remains to be seen. Determined to find common ground with precedent-led planners and to chip away at the status quo, Felson leads the charge in this emerging field. He is under no illusion that the interplay between city planning and urban ecology will be anything but difficult. “I decided early on that I wanted to bridge ecological research and urban design,” he says. Because his palette of expertise is rare, Felson suggests that it may take the development of new interdisciplinary, dual-degree programs to provide the human intellectual fuel that will keep the interdisciplinary fire burning. Yoshiki Harada, Mark Bradford, and Emily Oldfield conducted field research in 2011 to measure tree biomass through destructive sampling as part of NY-CAP (the New York City Afforestation Project). Photograph: Alexander J. Felson. Why expend so much energy and effort to rethink the status quo? “The Million Trees initiative [MillionTreesNYC, a New York City Afforestation Project (NY-CAP) initiative] is the perfect example,” says Felson. “We are spending millions of dollars on it, but it was [initially] a little bit haphazard,” he explains, in that decisions about how far apart to plant the trees, what species to plant, and how to plant them were based on practice in the field and trial and error rather than experimental ecological knowledge. Felson was in the right place at the right time in terms of being able to work with the City of New York Department of Parks and Recreation to include experimental research in their mammoth planting effort, the PlaNYC Reforestation initiative ( www.nycgovparks.org/greening/planyc/reforestation ). In 2007, the Department of Parks and Recreation put out a request for proposals to develop the PlaNYC Reforestation initiative, a component of the MillionTreesNYC project on public land. One of their on-call landscape architects, Donna Walcavage, was familiar with Felson's work and brought him on board. In the NY-CAP proposal, Felson suggested both research and monitoring. Monitoring was already on the radar for inclusion, but he sought to position research to inform urban forestry beyond making inferences from the alive-or-dead assessment of trees that characterized the typical approach. Working with both the Natural Resources Group and the Capital Projects Division (programs embedded in the Department of Parks and Recreation), Felson proposed the radical idea of incorporating research experiments into the tree-planting strategy. Felson and Walcavage were awarded the bid, supported by a team of geographic information systems experts and landscape architects from AECOM, a large environmental consulting firm where Felson was employed at the time. Work began in 2008. One of many hurdles to overcome was that a typical experimental plot lacked the aesthetics that both planners and users were accustomed to seeing in eye-pleasing parks. Felson had already learned this the hard way in a previous project, in which his experimental design was ditched at the last minute because the park planners were uncomfortable with the way it looked. The trick, he found, is to get creative with design. In the NY-CAP, Felson embedded the research grid in what landscape architects refer to as a “picturesque style,” meaning that the study plots are stitched into a parklike setting. One of Felson's partners in crime on the New York City urban forest project is fellow Yale professor Mark Bradford. Bradford conducted his doctoral research on forest soils and a post-doc on soils in natural and managed forests and grasslands. Felson, seeing an opportunity to benefit from Bradford's wealth of knowledge on dirt, suggested that Bradford take baseline measurements on soils before planting began for the MillionTreesNYC project. “We can actually work out what happens to the soil when we plant trees,” explains Bradford. “Things like more efficient drainage, carbon storage, and better nutrient cycling all rely on the soils.” Bradford admits that he initially put off Felson's request—until, that is, Felson showed up to say that “they are prepping the site for planting next week, and if we want to get this data, we have to go out now and sample hundreds of plots.” This marked Bradford's initiation into ecological research in the urban realm. Alexander J. Felson and Mark Bradford's NY-CAP (New York City Afforestation Project) team sampled soils in 2009, prior to the project's establishment; in 2010, following the site's reparation; and again in 2011, 1 year after the 5–6-year-old saplings were planted. Photograph: Alexander J. Felson. Qualities of urban soil are just one of the many mysteries of urban ecology still being investigated. A dozen different orders of soil form naturally through geology and biology, but soils in the human-dominated realm are very different. There is currently talk of creating a 13th order representing a human-altered soil, explains Bradford. “One of the most interesting things to me, as someone hijacked into urban ecology, is that many … questions pop out that we really do not have the data to address. So the idea that we could plant 1 million trees in the city and expect them to grow into a forest, with new baby trees that recruit, is purely untested.” Despite this huge knowledge gap, cities all over the world are putting millions of dollars into tree planting, without knowing whether these planted trees will actually grow into the forests as intended. “One would not build a wastewater treatment plant if it did not achieve water-quality standards, so why plant an urban forest without knowing that it provides the intended function?” as Felson, Emily Oldfield, and Bradford argue (see p. 882). Their questions—such as whether you can plant native trees in a city to grow a native forest that is self-sustaining—are being incorporated into experiments in which species richness is varied and in which the physical and biological properties of the soil are tested. Bradford uses the analogy of the three little pigs: “At the moment, we're saying the equivalent to ‘we want to go and build a house'—except in this case, it's a forest—and we need to know whether to build it out of straw, sticks, or stones so that it can stand up to all the different pressures that an urban forest might face.” (a) The original plot design as developed by AECOM with the New York City Department of Parks and Recreation. (b) The revised NY-CAP (New York City Afforestation Project) plot design, with shrubs and herbs and with species reorganized into patches mimicking urban forest regrowth, creating an aesthetically pleasing “naturalistic” plot. (c) The citywide plots include an altered plant palette, planted more densely and in regular grids to accommodate volunteer planting. The abbreviations refer to different species. Source: Alexander J. Felson. The standard in following up on tree-planting exercises is to score whether the tree is alive or dead, explains Bradford. He's fond of quoting Rich Hallett, of the US Forest Service (USFS), who says that if your primary care physician were scoring whether you were alive or dead, you would probably want to change your doctor. As knowledge grows over time, finer-scale measurements can replace these coarse measurements, to allow more sophisticated health checks of the urban forest. At what point does a group of trees become a forest? That is a question that still has no clear answer and one that Bradford recently discussed with Hallett, on the Bradford, original was of the by the project's also been a One of has been to the of an urban forest by of A developed by the in with and provides into tree health and ecosystem and suggests how many and where trees be planted. the and in and also a in the NY-CAP points out that with different management is not new to the management of New York A at the City of New York Department of Parks and Recreation before embarking on a PhD at and then the was in the recently doctoral who has areas in New York City as an experimental treatment to with areas. 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