Nina-Marie Lister, MCIP, RPP, Affiliate ASLA, is Associate Professor of Urban & Regional Planning at Ryerson University, and Visiting Associate Professor of Landscape Architecture at Harvard University’s Graduate School of Design (GSD). She is a contributor to Ecological Urbanism and co-editor of The Ecosystem Approach: Complexity, Uncertainty and Managing for Sustainability. Lister recently served as the Professional Advisor to the ARC International Wildlife Crossing Infrastructure Design Competition.
In Ecological Urbanism, you argue that ecology is now central to contemporary urban landscapes. How did this change occur? What must these new ecological landscapes accomplish to be successful?
There has been a paradigm shift in ecology over the last quarter century. As scientific research and published evidence on whole ecosystem function mounts, we’ve seen the paradigm of ecology move toward a more organic model of open-endedness, flexibility, resilience, and adaptation and away from a mechanistic model of stability and control. In other words, ecosystems are now understood to be open systems that behave in ways that are self-organizing and that are to some extent unpredictable. Change is built into living systems; they are characterized in part by uncertainty and dynamic change.
For decades high school biology and ecology has taught—and in some places, still teaches—that ecosystems gradually and steadily succeed into stable “climax” states from which they don’t move unless “disturbed.” An old growth forest is one of the classic examples usually given, in which the forest matures and then remains in that state permanently such that any disturbance from that state is considered an aberration. Yet we now know that change is not only built into these systems, but in some cases, an ecosystem is actually dependent on change. For example, fire-dependent forests contain tree species that require the extreme heat of fire to release and disperse seeds and to facilitate forest renewal—and sometimes, a shift in the complement of species. All ecosystems are constantly evolving and often in ways that are discontinuous and uneven. While some ecosystem states are perceived by us to be stable, this is not strict stability in a mathematical sense; it’s just our time-limited perception of stasis. The work of Canadian ecologist, C. S. “Buzz” Holling, pioneered this concept in terms of resource management. He called ecosystems “shifting steady-state mosaics” which means that stability is patchy, and it’s scalar; it’s not something that defines a whole system at any one point in time or space.
Much recent work in applied ecology has been about trying to understand what are those ecosystem states that we perceive as stable, and useful to us, such that we as humans want to encourage. This perspective rests on the recognition that we’re not outsiders to the ecosystem—we’re participants in its unfolding. Of course, we are designers as well. We shape the ecosystems in which we live—sometimes profoundly and irrevocably. This means that understanding the states in which an ecosystem appears to be stable is very important to being able to “steer” or guide it back to some recognizable, desirable, and resilient state after a sudden or surprising change. Most of this research has been focused on wilderness and large natural landscapes, although my own research and practice takes this work into urbanizing landscapes, where there are many applications for design.
Some of the classic examples of normal (yet often catastrophic) ecosystem change include forest fires, pest outbreaks, and significant storm events. These are taking on a new relevance today as we observe that the frequency and magnitude of storm events is increasing—a change which is being attributed to climate disruption. When major storm events happen (particularly in densely populated or urbanizing regions), they can push an ecosystem into a new state which might ultimately be inhospitable for certain species, resources, or people. Given the uncertainty inherent to ecosystems in this complex systems paradigm, coupled with the uncertainty around climate disruption, it’s likely necessary to change the way we are used to managing our ecosystems. In fact, what we really need to do is realize that we can’t efficiently or even effectively manage complex ecosystems at all—rather, what we can do is manage ourselves and our activities.
We can shift our focus from managing ecosystems from a principally economic perspective to managing human actions within ecosytems. We’ve already seen evidence of this change, beginning in the conservation movement in wilderness areas. For example, in the late 1980s, when Yellowstone National Park was ravaged by forest fires, the National Parks Service management approach still included a general fire suppression policy (although they had begun to allow small controlled burns in some National Parks since the 1970s). Forest ecologists have argued that it was the legacy of this policy and a century of fire suppression in the parks that essentially created a set of ecological conditions that allowed Yellowstone to burn at the scale and intensity that it did. Today we understand that it’s a better management practice to allow smaller, natural fires to burn more frequently—and in some cases, to prescribe and set small-scale controlled burns, even in urban areas. For example, prescribed burns take place annually in the Oak Savannah of Toronto’s High Park, which is a culturally and ecologically significant ecosystem. In this case, prescribed burns are used to maintain the Oak Savanndah, a transitional state in this ecosystem, which would eventually evolve to a closed canopy mixed forest without fire. Whether wild or urban, certain ecosystems are now recognized as adapted to and dependent on fire to renew, evolve and change.
