The environmental movement in the developed world, and to a lesser extent in the developing world, has succeeded far more than might be expected. Its success must confound those who believe that political and economic leaders are cynically concerned only with their personal power and profit. And it must also confound those who doubt the ability of democratic polities to decide rationally on the course that society should take. People have shown that they can be convinced to sacrifice nontrivial immediate interests for the sake of the natural environment that surrounds them. They can be convinced both because of their inclination to place a spiritual value on nature and because of the rational dangers that can be shown to arise from unwanted environmental changes. However, the growth in recent years of extremism among environmentalists, particularly that associated with the concept of "deep ecology", suggests dangers ahead. The environmental movement's continuing health and success depend on the extent to which those most deeply involved in the movement continue to express a balanced appreciation of the spiritual and material opportunities and costs attendant on environmental change. To ensure this balance, environmentalism must come to be regarded as a movement and field of study dedicated to a positive and creative understanding of the relationship of humanity to the environment rather than a negative, conservative, and preservation-based understanding.

The popular discussion of environmental and ecological issues has been confused by the intergrading of two common senses in which the word "natural" is employed. In one sense, whatever human beings do in or to the environment is inescapably natural, for all activity is governed by what used to be referred to as "natural laws". In this sense, all scientists are naturalists. The academic disciplines that are in the center of the current environmental struggle, such as ecology and geography, began as sciences dedicated to the study and description of the natural world and to the discovery of laws that regulate relationships within that world. But "natural" also derives from the spiritual or pantheistic understanding of nature as an "other" that includes, but is distinct from, human beings and their day-to-day pursuits. One does not study as much as contemplate or appreciate or "get in tune with" this nature. Often those thinking in terms of this second concept of nature imagine this other to exist both outside and previous to modern or industrial civilization and to be in some degree antagonistic to this civilization. They consider humanity, which once lived "in nature" or "with nature", to have largely abandoned nature. Its reckless expansion over the face of the earth has progressively "destroyed nature". In this sense, a prominent environmentalist can write of "the end of nature" that he believes has occurred or is about to occur. ¹

Both senses of nature are legitimate, proper, and useful, but confusion results when they are not kept separate, when terms such as "destruction" and "damage" are used in the course of what is otherwise understood to be scientific discourse on the condition of the environment. It is important to remember that ecology was once understood by its practitioners to be a nonjudgmental science of the interrelationships and interdependencies of organisms in particular environmental situations. In the 1940s, ecology texts were as neutral and nonjudgmental in tone as mineralogy or astronomy texts. As late as the 1960s, the ecologist Edward Karmody could write:

. . . the so-called pollutants, a value and emotion-laden word in today's society, are in fact normal by-products of man as a creative social being. . .(They) are stimulants, or insults, that may terminate some or initiate other biological processes, alter efficiency, affect species composition or structure, and in general thereby alter the dynamics of an ecosystem. ²

But ecology has come increasingly to be viewed by the general public, and to some degree by professional ecologists, to be a political or humanistic movement dedicated to the preservation of specific environments (sets of ecological relationships) as they are today, or as they were in the recent past. In part, this is due to the publicity given ecological controversialists and advocates, such as Rachel Carson and the Ehrlichs, over the past generation, and the continued prominence of such "ecology" today. ³  In part, this is due to a change within the professional ecological community itself. In a formal compendium on the state of biology published in 1970, the section on ecology still reflects primarily the concerns of the "pure scientists" of the past. However, a new vocabulary has become to creep in, as when the text reports: "Ecologists are . . . far from ready to grapple with the galloping degradation of the human habitat". ⁴   It is significant that the ideal agricultural community discussed in the ecology section of this volume is based on a relative unchanging and primitive way of life in New Guinea in which an "undegraded biotic environment is maintained". "Undegraded" appears to mean that while the environment is not "untouched" by human hands, it is at least maintained in a stable equilibrium. ⁵

Significantly, the example of ecological balance given in the foregoing review of the state of biology is taken from the work of a professional anthropologist rather than a biologist. This reminds us that cultural anthropology, this writer's original profession, has in this respect had a parallel evolution to ecology's. Today many cultural anthropologists specializing in the study of small, peripheral societies see themselves as much as the defenders of "their peoples" as students of their societies and history. Many anthropologists see their primary task to be the defense of threatened cultures against the encroachments of the outside world. They have become "cultural survivalists". ⁶   Many in both professions have deemphasized disinterested science in favor of fighting a rearguard action against the forces of change. (Of course, many scholars taking this position are likely to deny the possibility of disinterested science or disinterested scientists.)

