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American Academy of Political and Social Science The Place of Nature in the City of Man Author(syf , D Q / 0 F + D U g Source: The Annals of the American Academy of Political and Social Science, Vol. 352, Urban Revival: Goals and Standards (Mar., 1964yf S S 2 Published by: Sage Publications, Inc. in association with the American Academy of Political and Social Science Stable URL: http://www.jstor.org/stable/1035408 Accessed: 29-06-2017 21:16 UTC JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact [email protected]. Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://about.jstor.org/terms Sage Publications, Inc., American Academy of Political and Social Science are collaborating with JSTOR to digitize, preserve and extend access to The Annals of the American Academy of Political and Social Science This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms The Place of Nature in the City of Man By IAN L. MCHARG ABSTRACT: Unparalleled urban growth is pre-empting a million acres of rural lands each year and transforming these into the sad emblems of contemporary urbanism. In that anarchy which constitutes urban growth, wherein the major prevailing values are short-term economic determinism, the image of nature is attributed little or no value. In existing cities, the instincts of eighteenth- and nineteenth-century city builders, reflected in the pattern of existing urban open space, have been superseded by a modern process which disdains nature and seems motivated by a belief in salvation through stone alone. Yet there is a need and place for nature in the city of man. An understanding of natural processes should be reflected in the attribution of value to the constituents of these natural processes. Such an understanding, reflected in city building, will provide a major structure for urban and metro- politan form, an environment capable of supporting physiolog- ical man, and the basis for an art of city building which will enhance life and reflect meaning, order, and purpose. Ian L. McHarg, M.L.A., M.C.P., Philadelphia, Pennsylvania, is Chairman of the Department of Landscape Architecture and Professor of City Planning at the University of Pennsylvania. He has a private practice in City Planning and Landscape Architecture in partnership with Dr. David A. Wallace. His interest in the subject of values toward nature and the physical environments which are their products has been reflected in many articles, among them "Man and Environment," a chapter in The Urban Condition, edited by Leonard Duhl, "The Ecology of the City," published in the American Institute of Architects Journal, 1963. On this same subject, he conceived and moderated a series of twenty-four television programs entitled "The House We Live In," initiated by WCAU- CBS and subsequently shown by National Educational Television. 1 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE ANNALS OF THE AMERICAN ACADEMY EFORE we convert our rocks and rills and templed hills into one spreading mass of low grade urban tissue under the delusion that because we accomplish this degradation with the aid of bulldozers, atomic piles and electronic computers we are advancing civilization, we might ask what all this implies in terms of the historic nature of man. .. ."-Lewis Mumford.1 The subject of this essay is an inquiry into the place of nature in the city of man. The inquiry is neither ironic nor facetious but of the utmost urgency and seriousness. Today it is necessary to justify the presence of nature in the city of man; the burden of proof lies with nature, or so it seems. Look at the modern city, that most human of all environments, observe what image of nature exists there-precious little in- deed and that beleaguered, succumbing to slow attrition. William Penn effectively said, Let us build a fair city between two noble rivers; let there be five noble squares, let each house have a fine garden, and let us reserve territories for farming. But that was before rivers were discovered to be convenient repositories for sewage, parks the best locus for expressways, squares the appropriate sites for public monuments, farm land best suited for buildings, and small parks best trans- formed into asphalted, fenced play- grounds. Charles Eliot once said, in essence, This is our city, these are our hills, these are our rivers, these our beaches, these our farms and forests. I will make a plan to cherish this beauty and wealth for all those who do or will live here. And the plan was good but largely disdained. So here, as else- where, man assaulted nature disinter- 1 Lewis Mumford, Man's Role in Changing the Face of the Earth (Chicago: The Uni- versity of Chicago, 1956yf S . estedly, man assaulted man with the city; nature in the city remains pre- cariously as residues of accident, rare acts .of personal conscience, or rarer testimony to municipal wisdom, the subject of continuous assault and at- trition while the countryside recedes before the annular rings of suburbaniza- tion, unresponsive to any perception beyond simple economic determinism. Once upon a time, nature lay outside the city gates a fair