The sustainable city.

IF WE CAN LEARN TO BRING NATURE BACK IN AND GIVE HER A HAND WHERE NEEDED, WE CAN CREATE PLACES TO LIVE THAT ARE VITAL AND SELF-NURTURING.

NATURAL MARSHES ARE REPLACING expensive man-made sewage treatment plants. Leaves that once wound up in landfills are now enhancing soils. Ecological landscaping is cooling entire communities and reducing energy use. In coming to view our cities as ecosystems, we are learning to apply the concepts and principles that have sustained rural forests and farms for generations. The question now is, how can those concepts be applied to cities, and how can individual citizens--as well as community leaders--act to improve the sustainability of the places they call home.

PRINCIPLES OF SUSTAINABILITY

If an ecosystem is to have a chance at ing sustainable, it must do four things:

* Maximize energy efficiency--and get more useful products out of the energy used; Minimize waste production and pollution;

* Capture the benefits of natural processes while minimizing damage from natural events; and,

* Meet the economic and social needs of all its people in a manner that does not degrade or destroy the productivity or health of its natural systems.

ENERGY EFFICIENCY

It takes an enormous amount of energy to keep a city going, and that energy often must be brought from great distances at considerable cost. Improving the way we use energy--and finding renewable energy sources--means cost reductions now and a hedge against future shortages or price increases.

Improving energy efficiency begins, literally, on the drawing board. Many building designs today pick up on natural energy "helpers." These include orienting the building and its features to take maximum advantage of sun, wind, and other location features; using "cool" colors that reduce the need for air conditioning; and locating trees and shrubs to take advantage of summer shading and winter sun.

These techniques are the basis for AMERICAN FORESTS' Cool Communities program, which is being implemented in seven demonstration cities nationwide. As evidence mounts in support of the energy and financial benefits provided by these low-tech, low-cost practices, it becomes more obvious that they can be major contributors to the sustainable cities of the future.

City governments, homeowners, and businesses can take advantage of the heating and cooling benefits from cool colors and effective landscaping--often without spending an additional cent. The difference lies in the choices made when buildings are remodeled or landscaping replaced. Effective landscaping and management of street trees, parks, and other open spaces can significantly reduce the "heat island" that hangs over most large cities.

The dark-colored asphalt used for streets and parking lots can be replaced with a lighter, less heat-absorbing color that will cut down on the heat generated during the hot summer months. And lowering a community's heat island can mean energy efficiency, savings, and reduced air pollution--an important step in moving toward a more sustainable community.

POLLUTION AND WASTE REDUCTION

From food scraps and tree trimmings to construction debris and toxic chemicals, cities produce a huge waste stream. Compare that to the natural world, where one organism's waste is another's food; nothing piles up to poison the system. Humans alter that balance, producing wastes that either overpower natural recycling systems or are too foreign to be used by them. Coping with the problem represents both an enormous cost and a threat to sustainability. No system that poisons its air, water, or soil can persist.

Many natural resources become pollutants when they are overproduced or are out of place. But these wastes can be beneficial, even on a city-wide scale. Rainfall in the city historically has been treated as a hazard. With so much of a city covered with roofs and concrete, it is difficult for the water to reach the soil and normal rains become floods. Complex, costly stormwater systems keep water off the streets and off our feet.

But carrying this so-called "wastewater" away from the city degrades water sources and increases the cost of treatment. Stormwater control systems can also increase the damage from floods when they are not designed to deal with peak water flows, or when they divert runoff into sewage-treatment systems. This overwhelms the treatment capacity and flushes untreated sewage into streams and lakes.

Cities designed to increase water absorption and route flood waters into open areas capture the natural water cycle more effectively. Trees and other vegetation help control stormwater. Their leaves catch and slow rainfall, lengthening the time it takes the water to reach the ground. Some of that water clings to tree branches and leaves, evaporating back into the atmosphere. With the flow of water from surfaces like pavements and roofs spread out, gutters and storm sewers have time to carry the water away in a more normal flow. It also allows more time for water to soak into the city landscape's limited open soil. Water absorption areas can also be added to the city by increasing tree lawns.