In noting this change, there is no implication that good scientists cannot, or should not, be advocates. But there is a suggestion that the change in emphasis within these fields makes it difficult for outside observers to know whether the messages being communicated from these fields of study are to be taken as the result of the disinterested study of a subject or condition, or the humanistic evaluation or "treasuring" of that subject or condition. In particular, it makes it difficult to understand the nature of the highly conservative messages that are being communicated to the public from within these fields. It makes a great deal of difference whether ecological change is discussed in the older scientific manner in which major change in an ecology is discussed with words such as" . . . an upset may lead to an alteration of the whole picture . . . but soon a new equilibrium is produced" ⁷  with words that define major ecological change as "destruction" or "collapse". The first approach develops a useful common basis for policy discussion among individuals with a variety of values; the second fails to develop such a common basis because of the interpenetration of scientific "fact" and individual "value" in the presentation of "scientific findings". One can argue that this tendency of the present generation of ecologists to mix science and values does little more than balance the tendency to mix fact and value in the work of other "scientists" adhering through inclination or for material gain to the values of untrammeled development. However, those deeply concerned with environmental issues will accomplish more in the long run for the health of the planet if they maintain the credibility of their scientific base regardless of the sins of those they see as their opponents.

During his lifetime, the author has spent an inordinate amount of time in the sheer appreciation of nature. He has enjoyed nature in a variety of forms, from the relatively wild to the relatively tame. The carefully tended landscapes of the British Isles and Western Europe may be too tame for many Americans, but he finds them beautiful manifestations of nature. One of the joys of contemplating, in field or library, environments such as that of New England is the opportunity to consider the many phases through which such a landscape has gone, from primeval to sparse Amerindian (which reduced the tree cover), to the colonial period marked by large-scale clearing for cultivation or pasture, and the accompanying gathering of field stones into a pervasive network of stone fences, and finally to the period of subsequent agricultural abandonment and reversion back to woods. Recent changes wrought by suburbanites and exurbanites in the New England landscape pale by comparison with the magnitude of these processes.

Thus, in spite of his love affair with nature, the author has never felt that a natural environment untouched by human hands is the only "true nature" or that human intervention is necessarily destructive. The world has been much improved by the messages of individuals such as Thoreau or Muir. But formerly such persons were rare prophets on the fringes of society. Today, it comes as somewhat of a shock to realize that many highly educated people with scientific training regard human activity as necessarily destructive of nature. In their view, the size and extension of humanity and human activity are inevitably destructive.

The extremes to which conservative environmentalism, ostensibly in the service of "nature", has gone was brought home by a recent personal experience. I tried to bring up with a young man charged with the protection of the Connecticut River the possibility of developing ponds on a property in the Berkshires. I explained that the sites filled with water in the winter and spring, but went dry by the end of summer, so that there could be little permanent life in them. I was disturbed to find that my interlocutor, the new "river warden", was unwilling to discuss what might be done. I understood that ecologists had become convinced that these "vernal pools" were important to the ecosystem, and important to the survival of salamanders and other aquatic creatures that could not survive in the presence of fish. However, the river warden's position was that essentially anything that a human did in the Berkshires would be harmful. In cases such as I described, we should, he said, learn to "leave it to nature" and "not attempt to improve on nature". The mode of thought suggested by the warden is reflected in the comment in a recent work on India's ecological history:

The belief that science provides an infallible guide has encouraged major interventions in natural ecosystems, and these have had unanticipated and usually unfortunate consequences. ⁸

Characteristically, one "belief system" is juxtaposed to another, with science (that is, disinterested, pre-values science) juxtaposed to right-thinking conservatism. Equally characteristic is the suggestion that even scientific knowledge cannot help, for even interventions undertaken on the basis of available knowledge are "usually unfortunate" (that is, result in change that the writers do not approve). For some, ecology seems to have become not a basis on which to act on the environment, but a quasi-scientific belief system used to limit environmental change.