A more timely and urban example of this paradigm shift in ecology and related management approaches can be seen in how we deal with floods. We can see this specifically through a gradual transition from flood control to flood management. At least a decade before the devastation of Hurricane Katrina, ecologists and hydrologists were warning that the U.S. Army Corps of Engineers’ approach to flood control was effectively pushing the lower Mississippi basin towards a catastrophic threshold for change and potential collapse. Through a long-term policy of flood suppression, dyking and damming, coupled with the removal of coastal wetlands, and intensive settlement of the floodplains, the natural flood-adaptation mechanisms of the basin were comprised and impaired. When the big storm hit in 2005, we know that the devastation was catastrophic not only for the resources and the economy of the region, but for the lives of many of its most vulnerable citizens. In this very poignant example, it’s clear that traditional top-down or command-and-control engineering approaches to living systems don’t work. What is needed are more flexible, adaptive approaches to managing human activities and to designing within the systems that sustain us.
You quote Jane Amidon, a landscape architecture professor, who says, “The idea of nature has been remarried with the real thing, working ecologies.” What are some examples of this?
This is part of the paradigm shift that recognizes a productive working landscape is a model for a healthy, resilient ecology. Over the last 20 years, our conservation policies have focused less on ecosystem structure or objects of nature and more on function. So while we’ve always valued objects of nature, for example, charismatic wildlife and other iconic species that we want to protect, those are essentially structures. We’ve shifted our collective understanding at least in conservation management to recognize that ecological functions are now equally important but they’re less tangible and visible to people. Amidon’s reference to working ecologies reflects this contemporary thinking. I have often used the term “productive ecologies” to refer to working landscapes, or cultural-natural ecosystems that provide food, water, clean air, agricultural produce, raw materials for industry and so on. Making these functions visible, as opposed to just the objects or structures of nature, is a powerful way of communicating what an ecosystem does for us, and in turn, how we value those services.
For a designer, it’s a potent and revelatory act to be able to show how ecosystems work so that people then appreciate and participate in the unfolding and working of a landscape in which they are participants, not merely consumers. The increased use of green infrastructure in our cities is a good example in which people can see the functions of a working ecosystem—whether in green walls that stabilize an embankment, or green roofs that provide food, or bioswales that filter and slow stormwater runoff. By making these processes visible, we have the potential to make ecology directly relevant to our publics. But really smart green infrastructures that are instrumental to productive ecologies go a step further: they facilitate hands-on learning or they require citizen participation in the ecological function. For example, many wetland creation and restoration projects rely on community volunteers for planting and maintenance; urban bioswales and green streets rely on stewardship by the community to function properly; and urban agricultural projects engage youth to work with native plants, bees, or chickens, etc, and become ambassadors for the project through outreach and education.
Green infrastructure is a practical way to understand working landscapes. As interest in local food continues to increase, we might think of food landscapes as a type of green infrastructure. Whether as vernacular community gardens or as a designed urban farm, or turning city parks into foraging landscapes with fruit and nut trees—these are all illustrations of our landscapes at work and in which people can and do participate. To my mind, this is a productive ecological urbanism.
You argue that brownfield sites, once stripped of layers of toxic soils, are often locations for new “hybrid ecologies.” What are some examples of those? Are these a good thing?