prospect from the city walls, but no longer. Climb the highest office tower in the city, when atmospheric pollution is only normal, and nature may be seen as a green rim on the horizon. But this is hardly a common condition and so nature lies outside of workaday experience for most urban people. Long ago, homes were built in the country and remained rural during the lives of persons and generations. Not so today, when a country house of yesterday is within the rural-urban fringe today, in a suburb tomorrow, and in a renewal area of the not-too- distant future. When the basis for wealth lay in the heart of the land and the farms upon it, then the valleys were verdant and beau- tiful, the farmer steward of the land- scape, but that was before the American dream of a single house on a quarter acre, the automobile, crop surpluses, and the discovery that a farmer could profit more by selling land than crops. Once men in simple cabins saw only wild nature, silent, implacable, lonely. They cut down the forests to banish Indians, animals, and shadows. Today, Indians, animals, and forests have gone and wild nature, silence, and loneliness are hard to find. When a man's experience was limited by his home, village, and environs, he lived with his handiworks. Today, the automobile permits temporary escapes 2 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE PLACE OF NATURE IN THE CITY OF MAN from urban squalor, and suburbaniza- tion gives the illusion of permanent escape. Once upon a time, when primeval forests covered Pennsylvania, its original inhabitants experienced a North Tem- perate climate, but, when the forests were felled, the climate became, in summer, intemperately hot and humid. Long ago, floods were described as Acts of God. Today, these are known quite often to be consequences of the acts of man. As long ago, droughts were thought to be Acts of God, too, but these, it is now known, are exacerbated by the acts of man. In times past, pure air and clean abundant water were commonplaces. Today, "pollution" is the word most often associated with the word "atmos- phere," drinking water is often a dilute soup of dead bacteria in a chlorine solution, and the only peoples who enjoy pure air and clean water are rural societies who do not recognize these for the luxuries they are. Not more than two hundred years ago, the city existed in a surround of farm land, the sustenance of the city. The farmers tended the lands which were the garden of the city. Now, the finest crops are abject fruits compared to the land values created by the most scabrous housing, and the farms are defenseless. In days gone by, marshes were lonely and wild, habitat of duck and goose, heron and egret, muskrat and beaver, but that was before marshes became the prime sites for incinerator wastes, rub- bish, and garbage-marshes are made to be filled, it is said. When growth was slow and people spent a lifetime on a single place, the flood plains were known and left un- built. But, now, who knows the flood plain? Caveat emptor. Forests and woodlands once had their own justification as sources of timber and game, but second-growth timber has little value today, and the game has long fled. Who will defend forests and woods? Once upon a time, the shad in hun- dreds of thousands ran strong up the river to the city. But, today, when they do so, there is no oxygen, and their bodies are cast upon the shores. THE MODERN METROPOLIS Today, the modern metropolis covers thousands of square miles, much of the land is sterilized and waterproofed, the original animals have long gone, as have primeval plants, rivers are foul, the atmosphere is polluted, climate and microclimate have retrogressed to in- creased violence, a million acres of land are transformed annually from farm land to hot-dog stand, diner, gas station, rancher and split level, asphalt and concrete, billboards and sagging wire, parking lots and car cemeteries, yet slums accrue faster than new build- ings, which seek to replace them. The epidemiologist can speak of urban epi- demics-heart and arterial disease, renal disease, cancer, and, not least, neuroses and psychoses. A serious proposition has been advanced to the effect that the modern city would be in serious jeop- ardy without the safeguards of modern medicine and social legislation. Lewis Mumford can describe cities as dys- genic. There has arisen the recent specter, described as "pathological to- getherness," under which density and social pressure are being linked to the distribution of disease and limitations upon reproduction. We record stress from sensory overload and the response of negative hallucination to urban an- archy. When one considers that New York may well add 1,500 square miles of new "low-grade tissue" to its perime- ter in the next twenty years, then one recalls Loren Eiseley's image and sees 3 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE ANNALS OF THE AMERICAN ACADEMY the cities of man as gray, black, and brown blemishes upon the green earth with dynamic tentacles extending from them and asks: "Are these the evidence of man, the planetary disease?" WESTERN VIEWS: MAN AND NATURE Yet how can nature be justified