Of course, working environmentalists and ecologists, even the river warden, do not really believe this we should "leave it to nature". In part, their communications are meant for public consumption rather than professional guidance. The many projects undertaken by environmentalists, or with their backing, to improve the environment, such as those required to reestablish the salmon runs in the Connecticut River or to clean up Seattle's Lake Washington, suggest they are quite willing to go beyond blind preservationism. But it seems to the author that the spread of the thinking that this communication strategy reflects within the concerned environmentalist community is bound to inhibit actions by people and governments at all levels that would improve the ecological and environmental "health" of the world, however that might be defined. In addition, reiteration of this ideology is bound to alienate many persons who might otherwise be enlisted in the struggle for environmental improvement.

Toward a New Environmental Ideology

To put environmentalism and the love of nature that motivates it back on track, we need to develop the case for a more active and creative attitude toward the environment. It can be persuasively argued that the purely "anti-development" stance of environmentalism was necessary to make humanity wake up to the havoc uncontrolled human development has produced in so many parts of the world (defining "havoc" in terms of values the author and most of his readers are likely to hold). It was historically necessary, for example, to put "off limits" significant areas of the United States and other countries before development had reduced entire countries and their biota to a dull uniformity. The system of federal and state lands that includes national parks, monuments, national and state forests, and wilderness areas has had great and uncounted returns for all Americans. However, today environmentalism in the traditional liberal democracies has come of age, and many political leaders representing a variety of political persuasions, endorse its general principles. Now, to avoid undercutting the gains of previous generations, and to raise its level of accomplishment, environmentalism must develop a broader and more inclusive framework.

The rethinking process should begin by noting a few homely truths. The first is that whatever humanity has done to "nature" was itself "natural". All species have unavoidably used their capabilities and their reproductive abilities to increase their numbers, and this increase has often come at the expense of other species. It is as natural that homo sapiens has become the dominant mammal in the world as that beetles have become the most common insect. It is also natural that human beings will destroy many of those organisms that stand in their way. The natural order is not always the order with which human beings can be expected to peacefully coexist. Humanity has eliminated the smallpox virus and is well on the way toward eliminating the virus that causes poliomyelitis. No matter how extreme in their concern for "nature", very few environmentalists would oppose striving to resist and if possible destroy the causative agents for AIDS. The point is not to equate such destructions with the elimination of the white rhino, but to point out that when it comes to the preservation of nature, humanity has always had to make choices. Some of its choices are to preserve an existence within the prior natural world; in other cases to destroy it.

Human beings cannot escape making both kinds of decisions. Fortunately, in our relations with most organisms, the decisions need not be as stark as in these examples. In most cases the relationship of human beings to the nonhuman world will be one of adjustment, of harmonizing our needs and wants with those of other organisms in such a way that neither we nor they are driven to the wall.

The next homely truth is that most of what we treasure as the natural environment actually represents the latest stage in a process of continual natural change. Changes have been brought about by a variety of causes, including disease, fire, and climatic change. For example, the natural cycles through which a lake comes into being, and then gradually evolves are well known. Often this natural process culminates in eutrophication and the subsequent elimination of the lake. The former lake bed under certain conditions will eventually merge into the surrounding countryside (with consequent loss in the diversity of the area's biota). Alongside nonhuman natural processes have been those partly or even wholly ascribable to human activity. Human beings have carried plants and animals over long distances. The result has been sometimes to increase the biodiversity of the new locales, and, at least in recent years, to decrease biodiversity across locales. Perhaps the most famous environment-affecting human activity has been agriculture. Even the simplest agriculture, such as that of Amazon basin Amerindians, has had the effect of continually changing and diversifying local environments. In the more highly developed world the result has been the fundamental transformation of many areas, sometimes with a resultant loss in biodiversity. (However, at least until recently, the plethora of agricultural "varieties" developed for human purposes formed a countercurrent to this general simplification.) In some cases, overuse of the land has resulted in the impoverishment of both its human and nonhuman inhabitants. An often cited example is the desiccation of the Middle East through overuse and resultant climatic change.

If we accept these two principles: (1) the necessity to discriminate in our relationship with the natural world among choices along a spectrum from destruction to harmonization, and (2) the inevitability of change in the natural environment due to both human and nonhuman forces, we will have laid the basis for enunciating an additional principle (3) human beings individually and collectively are responsible for guiding and shaping the change that is occurring and will occur in local and global environments through both negative (preservationist) and positive (environment enhancing) activities.

The preservationist approach alone will not be an adequate means of shaping change.

