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Ecology

Ecology

is a scientific discipline that focuses on the distribution and abundance of living organ­isms and how this distribution and abundance are affected by interactions between organisms and their environment. The term is derived from the Greek words oikos, meaning home, and logos, meaning study. Therefore, ecology might be described as the study of the home life of living organisms. The environment of an individual organism is composed of biotic factors, including other animals, plants, fungi, or microbes living in the same , and abiotic (physical and chem­ical) factors, for example, local climatic or hydro­logic conditions.

Ecology is commonly considered a branch of biology, but it might be better characterized as a multidisciplinary science. Because it also focuses on the interactions between organisms and their abiotic environment, many other scientific disci­plines that help to explore environmental relation­ships contribute to ecological knowledge, like anthropology, chemistry, climatology, geography, geology, and physics.

Regarding distribution and abundance of living organisms, ecology deals with three levels: the indi­vidual organism; the population, consisting of indi­viduals of the same species; and the , comprising all populations living in the same habi­tat. Additionally, ecologists study the pathways fol­lowed by energy and matter through the interacting biotic and abiotic components that compose the so-called ecosystem and the relationships across multiple ecosystems. According to these levels of examination, the subdisciplines of ecology are com­monly classified into autecology (also called species ecology), population ecology, synecology (also called community ecology), ecosystem ecology, and . Nevertheless, ecology can also be subdivided according to other categories. Different kinds of this scientific discipline can be defined, for example, by organism of interest (e.g., ), by habitat (e.g., urban ecology), or by application (e.g., conservation ecology).

Although ecology as a scientific discipline does not dictate what is right or wrong, the term eco­logical is also used as a synonym for environmen­tal concern; because of this, it has acquired a positive connotation regarding moral judgments about human action in the nonhuman natural world. This meaning, tending to mix up results of scientific research and ethical values, emerged with the transformation of the ecological movement in the 1960s. For an exact distinction between ecol­ogy as a pure scientific discipline and the ideas and goals of the political movement of nature preserva­tion, it is helpful to speak of ecology and environ­mentalism. Nevertheless, both try to see nature as a whole, and they continue to influence one another. Ecological knowledge provides a scientific basis for expressing and evaluating the aims of the environmental movement. Ecologists themselves also respond to the call of the environmental movement in directing much of their research to the environmental problems that have become increasingly pressing.

The concept of time is an increasingly important theme within the field of ecology, including both the science and the political movement. Both have their own history of development, which at some points are intertwined. Further, the history of ecol­ogy shows that for a long time, nature was thought of as being inherently balanced, wherefore it was largely ignored that history as one conception of time is applicable to the ecosphere. Such ideas were increasingly questioned after World War II, and nowadays it has become widely accepted that the natural world changes continually through time and that ecological and evolutionary pro­cesses affect each other. On this basis, the disci­pline of started to develop in the 1950s. But time does not only play a role in ecology in its historical sense: All organisms are embedded within the cyclical structure of the natu­ral world. Ignoring the timescales of natural cycli­cal processes, like the flux of energy and matter through ecosystems, is thought to be a causal factor in the present environmental crisis.

History of Ecology

Ecology is generally spoken of as a new scientific discipline that has gained in importance in the second half of the 20th century and the beginning of the 21st. Nevertheless, prehistoric cultures probably passed down forms of ecological knowl­edge from generation to generation as a way of increasing their chances for survival. Information about the interactions between organisms and their environment was probably gathered from everyday experiences and closely intertwined with religious beliefs and myths.