in the city? Does one invoke dappled sun- light filtered through trees of eco- systems, the shad run or water treat- ment, the garden in the city or negative entropy? Although at first glance an unthinkable necessity, the task of justi- fying nature in the city of man is, with prevailing values and process, both necessary and difficult. The realities of cities now and the plans for their renewal and extension offer incontro- vertible evidence of the absence of nature present and future. Should Philadelphia realize the Comprehensive Plan, then $20 billion and twenty years later there will be less open space than there is today. Cities are artifacts be- coming ever more artificial-as though medieval views prevailed that nature was defiled, that living systems shared original sin with man, that only the artifice was free of sin. The motto for the city of man seems to be: salvation by stone alone. Of course, the medieval view of nature as rotten and rotting is only an aspect of the historic Western anthropocentric- anthropomorphic tradition in which nature is relegated to inconsequence. Judaism and Christianity have been long concerned with justice and com- passion for the acts of man to man but have traditionally assumed nature to be a mere backdrop for the human play. Apparently, the literal interpretation of the creation in Genesis is the tacit text for Jews and Christians alike-man exclusively divine, man given dominion over all life and nonlife, enjoined to subdue the earth. The cosmos is thought to be a pyramid erected to support man upon its pinnacle; reality exists only because man can perceive it; indeed, God is made in the image of man. From origins in Judaism, exten- sion into classicism, reinforcement in Christianity, inflation in the Renais- sance, and absorption into ninteenth- and twentieth-century thought, the anthropocentric - anthropomorphic view has become the tacit Western posture of man versus nature. The nineteenth- and twentieth-century city is the most complete expression of this view. Within the Western tradition exists a contrary view of man and nature which has a close correspondence to the Oriental at- titude of an aspiration to harmony of man in nature, a sense of a unitary and encompassing natural order within which man exists. Among others, the naturalist tradition in the West includes Duns Scotus, Joannes Scotus Erigena, Francis of Assisi, Wordsworth, Goethe, Thoreau, Gerald Manley Hopkins, and the nineteenth- and twentieth-century naturalists. Their insistence upon nature being at least the sensible order within which man exists or a Manifestation of God demanding deference and reverence is persuasive to many but not to the city builders. Are the statements of scientists likely to be more persuasive? David R. Goddard:2 No organism lives without an environ- ment. As all organisms are depletive, no organism can survive in an environment of its exclusive creation. F. R. Fosberg:3 An ecosystem is a functioning, inter- acting system composed of one or more organisms and their effective environment, 2 Transcript, WCAU-TV, "The House We Live In." 3 F. R. Fosberg, "The Preservation of Man's Environment," Proceedings of the Ninth Pacific Science Congress, 1957, Vol. 20, 1958, p. 160. 4 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE PLACE OF NATURE IN THE CITY OF MAN both physical and biological. All eco- systems are open systems. Ecosystems may be stable or unstable. The stable system is in a steady state. The entropy in an unstable system is more likely to increase than decrease. There is a tend- ency towards diversity in natural eco- systems. There is a tendency towards uni- formity in artificial ecosystems or those strongly influenced by man. Paul Sears:4 Any species survives by virtue of its niche, the opportunity afforded it by environment. But in occupying this niche, it also assumes a role in relation to its surroundings. For further survival it is necessary that its role at least be not a disruptive one. Thus, one generally finds in nature that each component of a highly organized community serves a constructive or at any rate, a stabilizing role. The habitat furnishes the niche, and if any species breaks up the habitat, the niche goes with it. ... To persist organic sys- tems must be able to utilize radiant energy not merely to perform work, but to main- tain the working system in reasonably good order. This requires the presence of organisms adjusted to the habitat and to each other so organized to make the fullest use of the influent radiation and to con- serve for use and reuse the materials which the system requires. Complex creatures consist of billions of cells, each of which, like any single- celled creature, is unique, experiences life, metabolism, reproduction, and death. The complex animal exists through the operation of symbiotic rela- tionships between cells as tissues and organs integrated as a single organism. Hans Selye describes this symbiosis as intercellular altruism, the situation under which the cell concedes some part of its autonomy towards the operation 4Paul B. Sears, "The Process of Environ- mental Change by Man," in Man's Role in Changing the