- Replacing turf lawns with native prairie grasses increases carbon sequestration and water infiltration — and also reduces cost
- The ecosystem-services solution offers a more attractive, cost-effective alternative to cement drainage systems
- The Sustainable Sites Initiative offers information and incentives for businesses to develop ecosystem-sensitive landscapes
Wet pond at Mueller development in Austin, Texas (Marsha Miller)
Rain garden at Stacy Park in Austin, Texas (City of Austin)
Sand Beach Biofilter in Austin, Texas (City of Austin)
Cement drainage bunker on Brodie Lane in Austin, Texas (Matt Turner)
The cityscape of the future will be much greener and more useful, if landscape ecologists have their way. Even business properties in tomorrow’s deliberately planned urban landscape will use nature’s full potential to provide elegant solutions for a host of urban problems — among them energy waste, excess carbon, the heat-island effect, and polluted air and water. And even better, landscape ecosystems can actually help businesses save money.
Nature’s Original Green Machine
Even in landscape design, plants are an amazingly underused resource, says Dr. Mark Simmons, director of the Ecosystem Design Group at The University of Texas’ Lady Bird Johnson Wildflower Center. Simmons is one of only a handful of U.S. ecologists actively involved in research on landscape design, normally the domain of landscape architects.
The key to plants’ usefulness, Simmons says, is that in the process of photosynthesis, they soak up much more than sunlight. Plants can function as sponges (soaking up sun, water, and atmospheric carbon) and filters (removing toxins and impurities), as well as storage facilitators (sequestering carbon in the soil to reduce atmospheric carbon dioxide, a greenhouse gas).
Optimizing plant resources in a landscape ecosystem, according to Simmons, can be both simple and cost-effective. A basic example is knowing where and what to plant. Replacing a business’ manicured turf lawn with native prairie grasses, he explains, not only increases carbon sequestration and water infiltration, but greatly reduces cost. Requiring reduced irrigation and fewer fertilizers and pesticides, native grasses are naturally frugal. And savings on maintenance service alone is huge — many native prairie grasses need mowing only once a year (as opposed to 20 to 30 times a year for traditional lawns). In fact, Walmart has funded native turf-grass research at the Wildflower Center because of its potential.
Another example: Deciduous trees placed on a building’s southwestern exposures block direct sunlight during the summer, which reduces cooling costs while still allowing solar warmth in the winter, which saves on heating.
Cement Bunker vs. Wetland
Buildings and parking lots create expanses of impenetrable ground cover, creating problems during rainstorms when too much water rushes into storm drains at once. Rain runoff can pose serious health issues for cities whose street drainage links to sewage systems, as the water picks up large amounts of nitrogen from fertilizers and bird excrement, and oil, hydrocarbons, heavy metals, and other toxins from roadways. These chemicals are dumped into our rivers from which they must be filtered at high cost before the water can be used for drinking.
Most businesses currently solve the problem by building a giant cement bunker with sand in the bottom. Runoff water is channeled into this retainer, where it gradually sinks into the soil. This slows the volume of water long enough to filter out some of the pollutants before the water gets to the drainage system.
The same problem can be solved using what Simmons calls the ecosystem-services solution, which involves building a small wetland that looks like a natural pond filled with native plants. In Texas, these include switch grass and bushy bluestem, which thrive in wet areas but can also tolerate long periods of drought.
This system may sound simplistic, but it offers substantial benefits, says Simmons. Like the cement bunker, the wetland holds back water, and the plants do a better job of filtering pollutants than sand and soil do.
“Plants filter water and degrade such things as aromatic hydrocarbons, they clean toxins from the air, and they pull carbon from the air and sequester it in the ground,” he says. “What’s more, many wetland plants like cattails pump water like nobody’s business.”
Because these water-loving plants readily shed water into the air (a process called transpiration), the wetland could be smaller than the bunker, which can help reduce overall costs. Wetlands created for containing and filtering runoff can also be wildlife habitats. Fish and turtles can be stocked in the pond. Wood duck enclosures and screech owl boxes can be added to attract birdlife. Paths with informative signs can be installed to engage the local community. Boardwalks can be designed to lead over the water straight to a storefront.
“What you’ve done,” Simmons continues, “is taken a development requirement and turned it into an asset. Instead of an ugly cement pond with a chain-link fence and ‘Do Not Enter’ sign, you’ve got an inviting park-like area with multiple functions.”
Some local examples of constructed wetlands for storm water management include the naturalistic pond behind Central Market on North Lamar Boulevard and the Sand Beach biofilter at West Cesar Chavez Street at Lamar, which is only inundated after rains.