The birth of modern natural sciences took place during the period of Greek antiquity. Presocratic philosophers (c. 600 BCE) went beyond myths in their attempt to explain nature. By studying phe­nomena of nature, they searched for the natural laws behind them and developed the first scientific theories. Later, Aristotle (384-322 BCE) developed biology to an independent scientific theme. Though ecological aspects can be found in his writings and in the writings of other philosophers and scientists of the ancient (e.g., Theophrastus, 371-287 BCE), medieval (e.g., Albertus Magnus, c. 1200-1280) and early modern (Carolus Linnaeus, 1707-1778) periods, the birth of ecology is generally dated to the year 1866. In this year, the German zoologist Ernst Haeckel (1834-1919) published his book General Morphology and with this the first defini­tion of the term ecology: “By ecology we mean the body of knowledge concerning the total relations of the organism to its environment, to that we may reckon all conditions of existence. These are of both, organic and inorganic nature” Basically, the same definition is used today. Haeckel’s definition was strongly influenced by the proto-ecological view the great naturalist Charles Darwin (1809­1882) provides in his 1859 book On the Origin of Species (1859). The theory unfolded here replaced the conception of the natural world as an enduring system with a conception of it as an open-ended historical process. Without using the word ecol­ogy, Darwin shows the ecological orientation of his thinking insofar as he refers to the impact of the inorganic and organic conditions of life on natural selection and therefore on the development of new species. The very fact that Haeckel’s defini­tion of ecology refers specifically to Darwin’s the­ory of evolution indicates that time is an important factor in the study of ecology.

Haeckel did not elaborate the concept, and therefore the term ecology became an independent and established scientific discipline only after the publication of Plantesamfund in 1895 by the Danish botanist Eugen Warming (1841-1924). It is no surprise that this first significant textbook on the subject focuses exclusively the ecology of plants, because a second important strand in the development of ecology has been plant geography. Here ecological thinking can be recognized at least since Carolus Linnaeus published his writings, but the most important name in this context is Alexander von Humboldt (1769-1859), who explained the geographic distribution of plants with respect to geological data and went into the question of plant communities. For this reason, like Haeckel, he is called the father of ecology.

In the light of Darwin’s theory of evolution and of plant geography, ecology developed into an independent scientific discipline in the second half of the 19th century. Around 1900, the first books were published under the headline ecology. Still, animal and plant ecology were explored separately in independent disciplines of zoology and botany, hindering a more synthetic understanding of their interdependence.

The first comprehensive works of ecology evolved within the field of hydrobiology—probably because a freshwater lake, for example, can easily be seen as a system. Therefore it is no surprise that the term biocoenosis (all interacting organisms liv­ing together in a specific habitat) was coined in 1887 by the German biologist Karl August Möbius (1825-1908). He was the first to describe in detail the interactions between the different organisms in the ecosystem of the oyster bank. In the same year, Stephen A. Forbes (1844-1930) published his paper “The Lake as a Microcosm.” Two important ecological terms developed in response to Möbius. First, in 1908 the German zoologist Friedrich Dahl (1856-1929) introduced the term biotope, which means an area of uniform environmental condi­tions. Then, in 1935 the British botanist Arthur G. Transley (1871-1955) introduced the term ecosys­tem, which comprises “not only the organism­complex, but also the whole complex of physical factors forming what we call environment.” Another important term not only in ecology but later on also within the theory of evolution, the ecological niche, was coined by the English animal ecologist Charles Elton (1900-1991) in 1927: “the ‘niche’ of an animal means its place in the biotic environ­ment, its relations to food and enemies.” The most important contribution to the development of a comprehensive ecology was made by the German biologist August Thienemann (1882-1960), who argued that autecology and synecology are just dif­ferent steps of the ladder to ecological knowledge. Nevertheless, throughout the 1940s, 1950s, and 1960s, the debate continued regarding whether ecology is not more than autecology, or alterna­tively is not more than synecology. Intensive research under the title “ecosystem” began only in 1960, with the synthetic understanding of animal and plant ecology. It incorporated the advances from many scientific disciplines, such as pedology and climatology, but also statistics and informatics, expanding the options for ecological research by computer-aided modeling.

