Placing Nature: Culture and Landscape Ecology / Edition 1 available in Paperback
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- Island Press
Placing Nature is a groundbreaking volume in the field of landscape ecology, the result of collaborative work among experts in ecology, philosophy, art, literature, geography, landscape architecture, and history. Contributors asked each other: What is our appropriate role in nature? How are assumptions of Western culture and ingrained traditions placed in a new context of ecological knowledge? In this book, they consider the goals and strategies needed to bring human-dominated landscapes into intentional relationships with nature, articulating widely varied approaches to the task.
In the essays:
Every possible future landscape is theembodiment of some human choice. Placing Nature provides important insight for those who make such choices-ecologists, ecosystem managers, watershed managers, conservation biologists, land developers, designers, planners-and for all who wish to promote the ecological health of their communities.
|Product dimensions:||11.00(w) x 8.50(h) x 0.50(d)|
About the Author
Joan Iverson Nassauer is Professor of Landscape Architecture at the University of Michigan.
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Culture And Landscape Ecology
By Joan Nassauer, Chris Faust
ISLAND PRESSCopyright © 1997 Joan Iverson Nassauer
All rights reserved.
Human Impacts on Ecosystems and Landscapes
EVILLE GORHAM is an ecologist at the University of Minnesota who specializes in studies of acid rain, aquatic chemistry, and the ecology and biogeochemistry of wetlands. A member of the National Academy of Sciences and a fellow of the American Academy of Arts and Sciences and the Royal Society of Canada, he has served on numerous national and international committees concerning acid rain, wetlands, and global warming.
We are essentially inseparable from the earth, from its creatures, and from each other. We are they, and they are us, and when any one person, species, or ecosystem is impoverished, we are all impoverished.
—Donella Meadows, "A Reaction from a Multitude"
DURING EARLY HUMAN HISTORY, caring for the land was unnecessary; as a part of the natural world it took care of itself. Later, with the development of agriculture, caring for the land meant the maintenance of soil fertility by farmers. Later still we added the prevention or mitigation of local water and air pollution to our evolving concept of care. Now it is becoming increasingly clear that human societies, if they are to survive and prosper, must care, and care deeply, for the planetary ecosystem as an integrated whole.
Human Impacts on the Biosphere
The planetary ecosystem, often called the biosphere, forms a thin envelope about 10 miles deep around the outer part of the earth's crust, where solid, liquid, and gaseous phases (the lithosphere, hydrosphere, and atmosphere) are intermingled. The reasons for our concern about the health of the biosphere are not far to seek. When we look at other species of large mammals, such as the various kinds of seal, deer, and dolphin, we see that their populations worldwide do not exceed a few millions or at most tens of millions. Before the development of agriculture, the global human population was of a similar magnitude, perhaps 5 million, so that its impact on the life-supporting capacity of the biosphere was very small. Now, with the human population increased a thousand-fold and exceeding 5 billion, supplemented by more than 4 billion large domesticated mammals—cows, pigs, sheep, goats, camels, and water buffaloes—that impact has become so large that it threatens to disrupt and degrade the biosphere in a number of important ways. Indeed, we are now at a point where some scientists believe that we have already exceeded considerably the capacity of the global ecosystem to maintain for all its different peoples a reasonably adequate (i.e., Western) standard of living. Arthur Westing, for instance, of the International Peace Research Institute in Oslo, has estimated that carrying capacity to be about 2 billion people, much less than the more than 5 billion present inhabitants and the 8 billion or so projected by the year 2020. At the average living standard of the Third World, the carrying capacity might be about 10 times higher, 20 billion—based on per capita energy use as an index of environmental impact.
The effects of population growth have been greatly enhanced by a vast increase in the per capita use of energy—for industry, agriculture, and transport—by people in developed countries such as the United States. They use hundreds of times as much energy per capita as people in the poorest countries of the world, for instance, Ethiopia and Nepal, whose consumption is, nevertheless, much greater than that in the most primitive hunter-gatherer societies. Because that energy is derived largely from fossil fuels, we have seen a toxification of our environment by acid rain, mercury, and other trace elements abundant in coal and oil, and we face the prospect of severe "greenhouse" warming of the climate by carbon dioxide released to the atmosphere following the combustion process.