Brownfields by definition are former industrial or commercial sites which may be contaminated, and which are almost certainly abandoned, underused or disused. As such, these are sites with both liabilities and opportunities, and where ecological processes may be shaping the transformation of the site quite independently of human intervention. The very act of neglect opens a variety of ecological niches, exploited by plants, animals and people who use the site informally. Brownfields are often populated by co-evolving assemblies of introduced and native species which form new ecological communities—the kind that are usually associated with derelict lots, urban decay and the image of the shrinking city. But these hybrid ecologies can be useful. Weedy plants (both native and non-native) are able to rapidly colonize disturbed and moderately contaminated sites; they can often tolerate and metabolize toxic materials such that they begin to remediate the site. For example, Steven Handel, an ecologist at Rutgers, has done considerable research in restoring ecological functions to brownfields. While weedy sites maybe an eyesore to some, they are also a legitimate ecosystem in so far as they perform a variety of ecological functions such as stormwater infiltration and carbon sequestration in addition to pollution uptake, soil remediation, and so on. If we look at these functions as value-added services, brownfields take on a new importance as beneficial transitional sites in the urban landscape. We could see brownfields as hosts to ephemeral, hybrid ecologies that provide free services to the city while a site is awaiting a new use.
Interestingly, the environmental movement has become an inadvertent opponent of brownfield remediation using a hybridized ecological approach. A considerable portion of fast-growing, resilient but undesirable plants, commonly called “weeds,” are non-native. I would point out that Peter del Tredici, an ecologist at Harvard, has re-branded weeds as “wild urban plants,” alluding to their important role in the urban landscape. Not all non-native plants are invasive, but the unintended consequence of campaigns to eradicate non-native plants and to grow native species at all costs has been to overlook the potential benefits provided by non-natives in site remediation.
I want to emphasise that I am using the word “remediation” quite explicitly. I don’t like to use the word “restoration” in this context, because it’s rarely made clear what state we’re restoring towards and why. Restoration implies that a particular moment in an ecosystem’s evolutionary trajectory can be captured and preserved. But there is no pristine state in a world where the human animal is a participant in the ecosystems of which we’re evolved. The ecological restoration rhetoric has been over-simplified to the point where well-meaning citizen volunteers are pulling out any species that “don’t belong here.” There’s a xenophobic overtone to the language of restoration ecology that I find somewhat concerning. It’s not dissimilar to the language we use to describe people who “don’t belong”: non-natives, aliens, foreigners, exotics, intruders, etc.
So when I talk about hybridized ecologies in the context of remediating an urban place, I’m referring not only to repairing the physical ecological functions of an evolving ecosytem, but also at a higher level, to (re)mediating the metaphorical relationship between culture and nature. We don’t exist outside the ecosystem—we are born of it, we depend on it and we ought to design within it, with respect for both the culture and the nature of the place. Surely this would be a good thing.
The Evergreen Brickworks in Toronto is cited as a new model for an ecological urban landscape. Why is this project important? How does it present a new model for engaging the community? How is it different from any other nature discovery center?
The Evergreen Brickworks is unique for several reasons. It’s first and foremost a center for the discovery of culture and nature in the city. Neither domain is prioritized, and the synergy between culture and nature in an urban context is what makes the place and its programs unique. It also represents an unusual partnership and an innovative business model, at least in the Canadian context. Evergreen Brickworks is a $55 million dollar project that has been conceived, developed, and run entirely by a not-for-profit organization, with contributions from three levels of government and various corporate and philanthropic sponsors, and it’s built and operated on public land.
The project demonstrates integrated thinking and systems-oriented design—one we might say represents a tangible model for sustainability. I’d call it ecological urbanism in practice. Evergreen Brickworks features adaptive re-use of most of the heritage industrial buildings; the only new building is the LEED-Platinum Center for Green Cities which features a variety of state-of-the art green technologies. Together, the buildings and their programs have been designed to activate and curate a working, productive landscape in the heart of Canada’s largest city. The landscape is designed principally for education and the production of food—from farming to markets and kitchens. Programming focuses on cultural and biological diversity—from people to food to native plants—with a particular emphasis on children and youth-at-risk.
The Evergreen Brickworks breaks the mould of a “nature center” in a lot of ways: It’s geographically in the center of the city, it’s on public land, and it’s run by a not-for-profit. Its entire model of governance represents a social ecology that’s very different from the traditional, top-down government-run or philanthropic organizations. It’s very much a model of collaboration and partnership. As such, Evergreen Brickworks sets a precedent for the way in which we bring people and nature together in an urban landscape—and this is a productive, generative model that transcends the old dualism of “culture versus nature.”
