Many people believe that much of the damage done to the Earth is so profound that it is now irreversible. Fortunately, this pessimism is probably unjustified because ecosystems have enormous powers of recovery from traumatic damage. Ecosystems possess several mechanisms for self-healing. Some of these are analogous to the homeostatic mechanisms of animal life; they enable ecosystems to overcome the effects of outside disturbances simply by reestablishing progressively the original state of ecological equilibrium. More frequently, however, ecosystems undergo adaptive changes of a creative nature that transcend the mere correction of damage; the ultimate result is then the activation of certain potentialities of the ecosystem that had not been expressed before the disturbance.
A recent bulletin from the University of Rhode Island Agricultural Experimental Station provides a typical illustration of the restorative ability of Nature in the temperate zone. Two centuries ago, 70 percent of the land in Rhode Island had been cleared of the deciduous forest that once covered it almost completely. The primeval forest had been transformed into agricultural land by the original white settlers. During the late nineteenth century, however, the less productive farms were abandoned, and trees returned so rapidly that less than 30 percent of the state remains cleared today. Nature provided the mechanisms for a spontaneous step-by-step restoration of the original ecosystem. Similarly, forest is reoccupying abandoned farmlands in many other areas of the eastern United States. For example, although Massachusetts is one of our most heavily populated states, it has now become one of the most heavily forested. The return of the trees is not peculiar to the Atlantic coast. In Michigan, the Porcupine Mountain forest, which had been badly damaged by mining during the nineteenth century, has now recovered so well that it is called the Porcupine Wilderness State Park.
Similar phenomena of restoration can be observed in tropical and subtropical countries. When the Korean War ended in 1953, a de-militarized zone (DMZ) of 2.5 miles' width was agreed upon between North and South Korea. The DMZ was then a wasteland pockmarked with bomb craters and shell holes; yet it has now become one of Asia's richest wildlife sanctuaries. Abandoned rice terraces have turned into marshes used by waterfowl; old tank traps are overgrown with weeds and serve as a cover for rabbits; herds of small Asian deer take refuge in the heavy thickets. Korean tigers and lynx now roam in the mountains of the eastern part of Korea. Birds prosper throughout the DMZ because they are almost completely out of reach of guns; pheasants are so plump that they have difficulty getting off the ground; the rare Japanese ibis has recently been spotted; the monogamous Manchurian crane, a white, black, and red bird with a majestic wingspan of eight feet, can be watched performing its elaborate mating
ritual, which consists of bows, wing flapping, and leaps in the air . . . even some of the most fragile ecosystems can recover under special circumstances. Recovery can take place when the proper species reach the damaged ecosystem either by accidental transportation or by active migration.
In 1883, Krakatoa island in the Sunda Strait near the Malay Peninsula was partly destroyed by a tremendous volcanic eruption that killed all its forms of life. Experts have estimated that the explosion had the violence of a million hydrogen bombs. The seismic wave it generated reached 135 feet above sea level, destroying seaside villages in Java, Sumatra, and other neighboring islands. Ash and gases rose 50 miles into the sky, blocking out sunlight over a lSD-mile radius. Vast quantities of pumice hurtled through the air, defoliating trees and clogging harbors. When the eruption ended, what was left of Krakatoa island was covered by a thick layer of lava and was completely lifeless.
The wind and the sea currents, however, soon brought back some animals and plants, and life once more took hold on the lava. More than 30 species of plants were recognized as early as 1886. By 1920, there were some 300 plant species and 600 animal species including birds, bats, lizards, crocodiles, pythons, and of course rats. Today, less than a century after the great eruption, the plant community on Krakatoa is fairly complex, although it has not yet reached the composition of the climax forest in the rest of the Malay Archipelago.