Humans have also become great earthmovers, so that collectively they must now be regarded as a major geological agent, causing immense destruction of habitats. For example, tremendous transformations have been wrought in landscapes as American agribusiness has displaced the family farm. In this connection, industrial production of nitrogenous fertilizers from the nitrogen present in the atmosphere has doubled the nitrogen circulating through the biosphere, which is affecting in major ways nitrogen cycles—and other ecological processes—far from the farm fields to which the fertilizer is applied. Likewise, toxic pesticides and herbicides, several of them molecules so newly invented by agricultural chemists that microbial decomposers have not yet evolved metabolic techniques to destroy them effectively, have been spread widely throughout the biosphere. Chlorofluorocarbons, an industrial class of molecules also newly invented as refrigerants and spray-can propellants, have been even more widely dispersed, reaching the stratosphere and destroying a part of the ozone layer that protects us from damaging ultraviolet radiation.
Humans have transported, often inadvertently, so many plants and animals around the globe that substantial fractions of the species in a given region have been introduced. In the eastern United States, for example, the proportion of nonnative plants is 20 percent. Such introductions have often caused serious disruption in local ecosystems, as is currently the case with invasion of North American wetlands by the European purple loosestrife and of waterways by the zebra mussel. Largely through destruction of habitats, humans are causing a holocaust of species extinction seen only five times in the history of the earth, the last of them about 65 million years ago in response to a massive asteroid impact at the boundary between the Cretaceous and the Tertiary periods.We also face dangers from the obverse of species extinction, that is, from genetic engineering and its applied offshoot biotechnology, which is just now beginning a phase of rapid expansion. Many scientists believe that adequate safety measures have yet to be devised for the release of genetically altered organisms into unconfined environments.
Finally, if we look with Stanford ecologist Peter Vitousek and his colleagues at the terrestrial production of organic material by plant photosynthesis, we find that a large part of it (40 percent) is now either used directly as food, fodder, and wood products by humans (3.5 percent), lost owing to human activities such as conversion of forests to agriculture and desertification (12 percent), or co-opted by altering natural communities for human purposes such as agriculture and forestry (24 percent). Such activities often have a strong impact on the cycles of carbon, nitrogen, phosphorus, sulfur, and other elements whose balanced interactions are essential to maintaining the smooth functioning of the biosphere. They also lessen considerably the diversity of plants and animals that is equally essential to biospheric function. It is clear from a consideration of these and many other impacts, including inadvertent, indirect, synergistic, and cumulative effects of the activities mentioned, that human beings are altering the structure and function of the biosphere very significantly in many ways that scientists have only recently been able to measure and understand (figure 1).
Land Use and Its Regulation
What does all this mean for our stewardship of the biosphere? First and foremost it means that we must reconsider many of the social and economic policies that have contributed to ecological degradation. Having done so, we must craft new policies that will preserve, insofar as possible, the life-support systems of the biosphere. Whether we can in fact have "sustainable development" worldwide or will eventually find it to be a facile and cruelly deceptive oxymoron remains to be seen; certainly the policies that will bring it about in a politically acceptable manner are far from evident. The underlying basis for such policies is, however, clear: We must regulate, or "zone," the uses of landscapes (and seascapes) for specific purposes far more rigorously and effectively than has hitherto been possible. We do, of course, practice such zoning regularly in our cities; in addition, we pass open-space and greenbelt legislation and set aside land for national and state forests, parks, wildlife refuges, and wilderness areas. On the other hand, current political trends in many parts of the world are strongly opposed to the philosophy behind such zoning policies, which are taken to interfere with individual property rights, and they will be very difficult to expand until the need becomes much more apparent. That it is likely to do so within the coming century seems obvious to many ecosystem and landscape ecologists.