In a recent talk at Dumbarton Oaks, you also introduced the idea of adaptive design, which involves building ecological functions into a landscape so it’s more resilient to climate change and other environmental impacts. The idea is to create landscapes that are “safe to fail” and can actually thrive with change. Please describe this idea. How can it work in practice?
Adaptive design is a term that I’ve used for some time now to describe an approach to planning and design that explicitly recognizes ecological systems. Design, planning, and management are all part of the same spectrum of activities in which we engage with our landscape and living ecology. The central notion of adaptive design is that if we understand that landscapes and their ecosystems are fundamentally dynamic, that they’re constantly changing, this means that there is an inherent amount of uncertainty in terms of how they behave. Within complex living systems we cannot predict with certainty and precision, no matter how much scientific evidence we have, exactly what will happen or when it will happen. For example, we know very well that certain areas are subject to seasonal flooding. We know that under a scenario of climate change, we can expect more flooding. So while we know that flooding is to some extent an inevitability, and that floods will happen, what we can’t say with certainty is exactly when those events will happen. The point is that ecosystem change is inevitable: it’s built into these living systems, but we can not predict with certainty how and when they’re going to change, or the extent of the change. One cynical response has been to say, “oh well, if we can’t predict what’s going to happen, then what’s the point of planning? We should just give up and adapt when disaster strikes.” This is the “passive adaptation” theory, and it’s a naive response which few of us would take seriously. Adaptive design, by contrast, is a more nuanced response that is based on understanding the history, context and trajectory of a living system, and the pressures that the system is facing.
Let’s return to the flood example. In a given river basin, we often understand very well where the 50 or 100 year flood level is and we zone people outside of susceptible flood plains. In flood-prone regions, people have tracked water levels for hundreds of years and often have a good idea of the scale and extent of inevitable floods. However, modern civil engineering has de-emphasized local knowledge at local scales and focused instead on large-scale efforts at flood control rather than management. Adaptive design is, in part, an approach that re-emphasizes local knowledge and knowledge at various temporal and spatial scales. For example, if we study an ecosystem at and across several scales (taking into account historical knowledge) we can begin to understand this system’s normal behaviour patterns and which of its ecological structures and functions help to return the system to the desirable state following a disturbance event, such as flooding. These structures and functions are said to build resiliency. Assembling this type of cross-scale knowledge about an ecosystem might be called a “resilience profile.”
Another important characteristic of adaptive design is that it ought to be safe-to-fail. We know that structural engineers must design bridges and buildings to be fail-safe (i.e. a collapse or structural failure would be unacceptable). But living systems differ in several important ways from mechanical and structural systems. We use the notion of “safe-to-fail” to recognize that living systems are different particularly in that they regularly undergo change events that move the system from one apparently stable state to another. The underlying idea is that if change is inevitable, then we ought to facilitate small-scale, manageable changes to happen without causing catastrophic failure.
In ecosystems which are adapted to fire or flood, the evidence suggests that it is more reasonable to facilitate, rather than (attempt to) prevent the disturbance from happening. So an adaptive design that is safe-to-fail in a flood-prone watershed, would rely on a proactive flood management approach based on a landscape design that facilitates regular safe flooding, rather than pre-empting any flooding and risking a catastrophic flood.
Adaptive design must necessarily reply on an evidence-based approach. I’ve asked my design colleagues to form research partnerships with ecological scientists so that we can track small-scale examples of ecological design and learn what happens under various change events. The idea is to learn from failure, and when we make mistakes, we do so safely, without long-term consequences. We need to scale back on the size of our plans in some cases, and most importantly, we need to design and conduct our interventions as rigorous, empirical, evidence-based experiments so that we can learn from them, track the data, understand how they respond to change events.
The lack of well designed wildlife crossings, has led to a 50 percent increase in collisions between wildlife and cars over the past 15 years in the U.S. Not only do these collisions take a huge toll of wildlife and people, but they cost the U.S. economy $8 billion a year. You advised the ARC Design Competition, which aimed to come up with a improved model for wildlife crossings. What are the next steps for the winning design by Michael Van Valkenburgh and HNTB? What is really needed to get these rolled out across the U.S. and Canada?