The introduction of biota from an exterior source is not always needed for the recovery of a fragile ecosystem. Many plants or their seeds can persist in a dormant state for long periods of time and prosper again as soon as conditions are favorable for their development. The Wadi Rishrash region of the Eastern [Arabian] Desert in Egypt, for example, was shut off to grazing in the 1920s. Within a few years, the vegetation was so dense that it resembled an irrigated oasis; desert animals took refuge in it during the breeding season. With its new biota, the region appears almost out of place in its barren surroundings. Recovery of a damaged ecosystem occurred recently in west Texas near the city of San Angelo, at the confluence of the three Concho Rivers. The process began with Rocky Creek, which dried up thirty years ago but now makes an important contribution to the municipal water supply of San Angelo.
At the turn of the century, Rocky Creek was a never-failing clear stream that ran through a valley of tall grasses, dotted occasionally here and there by mesquite or some other form of brush. Fish and waterfowl were abundant in the stream; deer and smaller game sought refuge from summer heat under the trees of its banks. Throughout the early decades of the twentieth century, however, brush increasingly invaded the floor of the valley and hillsides. Rocky Creek became progressively narrower and shallower and eventually ceased to flow during the drought of the 1930s. Fish, waterfowl, deer, and other game, virtually disappeared.
While the drought contributed to the impoverishment of Rocky Creek, most of the damage seems to have resulted from changes in land use. Before the white settlements, herds of buffalo and other grazing animals periodically migrated down from the plateaus. They were so numerous that they left in their wake a hoof-scarred land almost denuded of grass, but the damage was only temporary because they stayed for a relatively short time; they did not return to the same place for a year, or perhaps for several years, thus allowing grass to grow back. The situation changed when white ranchers made a practice of enclosing cattle within barbed wire fences and keeping them in the same area year after year. As a result of overgrazing, the better types of native grass progressively disappeared and were replaced by mesquite and other brush. The deeply growing roots of these plants sapped the underground water that had formerly found outlets into creeks and rivers and had permitted the growth
of desirable varieties of grasses.
Around the middle of the twentieth century, a few ranchers began to change their grazing practices in order to protect their cattle against the drought. They reduced the number of livestock so that the level of grazing enabled tall grasses to return, and they started a program of brush destruction by herbicides. The result was beyond expectation. In 1964, a half-forgotten spring began to flow for the first time in some thirty years. Its flow progressively increased, and soon Rocky Creek also came back to life. As more and more brush was eliminated, new seeps and springs began to flow in the valley. Many of them continued to yield clear water even during a hot, dry summer. Rocky Creek has flowed the year around since the late 1960s, all the way to the Middle Concho. Fish, waterfowl, deer, and other game are once more part of the scenery.
A few details concerning Jamaica Bay in New York City illustrate the improvement that can be achieved even under the least promising conditions.
Jamaica Bay is a large Atlantic bay adjacent to John F. Kennedy Airport. It used to be the site of an important shellfish industry and offered refuge to hundreds of thousands of migrating waterfowl during the spring and fall, but it suffered extensive damage as a result of its proximity to the large population of New York City and later to the airport. Sand was dredged from its bottom; its water was polluted by discharges from more than 1,600 sewers; the marshes on its periphery were filled with garbage that formed artificial islands.
During the past two decades, however, attempts have been made to save the bay. W:ner pollution control facilities have been established; the dumping of garbage has been discontinued; grasses and shrubs have been planted on the existing islands of garbage. As a result, shellfish, fin fish, and birds are once more abundant. The center of the bay has become a wildlife refuge. The bird population is remarkable not only for its abundance, but also for its diversity and for the presence of a few unusual species. There are large numbers of wading shore birds such as sandpipers, dowitchers, and green herons. Migration time brings wave upon wave of scaup and brandt, mallards and canvasbacks, Canadian geese and teal. The glossy ibis and the Louisiana heron also have come back, as well as the snowy egret, a bird that was almost extinct in the 1920s.
The return of the glossy ibis to Jamaica Bay, of the wild turkey and the peregrine falcon to their old habitats of the eastern United States, of the salmon to the Willamette River and more recently to the Thames illustrates that once disturbing influences have ceased, some of the original ecological order reestablishes itself spontaneously. Similar phenomena of ecological recovery have been observed in many other parts of the world, particularly in North America and Europe. It is probable therefore that environmental degradation can be interrupted in many cases and that the rate of improvement can often be more rapid than is commonly believed. With good management and human commitment, Nature often takes over and heals itself.