Face of the Earth, ed. W. L. Thomas, Jr. (Chicago: University of Chicago Press, 1956yf . of the organism and the organism responds to cellular processes. Aldo Leopold has been concerned with the ethical content of symbiosis:5 Ethics so far studied by philosophers are actually a process in ecological as well as philosophical terms. They are also a process in ecological evolution. An'ethic, ecologically, is a limitation on freedom of action in the struggle for existence. An ethic, philosophically, is a differentiation of social from anti-social conduct. These are two definitions of one thing which has its origin in the tendency of interdependent individuals and groups to evolve modes of cooperation. The ecologist calls these symbioses. There is as yet no ethic deal- ing with man's relation to the environment and the animals and plants which grow upon it. The extension of ethics to in- clude man's relation to environment is, if I read the evidence correctly, an evolu- tionary possibility and an ecological neces- sity. All ethics so far evolved rest upon a single premise that the individual is a member of a community of interdependent parts. His instincts prompt him to com- pete for his place in the community, but his ethics prompt him to cooperate, per- haps in order that there may be a place to compete for. The most important inference from this body of information is that inter- dependence, not independence, charac- terizes natural systems. Thus, man- nature interdependence presumably holds true for urban man as for his rural contemporaries. We await the discovery of an appropriate physical and symbolic form for the urban man- nature relationship. NATURAL AND ARTIFICIAL ENVIRONMENTS From the foregoing statements by natural scientists, we can examine certain extreme positions. First, there 5 Aldo Leopold, A Sand County Almanac (Oxford: Oxford University Press, 1949yf S S . 202, 203. 5 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE ANNALS OF THE AMERICAN ACADEMY can be no conception of a completely "natural" environment. Wild nature, save a few exceptions, is not a satis- factory physical environment. Yet the certainty that man must adapt nature and himself does not diminish his de- pendence upon natural, nonhuman proc- esses. These two observations set limits upon conceptions of man and nature. Man must adapt through both biologi- cal and cultural innovation, but these adaptations occur within a context of natural, nonhuman processes. It is not inevitable that adapting nature to support human congregations must of necessity diminish the quality of the physical environment. Indeed, all of preindustrial urbanism was based upon the opposite premise, that only in the city could the best conjunction of social and physical environment be achieved. This major exercise of power to adapt nature for human ends, the city, need not be a diminution of physiological, psychological, and aesthetic experience. While there can be no completely natural environments inhabited by man, completely artificial environments are equally unlikely. Man in common with all organisms is a persistent configura- tion of matter through which the en- vironment ebbs and flows continuously. Mechanically, he exchanges his sub- stance at a very rapid rate while, addi- tionally, his conceptions of reality are dependent upon the attribution of mean- ing to myriads of environmental stimuli which impinge upon him continuously. The materials of his being are natural, as are many of the stimuli which he perceives; his utilization of the ma- terials and of many stimuli is involun- tary. Man makes artifices, but galactic and solar energy, gases of hydrosphere and atmosphere, the substance of the lithosphere, and all organic systems remain elusive of human artificers. Yet the necessity to adapt natural en- vironments to sustain life is common to many organisms other than man. Creation of a physical environment by organisms as individuals and as com- munities is not exclusively a human skill. The chambered nautilus, the bee- hive, the coral formation, to select but a few examples, are all efforts by organ- ism to take inert materials and dispose them to create a physical environment. In these examples, the environments created are complementary to the or- ganisms. They are constructed with great economy of means; they are expressive, they have, in human eyes, great beauty, and they have survived periods of evolutionary time vastly longer than the human span. Simple organisms utilize inert ma- terials to create physical environments which sustain life. Man also confronts this necessity. Man, too, is natural in that he responds to the same laws as do all physical and biological systems. He is a plant parasite, dependent upon the plant kingdom and its associated microorganisms, insects, birds, and ani- mals for all atmospheric oxygen, all food, all fossil fuel, natural fibers and cellulose, for the stability of the water cycle and amelioration of climate and microclimate. His dependence upon the plant and photosynthesis establishes his dependence upon the microorgan- isms of the soil, particularly the de- composers which are essential to the recycling of