The function of plant life and wildlife of the city, particularly the fish of the streams and animals that live in close contact with the water, is of peculiar importance to people. If these habitats of the city are healthy, if they are viable ecosystems with vigor and stability, then the indication is that the biological quality of the environment is high for people as well.

The wildlife in man's environment is an indication of his overall ability to manage and husband the land through ecosystem regulation. The name of the wildlife management game is habitat management; the entire endangered species program is a matter of providing proper habitat in which the endangered species can survive.

The same principles apply to wildlife in the city. If the habitat for urban wildlife Is properly managed, the city will have a healthy wildlife population. The manner, type, and quality of habitat will determine the manner, type, and quality of the animals that inhabit it.

Man is just beginning to understand the regulation of ecosystems. Single—minded exploitation of the environment for single—purpose motives is giving way to analysis of the multifaceted ecosystem; the optimization of the total ecosystem value is being considered at last, rather than pushing for any single factor or set of factors. We are moving away from the concept that led us to exploit ecosystems and environments for single commodities and beginning to recognize the benefits to be reaped from maintaining whole, healthy ecosystems.

When the optimization of the ecosystem of the city is considered over the maximization of any single use of it, we will discover that the wildlife of the city is far more than a mere entertainment or ornamentation. It is the barometer by which we can judge the overall quality of life. It will not benefit mankind to exploit ecosystems if in so doing the wildlife it harbors is destroyed.

The "whole ecosystem" concept is based on stabilization of the energy flow that produces the various and diverse components of the ecosystem. Human regulation of this process means that if the ecosystem is husbanded, maintained, and kept in good working order, an abundance of materials and goods are available for man's use.

The wildlife and plant life of the city are an integral part of the living components of the human ecosystem. Their life, their health, their viability are directly related to the health and viability of people. The character and quality of the ecosystem will be determined by the character and quality of human management of the ecosystem. Man can easily be judged by the company he keeps.

The presence of songbirds, squirrels, and other animals that are pleasing to the ear and the eye, the presence of bass, pike, sturgeon, and other desirable game fish, all tell us a great deal about man and his ecosystem. On the other hand, if man's companions are lice, vermin, and the trash fish of his polluted streams, we can deduce much about the way he manages his ecosystem.

We have yet to understand fully and calculate all the additional wealth to be derived from a healthy ecosystem. When such a cost/benefit ratio sheet is drawn up, we will have no other recourse than to conclude that single—factored exploitation of the environment for the benefit of the few causes deterioration of the ecosystem as a whole, with consequent loss to all.

When the viability of the human ecosystem is recognized as essential to the system's wealth—producing capacity, the corrective measures necessary to make the systems healthy and viable for man and wildlife will be taken forthwith.

The city provides a marvelous opportunity for humanity to display its inventive genius—not only in providing areas of scenic beauty but in the exercise of technology blended with good ecosystem concepts in ways that preserve the natural diversity and even provide habitat for endangered species.

The most common example of this is in the design of city parks. City parks can be completely formal gardens that also contain niches for wildlife. The formal park can add to its formal plantings certain water plants that will attract waterfowl and support a turtle population. The walks and borders can include shrubs and other plantings with edible seeds or fruits. Such gardens and ponds with the wildlife they attract require less maintenance, and this by no means exhausts the list of advantages.

Perhaps the ecological tour de force of urban wildlife planning is the concept of the rooftop refuge. The rooftop refuge has the modern potential of the hanging gardens of ancient Babylon—those enormous masonry works with terraces supported by arched columns that qualified as one of the Seven Wonders of the World. Large enough to support summer homes complete with gardens, these terraces rose above the Tigris—Euphrates floodplain to catch the breeze and provide a vista. The upper surfaces of the terraces were thatched with reed and plastered with mud. They were then covered with lead sheets and sealed with pitch and tar. Over this now water—impervious surface, soil was placed in which the plantings were made and upon which the buildings were built. A system of pumps lifted water from wells beneath the gardens to the highest terrace, where by gravity flow the entire hanging gardens were watered. The surplus water was returned to the well.

Rooftop refuges could occupy many acres of building tops in cities of all sizes. Like the hanging gardens, they would be integral with the roofs on which they were placed. Such a scheme could markedly reduce the cost of roof maintenance by eliminating the environmental stress on roofs subjected to extremes of temperature—thawing and freezing and attendant water penetration.

The roof would be sealed with a moisture barrier buried under several feet of soil and then planted with a variety of plants from grasses and herbs to trees. The plantings could be formal and provide people spaces, such as restaurants or rooftop cocktail lounges, or could be wild with little or no human intrusion. The main fact to consider at this juncture is the engineering function of the rooftop refuge, which simply is a weatherproof roof seal that reduces roof maintenance. The attendant aesthetic qualities of living plants and animals and the notion of endangered species refuges, are spin—off benefits. But what benefits!

This is the ideal habitat for the urban peregrine falcon and myriad songbirds. Moreover, rooftop refuges would be ideal habitat for sedentary amphibians and reptiles—like salamanders and turtles and snakes. The areas of the city that seem the most devoid of life could have life literally "spring from the rooftops," providing isolated and secure niches for many plants and animals, and a continuity of habitat for many insects and birds that could then travel safely between them. They would be literally islands of vegetation floating above the city—testimony to the technological genius and the ecological wisdom of man—bespeaking his understanding of the relationship between the natural ecosystems of the biosphere and the technological ecosystem of man.

In concert with whole—ecosystem planning of urban parks, the city rooftop refuge could crown the achievements of managers in providing optimum habitat for all the inhabitants of the city. A well—known axiom in wildlife management says the most biologically productive land produces the most and best wildlife. Adapting this concept to the city would help close a gap between man and his environment and would provide a solid management basis for judging the effectiveness with which technological man can come to grips with balancing his books and nature's. The presence of hawks, trout, sturgeon, weasels, squirrels, martins, beaver, deer, quail, and other remaining treasures of the life forms of earth in the city environment would be living proof of man's success in achieving on—going partnership with nature.

—Theodore W. Sudia.