from The New Book of Knowledge®
Conservation is the sustainable use of natural resources. "Sustainable use" means managing and using a resource carefully so that it may last for future generations.
Natural resources fall into two broad categories. Renewable resources are those that can be replaced by natural processes at rates similar to the rates at which they are used. Nonrenewable resources are those that have limited supplies and are used faster than they can be replaced. Water is a renewable resource because rain replenishes local supplies. Petroleum is a nonrenewable resource because it takes millions of years for dead plants and animals to be converted into fossil fuels.
We all rely on natural resources for food, water, housing, clothing, recreation, and energy. The wise use of natural resources is an increasingly important issue because the human population continues to grow. Since 1960, the Earth's population has increased from 3 billion to 6 billion people. It may increase to over 9 billion people by 2050. Each of these people will need natural resources to live. The conservation of natural resources depends not only on how many people live on Earth, but also on how wisely they use those resources.
The goal of the conservation of renewable resources is to maintain the ecological processes that provide them. Ecological processes are those things that make the natural world run. An example is the water cycle, in which water evaporates from the Earth's surface and then falls back to Earth as rain or snow. The goal of the conservation of nonrenewable resources is to use them sparingly so that their supplies last as long as possible.
Every living thing needs water to survive. However, humans are using an ever-increasing share of the Earth's water. Between 1900 and 1995, the amount of water used by people increased six-fold worldwide. Most of this increase went to irrigation for farming, which accounts for 70 percent of water use.
Another threat to water supplies is pollution. Sources of pollution include runoff from fertilizers, contamination with heavy metals from mining, acidification from airborne pollutants (in the form of acid rain), and the accumulation of pesticides.
Watersheds (areas where rain enters the ground and replenishes groundwater supplies) are threatened. Problems include deforestation (the process of clearing forests for timber and agricultural land), dams, and urban sprawl.
Conservation of water can take many forms. Hydrologists suggest that better management could dramatically decrease consumption of water. For example, 75 percent of irrigation water evaporates before it reaches its crop. This loss could be lowered with drip irrigation, which applies water directly to plant roots. In addition to better management, the sources of water must be protected by limiting pollution and preserving watersheds.
Soil and Agricultural Lands
Almost all land plants rely on soil as an anchor, a supply of nutrients, and a source of water. Topsoil is the fertile uppermost layer of soil on which most plants depend. It can be lost quickly through erosion and is extremely slow to form again. Some estimates suggest that it may take as many as 100 years of careful management to create 1 inch (2.5 centimeters) of topsoil. Erosion occurs when vegetation is cleared from a site.
Globally, 5 billion acres (2 billion hectares) of soil have been degraded by human activities. These include agriculture, grazing of livestock, and deforestation. Soil conservation focuses on better management practices in agriculture and forestry. Strip cropping, contour tilling, and no-till farming limit erosion from agricultural fields. Selective harvesting of forests allows some trees to remain when a forest is harvested, which decreases erosion. Finally, maintaining buffer zones of vegetation along streams will trap soil that washes from agricultural fields and recently harvested forests.
Forests are a source of many products, including lumber, wood pulp, fuel, and food. They provide habitat for wildlife and places for recreation. Forests also remove carbon dioxide from the air and generate oxygen through the process of photosynthesis. The major threat to forests is deforestation. In addition to limiting deforestation, conservationists wish to maintain the health of remaining forests. They monitor and manage a forest's genetic diversity, age profile, structural diversity, and stress levels caused by pollutants such as acid rain.
The conservation of forests includes better management techniques. The U.S. Forest Service, which is in charge of the federally owned forests in the United States, has recently adopted a plan of ecosystem management. It has the goal of maintaining natural habitats while still harvesting trees.
Biodiversity refers to the variety of life at all levels of organization, including genes, species, and ecosystems. The simplest, and most used, method for measuring biodiversity is counting the number of species in a specific area.
Biodiversity is a natural resource because it is used and valued in many ways. For example, biodiversity has economic value when a new drug to combat breast cancer is found in a tree from the Pacific Northwest. It is valued when people enjoy feeding and watching birds. And it is valued for simply existing. All the threats to other renewable natural resources (soil, water, and forests) threaten biological diversity because the other resources make up the habitats where organisms live.