In a prescient article published more than a quarter-century ago, Eugene Odum, the doyen of American ecology in the years after World War II, offered a useful approach to land-use regulation by proposing a four-compartment model of the landscape divided into urban-industrial, productive, protective, and compromise ecosystems, the last type being responsible for both productive and protective functions. He argued for a model in which towns and cities occupying a given amount of space would require for their sustenance a certain amount of land to trap solar energy for food production. They would also require a certain amount of protective landscape, such as national parks and wilderness areas, to provide those basic services of air and water purification, soil formation, temperature control, and protection of biological diversity that nature provides to us at no cost. To be effective, Odum's global categories would of course require refinement and division into subcategories on both regional and local scales to take into account different sorts and areas of croplands, forests, grasslands, wetlands, and other ecosystems.
Let us focus on the importance of productive and protective ecosystems and the value of the services they provide. As a crude indication of what the costs of those services might be were it to become necessary for us to pay for them, consider the case of Biosphere 2 (earth being Biosphere 1). Biosphere 2, conceived as an ecotechnological model for exploring and colonizing space, is a futuristic "greenhouse" of glass and steel engineered to be a self-sustaining landscape without exchange of materials (including atmospheric gases) with the outside world. It did, however, require substantial inputs of fossil-fuel energy costing about a million dollars a year to drive a variety of engineering systems that enhanced the life support provided by the almost 4,000 species of plants and animals inhabiting individual tropical rain forest, marsh, desert, savanna, stream, and agricultural ecosystems. The cost of building and maintaining the closed system that was designed (but failed) to support eight "Biospherians" on three acres of totally enclosed land through two years of operation was about $150 million, or almost $19 million per person. With costs such as these, can we really afford to overpopulate and tox-ify the planet at the same time that we severely decimate the rich array of millions of species engaged in providing our (and their) life support free of charge?
It is worth pointing out here that the inhabitants of Biosphere 2 made great efforts to recycle wastes effectively and efficiently and to avoid wherever possible the use of toxic chemicals. Unfortunately, this is not the case in our agricultural and urban-industrial systems where much of the waste is discharged to the air and water to pollute and degrade adjacent and even far distant ecosystems. Moreover, toxic chemicals are in widespread use, and many are discharged to the environment. Both wastes and toxins are treated as "externalities" in economic terms, uncounted in the balance sheet of credits and debits and left for others to pay now or in the future. Fortunately, a new breed of ecological economists is teaching us not only the true costs of these and other externalities but also how to include them in the balance sheet, so that their costs will be paid by those responsible for generating them.
The life-support activities of protective ecosystems can, fortunately, be assisted in large part by those that Odum designated as compromise, or multiple-use, ecosystems, which are designed to provide us with goods as well as services. These are the forests, grasslands, waters, and other ecosystems that we maintain in a semi-natural condition to help in cleansing our air and water and in maintaining the hydrologic cycle and other ecosystem functions while we harvest wood, cattle, fish, and other useful things on what we hope will be a sustainable basis. They may vary in scale from a woodlot or a small pond to a national forest or the Great Lakes.
Much forest land is managed in this way to allow the harvest of trees, deer, fish, and other resources while meeting the needs of hikers, campers, boaters, bird-watchers, and others. How successful forest management has been depends, as is often the case, on whom one asks. The failure of our management practices is, unfortunately, not at all uncommon. A recent and dramatic example is the cod fishery on the Grand Banks of Newfoundland, which, through overfishing (aided probably by shifts in oceanic temperatures) has undergone a catastrophic decline in the last decade, after centuries of harvest, thereby destroying the livelihood of thousands of fishermen.