Already in the 1920s, some ecologists were aware of the fact that humans are a major ecologi­cal factor and advanced the view that ecology could help to solve environmental problems in the future. A conservationist movement also developed in the 20th century, parallel to ecology as a scien­tific discipline, inspired by such figures such as the American author and philosopher Henry David Thoreau (1817-1862). Thoreau argues in his 1854 book Walden; or, Life in the Woods that people should become intimately close with nature. Another American, the ecologist Aldo Leopold (1887-1948), claims in his famous and influential book A Sand County Almanac (1949) that humans should morally respect their natural environment. Nevertheless, environmental ideas reached public consciousness only after the 1960s, when the changes in the natural environment due to human influence began to be understood as the environ­mental crisis. At this time, the environmental movement was transformed, especially after the publication of Rachel Carson’s (1907-1964) book Silent Spring in 1962. It emboldened a new genera­tion of thinkers searching for an ethical basis for preserving the environment. This question has remained an issue within the philosophical subject of environmental ethics. The public desire for a bet­ter environment led to increasing financial support for ecological research, and the 1960s and 1970s were a period of rapid growth in both fundamental and applied ecology. Other indications of the developing public interest in ecology and environ­mentalism are, for example, the publication “Limits to Growth” (1972), commissioned by the Club of Rome; the research program “Man and Biosphere,” which was launched by UNESCO in 1972; and the first international conference on the human envi­ronment, which was held by the United Nations in Stockholm in 1972. At the same time, in some countries political groups that are self-identified as ecological parties and environmental organiza­tions, such as Greenpeace, were founded. The highly visible public support for the environmental movement declined during the 1980s, but recently it has been renewed by the concern over the effects of global warming. The increasing dangers of the greenhouse effect were recognized internationally at a conference in Kyoto in 1997.

In response to the interests of the environmen­tal movement, the application of ecological thought to societal problems is one important direction in ecology today. This goes beyond the scope of ecol­ogy as a scientific discipline, but understanding human social behavior plays a role in some eco­logical research programs. To distinguish ecology as a pure scientific discipline from all other sci­ences that help to explore human environmental relationships, the term environmental studies is proposed. Nevertheless, the attention to scientific rigor is still an important direction in current ecol­ogy, in addition to a continued interest in inter­preting ecological phenomena in terms of evolution.

Evolutionary Ecology

“Nothing in Biology Makes Sense Except in the Light of Evolution,” the title of a 1973 essay by Theodosius G. Dobzhansky (1900-1975), applies to all disciplines of biology and therefore also to the study of ecology. However, whereas ecology is the field concerned with interactions between living organisms and their abiotic and biotic envi­ronments, evolutionary biology deals with the question of how populations change through time, split, and go extinct. So, how are ecology and evolution linked? Ecological and evolution­ary processes affect each other. Interactions between organisms and their environment drive the evolution of populations by the pressure of natural selection, and this again leads to changes of the interactions and of the environmental pro­cesses themselves. Therefore, evolutionary and ecological biologists have a lot to say to each other, and the field where they meet is called evo­lutionary ecology.

Evolution, and therefore change though time, is one theme that tends to unite the different subdis­ciplines of ecology. Nevertheless, the use of the concept of evolution is not of equal intensity. Whereas it is strongly integrated into autecology, population ecology, and synecology, in ecosystem and landscape ecology the concept of evolution is a peripheral theme.

Balance of Nature, or Change Through Time?

The conception of ecological balance long pre­cedes the development of ecology as a science. The ancient Greeks had ascribed balance to the natural world, whereas stability was thought rarely true for human societies. In most cases, this idea has its basis in the belief that this ordering is the work of a divine agency, but in some cases, the condition of equilibrium is described as an internal feature of nature itself. In Western cul­tures during the Middle Ages, the belief in divine order strengthened the belief in natural order and became a background assumption. Later, expressed in the metaphor of the great “chain of being,” 17th-century rationalists continued to hold to the notion of a well-balanced nature but believed that laws accessible to human reason, and not a divine power, governed nature. Carolus Linnaeus assumed that harmonious relations between spe­cies according to the divine plan create order and stability; this he called the economy of nature. His hypothesis was later adopted by modern ecolo­gists, who usually discuss the issue of balance of nature—using the term ecological equilibrium—in connection with segments of the natural world identified as communities or ecosystems. These terms indicate the existence of a certain structure ensuring order and stability. This seems surprising in light of Darwin’s revolutionary theory of natu­ral selection, which shows how the hereditary characteristics of a population change over time due to their differential reproduction arising out of their struggle for life. Though the emergence of a historical view on nature challenged the tradi­tional belief of a divinely created world, even Darwin went along with Linnaeus’s assumptions and considered equilibrium in nature. He wrote in Origin of Species, “Battle within battle must be continually recurring with varying success; and yet in the long-run the forces are so nicely bal­anced, that the face of the nature remains uniform for long periods of time, though assuredly the merest trifle would often give the victory to one organic being over another” The Scottish moral philosopher and pioneering political economist Adam Smith (1723-1790) contributed the idea that competition can lead to equilibrium in a com­munity. From this point of view, Darwin’s theory serves to explain the balance of nature and leaves intact the confidence that even in the evolution of life, order would prevail at last, and out of the tangled history of competitive struggle would come progress, harmony, and stability. The knowledge about periods of rapid changes within the course of evolution did not disturb the belief in the overall stability of the system, given that these are externally caused. Additionally, evolu­tionary change was sufficiently drawn out to leave the relatively stable world of ordinary experience intact.

