Free Study Guide for Silent Spring by Rachel Carson - Book Summary

CHAPTER SUMMARIES - SILENT SPRING

CHAPTER 6 - Earth’s Green Mantle

Summary

Without plants, we would not be able to live. Yet people tend to treat plants recklessly. If a plant is beneficial, people grow it in excess and if it is harmful or even just in the way, people destroy it utterly. Plants are part of the intricate interconnections of the world, interconnections between plants and the earth, between plants and animals, and among plants themselves. If people have to disturb these relationships, they should do so carefully, recognizing that whatever is changed will have far-reaching consequences. The widespread use of weed killers do nothing of this sort.

One sad example of this trend is seen in the case of the sagebrush lands of the West. There has been a widespread campaign to destroy sagebrush altogether so that it can be replaced with grass alone and grazed by cattle. If the people initiating this campaign would consider the history of the land, they would not act so destructively. The sagebrush land is in the western United States at the uplift of the Rocky Mountain system. The land sees extremes of climate. As the landscape evolved, mainly only one plant survived the harsh climate. That is the sage. Along with the plants, there were two animals that evolved to fit the conditions of the sagebrush land. They are the antelope and the sage grouse.

The sage and the sage grouse operate together as mutually beneficial companions. The sage grouse uses the sage as nests, as roosts, and even as food. The sage grouse in turn helps the sagebrush. During their mating season, the grouse loosen the soil beneath and around the sage. This loosened soil is implanted with grass seeds. The antelope have also adjusted to the sage. The sage remains evergreen and so can be used as food by antelope in the winter and summer. Another beneficiary of the sagebrush is the mule deer, which feeds off the foliage.

Despite the intricate balance of life on the sage lands, cattle growers have determined to wipe it out in order to grow grass alone. They are pouring loads of chemical sprays on the land to kill the plants. People don’t yet know what will happen to the land, plants, and animals of the western sagebrush lands. However, they can be sure that grass grows better in this harsh climate when it’s protected by the moisture-retaining sage plants. The livestock might have green grass in the summers, but there won’t be any grass to eat in the winters.

The wider implications of this widespread use of chemical pesticides will be felt when other plants die, plants that were not intended to be killed. One of the U.S. Supreme Court justices wrote a book about the wholesale destruction of the landscape of his childhood home of Wyoming. The United States Forest Service sprayed 10,000 acres of sagelands in the Bridger National Forest. It killed the sagebrush and it also killed the willows that had followed along the meandering streams. Moose that lived in willow thickets were killed off, beaver that had made dams and thus produced a trout-rich lake were also killed off. The lake disappeared and with it the waterfowl disappeared.

Other kinds of land is also under attack. There is more than 50 million acres of land under the control of utility corporations. These corporations routinely treat roadsides and access roads with herbicides to kill brush. In the Southwest, 75 million acres of mesquite trees are treated with herbicides. Timber producing land is also treated with herbicides. Agricultural land is treated with herbicides. Herbicides are used liberally in private lawns, parks, and golf courses. People treat herbicides as if they were harmless to the environment. The use of herbicides is cheaper in the short term than mowing, but in the long run, it is phenomenally more expensive.

People should realize the effect this destruction of the roadsides of the U.S. will have on tourism. In the summer of 1960 a group of conservationists got together in Maine to discuss the destruction of the earth by the use of herbicides. Everyone noticed the destruction of the landscape along the roadsides by government officials engaged in brush control. The same is happening in Connecticut where people have noticed the loss of roadside plants like azaleas, mountain laurel, blueberries, huckleberries and other beautiful plants. The wildflowers have also been killed off.

The practice of spraying herbicides on the roadsides is notorious for its abuses. People who are hired to spray roadsides will spray more than they were contracted to spray,

they will dump excess chemicals on the roadsides after doing a job, and they will kill plants that were not considered a problem. The designation of a wide variety of plants as "weeds" is wrong. They have been named weeds largely by the chemical companies that want to convince people of their deleterious effects. The chemical companies tend to scoff at the conservationists’ attachment to flowers and plants, not taking into account the fact that people have as much right to enjoy the flowers and bushes of the roadsides as the lumber company has to claim a tree.

There is more than just the aesthetic argument for preserving the plants of the roadsides. The shrubs along roadsides provide homes and food for wildlife. This vegetation is also the home of bees. People don’t realize the importance of wild pollinators in growing food.

