Recreating Wildlife Habitat in Cities

During the Dumbarton Oaks symposium on “Designing Wildlife Habitats,” ecologists and landscape architects also explored challenges and opportunities with wildlife habitat restoration in urban areas, and the impact of climate change. Speakers offered more variations on the idea of ecological infrastructure, arguing that interdisciplinary design teams are needed to create these multi-use systems. Speakers also concluded that designers and scientists must work harder to tell stories that spark the imagination of the broader public. Otherwise, the value of biodiversity won’t be understood.

Nina-Marie Lister, Associate Professor of Urban and Regional Planning, Ryerson University, and Visiting Associate Professor, Harvard University Graduate School of Design, discussed the idea of “adaptive infrastructure,” which provides a landscape “network stategy.” The idea is that landscape is infrastructure and features edges, nodes, and bridges. Designers can use these landscape components to plan for “complex ecological interaction.” Landscape networking strategies relate to connecting habitat across scales. By building connecting habitat and building complex functions into the landscape, communities (and wildlife) can become more resilient to climate and other major changes.

Ecosystems are complex, diverse, resilient, and unpredictable. “Change is both discontinuous and gradual,” Lister said. Designing for biodiveristy means starting with small, “safe-to-fail” experimentations within larger landscapes. Evidence-based collaborative design practices should be used to figure out what works in a network.

Lister pointed to a few urban ecological infrastructure projects, including the Spadina Quay wetlands in Toronto, Lake Ontario Park master plan (designed by James Corner Field Operations), and Lower Dons master plan (designed by Michael Van Valkenburgh & Associates), as well as the Evergreen Brickworks, which have all restored wetlands. In the case of the Evergreen Brickworks project, the recreated wetland “brought nature, culture, and community together.” In total, Lister said, it’s about “innovation and discovery, food and community, natural and cultural heritage, and gardening and greening.” All projects also incorporate sustainability education into the visitor’s experience. 

On using a network strategy to increase habitat connectivity, Lister pointed to innovative wildlife crossings developed in Banff, Canada, which demonstrate the idea of “infrastructure as safe passage.” She showed great nightime videos of mama bears successfully leading their cubs across earth and grass passages constructed above highways, and explained: “it takes about three years for the crossing to take off. Animals need to know it’s going to stay there and then they test it, eventually using it.” She described how there is a threshhold width needed for large animals to cross a passage. Overpasses are also much more popular than underpasses in the animal kingdom.

Lister said climate change will only complicate habitat connectivity plans because migration patterns will change. She also pointed to a new design competition to build a better wildlife corridor structure. Learn more and submit an idea.

Steven Handel, Professor of Ecology, Department of Ecology, Evolution, and Natural Resources, Rutgers University, has worked on a number of innovative habitat restoration projects, including Fresh Kills Park in New York City, and the Orange County Great Park in Orange County, California. To prevent engineering successes but environmental disasters, which is the case when landfills have been turned into dull grass-covered wastelands, designers need to work closely with ecologists to restore habitats. However, on the flip-side, “high art gardens” are not restoration ecology.

Handel said he often uses the “ecosystem services” concept to sell the benefits of habitat restoration projects to city government officials. Habitat restoration projects provide a range of valuable ecosystem services, including the generation and preservation of soils, cycling and movement of nutrients, partial stabilization of climate, mitigation of droughts and floods, and purification of air and water. He thinks the sell is pretty easy: “You don’t have to sell public finance officials on this.”

For Fresh Kills Park, a massive 2,000-acre project that is restoring habitat on top of a huge landfill in Staten Island, Handel got creative. City dirt is usually “variable, compacted, polluted, and features a hydrophobic crust, higher soil temperatures, elevated PH levels, and restricted aeration.” So Handel and his team trucked in dirt from building excavation projects in Manhattan. The dirt was still good because it has been buried deep in Manhattan for ages. An added plus: they gave it away for free because they had to get rid of it. For composting materials needed to regrow plant life, Handel sourced yard waste from New Jersey, which they were also happy to give away.

New York City has relatively little funding available to restore 2,000 acres of Fresh Kills so Handel also employed nature to do much of his restoration work. Planting bushes with fleshy fruits (beach plum, blueberry, blackberry, wildrose) attracts birds who help spread the seeds cheaply. Ants are also the “landscape contractor” of the forest floor and are critical to spreading plant diversity. Handel also used seed trays, and clusters of plants, or “clustering nuclei,” to spread native plants. But Handel offered cautious advice: “You can’t get a naturalist site because you want it.” Nature works on its own schedule.

In the case of Orange County Great Park, a new park built out of an army air base, a 30-feet deep canyon will be constructed and include a “mosaic of habitats,” which will be “mixed-up,” because this is the safest thing to do.

Handel said it’s important in projects like these to determine the targets of ecological restoration. “What are you trying to restore? How far do you go back?” These types of questions are critical, particularly if a city puts up $50,000 to restore a space, “then everything is dead five years later. That’s what we’re worried about.”