Rain water, if properly stored for irrigation, can become an important resource, especially in drought-prone areas. Sewage treatment systems can use woodland and agricultural soils as filters, cleaning the water from the effluent, which contains nutrients that can build soil. In fact, farmers and forestland owners are seeing higher yields from lands spread with treated sewage (see TURNING WASTE INTO PROFIT).

CAPTURING NATURAL PROCESSES

Just as farmers have learned to benefit from the nutrients of treated sewage, urban planners must learn to take advantage of the species that thrive in--and benefit--the city. When we try to force tree species that cannot tolerate urban conditions and stresses to live in that environment, we set ourselves up for ongoing costs, losses, and problems. A move toward tree selection based on compatibility with local conditions is a move toward a city that survives.

In some cases, this can be a prescription for relying on native species, but many cities are finding that choosing what evolved in the region before the city existed is not always the best answer. What is planted should be what grows well in the current conditions--not those that no longer exist.

In Irvine, California, a sustainable landscaping ordinance was developed in 1991 to guide new developments and restructure existing ones. According to Tim Kirkham, senior landscape architect for the city of Irvine, the new landscaping approach includes planting more shrubbery, less turf, and carefully selected and placed trees--all of which have resulted in a more colorful and diverse urban forest. "The greatest success we've had is that the developers have really gotten behind the idea that sustainable landscaping can sell," he says.

At the same time, the Irvine Ranch Water District created a tiered water-rate structure that rewards conservation with low prices and penalizes overuse. Tim Ash, a horticulturist with the water district, says this allows for a focus on customers who use excessive amounts of water and for an easy analysis of the problems. "Before the ordinance and structure, landscapers were over-watering by any where from 25 to 250 percent. Trees were doing poorly because they were overwatered or inappropriately placed, or the water was running off the property," he says. Although a payback period is usually three to five years, water use has already dropped half an acre/foot from the four acre/feet of water used in 1991, Ash says. "The results have been a reduction in resource use, an increase in biomass, and a reduction in cost. This is due to education, education, education," says Ash.

In an urban area, ample growing space is as important for a tree's health as adequate water. The average life span of an urban tree--10-35 years--can easily be extended if planted in a proper growing space. An appropriate tree, planted in a setting where it can thrive, produces social and economic benefits naturally, without expensive added care such as fertilization and irrigation.

But ensuring that a city is sustainable requires more than just smart tree planting. Incorporating natural processes into the design of a city can also help avoid natural hazards. Flood plains are a well-known hazard, and for many communities, protecting against floods has meant enormous expenditures in levees, dikes, and other protective measures. Natural forces tend to overwhelm many of these efforts as was so clearly shown by the great Midwestern floods of 1993.

In the wake of those terrible losses, many communities are rethinking their strategies, and relocating has been the answer for some. Valmeyer, an Illinois town that lost 85 percent of its 343 houses in the floods of 1993, opted to rebuild other open spaces in flood-prone areas to reduce potential damage.

MERGING ECOLOGICAL, ECONOMIC, AND SOCIAL FACTORS

Many past management decisions in cities have been made on the basis of economic and social considerations, without much attention to the ecological impacts. But when the biological system fails, enormous economic and social costs usually follow. The crippling outbreak of Dutch elm disease is an off-cited lesson in urban forestry. Communities that lined street after street with the stately elms did not think about the potential ecological consequences of having one species so dominant in an area.

In today's ecosystem management scenario, people are looking for management approaches that bring together ecological, social, and economic considerations. Are there any communities that meet this criteria? Builders in south Florida hope they soon will be able to point with pride to Jordan Commons, a Habitat for Humanity development near Miami.

Planned in the wake of Hurricane Andrew, Jordan Commons is a model ecological community of innovative, affordable homes for low-income families. The goals of the development are to build the homes for less than $35 a square foot, reduce energy use by 40 percent, and keep mortgage and utility costs to 35-40 percent of the homeowner's gross income. Many of the guiding principles of sustainability are employed to meet these goals.