essential nutrients, the insects, birds, and animals which are in turn linked to survival of plant systems. He is equally dependent upon the natural process of water purification by microorganisms. The operation of these nonhuman physical and bio- logical processes is essential for human survival. Having concluded that there can be neither a completely artificial nor a completely natural environment, our attention is directed to some determi- nants of optimal proportions. Some 6 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE PLACE OF NATURE IN THE CITY OF MAN indication may be inferred from man's evolutionary history. His physiology and some significant part of his psy- chology derive from the billions of years of his biological history. During the most recent human phase of a million or so years, he has been pre- ponderantly food gatherer, hunter, and, only recently, farmer. His urban ex- perience is very recent indeed. Thus, the overwhelming proportion of his bio- logical history has involved experience in vastly more natural environments than he now experiences. It is to these that he is physiologically adapted. According to F. R. Fosberg:6 It is entirely possible that man will not survive the changed environment that he is creating, either because of failure of re- sources, war over their dwindling supply, or failure of his nervous system to evolve as rapidly as the change in environment will require. Or he may only survive in small numbers, suffering the drastic re- duction that is periodically the lot of pioneer species, or he may change beyond our recognition. . . . Management and utilization of the environment on a true sustaining yield basis must be achieved. And all this must be accomplished without altering the environment beyond the capac- ity of the human organism, as we know it, to live in it. HUMAN ECOSYSTEMS There are several examples where eco- systems, dominated by man, have en- dured for long periods of time; the example of traditional Japanese agri- culture is perhaps the most spectacular. Here an agriculture of unequaled in- tensity and productivity has been sus- tained for over a thousand years, the land is not impoverished but enriched by human intervention, the ecosystem, wild lands, and farm lands are complex, 6F. R. Fosberg, "The Preservation of Man's Environment," Proceedings of the Ninth Pacific Science Congress, 1957, Vol. 20, 1958, p. 160. stable, highly productive, and beautiful. The pervasive effect of this harmony of man-nature is reflected in a language remarkable in its descriptive power of nature, a poetry succinct yet capable of the finest shades of meaning, a superb painting tradition in which nature is the icon, an architecture and town building of astonishing skill and beauty, and, not least, an unparalleled garden art in which nature and the garden are the final metaphysical symbol. In the Western tradition, farming in Denmark and England has sustained high productivity for two or more cen- turies, appears stable, and is very beautiful; in the United States, com- parable examples exist in Amish, Mennonite, and Pennsylvania Dutch farming. Understanding of the relationship of man to nature is more pervasive and operative among farmers than any other laymen. The farmer perceives the source of his food in his crops of cereal, vegetables, roots, beef, fish, or game. He understands that, given a soil fer- tility, his crop is directly related to inputs of organic material, fertilizer, water, and sunlight. If he grows cotton or flax or tends sheep, he is likely to know the source of the fibers of his clothes. He recognizes timber, peat, and hydroelectric power as sources of fuel; he may well know of the organic source of coal and petroleum. Experi- ence has taught him to ensure a func- tional separation between septic tank and well, to recognize the process of erosion, runoff, flood and drought, the differences of altitude and orientation. As a consequence of this acuity, the farmer has developed a formal expres- sion which reflects an understanding of the major natural processes. Charac- teristically, high ground and steep slopes are given over to forest and woodland as a source of timber, habitat for game, element in erosion control, 7 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE ANNALS OF THE AMERICAN ACADEMY and water supply. The more gently sloping meadows below are planted to orchards, above the spring frost line, or in pasture. Here a seep, spring, or well is often the source of water supply. In the valley bottom, where floods have deposited rich alluvium over time, is the area of intensive cultivation. The farm buildings are related to conditions of climate and microclimate, above the flood plain, sheltered and shaded by the farm woodland. The septic tank is located in soils suitable for this purpose and below the elevation of the water source. Here, at the level of the farm, can be observed the operation of certain simple, empirical rules and a formal ex- pression which derives from them. The land is rich, and we find it beautiful. Clearly, a comparable set of simple rules is urgently required for the city and the metropolis. The city dweller is