To conclude, Handel argued that diverse habitats offer value by: supporting complex life histories; feeding sites through time; protecting species from predators/storms; and enabling change through the years. However, restoration ecology isn’t for the faint of heart. Handel said it’s not easy to do restoration. “Invasives are really hard to deal with.” Seed dispersal is difficult, particularly if the site is surrounded by degraded urban communities. Unfortunately, “we live in a fragmented world.” Climate change will only add additional complexity.

Kristina Hill, Associate Professor and Chair, Department of Landscape Architecture, University of Virginia, said cities throughout history have often been built on natural levees, and reside in spaces with basins and backslopes. Early cities also featured surface drainage systems — networks of canals, which still exist in Tehran, a city of 11-12 million. So, cities aren’t just “collections of buildings,” but are really all about diversity and gradients — “they have a set of internal richness.” The ecology of the the modern urban heat island is of great interest to Hill. Cities are always warmer than surrounding areas so they are the precursors of climate change. “Cities are at the edge of climate change.”

Hill says it’s more efficient for species migrating to escape climate change to move up in elevation as opposed to north. “Elevation gradients are very important.” Unfortunately, for many species there isn’t much room to move up anymore. Hill argues that climate change will yield suprising changes in the distribution of species and their traits. While some species may even benefit from climate change, they have to stay around long enough to reap those benefits.

Patches with northern aspects may act as corridors, stepping stones or “ladder rungs” within regional landscapes, providing a migration path for a range of species. Basic climate change wildlife habitat adaptation strategies include: maintain existing reserves; enlarge reserves northward; add high-elevation corridors; add riparian corridors, and “reduce matrix hostility.”

In Chicago, the are coyotes who are, in effect, trapped in the matrix. “Many coyotes in Illinois are disassociated from natural areas.” Hill showed images of coyotes showing up on subways, inside supermarket refrigerators, and other suprising places. In New Delhi, India during a recent drought, monkeys living in urban areas survived better than ones in outlying rural areas because there was more water available in the cities. In King County, Washington, human and crow populations have grown together because of the growth of dumpsters.  “Animals are becoming climate change refugees. Cities are becoming animal habitats.”

Things could be made much easier for wildlife migrating through urban areas. Exclosure fences and habitat corridors can help prevent roadkill. Green roofs can be designed to support migrating birds and other wildlife. “Telescoping swales” and green streets can reduce stormwater runoff so fish eggs don’t get flushed away during rainstorms. In Seattle, the SEA street, a model green street, helped reduce runoff by 97 percent. High Point, an affordable housing complex also in Seattle, also uses combined green / grey infrastructure to limit runoff. At a broader scale, London’s thousands of household gardens are actually creating an urban ecosystem. In Rotterdam, the Dutch are using natural sand banks, which function as habitat, to prepare coasts for climate change-driven sea level rise (see earlier post).

Hill said climate change may mean we may end up focusing on traits instead of species to sustain ecosystem functions. The ecological infrastructure systems needed to preserve species should be multi-use and designed by interdisciplinary teams to help build resiliency into urban environments.

Alex Felson, ASLA, Lecturer, School of Architecture and School of Forestry and Environmental Studies, Yale University, said forging a partnership between ecologists and landscape architects on habitat restoration is challenging because “designers like to stay up all night, and ecologists like to get up at the crack of dawn.” For the past century, “we’ve been struggling about design and ecology.” As a result, integrating ecology and design into new “designer ecosystems” will be challenging, but also provide major opportunities.

Right now, Felson argued, “LEED has no design aesthetic.” Sustainability has not settled on a design aesthetic yet. “The messy, complex landscape” Yu Kongjian discussed may provide a model. But this model then needs to be turned into a design template that can be plugged in. “We need working design practices, scales of application, and ecological planning.” Furthermore, there’s a real challenge in conveying these ideas to the broader public: “biodiversity is still not widely understood, or even as understood as ecosystem services.” To combat a public lack of understanding, we need “narratives, stories we can tell.”

Felson pointed out the Sustainable Sites Initiative, but argued there are no credits for wildlife biodiversity in the new sustainable landscapes rating system. While SITES is not designed to be a wildlife biodiversity rating system, it still presents a real model for designing sustainable habitats, with restored soils, water systems, and native plants, which can then draw diverse species.

More discussion on this and other topics will definitely continue. Add your thoughts.

This is part three in a three-part series on the “Designing Wildlife Habitats” symposium held at Dumbarton Oaks in Washington, D.C. Read part one, “Designing for the Full Range of Biodiversity” and part two, “Restoring the Balance between People and Nature Through Wildlife Habitat Design.”

Image credit: ASLA 2010 Award of Excellence. Shanghai Houtan Park: Landscape as a Living System. Shanghai, ChinaTurenscape, China and Peking University Graduate School of Landscape Architecture

One thought on “Recreating Wildlife Habitat in Cities

  1. Todd Yingling 05/25/2010 / 11:00 pm

    I like the Seattle references. There are many good things about High Point, but I question the validity of a walkable neighborhood with no commercial establishments and extremely limited bus service.

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