In the 19th century, plant biologists began to focus on the roles of change and history of plant communities on smaller timescales. In 1899 the American botanist and ecological pioneer Henry Chandler Cowles (1869-1939) published a descrip­tion of the patterns of vegetation change on sand dunes surrounding Lake Michigan. In his book Vegetation of Sand Dunes of Lake Michigan, he formalized the idea of dynamic vegetation succes­sion. Nevertheless, his ideas did not lead to the notion that community change is an unceasing process. Influenced by Cowles’s work and his own observations of prairie ecosystems, Frederic E. Clements (1874-1945) developed a comprehen­sive theory describing the mechanisms and pat­terns of successive change. This theory of succession, which was widely accepted by ecologists until the 1960s, hypothesizes an orderly sequence of changes in plant communities. One central assertion was that regardless of the types or varieties of distur­bances that initiate successive change, succession inevitably leads to a single stable climax commu­nity whose composition is determined by the char­acteristics of the region’s climate and has the potential to remain essentially unchanged forever. Though this theory postulates that plant commu­nities change through time, it tends to support the conception of nature as balanced, because the changing occurs according to ascertainable laws and results in a steady state. Furthermore, it indi­cates that chance historical accidents and past disturbances in a community are erased by succes­sion, whereas the composition of later successive ecosystems contains little or no information about their past history.

After the brothers Howard Odum (1924-2002) and Eugene Odum (1913-2002) developed and formalized the ecosystem theory in the 1950s, nature was conceived as an interlocking series of self-regulating and self-organizing hierarchically ordered ecosystems at various stages of develop­ment. Mature ecosystems—characterized by greater stability, increased diversity, and minimal loss of minerals and nutrition—were distinguished from immature ecosystems. Howard Odum even assumed a strategy of development in all ecosystems that is directed toward a world of mutualism and coop­eration among organisms living in the same habi­tat. This goal, which is characterized by a no-growth economy, he called “homeostasis.” His idea reap­pears in John Lovelock’s (b. 1919) Gaia hypothesis, which proposes that biotic and abiotic parts of the earth form a complex interacting self-regulating system. This system can be viewed as a single organism promoting life, which Lovelock named after the Greek goddess of Earth.