Let us consider the following argument. Humanity has continually growing and changing needs, and there is little reason to expect that growth and change will not continue. It will use the environment in ways that meet its current needs, and from some perspectives this use will appear to be abuse. At the same time, old uses and old economic realities will fade, offering opportunities to recoup many past "losses" (in terms of preservationist values). The once cleared hills of New England and much of the South are now forested. Much of the West that was put to the plow has been abandoned as not sufficiently productive. Grazing on federal lands has for some years been an economically questionable activity for the ranchers themselves, and is likely to gradually die out in most areas. The surface extraction of coal and other minerals leaves behind damaged terrain that will eventually be reclaimed by "nature", although society can assist and "improve" the proess.

As needs change and use changes, we will have the choice between allowing natural processes to occur or of guiding and shaping these processes to enhance the environment as we see fit. This can mean that we will take the opportunities afforded by development to recreate the diversity that existed before the land's more recent uses or to create an enhanced or different kind of diversity.

It is becoming increasingly evident that there are few situations in which we cannot set lands aside for "nature to take care of" and expect the most felicitous outcomes. Recently, a New York Times article reported the alarming result of a census of plants in the Middlesex Fells conservation area north of Boston set aside a hundred years ago. ⁹   Fortunately for researchers today, a plant inventory was made when the reserve was set aside. A similar inventory in the 1990s shows over one-third of the plants noted at the beginning of the period have disappeared. The article stresses the argument that the exposure of the reserve to human visitors was responsible for the impoverishment of native plant life. However, two other processes appear to be at least as important. First, when the land was set aside, it had only recently emerged from the mixed agriculture of traditional New England. As a result, the area still retained a patchwork of recently tilled fields, pastures, and woodlots that provided more diverse micro-environments than are available today under a more uniform forest cover. Second, nonnative plants have come in from outside, taking over niches once occupied by native (or locally native) species. Some of these nonnative species are fierce competitors and adapt to a wider range of micro-environments than native species. Of course, many other factors are likely to play a role. For example, the expansion of the deer population in many parts of the Northeast, particularly in suburban areas where hunting is less acceptable than a hundred years ago, may also have had a deleterious affect on some native species.

To problems such as these, further restricting human access, making sanctuaries "more natural", is an inadequate response. If we are to make a reserve such as Middlesex Fells a preserve for a wide range of native species, we must take a more active stance. This may include destruction of some of the stands of introduced or overgrowing species, the reintroduction of species now extinct in the reserve (by analogy to the reintroduction of wolves in Yellowstone Park), the planting and propagation of still surviving but threatened species, the creation and careful preservation of a greater variety of habitats than exist today, and perhaps control of deer and other animal populations.

In New England as a whole, many relatively natural areas have been invaded by, and even conquered by, expanding or intrusive species. Lists of such species will vary among naturalists and other New Englanders. High on many lists will be deer (especially in suburban areas), canada geese, mute swans, herring gulls, starlings, phragmites, and purple loosestrife. The accomplishments of these species are surely as natural as those of the human beings among whom they thrive. However, whether these successful natural competitors drive to extinction other species will be in part due to our collective human decisions.

In making these decisions, environmentalists and naturalists must take the lead. If they are willing to "let nature take its course", then so be it. If they are not willing, then they should encourage those steps that will alter the balance between these species and those they compete with in a way that stacks the deck in favor of the weaker. Many possible approaches come to mind, such as biological controls or restructuring marshlands and waterways. Whatever strategy or mix of tactics is chosen, it will be bound to have drawbacks and dangers. But the key point will remain: if we wish to counter environmental changes in New England occasioned by the actions of intrusive or overly successful species, then environmentalists can and should study the situation with a view to developing effective rehabilitative strategies. To not do so, would be as much an abdication of responsibility as would an unwillingness to oppose rampant and unregulated human expansion at the expense of "nature".

Recently, during several months in India devoted to studying environmental policy problems, two serious environmental issues were noted for which a more positive approach is indicated. The first is the argument for the desirability of large scale dam projects. Many developing countries focus on such projects to meet a wide variety of urgent needs. The most highly publicized recent example is the massive dam project now underway on the Yangtze in southern China. In India, the Narmada project is perhaps the most well-known project: it has been a center of controversy for years, and continues to be. But it is only one of many similar projects of the recent past or present. Many knowledgeable Indians are convinced that the country's continuing and growing requirements for water and power will inevitably lead India to undertake such projects. In a world in which burning carbon fuels to produce power is becoming ever more dangerous to the environment and the once-promising nuclear alternative is increasingly rejected, intensive exploitation of water power has many arguments in its favor. In India and elsewhere, increasing scarcity of water for both agriculture and modern living makes an equally persuasive argument.