HUMANIZATION OF THE EARTH
When the Bengali poet Rabindranath Tagore (1861-1941) first traveled as a student from India to England in 1878, he realized immediately that the visual charm and the agricultural productivity of the European countryside were the result, in his words, of "the perfect union of man and nature, not only through love but also through active communication." Traveling by railroad from Brindisi to Calais, he "watched with keen delight and wonder that continent flowing with richness under the age-long attention of her chivalrous lover, western humanity." For him, the shaping of the European continent by human labor constituted the "heroic love-adventure of the West, the active wooing of the earth" [italics mine). Yet it is unlikely that Tagore fully appreciated the extent to which the countryside he saw from the train had been shaped by more than a hundred generations of peasants out of the forests and marshes that covered most of western Europe before human occupation.
Tagore's use of the phrase "wooing of the earth" suggests that the relationship between humankind and Nature should be one of respect and love rather than domination. Among people the outcome of wooing can be rich, satisfying, and lastingly successful only if both partners are modified by their association so as to become better adapted to each other. Furthermore, the outcome is more interesting when both partners retain elements of their individuality -of their own wildness.
The same criteria are applicable for a successful association between humankind and our planet. It is because these criteria are rarely fulfilled that few human settlements have long remained in a tolerable condition of ecological health and prosperity. Fortunate are the people, among whom I am one, who have spent their formative years in places where human beings and the planet have long been in close association, experiencing difficulties of course as is the case for all associations, "but also continuing to create new values. [EDITOR'S NOTE: Dr. Dubos was raised in the lle-de-France.] Having lived in several old countries that still provide vital, pleasant human settlements helps me to have confidence in the future of both humankind and the planet.
In human settlements that have been lastingly successful, both the people and the environment have continuously undergone reciprocal adaptive changes. Examples in many different parts of the world show that this process of change is resulting in the progressive humanization of the planet. Conversely, there has also been going on what could be called a planetization of humankind, which began when Stone Age people changed from hunting-gathering to agriculture.
Whereas hunter-gatherers did not need to look further ahead than a single year, Neolithic farmers had to practice long-range planning to select strains of domestic animals and plants. Agriculture, moreover, eventually implied a certain degree of permanence of a culture. This increased the identification of people with a particular place, a process that may have resulted in a greater diversity among civilizations. Agriculture also made farmers aware that certain of their practices changed the character of the land, for good or for bad, and gave them an empirical knowledge that eventually led to a greater understanding of ecology. It seems very likely therefore that agriculture resulted in a broadening of the human mentality, but perhaps at the cost of some loss in the direct perception of nature—the ripening of berries, the snapping of a twig, the rustle of a leaf were
no longer so significant to humans.
Industrialization was even more conducive to the cultivation of long-range views, first for the development of new products and then for the extension of markets. Although industrialization caused a great deal of environmental damage, the present awareness of this danger is leading to the formulation of long-range policies for the protection of the environment. Progressively also we have come to realize that many human activities affect larger and larger areas of the planet, to such an extent that we have now reached a point where we consider many problems from a global perspective.
Thus while the biological aspects of the human species have not changed significantly during the past fifty thousand years, human attitudes have been constantly modified by the evolution of our relationships with the planet. Stone Age people related almost exclusively to their immediate surroundings, whereas today we begin to have the whole planet in mind and to be concerned with its distant future even when we engage in local action. We are becoming planetized probably almost as fast as the planet is becoming humanized, both processes being greatly accelerated by the increase in world population and by technological development.
THE MANAGEMENT OF EARTH
The belief that we can manage the Earth and improve on Nature is probably the ultimate expression of human conceit, but it has deep roots in the past and is almost universal. The manifestations of this conceit can be recognized in the Stone Age people who domesticated animals and plants some ten thousand years ago; in the farmers of all ages who created agricultural land by cutting down the primeval forest, draining the marshes, or irrigating the deserts; in the planners of all historical periods who have converted natural landscapes and waterscapes into artificial parks and gardens; in today's homeowners who maintain lawns where brush and trees would naturally grow.