commonly unaware of these natural processes, ignorant of his dependence upon them. Yet the problem of the place of nature in the city is more dif- ficult than that of the farmer. Nature, as modified in farming, is intrinsic to the place. The plant community is relatively immobile, sunlight falls upon the site as does water, nutrients are cycled through the system in place. Animals in ecosystems have circum- scribed territories, and the conjunction of plants and animals involves a utiliza- tion and cycling of energy and ma- terials in quite limited areas. The modern city is, in this respect, pro- foundly different in that major natural processes which sustain the city, provide food, raw materials for industry, com- merce, and construction, resources of water, and pure air are drawn not from the city or even its metropolitan area but from a national and even interna- tional hinterland. The major natural processes are not intrinsic to the locus of the city and cannot be. NATURE IN THE METROPOLIS In the process of examining the place of nature in the city of man, it might be fruitful to consider the role of nature in the metropolitan area ini- tially, as here, in the more rural fringes, can still be found analogies to the empiricism of the farmer. Here the operative principle might be that natu- ral processes which perform work or offer protection in their natural form without human effort should have a presumption in their favor. Planning should recognize the values of these processes in decision-making for pros- pective land uses. A more complete understanding of natural processes and their interactions must await the development of an eco- logical model of the metropolis. Such a model would identify the regional inventory of material in atmosphere, hydrosphere, lithosphere, and biosphere, identify inputs and outputs, and both describe and quantify the cycling and recycling of materials in the system. Such a model would facilitate recogni- tion of the vital natural processes and their interdependence which is denied today. Lacking such a model, it is necessary to proceed with available knowledge. On a simpler basis, we can say that the major inputs in biological systems are sunlight, oxygen-carbon di- oxide, food (including nutrientsyf D Q d water. The first three are not limiting in the metropolis; water may well be limiting both as to quantity and qual- ity. In addition, there are many other reasons for isolating and examining water in process. Water is the single most specific determinant of a large number of physical processes and is in- dispensible to all biological processes. Water, as the agent of erosion and sedimentation, is causal to geological evolution, the realities of physiography. Mountains, hills, valleys, and plains 8 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE PLACE OF NATURE IN THE CITY OF MAN experience variety of climate and microclimate consequent upon their physiography; the twin combination of physiography and climate determines the incidence and distribution of plants and animals, their niches, and habitats. Thus, using water as the point of departure, we can recognize its impact on the making of mountains and lakes, ridges and plains, forests and deserts, rivers, streams and marshes, the dis- tribution of plants and animals. Lack- ing an ecological model, we may well select water as the best indicator of natural process. In any watershed, the uplands represent the majority of the watershed area. Assuming equal dis- tribution of precipitation and ground conditions over the watershed, the maxi- mum area will produce the maximum runoff. The profile of watersheds tends to produce the steeper slopes in the up- lands with the slope diminishing toward the outlet. The steeper the slope, the greater is the water velocity. This combination of maximum runoff links maximum volume to maximum velocity -the two primary conditions of flood and drought. These two factors in turn exacerbate erosion, with the conse- quence of depositing silt in stream beds, raising flood plains, and increasing intensity and incidence of floods in piedmont and estuary. The natural restraints to flooding and drought are mainly the presence and distribution of vegetation, particularly on the uplands and their steep slopes. Vegetation absorbs and utilizes consid- erable quantites of water; the surface roots, trunks of trees, stems of shrubs and plants, the litter of forest floor mechanically retard the movement of water, facilitating percolation, increasing evaporation opportunity. A certain amount of water is removed tempo- rarily from the system by absorption into plants, and mechanical retardation facilitates percolation, reduces velocity, and thus diminishes erosion. In fact, vegetation and their soils act as a sponge restraining extreme runoff, re- leasing water slowly over longer periods, diminishing erosion and sedimentation, in short, diminishing the frequency and intensity of oscillation between flood and drought. Below the uplands of the watershed are characteristically the more shallow slopes and broad plains of the piedmont. Here is the land most often developed for agriculture. These lands, too, tend