Yet, in India, large dams are routinely opposed by those environmentalists and ecologists who see all such projects as unnecessary and inevitably destructive. They are destructive and dangerous in many ways, but two of the criticisms are particularly germane to this discussion. First, they inundate the properties and homes of thousands of Indians. Governmental authorities promise this displaced population will receive alternative properties or employment, but many Indians do not trust the promises — and sometimes the promises have not been fulfilled. Secondly, the dams inundate large areas of natural habitat, often areas famous for their scenery or history (leading to a propaganda struggle reminiscent of the Glen Canyon controversy some years back in the United States). In fact, the final outcome of such controversies in India is generally that the dam is built in any event. Unfortunately, this leaves a psychological residue that includes a festering hatred of "the system" in the hearts of India's "greens" and a hardening of positions as subsequent projects are developed. ¹⁰

A more promising approach for environmentalists in India and elsewhere would be two-fold. First, they should develop environmentally and economically sound alternatives to great dams. These alternatives must be more persuasive than insistence that society must reduce its energy and water usage. Of course, reducing waste will help, and this should have a central role in any development strategy. But fixation on this approach should not lead to a denial of the legitimate and developing needs of people to raise consumption. Too often, the "reduce consumption" approach suffers from the defects of campaigns against sexually transmitted diseases or unwanted pregnancies that are limited to an insistence on abstinence. Secondly, concerned environmentalists must develop strategies that would make it possible for large dam projects to create new and productive environmental niches for both human and "natural" life. By increasing the size of water reserves in an area and by increasing the availability of water, many species can flourish more than before, if a sustained effort is made to use new environmental opportunities as they come into being. Dams also create conditions that make it possible for species not existing in an area to become naturalized. If sufficient thought were applied to the problem, it is likely that some dam projects could provide new environments that could be used for programs to replenish endangered species elsewhere in India or the world where environmental conditions no longer make their existence feasible.

In considering the effects of establishing great dams, environmentalists should study the history of lake and species evolution and survival over past millennia. Many natural processes have been responsible for the creation of lakes. These include ancient tectonic movements, more recent glacial action, and quite recent landslides and lava flows. Understanding the evolution and diversification of an area's biota after the creation of such "natural lakes" could assist planning for environmental rehabilitation under the conditions created by large dams.

Another Indian environmental problem that requires adoption of a more positive and active approach is the preservation of endangered species. ¹¹   The Indian government has long taken seriously the danger that its major endangered species, such as the snow leopard, and Indian subspecies or species of rhinoceros, elephant, lion, or tiger, could become extinct. This concern has been bolstered by that of the World Wildlife Federation and other foreign organizations that have contributed heavily to preservation efforts. Results have been encouraging. India's Project Tiger, for example, has reversed the decline in the tiger population. India's extensive network of reserves has been steadily enlarged and plans are afoot to enlarge these further. The great mammals are the psychological kingpins of the preservation effort, but the returns from efforts to maintain their numbers go far beyond these species. Under the umbrella of programs to preserve their numbers, and the resultant reserves, a much longer list of endangered plants and animals are being protected.

Unfortunately, the reserves have significant deleterious effects on the peoples living in or near them. Damage is both immediate and dramatic and general and long-term. The first, more dramatic, effect of the preservation of the great mammals is that every year many Indians living in or near the reserves are killed by resurgent tiger, crocodile, or lion populations, while their crops are destroyed by protected wildlife, particularly transiting elephants and wild boar. To understand the general damage to subsistence and way of life, we must recall that throughout the twentieth century India has had a rapidly growing population. This growth has also occurred among the hundreds of thousands of people living within or on the fringes of the wildlife reserves, and whose traditional livelihood was based on gathering food supplies within these areas. These peoples are sometimes excluded by the reserve administrations from their former homes or fields; more often, they are forbidden to continue many of their traditional subsistence or ritual activities. To some extent, these peoples have been included in the new reserve economy through employment. But from their perspective, the fencing off of reserves is seen as a confiscation of properties and rights that have been theirs since time immemorial, and against which they have little appeal in the current political system.