Though reporters and even scientists persist in using words like ecosystem, ecological equilib­rium, balance, and fragility, and many nonscien­tists still believe in the balance of nature, after World War II ecological thinking started to shift away from assumptions of order and stability. Until then, the few ecologists who were aware of the possibility of nonequilibria were ignored, but in the past several decades, a revolution has occurred in the worldview of ecologists. Soon after Clements published his influential works on plant succession, a few scientists challenged his theory of a stable climax. One of them was the American ecologist Henry A. Gleason (1882-1975), who worked largely within the theoretical structure of Clements’s ideas, before he began to doubt his organic theory of the climax community. Gleason rejected the existence of balance, equilibrium, or steady state in nature and offered, as an alterna­tive, “The Individualistic Concept of the Plant Association” (1926). In this article, Gleason argued that every plant association is nothing but a tem­porary gathering of strangers, a clustering of spe­cies unrelated to one another, and he advanced the view that we live in a world of constant change over time. Clements never responded in print to Gleason’s objections and they were largely ignored elsewhere, but gradually some ecologists came to realize that the available data were not sufficient to support Clements’s major assumptions. Research by a number of ecologists, for example, the American scientist Robert H. Whittaker (1920-1980) in 1953, supported Gleason’s thoughts. In the 1950s, palynologists showed that the vegetation of North America has been in continual flux for at least the past 40,000 years, and the first serious contributions to the discipline that is now called evolutionary ecology were published. Increasing evidence suggests that succession may be governed more by external than by internal factors and that past events influence the properties of current eco­systems. Now it is generally recognized that natu­ral disturbances are a normal part of most landscapes and that the evolution of a population or a species is not the necessary product of any natural laws but rather the outcome of a concate­nation of chance events. In 1973 William Drury (1921-1992) and Ian Nisbet challenged not only Clement’s but also Odum’s theory seriously and rejected completely the assumption that there is a progressive development in nature and that organic nature tends toward order. Many ecologists will now admit that even the ecosystem concept is only a human construct. None of them ever succeeded in isolating one in nature. It is suggested that nature should be seen as a landscape of patches, a patchwork quilt of living things, changing continu­ally through time and space, responding to an unceasing barrage of disturbances.

Scientists after World War II have been finding that contingency plays nearly as big a role in natu­ral history as it does in human history, and instead of seeing a world in balance, most scientists nowa­days see a world of flux and uncertainty and regard disturbances as the rule rather than the exception. This raises some questions: Why do the new ecological models seem more plausible to the scientific community than the former equilib­rium models? And why do ecologists like Clements and Odum tend to dismiss disturbances as threats to the order of nature? Understanding these ques­tions requires an understanding of how scientific concepts are culturally determined. One reason for the paradigmatic shift—besides empirical data that cast a scientific description of the natural order into doubt—could be the rapid political and cul­tural changes since World War II. Uncertainty today may seem more plausible than harmony. In addition, among ecologists, Social Darwinists are back on the scene generating new directions for ecology. For them a nature characterized by indi­vidualistic associations, unceasing disturbances, and permanent changes may be more ideologically satisfying. A third reason for post-Odum ecology could be the attempt of many ecologists to disas­sociate themselves from the environmental move­ment and some branches of environmental ethics, whose supporters still cling to the notion of natu­ral balance as a last bastion of certainty, as a major argument for nature conservation, and as one last source of metaphysical absolutes.

The truth probably lies somewhere in between. Nature works in more than two modes, balanced and unbalanced, and some ecological systems per­sist in spite of centuries of disturbances—eluding ecologists’ models and understanding. One impor­tant insight of modern ecology is that landscape patches have different levels of resilience to distur­bances. Resilience relying on ecological relation­ships does not mean the absence of change, for it is defined as the ability to undergo change and then return to a similar but not exact configura­tion. If ecological relations are broken beyond a certain threshold by a major disturbance, the sys­tem may lose resiliency and form a new commu­nity. Finally, it has to be stressed that scientific attempts to answer whether nature is balanced or dynamic depend on the selected perspective and the scale of an analysis.

Temporalities of Nature and Culture

The passage of time is a basic experience of human existence; as such, it has been of concern to those interested in religion, philosophy, and science. As discussed previously, however, temporal aspects of the natural world had long been ignored while the focus of attention was on the role of time in human societies. Within the 20th century, the idea that his­tory is not only a feature of human societies but also of the natural world became widely accepted.

Biological processes of change fundamentally entail cyclicalities, such as metabolic cycles, meta­morphic processes, and life cycles. They range from the very fast to the very slow. Empirical studies of chronobiologists demonstrate the cyclical behavior of all living organisms, from single cells to mam­mals, including humans, and with this the impor­tance of this temporal patterning of life. The varied cycles of the body’s physiological activities, such as respiration, digestion, or activity-rest cycles, are orchestrated into a coherent whole and function as biological clocks. However, as Barbara Adam (b. 1945) declared in 1990, this “body symphony” of internal time programs is not played in isolation. It is—because of evolution according to the direc­tion of the pressure of natural selection—embedded in the cycles of its environment. It exists as a kalei­doscope of different but connected timescales, con­stituted by the movement of the earth and its moon in relation to the sun. Therefore, it is the cyclical structure of the physical world that constitutes the cycles of organisms, populations, and ecological relationships. It appears, for example, in the form of circadian, lunar, or seasonal cycles.

