by Whit Gibbons

June 14, 2009

A query about what a virgin forest is made me wonder about people's knowledge of common environmental terms. To effectively discuss any subject, one needs a clear understanding of the terms and expressions that help define the topic. What follows is a short environmental lexicon of some terms I have been asked to define.

Virgin forest. Some of today's younger generation seem to be unclear on the meaning, possibly because we have so few virgin forests left. The original meaning is simple, from the word meaning "chaste," representing a forest that has never been timbered and in which the dominant, old-growth tree species have reached their maximum ages. By the beginning of this century, the United States had lost more than 99 percent of the virgin forests that had been on the continent at the time of European settlement.

Vast areas of longleaf or loblolly pine stands, cypress-gum swamps, redwood and Douglas fir or oak-hickory forests once covered the land. Only remnants remain of most. A forest once cut will not reach old-growth, virgin forest status during our lifetimes. However, some forests that were timbered almost a century or more ago, such as the Okefenokee Swamp, are beginning to be impressive again. Where they exist, these formerly sullied but now reborn forests deserve our appreciation. Let's not let them lose their reputations again.

Deforestation. An appropriate term to follow virgin forest, "deforestation" means to remove the trees (or forests). To many environmentalists, deforestation is equated with tree removal by logging companies. But deforestation can be a consequence of building highways, shopping malls, and apartment complexes or of converting land to agricultural use. In fact, these activities might be called "permanent deforestation." At least a forestry operation replants new trees to replace those it removes.

Greenhouse effect. A greenhouse operates on a simple principle: Light passes through a clear ceiling and the warmth created is trapped within, heating up the insides of the structure. Scientists concerned about global warming view earth as operating like a greenhouse. Some models predict that continual production of the high levels of CO2 resulting from an industrial world will create a blanket around the earth that allows light in but impedes heat from escaping to outer space. If global warming raises temperatures several degrees, some scientists predict that that changes in the earth's climates could have severe impacts on agriculture and on everyday living.

The dilemma about the greenhouse effect and global warming is that while an increase in CO2 has been detected, it has been difficult to demonstrate that it is linked to appreciable changes in atmospheric temperatures on a worldwide basis. Some scientists remain skeptical about whether the issue is one to worry about; others stake their reputations on their belief that it is a problem and that people are the cause.

Genetic engineering. Since the 1980s, studies in genetics have overwhelmed the field of biology. We know more than ever about chromosomes and the genes they carry, and we know about DNA and other materials inside genes. Geneticists are now able to substitute one gene for another in an organism, actually rebuilding the genetic structure that directs an organism's development, behavior, and physiology. Genetic engineering promises great advancements for controlling certain environmental processes.

In agriculture, enormous strides have been made toward producing pest-resistant crops, genetically modifying the pests themselves, or producing more effective predators on the pests. Will all be well in the field of crop production with genetic engineers at work? Could be, but we must proceed with caution, remembering that engineers handling other aspects of the environment have done much good but have also caused a few environmental train wrecks.

Environmentalism. Environmentalism is sometimes viewed as an emotional response that is based on insufficient scientific guidance. Yet people opposed to environmentalism can also respond emotionally, with equally insufficient levels of scientific knowledge. Effective environmental awareness is based on a foundation of findings by ecologists who, like other scientists, must be objective. Results of ecological studies can help scientists and laypeople make informed choices about our environment. Which brings us full circle, for to understand the findings, we have to understand the terms used to describe them.

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