The ARC project was a challenging opportunity for me to link my previous research and field work in conservation biology with my more recent work in ecological design. The primary reason I took on the ARC project was to contribute to a long-term, high-level strategy of reconnecting the North American landscape. Our landscapes and the diverse habitats they contain are under threat as they are increasingly fragmented through expanding road networks. As cities spread laterally and blend into other cities, the road networks connecting these mega-regions are carrying more traffic, and they fragment the remaining wilderness landscapes. Wildlife populations soon become isolated and are forced to move across roads for feeding and breeding. The result is that we’re seeing a marked increase in collisions between motorists and wildlife.
Landscape architects are uniquely positioned to remediate this problem by designing new, “connective tissue” in the form of wildlife crossing infrastructure that must function structurally and ecologically, as habitat. On a continental scale, a network of crossing structures, both under and over roadways, can literally weave the landscape together.
Wildlife crossing structures present an interesting design challenge in that they must serve two clients: the human and the non-human. Of course, the wildlife client’s needs are less clear than the human clients’ needs. This necessitates considerable ecological research by the design team, usually with an ecologist or conservation biologist.
The short-term tangible goal for the ARC competition was to get a wildlife bridge built over the I-70 at Vail Pass which is a particularly problematic location for motorists and wildlife. This stretch of the I-70 has been studied extensively for over a decade, and the preliminary environmental impact study for the I-70 Corridor calls for a mitigation strategy. There is clear evidence that there is a need for crossing structure, and when you look at the data in terms of overall costs of vehicle-wildlife collisions to motorists and the state– from personal damages to auto repair to insurance claims and premium increases to road maintenance—it’s staggering to see that nothing is being done. The competition has helped to raise awareness of the costs of these collisions to both humans and wildlife. To date, we’ve had a very positive response to the competition by the public as well as the Governor and the local Congressman. We’re currently at work on an implementation strategy with a number of stakeholders in the region.
A longer-term goal of the competition is to bring wildlife crossing infrastructure into the mainstream of public awareness as a cost-effective and ecologically viable solution to the growing problem of vehicle-wildlife collisions. We are doing this in several ways now that the competition is over. In addition to working towards implementation of the winning design at Vail Pass in Colorado, we are also showcasing all five finalists’ design concepts around the country and at conferences and other events. The idea is to demonstrate a compelling diversity of design solutions for wildlife crossings and highlight these as a specific type of infrastructure. We are also promoting all the finalists’ designs to other U.S. states and Canadian provinces where a wider range of context-specific mitigation structures are needed. We see a tremendous opportunity for growth in this sector, where the problem is clearly identified, the costs of doing nothing are rising, and the solution is proven.
Another longer-term strategy of the competition is to engage the public in a higher-level discourse about the importance of landscape connectivity and the role that connected, living landscapes play in the health of the environment. A key part of this communication strategy is to develop a traveling educational and experiential exhibit that brings the wildlife crossings to the public in a personal way. We also want to be able to use the structures themselves as an engagement tool for citizens to understand the need for them. For example, we can use the structures as live monitoring sites around which schools could develop educational programming, and scientists can gather data for research. There are infrared cameras already installed at a number of crossing locations and while these are currently used for research purposes, they could also be linked to a live Web feed through which scientists, students, and the general public could track and observe various wildlife species in real-time. These cameras—or others installed specifically for this purpose on new structures—could also be used to feed visual data to a mobile device, perhaps as an application for smartphones. These visual and interactive strategies have the added benefit of allowing people to become more engaged with a landscape that so far has been relatively invisible to an urban population traveling at 60 miles an hour along the interstate.
We do need a lot of public recognition and sustained attention to the problem of vehicle-wildlife collisions to get these structures accepted as viable solutions and into the mainstream of transportation infrastructure. Ted Zoli, a MacArthur “Genius Grant” Award winner in bridge engineering and the lead designer for the ARC winning team of HNTB and MVVA, has pointed out that the annual $8 billion USD cost of vehicle-wildlife collisions is several orders of magnitude more than the problem of bird strikes with aircraft. Yet, unlike the state Departments of Transportation, the FAA spends billions of dollars in research to avert a statistically minor problem. The point is that we have a very costly problem that is increasing, and for which we have a proven solution, and yet nothing is being done about it.