The use of herbicides on roadsides actually perpetuates the problem it is trying to solve. The use of herbicides has to be repeated year after year. There is a method of selective spraying that has been shown to work in the long term to control the growth of vegetation. The purpose of brush control is to get rid of plants that are so tall that they obstruct drivers’ vision or interfere with wires on rights of way. Most shrubs don’t present a problem for either of these needs. Selective spraying would get rid of trees that obstruct the view and interfere with wires while leaving the good growth of brush in place.

The most common forms of herbicides are 2,4D, 2,4,5-T and other compounds that are related to these two. These herbicides are considered safe, but they have been known to cause severe neuritis and even paralysis in people using them. They also have been shown to damage chromosomes. Some birds have been adversely affected.

There are indirect effects of the use of herbicides. It has long been recognized that just after plants have been sprayed, animals are strangely attracted to the plants. Often plants that are not eaten by livestock and wildlife in normal life are eaten voraciously just after they’ve been sprayed. The chemical changes the plant’s metabolism, making it produce more sugar. Another indirect effect is seen in the increase in nitrate content after a plant is treated. People have traced deaths in cattle to this indirect effect.

When people use weed killers, they usually don’t think about the soil. They need to remember that soil and living things are interdependent. The weed is taking something from the soil and it is contributing something to it. In one example, the people who ran some of the parks in Holland noticed a problem with the growth of roses. They discovered nematodes in the soil were infesting the soil. Instead of using a herbicide, they planted marigolds because this plant releases something from its roots that kill nematodes. The roses quickly improved.

Plants that are wiped out by herbicides might be performing a function we don’t yet know about. Weeds tend to indicate the condition of the soil. Learning about the indications of weeds would help people provide the proper treatment for their soil.

People who use herbicides need to realize the importance of preserving some natural plant communities. That way we can use these communities as a standard against which to test for changes in the environment wrought by human intervention.

There are warnings of gradual vegetation shifts that result from the use of herbicides. The chemical herbicide 2,4-D kills broad-leaved plants and allows grass to thrive in reduced competition. Now some of these grasses have gotten out of hand. Ragweed is one of the most bombarded of the weeds along roadsides. People don’t stop spraying it even when they realize that ragweed tends to grow back more after a herbicide attack. Since herbicides kill shrubs, they leave open space for ragweed to thrive and spread. Another common target is crabgrass. Yet it has long been known that crabgrass only thrives in poor soil. Improving the soil will get rid of the crabgrass.

Home gardeners have been taking the advice of nurserymen who are themselves led by chemical manufacturers of herbicides. They have no idea that many of the herbicides they use contain dangerous chemicals like mercury, arsenic, and chlordane. The recommended portions of mixture for treating a lawn or garden are often outrageously high.

There are alternatives to the widespread use of herbicides. Selective spraying, mentioned above, creates long term solutions. Biological control is another successful way to control vegetation. One example is the case of the Klamath weed in California. It was brought over from Europe, where it’s called St. John’s Wort, and when it hit California it spread unchecked because none of its natural enemies had been imported with it. In Europe the natural enemies of St. John’s Wort are two kinds of beetles. These beetles were imported to the United States and they succeeded in controlling the weed beyond what anyone had hoped for. Another example is set in Australia where one sea captain brought cactus over. It spread and, like St. John’s Wort, grew rampantly, making huge amounts of land useless. The Australian entomologists studied the insect enemies of the cactus in North and South America. They brought back the eggs of an Argentine moth. Seven years later, the cactus was gone. These solutions have been cheap and effective.

If only people would look to these examples, the problem of herbicides could be eradicated.

Notes

Chapter 6 continues the plan of the book to describe the total environment and what insecticides do to each of its components. Here, the author describes the plants of the earth. It is a chapter that describes a world much more familiar to most readers than the subjects of the previous chapters. Whereas most of us know little of microscopic organisms of the earth or the structure of chemicals in the world, most of us live our lives thinking of trees and shrubs as our familiars, the furniture of the world outside our homes. Because of their familiarity, Carson’s persuasive technique in this chapter is to appeal to our affection for the beauty of the plants and flowers of our world. She invokes a protective impulse in her readers when she describes the pretty plants and trees being destroyed with irrational and ineffective methods which not only destroy the landscape but also contaminate the world further.

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