to be favored locations for villages, towns, and cities. Here, forests are residues or the products of regeneration on abandoned farms. Steep slopes in the piedmont are associated with streams and rivers. The agricultural piedmont does not control its own de- fenses. It is defended from flood and drought by the vegetation of the up- lands. The vegetation cover and con- servation practices in the agricultural piedmont can either exacerbate or di- minish flood and drought potential; the piedmont is particularly vulnerable to both. The incidence of flood and drought is not alone consequent upon the upland sponge but also upon estuarine marshes, particularly where these are tidal. Here at the mouth of the water- shed at the confluence of important rivers or of river and sea, the flood component of confluent streams or the tidal component of floods assumes great importance. In the Philadelphia metro- politan area, the ocean and the estuary are of prime importance as factors in flood. A condition of intense precipita- tion over the region combined with high tides, full estuary, and strong onshore winds combines the elements of poten- tial flood. The relation of environmental factors of the upland component and the agricultural piedmont to flood and drought has been discussed. The estua- rine marshes and their vegetation con- 9 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE ANNALS OF THE AMERICAN ACADEMY stitute the major defense against the tidal components of floods. These areas act as enormous storage reservoirs ab- sorbing mile-feet of potentially destruc- tive waters, reducing flood potential. This gross description of water- related processes offers determinism for the place of nature in the metropolis. From this description can be isolated several discrete and critical phases in the process. Surface water as rivers, streams, creeks, lakes, reservoirs, and ponds would be primary; the particular form of surface water in marshes would be another phase; the flood plain as the area temporarily occupied by water would be yet another. Two critical aspects of ground water, the aquifer and its recharge areas, could be identified. Agricultural land has been seen to be a product of alluvial deposition, while steep slopes and forests play important roles in the process of runoff. If we could identify the proscriptions and permissiveness of these parameters to other land use, we would have an ef- fective device for discriminating the relative importance of different roles of metropolitan lands. Moreover, if the major divisions of upland, piedmont, and estuary and the processes enumer- ated could be afforded planning recogni- tion and legislative protection, the met- ropolitan area would derive its form from a recognition of natural process. The place of nature in the metropolis would be reflected in the distribution of water and flood plain, marshes, ridges, forests, and farm land, a matrix of natural lands performing work or of- fering protection and recreational op- portunity distributed throughout the metropolis. This conception is still too bald; it should be elaborated to include areas of important scenic value, recreational potential, areas of ecological, botanical, geological, or historic interest. Yet, clearly, the conception, analogous to the empiricism of the farmer, offers oppor- tunity for determining the place of nature in the metropolis. NATURE IN THE CITY The conception advocated for the metropolitan area has considerable rele- vance to the problem of the place of nature in the city of man. Indeed, in several cities, the fairest image of nature exists in these rare. occasions where river, flood plain, steep slopes and woodlands have been retained in their natural condition-the Hudson and Palisades in New York, the Schuylkill and Wissahickon in Philadelphia, the Charles River in Boston and Cam- bridge. If rivers, flood plains, marshes, steep slopes, and woodlands in the city were accorded protection to remain in their natural condition or were retrieved and returned to such a condition where possible, this single device, as an aspect of water quality, quantity, flood and drought control, would ensure for many cities an immeasurable improvement in the aspect of nature in the city, in ad- dition to the specific benefits of a planned watershed. No other device has such an ameliorative power. Quite obviously, in addition to benefits of flood control and water supply, the benefits of amenity and recreational op- portunity would be considerable. As evidence of this, the city of Philadelphia has a twenty-two mile water front on the Delaware. The most grandiose re- quirements for port facilities and water- related industries require only eight miles of water front. This entire water front lies in a flood plain. Levees and other flood protection devices have been dismissed as exorbitant. Should this land be transformed into park, it would represent an amelioration in Philadelphia of incomparable scale. Should this conception of planning for water and water-related parameters 10 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE PLACE OF NATURE IN THE CITY OF MAN be effectuated, it would provide the major