The cyclical structure of nature seems to support the notion of an ahistorical natural world, but— contrary to the rhythm of a metronomic beat— cyclical does not mean invariant repetition. Rather it is in the very nature of those cyclical processes to differ in their recurrence. Something similar returns, instead of something identical, based on context­dependent adaptations. It is suggested that this openness of natural cyclic processes to variant repetition allows the evolution of the ecosphere. According to Barbara Adam, precisely these cycles of change, whereby past, present, and future can be experienced by humans, constitute time.

As with all organisms, human life is also ordered and regulated by internal biological clocks and external natural cycles. However, since the inven­tion of mechanical clocks and notably since the use of electricity for industrial applications, social time has become more and more disconnected from the ecological choreography of planet Earth. This cul­tural decoupling from the cycles of nature in con­temporary industrial societies, according to the time-is-money-principle based in the speeding up of social life and economic processes, is supposed to be associated with the current environmental crisis. Nowadays human action is structured not by the cycles of nature but by the context­independent and invariant metronomic beat. The 24-hour schedule of the machine dominates not only the temporal patterns of industrial work but also agricultural food production. One striking example is the acceleration of evolutionary pro­cesses by means of genetic engineering of plants.

Facilitated by the exploitation of nonrenewable resources such as fossil fuels, the speedup of produc­tion and consumption does not only affect human health but also has potent ecological implications, for it results in an increase of energy use and mate­rial flows. The industrial way of life and its approaches to time stand in conflict with the cycles of the natural environment, because renewable resources are used at rates incompatible with the rates of regeneration. One example is the degrada­tion of soils, caused by erosion, salting, compaction, pollution, acidification, and sealing. Because soil takes thousands of years to develop, the recent human action on soils—literally the basement of life on Earth—converts this renewable resource to a nonrenewable one.

Additionally, the vast production of often toxic chemicals results in environmental pollution when those substances introduced into nature cannot be readily decomposed. The process of global warming is an example currently being debated. This process, also called the greenhouse effect, is thought to be the outcome of an increased concentration of carbon dioxide in the atmosphere, based on combustion of fossil fuels associated with accelerated industrial activity and other human activities, like tropical deforestation. Nitrous oxide is another gas that absorbs infrared radiation and, therefore, also con­tributes to global warming as human activity increases its concentration in the atmosphere. To date, humans have roughly doubled the input rate of fixed nitrogen into the ecosphere by combusting fossil fuels, plant­ing nitrogen-fixing crops, clearing land, draining wetlands, and producing fertilizers. This not only has severe implications for the atmosphere. Nitric oxide is a principal cause of acid rain, which results in declines in soil fertility and acidification of freshwa­ter lakes and streams. Nitrogen washed into aquatic systems has caused blooms of toxic algae and die­offs of fish associated with eutrophication.

These few examples indicate how economical timescales endanger ecological timescales. There are further consequences for ecological relationships. If the environment changes slowly enough, popula­tions can ride with the tide of change by, for example, adapting via evolution or by migration. However, if the anthropogenic environmental changes exceed the maximal speed of adaptation, severe disturbances will follow. Ecological relations may be broken to the point that resilience of systems is lost and adaptation of the ecological processes to the new situation is no longer possible. Therefore, fast changes may destroy communities in a flash. This already takes place, as we have observed in the mass extinctions of species.