Human interventions in Nature have often been destructive. Many of them, however, have revealed potentialities of the Earth that would have remained unexpressed in the state of wilderness. We can improve on Nature to the extent that we can identify these unexpressed potentialities and can make them come to life by modifying environments, thus increasing the diversity of the Earth and making it a more desirable place for human life.
The interplay between humankind and the Earth has often generated ecosystems that, from many points of view, are more interesting and more creative than those occurring in the state of wilderness.
In many parts of the world that have been occupied for long periods of time, human beings have deliberately created artificial ecosystems that can be regarded as the analogues of natural communities. In Asia and Europe, particularly, large areas have been patiently shaped through a trial-and-error process similar to organic evolution. Early settlers have thus created artificial ecosystems possessing high levels of ecological diversity and stability in areas where the original ecosystem of the wilderness has been essentially destroyed.
Ecological diversity has been increased, of course, by the deliberate or accidental importation of animal and plant species. Even the honeybee, which is native to Europe, Asia, and Africa, was intro¬duced into America around the year 1600 and more recently into Australia and New Zealand. Today it prospers in all parts of the temperate zone.
Even more interesting than the introduction of plants and animals from one part of the world to another is the fact that ecological diversity can be modified and indeed can be increased by deliberate changes in the environment. Human analogues of natural communities have thus emerged in the replacement of the wilderness by a multiplicity of new microhabitats. There is such a wealth of successful artificial ecosystems throughout the world that it suffices to mention only a few types, selected because they correspond to sharply different climatic regions.
Most of the hedgerows that line the country roads in England and continental Europe and also separate the fields are completely artificial ecosystems dating from the very early Middle Ages or even before. The patchwork of small fields and hedges that was in the past the typical landscape of East Anglia was laid down much later, having been established as a result of the Enclosure Acts. Whether of ancient origin or dating from Enclosure time, European hedgerows now constitute an ecosystem of great diversity and charm. Unlike many American hedges, they are not rows of trimmed shrubs of a single species, but complex populations of trees, shrubs, flowering plants, grasses, small mammals, songbirds, and a host of invertebrates. They serve as reservoirs for animal and plant species that would not prosper in the primeval forest or in a completely cleared landscape. In other words, they have an ecological diversity of their own.
Hedges also contribute in many other ways to the quality of the landscape: for example, by providing habitats for spiders and other natural enemies .of insects that prey on crops; by acting as windbreaks and thus protecting the land; and by providing shade for domestic animals and hikers.
In Japan, substantial hedges commonly surrounding farmhouses serve as windbreaks and provide a decorative element. Their Japanese name, ikegaki, means "living curtain," a reflection of the fact that they harbor a great diversity of living forms. In the lowlands of the south Asian tropics, where population densities have long been extremely high, successful artificial ecosystems have been developed that closely integrate numerous types of animal and plant life in such a manner as to achieve an extremely high efficiency in the use of space and nutrients. The wet-rice ecosystem of southern China is as remarkable for its complexity and stability as for its productivity. The rice paddies are usually located in valleys that can be subjected to controlled flooding. The water may be first used to irrigate vegetable gardens that it fertilizes with its organic matter; it produces a fine bloom of algae that in turn supports various forms of aquatic animal life. Oysters and other shellfish are raised in it, and it sustains shoals of fin fish. The ecosystem is kept in smooth operation by natural processes of fertilization and pest control. Chemical pesticides are not used or needed because pigs, chickens, ducks, and frogs feed on the refuse; these animals become themselves succulent parts of the human diet. Weeds that are missed in the course of this cleaning process are pulled up and used as mulch or as feed for pigs and fish. All nutrients, including animal and human dung, are recycled into the system.
Each animal species of the wet-rice ecosystem has its own niche. Some species of carp are surface eaters, others are grass eaters, and still others are plankton feeders for different water levels; the mullet acts as a bottom detritus feeder. This completely artificial ecosystem is probably as stable as any in the world and more productive than most with regard to both quantity and diversity of food.