framework for the role of nature in the city of man. The smaller ele- ments of the face of nature are more difficult to justify. The garden and park, unlike house, shop, or factory, have little "functional" content. They are, indeed, more metaphysical symbol than utilitarian function. As such, they are not amenable to quantification or the attribution of value. Yet it is fre- quently the aggregation of these gardens and spaces which determines the human- ity of a city. Values they do have. This is apparent in the flight to the suburbs for more natural environments -a self-defeating process of which the motives are clear. Equally, the.selec- tion of salubrious housing location in cities is closely linked to major open spaces which reflects the same impulse. The image of nature at this level is most important, the cell of the home, the street, and neighborhood. In the city slum, nature exists in the backyard ailanthus, sumac, in lice, cockroach, rat, cat, and mouse; in luxury highrise, there are potted trees over parking garages, poodles, and tropical fish. In the first case, nature reflects "disturb- ance" to the ecologist; it is somewhat analogous to the scab on a wound, the first step of regeneration towards equi- librium, a sere arrested at the most primitive level. In the case of the luxury highrise, nature is a canary in a cage, surrogate, an artifice, forbidden even the prospect of an arrested sere. Three considerations seem operative at this level of concern. The first is that the response which nature induces, tran- quility, calm, introspection, openness to order, meaning and purpose, the place of values in the world of facts, is similar to the evocation from works of art. Yet nature is, or was, abundant; art and genius are rare. The second consideration of some im- portance is that nature in the city is very tender. Woodlands, plants, and animals are very vulnerable to human erosion. Only expansive dimensions will support self-perpetuating and self- cleansing nature. There is a profound change between such a natural scene and a created and maintained landscape. The final point is related to the pre- ceding. If the dimensions are appropri- ate, a landscape will perpetuate itself. Yet, where a site has been sterilized, built upon, buildings demolished, the problem of creating a landscape, quite apart from creating a self-perpetuating one, is very considerable and the costs are high. The problems of sustaining a landscape, once made, are also con- siderable; the pressure of human erosion on open space in urban housing and the inevitable vandalism ensure that only a small vocabulary of primitive and hardy plants can survive. These factors, with abnormal conditions of ground water, soil air, atmospheric pollution, stripping, and girdling, limit nature to a very constricted image. THE FUTURE Perhaps, in the future, analysis of those factors which contribute to stress disease will induce inquiry into the values of privacy, shade, silence, the positive stimulus of natural materials, and the presence of comprehensible order, indeed natural beauty. When young babies lack fondling and mother love, they sometimes succumb to mo- ronity and death. The dramatic reversal of this pattern has followed simple maternal solicitude. Is the absence of nature-its trees, water, rocks and herbs, sun, moon, stars and changing seasons-a similar type of deprivation? The solicitude of nature, its essence if not its image, may be seen to be vital. Some day, in the future, we may be able to quantify plant photosynthesis in the city and the oxygen in the atmos- 11 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms THE ANNALS OF THE AMERICAN ACADEMY phere, the insulation by plants of lead from automobile exhausts, the role of diatoms in water purification, the amel- ioration of climate and microclimate by city trees and parks, the insurance of negative ionization by fountains, the reservoirs of air which, free of combus- tion, are necessary to relieve inversion pollution, the nature-space which a bio- logical inheritance still requires, the stages in land regeneration and the plant and animal indicators of such regeneration, indeed, perhaps, even the plant and animal indicators of a healthy environment. We will then be able to quantify the necessities of a minimum environment to support physiological man. Perhaps we may also learn what forms of nature are necessary to satisfy the psychological memory of a biological ancestry. Today, that place where man and nature are in closest harmony in the city is the cemetery. Can we hope for a city of man, an ecosystem in dynamic equilibrium, stable and complex? Can we hope for a city of man, an eco- system with man dominant, reflecting natural processes, human and non- human, in which artifice and nature conjoin as art and nature, in a natural urban environment speaking to man as a natural being and nature as the environment of man? When we find the place of nature in the city of man, we may return to that enduring and ancient inquiry-the place of man in nature. 12 This content downloaded from 137.110.37.132 on Thu, 29 Jun 2017 21:16:15 UTC All use subject to http://about.jstor.org/terms