Changing the Landscape of Landscaping
Simmons is one of the technical committee members at the forefront of the Sustainable Sites Initiative (SITES), which began in 2005 as a joint effort of the Wildflower Center, the American Society of Landscape Architects, and the United States Botanic Garden. SITES offers information on techniques for businesses to develop carefully designed, ecosystem-sensitive landscapes, incentives for them to do so, and a four-star rating system by which they can benchmark their efforts.
Most of the SITES program’s incentives are tied to performance, so instead of simply installing a given feature and walking away, designers must come up with creative solutions and see the project through in order to obtain results.
The SITES guidelines are currently being piloted in more than 150 projects in 34 states and three foreign countries. A final rating system and updated reference manual will be produced based on feedback from the pilot program. For more on SITES, see “Turning Over a New Leaf.”
Following the LEED
To an architect designing for the 21st century, SITES may feel like déjà vu, since it echoes the Leadership in Energy and Environmental Design (LEED) construction standards for energy-efficient and environmentally sensitive buildings. The LEED rating system, produced by the U.S. Green Building Council (USGBC) in 2000, addresses water and energy efficiency, materials and resources, and indoor air quality.
Originally focused on new construction, LEED has since been expanded to address major renovations, homes, neighborhoods, and even retail. A 2008 study by the nonprofit New Buildings Institute showed LEED-certified buildings used 24 percent less energy than non-LEED buildings. LEED-certified office buildings fared even better, with 33 percent lower energy use than non-LEED-certified buildings.
LEED and SITES may be integrated in the future. Simmons thinks SITES may get even better results for landscapes than LEED has for buildings. “With buildings, all you can do is make them less bad, but with the landscape, you can actually turn that on its head — landscapes regenerate,” he says.
Beyond Sustainable: Regenerative Design
Simmons is most excited about the paradigm shift he sees in how we think about land-use decisions, from an emphasis has been on conservation to what he thinks should be our highest aspiration — the regeneration of ecosystem services.
“Ecosystem services,” he explains in an article he co-authored for Landscape Journal, “are the benefits that the environment provides to humans at no cost.”
Nature provides us breathable air, drinkable water, the cycling of atmospheric gases, pollination, and climate regulation. Yet these are generally taken for granted and are largely ignored by conventional cost accounting approaches, Simmons writes. However, landscapes can be designed specifically to increase nature’s ability to provide us with these, and in so doing the environmental capacity of the landscape can be actually improved. The term “regenerative design” has emerged to describe practices that create a better ecosystem than would have naturally occurred if the land had never been developed.
Urban settings offer some of the best opportunities for regenerative design. In such places where the land is already under development and about to be compromised, ecosystems can be designed with function in mind.
Simmons agrees there is still a need for pristine nature preserves, a classic example of conservation and one that provides ample ecosystem services. However, he points out, setting aside land for preserves is expensive, and relatively few people get to see or connect with that land. But when well-designed land in a city is put to use in an ecosystem, many people will benefit immediately. “It’s just a huge opportunity that shouldn’t be passed up,” he says.
SITES is meant to be a wake-up call to businesses, Simmons says. It’s also a way to call attention to ecosystem features that are underused in urban landscapes, such as green roofs, rain gardens, bioswales, and sustainable turf grasses (for more, see "Green Landscape Terms" below). These features use existing technology in a better way. But the cutting edge of ecosystem-services research is the effort to put whole ecosystems back into cities, Simmons says.
“We can make everything work better,” Simmons says. “We don’t even know what the technology is yet, because we haven’t even explored it.”
Green Landscape Terms
Biofilter: a basin that captures polluted stormwater, which passes through planted soil (or biofiltration) media. Pollutants are removed by filtering, plant uptake, and biological processes
Bioswale: a shallow, planted drainage ditch with gently sloped sides designed to slow down surface runoff and remove silt and pollution
Green roof: a flat or gently sloped roof partially or completely covered with vegetation, which is intended to insulate buildings, reduce the heat-island effect, decrease storm water runoff and improve water quality
Green wall: a wall supporting vines and other vegetation to reduce absorption of solar radiation, which is a major contributor to a city’s heat-island effect
Rain garden: a more formally planted and manicured bioswale; a shallow depression that collects rainwater from roofs, driveways, and walkways, which his often associated with residences and small businesses
Wetland: an area that is either seasonally or permanently saturated with water, frequently covered by shallow pools and aquatic plants, and often renowned for biological diversity