HUMANKIND AND THE EARTH
Most of us are ambivalent about defining environmental quality. Our attitudes are governed more by habit than by logic; they put us either in league with nature or in conflict with it, depending upon our past experiences and- what we mean by the words conservation and preservation.
On the one hand, we extol the virtues of the wilderness and want to preserve it intact for its own sake. The condors, the redwoods, the Far West canyons, the tropical rainforests and frozen tundras, the marine estuaries and other types of wetlands, the wildlife of the African savanna and of the Asian jungle, the whales, the porpoises, and the multifarious fauna and flora of the oceans mayor may not be of any use to us, but this is irrelevant. We fight on their behalf because we believe in their right to existence and in their importance as unique forms of creation.
On the other hand, we resent any change in our environmental heritage, even though it was created out of the wilderness by human activities. We want to protect the farmlands of New England, the hedgerows of East Anglia and the European bocage, the canal systems that artificially link natural bodies of water, the rows of trees planted in linear patterns, the villages and monuments that were erected at the cost of much environmental damage. We struggle to save these human creations, forgetting that all of them represent areas deforested, swamps drained, hillsides gouged of their stones and sand. In brief, we want to save both the wilderness and the environments that have been created by destroying the wilderness. Objecting to the destruction or alteration of these artificial eco-systems merely because of opposition to any change is an expression of the attitude that I've labeled "environmental ambivalence" . . . or more simply of the desire to keep everything as it was during one's youth. Change will continue to be because it is an inevitable condition of life. But it must be based on good reasons.
We shall continue to intervene in Nature, but we must do it with a sense of responsibility for the welfare of the Earth as well as of humankind, and we must therefore attempt to anticipate the long-range consequences of our actions. Human modifications of the Earth can be lastingly successful only if their effects are adapted to the invariants of physical and human nature. Fortunately, such constraints are compatible with diversity; there are many ways to deal with Nature that accord with natural laws.
From the point of view of human and environmental quality, it is probable that diversity and flexibility are more valuable than productivity and efficiency. Natural ecosystems are characterized not by high productivity but by resilience and flexibility, attributes that enable them to persist in the face of climatic disturbances and other uncertainties. Ecosystems are more likely to be durable when they contain a great diversity of species and when these are linked in complex symbiotic relationships. Furthermore, biological progress through evolutionary mechanisms tends to be more rapid when the total population is subdivided into colonies that are sufficiently small and separated to permit the survival of mutant forms, yet
sufficiently interconnected to permit interbreeding.
ENVOI
During the Old Stone Age, the human species lived in small bands that obtained their subsistence from hunting, fishing, and collecting wild plants. For the past ten thousand years, the immense majority of human beings have practiced agriculture, pastoralism, and a variety of small trades, in villages or nomadic groups small enough to allow close social relationships and direct contact with Nature. In recent times, the urban environment has given them new comforts, larger social contacts, and greater scope for the expression of individuality.
These different ways of life have left their stamp on human nature, in part through genetic coding but chiefly through physiological and social conditioning. As a consequence of this complex history of our species, most human beings long to recapture now and then each of the various experiences of their evolutionary past: that of the hunter-gatherer, of the farmer and pastoralist, and of the urban dweller. The wooing of the Earth thus implies much more than converting the wilderness into humanized environments. It means also preserving natural environments in which to experience mysteries transcending daily life and from which to recapture, in a Proustian kind of remembrance, the awareness of the cosmic forces that have shaped humankind. We cannot escape from the past, but neither can we avoid inventing the future. With our knowledge and a sense of responsibility for the welfare of humankind and the Earth, we can create new environments that are ecologically sound, aesthetically satisfying, economically rewarding, and favorable to the continued growth of civilization. But the wooing of the Earth will have a lastingly successful outcome only if we create conditions in which both humankind and the Earth retain the essence of their wildness. The symbiosis between these two different but complementary expressions of wildness will constantly engender unexpected values and new hopes, in an endless process of evolutionary creation.
