ABSTRACT
Our theme is that the natural environment is an essential part of man's total environment. Preservation of a substantial portion of the biosphere in a natural state, while not a panacea for all the ills of mankind, is nevertheless a necessity if we base the carrying capacity of the earth on the quality of human life. First, we define “natural environment” as that part of our environment that is essentially self-supporting, in that a minimum of human management is required for maintenance. In terms of function, “natural environment” is that part of man's life-support system that operates without energetic or economic input from the power flows directly controlled by man. “Natural environment” is a more restricted category than "open space,” a term widely used by planners to mean any part of the landscape, whether natural or man-made, that is, free of building structures. In this context, “natural environment” includes ecological systems ranging from little-used wildernesses to moderately used forests, grasslands, rivers, estuaries, and oceans, which produce useful products and recycle wastes on a continuous basis, but without appreciable economic cost to man. These self-maintaining ecological systems run on sun energy, including the energy of rain, wind, or water flow that are derived from sun power. In contrast, what we choose to call “developed environment” includes ecosystems that are structured and maintained by large auxiliary power flows from fossil or other concentrated fuels that supplement or replace the natural energy flow of the sun. A city, of course, is the ultimate developed ecosystem, but golf courses, suburban developments, agricultural fields, and channelized rivers are also developed ecosystems since they require a diversion of energy from man-controlled power flows to maintain them in the developed state even though natural elements (water, trees, grass, bacteria) may have important roles in such systems. Developed systems generate economic wealth, but the economic cost of maintenance increases as a power function of the intensity of development. For example, it is well known that the cost of maintenance (C) of a network of services increases roughly as the square of the number of units (AO in the network, as shown in the following equation: https://www.w3.org/1998/Math/MathML"> C = N ( N − 1 ) 2 , or approximately C = N 2 2 . https://s3-euw1-ap-pe-df-pch-content-public-p.s3.eu-west-1.amazonaws.com/9781315079370/a29137cc-3a16-4dcd-b85c-6f3678c91c2e/content/math2_B.tif" xmlns:xlink="https://www.w3.org/1999/xlink"/> Thus, if a city doubles from 10 to 20 million units, the cost goes up 4 times. Furthermore, the stress on supporting natural life-support systems increases markedly, again as some kind of multiplier, as the size and power demand of developed systems increases. Because the multiplying maintenance costs are too often not anticipated and the useful work of nature totally undervaluated, developed systems have an inherent tendency to grow beyond optimum size, and at the expense of natural systems.
