Chapter 6 Summary

Download PDF PDF Page Citation Cite Share Link Share

Last Updated on May 5, 2015, by eNotes Editorial. Word Count: 848

Although humankind acknowledges dependence on plants for sustenance, we arbitrarily destroy plants that do not provide immediate benefits as food or decoration. Plants have intricate and often complex relationships with the earth, with other plants, and with animals—including humans. Therefore, destroying any plant can have long-term consequences for the earth, other plants, and animals including humans.

Still, the market for generic “weed killers” is an ever-expanding proposition. To illustrate the ill effects of eradicating particular plant species, consider the sage. This plant thrives in the west. However, humans have made a concerted effort to replace large areas of sagebrush with grasslands that can be used for grazing cattle. The unintended consequences are far-reaching. Because the climate in the natural habitat of the sage is unforgiving, few species of plants or animals could survive and thrive in this region. Furthermore, the plants and animals that have managed to populate the area often have significant and reciprocal relationships. For instance, the sage grouse depends on the sage for shelter and food, while the sage relies on the grouse to loosen the soil around its base and prevent invading grasses from taking root beneath its foliage. Other animals, such as the pronghorn antelope, mule deer, and sheep, use the leaves of the evergreen sage for food during winter months when deciduous plants shed their leaves and snow accumulations cover other plants. Still, the effort to eliminate sage continues.

The aims of this replacement program may not prove authentically beneficial even to the cattlemen and their herds. The plentiful and succulent grasses used to feed these herds cannot thrive during harsh winter months. Without sage and other hearty native plants, the herdsmen will face a considerable deficiency of food for their herds. Already, the governmental program of “sage eradication” has produced actual, observable, and far-reaching effects. She cites a devastating illustration from Chief Justice William O. Douglas, who recounts the unintended consequences yielded by a particular herbicidal spraying. In this instance, the sagebrush was “killed,” but so were groves of willows. Moose and beavers that fed on the willows were also affected. Without the willows for food, the beavers left the lake. Subsequent to the departure of the beavers, the lake—previously plentiful in trout—became a parched, empty space. The water, the trout, and the waterfowl disappeared because the beavers had used the willows to dam the lake. Therefore, the death of the willows and the consequent exodus of the beavers resulted in the disappearance of the lake. Only a trickle of water meandering through a small creek remained.

Increasingly, widespread spraying has been used to clear roadsides of plant growth in highway safety efforts. The author indicates that the scorched brown roadsides represent only the most obvious result of the spraying. She notes, for instance, that sixty-five “species of shrubs and vines that are typical roadside species in the eastern states alone” are food sources for wildlife. Moreover, these plants offer habitation to the insects that pollinate both wild and agricultural vegetation.

Selective spraying, in which humans target specific trees (the most likely obstructions to drivers along the highway) creates far less ecological havoc. Furthermore, selective spraying requires “no respraying for at least twenty years.” This preferable means of plant control reduces the risks of chemical contamination. Specifically, 2, 4-D and 2, 4, 5 -T, two of the most commonly applied herbicides, introduce undetermined levels of toxicity into the environment. Wild animals and livestock are drawn to the increased sugar content in vegetation that has been treated with these chemicals. In cruel irony, the very presence of attractive extra sugar in these treated...

(This entire section contains 848 words.)

See This Study Guide Now

Start your 48-hour free trial to unlock this study guide. You'll also get access to more than 30,000 additional guides and more than 350,000 Homework Help questions answered by our experts.

Get 48 Hours Free Access

plants indicates an increase in nitrates, which hold lethal implications for these ruminating animals. The rumen bacteria found in of the stomach chambers of the animals transform the nitrates into nitrite. The nitrite begins a chain reaction that ultimately prevents oxygen transference to lung tissue. Often, the animal dies within hours from oxygen deprivation.

Other herbicides, such as those used to eliminate crab grass from otherwise pristine lawns, may contain lethal chemicals such as “mercury, arsenic, and chlordane.” Instead of the prevalent, repeated use of chemical poisons, the author suggests the use of natural, harmless competition between lawn grass and crab grass. If the soil is properly prepared, she states, the lawn grass will thrive and the crab grass will be literally choked out of the lawn because it requires “open space in which it can start from year to year.”

The author offers two examples of effective plant control that left no detrimental or unwanted effects to the environment. In the first instance, a shipment of weed-eating beetles was imported to devastate a ruinous, two-million-acre “population” of Klamath weed. In roughly ten years, the beetles contained the crop with no ill effects to the local environment. To the contrary, other beneficial growths of plant life have returned to the area. Similarly, the eggs of an Argentine moth were deposited among a 60-million-acre of growth of prickly pear cacti in Australia. Within seven years, the cacti were eliminated and millions of acres of land became available for habitation and grazing.


Chapter 5 Summary


Chapter 7 Summary