Ecological architecture will orient Jordan Commons' homes and buildings to take optimal advantage of cooling winds and solar energy. The project's probono consultant, renowned architect Elizabeth Plater-Zyberk, ensured that each of the 200 houses will make the best of seasonal wind patterns for natural cross ventilation and cooling.

The homes also will be equipped with the latest in appliances that reduce energy use. Solar-powered water heaters, low-volume toilets, and reduced-flow shower heads reduce the amount of water going through the water treatment and re-use system. Light metal roofs, which increase reflectivity (called albedo), reduce heating, ventilation, and air conditioning costs an average of 23 percent, according to the Florida Solar Energy Center. These costs total more than half the electricity used in a home.

Ecological landscaping can help lower energy costs, and Jordan Commons will place trees to shade homes, sidewalks, and pavements, lowering the ambient temperature for the entire community. The flowering and fruiting trees preferred by residents will provide beauty and a fresh food source.

Plater-Zyberk believes that the physical environment can shape people's perceptions and actions. For instance, community landscaping can help or hinder relations between residents. Using vegetation to provide a sense of space, order, and definition gives a neighborhood integrity and brings a sense of community responsibility and pride of ownership.

Dr. Jack Parker, chief energy advisor for Jordan Commons and professor of environmental studies at Florida International University, says Jordan Commons is unique in two ways. "What's different about this project--in terms of comprehensiveness of all the energy conservation and solar features as well as sustainable urban planning--is that it's the only time this has been incorporated into a low income development," he said.

"It's also the first time homeowners will be made a part of it; they will be educated, and there will also be a training program for children to teach them to conserve even more energy."

Involving residents is critical to guaranteering the success of sustainable communities, and each resident of Jordan Commons will receive a handbook that describes the basic elements of sustainability as well as the development's special features.

So what's the best way to help people appreciate their critical role in community sustainability? First of all, they need to understand the basic principles of sustainability. Then they need to be aware of their local environment and how it is likely to function in the future. More and more communities are turning to sophisticated computer technology called Geographic Information Systems.

American Forests has developed an Urban Ecological Assessment that uses GIS to convert satellite and aerial photographs into visual representations of local ecosystems. This technique details the costs and benefits of the ecosystem's existing natural features, allowing planners to see what the future might bring under a variety of design and management options.

"Unfortunately," says Gary Moll, vice-president for urban forestry at American Forests, "the potential value of the landscape for stormwater management, energy conservation, and air quality is not currently part of the decisionmaking process."

When community leaders see the value of trees--for example, in stormwater control and energy conservation--they can make better-informed decisions about their natural resources. If the ecosystem analysis shows that the addition of open space or the strategic planting of trees will result in significant cost savings on energy use or stormwater control, the decision of where to invest limited resources is much easier.

Political decisions need citizen support, and ecological assessment maps can help a broad array of people reach a consensus on what they want for their community's future.

We're all seeking sustainable cities; the question is how best to get there? These new tools--and a broader understanding of ecological concepts in the urban context--are helping communities arrive at that shared vision.

RELATED ARTICLE: TURNING WASTE INTO PROFIT

Two states and the District of Columbia have joined together to transform trash into treasure. Maryland Environmental Services (MES) was born as a government agency and recently privatized. MES turns sewage--called bio-solids--and green waste into compost and mulch, and the venture is proving profitable, both financially and environmentally.

Each week MES takes in 1,400 tons of big-solids from the Washington Suburban Sanitary Commission treatment plant that serves Washington, DC, and surrounding counties in Maryland and Virginia. MES produces 40,000 cubic yards of compost from big-solids and wood chips each year, says Tait Saderholm, compost marketing specialist for the company. Saderholm then sells the compost for $24 a cubic yard.

MES also makes Leafgro from leaves collected in county recycling programs. For every 120,000 tons of leaves, MES produces 50,000 tons of Leafgro. Both products significantly increase soil productivity for landscapers and gardeners. In the critical watershed of the Chesapeake Bay, Saderholm says MES is "saving the Bay one yard at a time."

Deborah Gangloff is AMERICAN FORESTS' vice president for program services.