The political and moral difficulties in this situation require the Indian government and environmentalists, domestic and international, to rethink their approach to wildlife preservation. One alternative to the present policy would be to identify lands for reserve development that are less inhabited and less inhabitable than those now targeted for wildlife reserve extension. In spite of population pressures, such lands remain available in India, particularly in areas that have been seriously damaged by overgrazing and erosion. These lands continue to have limited use as pasture, but the numbers displaced by new initiatives here would be far smaller than in the sanctuaries currently being developed. Of course, the lands would have to be made suitable to the targeted species, in terms of necessities such as cover, water supplies, and adequate natural food supplies. The expense of developing wildlife sanctuaries in such degraded lands would be many times that of improving and extending the present sanctuary network through concentration on the current or very recent habitats of endangered species. Yet it might in the long run be a more viable approach to maintaining biological diversity in a densely populated country, and would have the added benefit of bringing back into "production", if a novel kind of production, lands so degraded by misuse that they now have little value for either human beings or the "natural world".

The more active and positive environmental ideology sketched above is by no means new. It was promoted several years ago by a well-known environmentalist, Rene Dubos, in a number of writings. A life-long environmentalist, Dubos was one of the first scientists to defend Rachel Carson's Silent Spring against the attacks of his scientific colleagues. Yet he never moved in the direction of the radical preservationists. In a concluding note to a pamphlet entitled "The Resilience of Ecosystems: A Ecological View of Environmental Restoration", Dubos concludes:

The Earth is neither an ecosystem to be preserved unchanged, nor a quarry to be exploited for selfish and short-range economic reasons, but a garden to be cultivated for the development of its own potentialities and the potentialities of the human species. The goal of this relationship is not the maintenance of the status quo but the emergence of new phenomena and new values. Millennia of experience show that, by entering into a mutualistic symbiosis with the Earth, humankind can invent and generate futures not predictable from the deterministic order of things, and thus can engage in a continuous process of creation. ¹²

NOTES

1. Bill McKibben, The End of Nature (New York: Random House, 1989).

2. Edward Karmody, Concepts of Ecology (Englewood Cliffs: Prentice-Hall, 1969), page 180.

3. Often the problem is the attractive packaging of ecology by other than professional ecologists. Two recent examples: Richard Manning, Grassland (New York: Viking, 1995), and Sara Stein, Noah's Garden: Restoring the Ecology of Our Own Backyards (Boston: Houghton-Mifflin, 1993).

4. Philip Handler, editor, Biology and the Future of Man (New York: Oxford University Press, 1970), pages 431-473, especially page 436.

5. Ibid, pages 460-61.

6. For a summary of the controversy within anthropology, and how ill-considered resolutions by anthropologists have eroded their credibility, see "Anthropology Group Takes Activist Stand to Protect Cultures", The New York Times, March 19, 1996, page C11.

7. Ernest Neal, Woodland Ecology (Cambridge: Harvard University Press, 1958), page 104.

8. Madhav Gadgil and Ramachandra Guha, This Fissured Land: An Ecological History of India (Delhi: Oxford University Press, 1992), page 52.

9. The New York Times, "Plant Census Raises an Alarm and Leads to Restoration Effort", February 13, 1996, page C4.

10. For an idea of the controversy, see Pravin Sheth, Narmada Project: Politics of Eco-Development (New Delhi: Har-Anand, 1994); B. G. Verghese, Winning the Future (New Delhi: Konark, 1994); and B . D. Dhawan, editor, Big Dams, Claims, Counterclaims (New Delhi: Commonwealth, 1989).

11. Among references that are might be considered are Vijay Thapa and Rohit Brijnath, "The Perils of Protection", India Today, June 15, 1995, pages 152-155; "Elephants might have been poisoned", and "Need to 'involve' people in sanctuaries" Times of India, April 4 and April 18, 1995; "A tiger's right to live" and "The last post for the tiger and the elephant", The Pioneer, June 6 and July 7, 1995. Also WWF India, "World Wide Fund for Nature India: A Profile", New Delhi, 1994.

12. René Dubos, The Resilience of Ecosystems: An Ecological View of Environmental Restoration (Boulder: Colorado Associated University Press, 1978), page 25.