Balance of Nature

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Balance of nature

The ideal of a balance of nature is based on a view of the natural world that is largely an artifact created by the temporal, spatial, and cultural filters through which humans respond to the natural world. For a variety of reasons we have interpreted the natural course of events in the world around us to maintain equilibrium, and seek to return it to equilibrium when disturbed.

There are three components to nature's balance: ecological, evolutionary, and population. In an ecological sense, communities were thought to proceed through successional stages to a steady state climax. When disturbed, the community would return to that climax state. Stability was an endpoint, and once reached the community became a partly closed homeostatic system. In an evolutionary sense, the current compliment of species is interpreted as the ultimate product of evolution , rather than a temporary expression of a continually changing global taxa. In the population sense, concepts like carrying capacity and the constant interplay between environmental resistance and biotic potential is interpreted as creating a balance of numbers in a population, and between the population and its environment . Three ideas are fundamental to the above; that nature undisturbed is constant, when disturbed nature returns to the constant condition, and constancy in nature is the desired endpoint.

This interpretation of nature may be so strongly filtered by our cultural interpretation and idealization of balance, that we tend to produce conclusions not in keeping with our observations of nature. Assumptions of human centrality may be sufficiently strong to bend the usually clear lens supplied by science in this case. Although the theme of balance in nature has been formally criticized in ecology for over 65 years (since Frederick Clements and Henry Gleason focused the argument in the 1920s) the core of the science did not change until about 25 years ago. Since that time, a dynamic approach that pays no special attention to equilibrium processes has taken center stage in ecological theorizing.

The primary alternatives are part of the group of ideas termed intermediate disturbance hypotheses. These ideas offer a different view of how communities assemble, suggesting that disturbance is more frequent and/or more influential than performing a routine return to an equilibrium state. Furthermore, disturbance and non-equilibrium situations are responsible for the most diverse communities, tropical rain forests and coral reefs, through the reduction in competition caused by disturbance factors.

Few theorists, however, suggest that non-equilibrium settings are the single most powerful explanation, or are mutually exclusive with communities that do have an equilibrium. There are situations that seem to seek equilibrium, and smaller subsystems that appear virtually closed. In local situations, certain levels of resources and disturbance may create long term stability and niche differentiation or other mechanisms may be the principal cause of a species diverse situation.

Although theorists have been working to verify, revise, and examine new developments in ecology, very little attention has been given to alternative, more complex theoretical interpretations of nature, in terms of time, space, and dynamism in resource and environmental management. The implications of accepting a non-equilibrium orientation for environmental management are significant. Most of the underpinnings of resource management include steady state carrying capacity, succession , predator-prey balance, and community equilibrium as foundations.

There are three major implications of the shift from equilibrium to non-equilibrium approaches to the environment. First, until a more realistic theory is used, the rate of resource extraction from nature will be subject to considerably higher uncertainty than we currently suspect. Since we expect communities to seek equilibrium, we believe we can predict populations and species numbers to a greater degree than may be warranted. Second, we perceive that areas of high biodiversity are due to long and short term stability, when in fact the forces may be just the opposite. Therefore, management that attempts to maintain stability is the reverse of what is actually needed. Third, the kinds of disturbance we create in these diverse communities (deforestation , introduction of non-native species, or oil pollution ) may not mimic anything natural and a species may have little defense against them. A characteristic of communities with high species diversity is small population size, thus human disturbance may cause exceptionally high rates of extinction . A central facet of the burgeoning practice of ecological restoration should be an ability to accurately mimic disturbance regimes.

Balance in nature has a strong appeal to our sensibilities and has anchored natural resource management practices. Now practice stands well behind theoretical developments and increased integration of more modern ecological science is required to avoid costly resource management mistakes.

[Dave Duffus ]

RESOURCES

BOOKS

Botkin, D. E. Discordant Harmonies: A New Ecology for the Twenty First Century. New York: Oxford University Press, 1990.

Ehrenfeld, D. The Arrogance of Humanism. New York: Oxford University Press, 1981.

Pickett, S. T. A., V. T. Parker and P. L. Fiedler. "The New Paradigm in Ecology: Implications for Conservation Biology Above the Species Level." In Conservation Biology, edited by P. L. Fiedler and S. K. Jain. New York: Chapman and Hall, 1992.