The environmental movement reacts to this accel­eration of social life with its claim to conserve imperiled species and places. But this goal of conser- vation—though comprehensible given the fast anthro­pogenic changes of the natural world—may ignore the dynamic structure of nature as well as the indus­trial way of life. Environmental changes are the norm and occur across all timescales. Even natural cata­strophic changes, such as triggered by volcanic erup­tions or asteroid strikes, are able to destroy human resiliency. Nevertheless, the anthropogenic distur­bances seem to be of a new quality and quantity. This raises an important question: What rate, quantity, and quality of change can be accepted? This is not an ecological but rather an ethical question.

To systematically recognize and establish the relevance of the temporal dimension of cultural time for the so-called ecological crisis, the Time Ecology Project was initiated 1991 at the Protestant Academy of Tutzing in Germany. One member, Barbara Adam, is the author of numer­ous publications on cultural and natural time and the founding editor of the journal Time and Society. In her monographs on time, she charts the importance of recognizing the multiple time frameworks of nature for our daily lives. The field of time ecology focuses on the mutual impli­cations of time and ecology as one step toward ameliorative action with respect to environmental matters. In search of a time politics that shifts concern from the pursuit of total time control to the appreciation of the cyclical structure of nature, proponents of time ecology search for approaches to time that are sensitive to the tem­poralities of the environment. Human interven­tion into a natural system should allow a development of this system in its own timescale. Therefore, it calls for a balanced relationship between human technological interventions and environmental processes; it seeks a balance between the human timescale of consumption and resource depletion on the one hand and the environment’s capacity for regeneration and reproduction on the other. This shift in human attitude toward nature, associated with aware­ness of the ecological significance of time, is a step toward achieving sustainable development, minimizing environmental degradation, and halt­ing or reversing the process of exhausting natural capital faster than it can be replenished.

The Concept of Time in the Field of Ecology

In summary, the history of ecology as a scientific discipline shows that from its beginning, the con­cept of time played a central role. Early ecological thinking was especially influenced, for example, by Darwin’s theory of evolution and his protoeco- logical view. Nevertheless, for a long time most scientists ignored that history as one conception of time is not only applicable to human societies, but also to the ecosphere. They clung to the notion that nature is inherently balanced. It was thought that ecological communities have the potential to remain essentially unchanged forever and that serious changes occur only because of external disturbances. Even then, if climatic conditions persisted, a succession would lead inevitably to the former climax community. In this way, chance accidents of historical events were thought to be erased. Such ideas were increasingly questioned after World War II. Within the scientific commu­nity more recently, it has become widely accepted that the natural world changes continually through time and that evolutionary and ecological pro­cesses affect each other. On this basis, the disci­pline of evolutionary ecology developed.

Time plays a role in ecology in more than a historical sense as well. The evolution of the eco­sphere is influenced by the cyclical structure of the natural world. Time-consuming cyclical processes, like the flux of energy and matter through ecosys­tems, exist as different but connected timescales. All organisms, including humans, are embedded within these cycles. Nevertheless, after the Industrial Revolution an increasing decoupling of social time from the cycles of the natural world can be observed. Ignoring the ecological times­cales in favor of economic timescales is thought to be one important reason for the environmental crisis. The claim of the environmental movement to conserve imperiled species and places is a reac­tion to the fast anthropogenic changes of the eco­sphere. Nevertheless, environmental changes are the norm and occur across all timescales. The extent of acceptable anthropogenic changes is an increasingly pressing question—not only for ecological scientists but also for environmental ethicists.

Sabine Odparlik

See also Charles Darwin, ; Erosion; Organic Evolution; Global Warming; Ernst Haeckel

Further Readings

Adam, B. (1998). Timescapes of modernity: The environment and invisible hazards. London: Routledge.

Begon, M., Townsend, C. R., & Harper, J. L. (2006). Ecology: From individuals to ecosystems (4th ed.). Oxford, UK: Blackwell.

Dodson, S. I., Allen, F. H., Carpenter, S. R., Elliot, K., Ives, A. R., Jeanne, R. L., et al. (Eds.). (1999). Readings in ecology. Oxford, UK: Oxford University Press.

Hugget, R. J. (1997). Environmental change: The evolving ecosphere. London: Routledge.

Mayhew, P. (2006). Discovering evolutionary ecology: Bringing together ecology and evolution. Oxford, UK: Oxford University Press.

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