Odum has estimated recently that 70 percent of the land in the United States is maintained in protective and semi-natural compromise status; 24 percent is cultivated, often with nonnative species; and 6 percent is developed as urban-industrial space. He estimated further that in producing crops for human uses cultivated land requires about twice the energy input captured from the sun by protective and compromise ecosystems. The added energy comes from fossil fuels and is used to produce and spread fertilizers, herbicides, and pesticides; supply irrigation water; and power tractors. Nowadays, American agribusiness expends about 2.5 calories of fossil-fuel energy to produce 1 calorie of food, 50 to 100 times as much energy as expended by preindustrial farmers. Moreover, to bring that food calorie to the table requires, through processing, packaging, storage, and transport, another 5 calories. Refrigeration in the home and cooking add another 2.5 calories, so that the final ratio of energy input to output is an astonishing 10 to 1. The energy requirement of urban-industrial ecosystems, also supplied by fossil fuels, is about 10 times that of the natural systems.
Whether the landscape proportions characteristic of the United States are those best suited to long-term sustainable support of its present human population is a question not yet resolved, and one that will become moot as the population continues to increase both in numbers and energy use. The question must, moreover, be considered on a broader global basis, given the interdependence of all countries of the world for their supplies of food, energy, and raw materials. Major environmental problems such as the dust bowl of the 1930s and the ozone hole of the present, regional in their extent, or impending problems such as the increasingly likely greenhouse warming of the climate, global in its extent, will help to focus our minds on the essential point—that we humans are now operating not only locally but on regional and global scales as well, and largely as "sorcerer's apprentices" ignorant of the likely consequences for human welfare and, ultimately, for human survival.
The Values of Wilderness
It is legitimate to ask at this point: Cannot all of the necessary life-support systems be provided by managed compromise ecosystems without any need for the protective category of national parks (often themselves partly compromise systems) and true wilderness areas? The answer is that although compromise systems can indeed carry out many of the life-support functions of cleansing and detoxifying our air, land, and water while helping to maintain the natural cycles of nutrients, atmospheric gases, and so on, wilderness areas have their own unique values.
For some, wilderness preservation is a matter of ethics, dictating that we not knowingly cause the extinction of other creatures that inhabit the earth. This concern may have its roots in an inborn tendency to "biophilia," or love of the plants and animals that share the planet with us, although the concept of such a genetic bias is quite controversial at present. Whether or not it is genetic, it is widely demonstrated by gardeners, pet keepers, animal watchers, and even—in debased form—by those who purchase plastic flowers and lawn flamingos. For others, such as my fellow ecologist and environmentalist Herbert Wright, it is an aesthetic question, with pristine ecosystems analogous to original works of art; no connoisseur will accept that a copy—however good—can truly substitute for the real thing. Wilderness has the additional aesthetic appeal that it often gives us an accurate picture of the landscape as it was when Europeans came to it as settlers, providing us, as it were, with a living museum.
In more practical terms, wilderness is the best possible baseline against which to assess the effects that we humans have had on the land. In addition, because those human effects are absent, it is easier to work out how diverse plant and animal communities have responded over time to the interacting environmental factors of climate, topography, and soil. Wilderness is, moreover, the ultimate protector of biodiversity, which includes not only the millions of species of plants, animals, and microbes but also the genetic diversity within each species. Biodiversity is under severe threat from habitat destruction and fragmentation, particularly in the tropical rain forests. Wilderness must, therefore, be preserved on a very broad scale, particularly where large mammals with extensive and often migratory ranges are important elements in the landscape.
Excerpted from Placing Nature by Joan Nassauer, Chris Faust. Copyright © 1997 Joan Iverson Nassauer. Excerpted by permission of ISLAND PRESS.
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Table of Contents
Acknowledgments Introduction: Culture and Landscape Ecology: Insights for Action PART I. Urgent Realities Chapter 1. Human Impacts on Ecosystems and Landscapes Chapter 2. Farming and the Landscape Chapter 3. Inherit the Grid PART II. The Culture of Nature Chapter 4. Cultural Sustainability: Aligning Aesthetics and Ecology Chapter 5. The Beauty that Requires Health PART III. Landscape Ecology in Place Chapter 6. Urban Conservation: Sociable, Green, and Affordable Chapter 7. Politics at the Scale of Nature Chapter 8. Creating Pseudo-rural Landscapes in the Mountain West Conclusion: Action across Boundaries Index