The major threat to biodiversity is the extinction of species. Extinction means that individuals of a species no longer exist. Extinction is a natural process. Most species that have ever existed are now extinct. Prior to 1870, approximately one species of plant or animal became extinct each year. Now humans are causing thousands of species to become extinct each year. This extinction crisis is the result of habitat destruction, introduction of exotic species, overharvesting, and overhunting.
The most straightforward means of conserving biodiversity is to maintain the habitats in which plants and animals live by using resources in a sustainable manner. Additionally, substantial areas of all habitat types should be set aside as functioning ecosystems in parks and preserves that are protected from human disturbance.
In the case of endangered species, wildlife managers may need to take specific action to ensure that the species does not become extinct. For example, land managers in Michigan periodically burn forests to create habitat for the endangered Kirtland's warbler. This bird nests only in recently burned jack-pine forest. If the endangered species have no remaining natural habitat, botanists and wildlife biologists may keep the species alive in botanical gardens and zoos. But this is only a temporary solution until suitable habitat in the wild can be restored.
Fossil fuels are the organic remains of plants that lived in the Carboniferous era about 300 million years ago. They include coal, oil, and natural gas. They provide most of the power used by humans for heating, transportation, and manufacturing. Additionally, they are the source of plastics. Fossil fuels are useful sources of energy because they are easy to transport. However, because they are in limited supply, scientists are developing sustainable replacements.
Minerals present similar problems in conservation. For example, ores of metals such as iron and aluminum have limited supplies. Their conservation focuses on reducing their use, reusing them when possible, and recycling them if needed.
History of the Conservation Movement
Prior to 1850, humans had a fairly small effect on the environment. Because of our low global population size and limited technology, human actions caused only local environmental problems. The Industrial Revolution altered this with improvements in food production, water supplies, and medicine. These advances allowed the human population to grow extremely rapidly. It also led to new technologies, which had farther-reaching effects. By the end of the 1800's, many people realized that human activities were hurting the environment.
The first organized efforts toward conservation in the United States began in the 1890's. In California, John Muir became a prominent supporter of the preservation of natural areas. He helped establish Yosemite National Park and the Sierra Club, which is still active in efforts to preserve wilderness. In Massachusetts, a group of women established the Massachusetts Audubon Society to protest the use of bird feathers, wings, and even whole birds as decorations on women's hats. The group was quickly joined by groups in other states and eventually led to the creation of the National Audubon Society. In Washington, D.C., Gifford Pinchot became chief of what is now the U.S. Forest Service. In this position he developed a national conservation strategy. It involved managed use of the nation's forests. In 1903, U.S. president Theodore Roosevelt established the first national wildlife refuge.
The next burst of growth in the conservation movement occurred in the 1930's. The combination of environmental problems and lack of jobs led U.S. president Franklin Roosevelt to create the Civilian Conservation Corps. It employed thousands of men on conservation projects in the nation's forests, parks, and rangelands. He also created the Soil Conservation Service.
The modern environmental movement began in the 1960's. In 1962, Rachel Carson published Silent Spring, which detailed the harm synthetic pesticides have on the environment. The uproar caused by this book eventually led to the Clean Water Act, the Clean Air Act, the Endangered Species Act, the Marine Mammal Protection Act, and the National Environmental Policy Act. The decade ended with the creation of the U.S. Environmental Protection Agency and the first Earth Day celebration in 1970.
During the 1980's and 1990's, people realized that environmental problems were global in nature. It was determined that acid rain in Canada was largely caused by air pollution produced in the United States and that the ozone layer in the polar regions had been thinned by aerosol use worldwide. The United Nations Environment Program held a series of international meetings on ozone, development, population, and climate change to address these global issues.
Today the environmental and conservation movements involve a mix of many different people, private organizations, and governmental agencies. They work at local, national, and global levels.
Careers in Conservation
Careers in conservation are as varied as the people who use natural resources. Traditionally people think of park rangers, conservation biologists, botanists, hydrologists, and ecologists as conservationists, because they work directly with the resources in the wild. However, some conservationists focus on using and refining resources for human use. These people include engineers, fishermen, foresters, and farmers. Other people are conservationists because they work to prevent damage to the environment. Their jobs include controlling pollution, conserving soil, and safeguarding environmental health. Finally, land-use planners, lawyers, and politicians are involved in the large-scale planning and use of our natural resources.
Preparation for a career in conservation should include a strong background in the natural sciences, including biology, chemistry, and mathematics. It should also include training in the social sciences. This is because conservation issues are complex and solving them involves many people with many different perspectives and backgrounds.
—Robert B. Blair