Indeed we know that crossing structures work. The ARC competition relied on an extensive body of peer-reviewed scientific evidence from both Canada and Europe. In particular, we designed the brief to reflect lessons learned from a decade of research on more than 20 crossing structures in Banff, Canada which served as the prototypes for the competition.
We also undertook a cost benefit analysis comparing the proposed bridge for the Vail Pass to existing structures in Banff which cost approximately $10 to $12 million USD. These are conventional highway bridge structures that have a simple overburden of soil and vegetation. In this respect they are over-engineered, and yet they are also designed for a highway that is two lanes smaller than the expansion proposed for the I-70. We know we can build these structures for considerably less than the Banff prototypes, and a key advantage of the hypar-vault system proposed by the HNTB+MVVA winning entry is that the structure can be made smaller or larger as necessary.
A primary objective of the competition was to bring the cost of crossing structures down. We also wanted to show how we can use new materials, or how we can reinvent common, easily available materials ways that offer more flexibility and adaptation to the various landscape contexts in which these structures might be deployed. The jury was impressed with the winning entry on all accounts, but in particular by the use of an old material in a new, cost-effective way: precast concrete is a familiar material, the technology is well understood. The hypar-vault modules are cost-effective. This is principally because there are over 400 pre-casters throughout North America so transportation costs of getting the modules to where they are needed is reduced. The jury noted that the benefit of using a familiar technology is that it is more likely to be accepted, even if in a new way. Once several of these structures are implemented, it’s more likely that we’ll see a willingness to experiment with different materials. This too was an objective of the competition, and several of the finalist teams developed innovative concepts using newer materials and engineering approaches, including cast-in-place thin-shell concrete, reclaimed beetle-killed timber, wood-core plastic laminate, resins and steel mesh. In this way we can consider the ARC competition as the beginning of a new typology of infrastructure—and a new role for landscape architecture.
Instead of big theoretical approaches, you seem to say that any good ecological design has to be rooted in its natural place. How can landscape architects ensure they are doing this when they create these new ecological landscapes for people and wildlife in cities?
Throughout this conversation I keep coming back to the centrality of scale and context in ecology. Our cities are much larger than in the past, and more of us live in cities. So in a very real sense, our cities are landscapes with functioning ecologies, including both natural and cultural components. Making ecological context (or “place”) is central to all my work. Of course, this is not a new idea. It’s simply a timely emphasis on a very old idea. One that civilizations always understood when the ability to survive depended fundamentally on the ability to know an ecosystem intimately. Now that we’ve scaled up and supersized our cities, we’ve distanced ourselves from the ecological functions on which we ultimately but invisibly depend. The negative affects of this scaling are becoming clearer every day. But the good news is that landscape architects, ecologists and even some engineers (ok, many engineers) usually understand these ideas very well already. The fact that we are collaborating more than ever, finding creative synergies in our work, and taking on more complex projects are all good signs. We are seeing a more infrastructural and performative approach to landscape design, and there is growing recognition of the economic value and social benefits of ecologically-functioning landscapes. But I think we can work towards a more sophisticated ecological urbanism in a number of ways. Chief among them is to make our designs reveal and celebrate the complexity of the ecosystems that define and sustain us. I am an optimist, and I believe design has the power to cultivate a more ecologically literate and engaged citizenry.
Interview conducted by Jared Green.
Image credits: (1) Ecological Urbanism / Harvard Graduate School of Design, (2) Toronto High Park Controlled Burn / Torontoist, (3) Urban bioswale, Sherbourne Common, Toronto / WATERFRONToronto, 2010, (4) Evergreen Brickworks, Toronto / Nina-Marie Lister, (5) Hypar-Nature / Michael Van Valkenburgh Associates and HNTB, (6) Wildlife Crossing App / Michael Van Valkenburgh Associates and HNTB