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PARKS AND WILDLIFE REFUGES

The National Park System was originally composed of large, scenic areas in the West such as Grand Canyon and Yosemite Valley. Today, however, the National Park System has more cultural and historical sites-battlefields and historically important building and towns, for instance—than scenic wilderness. More than 300 different sites are part of the National Park System, and many of them have ht™ purchased with money provided by the Land and Water Conservation Fund Act of 1965. Urban parks, such as the Golden Gate National Recreation Area near San Francisco, have also been established.

One of the primary roles of the Park Service i-to teach people about the natural environment and management of natural resources by providing nature walks and guided tours of its parks. The popularity and success of national parks in the United States have encouraged many other nations to establish national parks (see Focus On: A National Park in West Africa). As in the United States, these parks usually have multiple roles, from providing wildlife habitat to facilitating human recreation.

The National Wildlife Refuge System contains more than 400 different parcels of land that represent all major ecosystems found in the United States, from tundra to temperate rain forest to desert. Newer acquisitions are

sometimes made to preserve the habitats of threatened or endangered species.

Threats to Parks

National parks are even more overcrowded than wilderness areas. All of the problems plaguing urban areas are found in popular national parks during peak, seasonal use, including crime, vandalism, litter, traffic jams, and pollution of the soil, water, and air. Many people think that more funding is needed to maintain and repair existing parks and that; in addition, new parks should be created to meet current and projected demands.

Some national parks have imbalances in wildlife populations. For example, in the 1920s wolves were exterminated in Yellowstone National Park because of their threat to herbivorous mammals such as elk. As a result, the elk population at Yellowstone has increased to the point where today it is endangering many plant species upon which it feeds. A similar elk problem exists at the Rocky Mountain National Park, where wolves have been absent since the turn of the century. Because national parks are supposed to preserve natural ecosystems, much conservation thinks that wolves should be reintroduced at Yellowstone and Rocky Mountain national parks.

Additional examples of wildlife imbalances on national park lands involve declining populations of many other types of mammals, including bears, white-tailed jackrabbits, and red foxes (see Chapter 1). For example, the number of grizzly bears in national parks in the western United States has greatly diminished. Grizzly bears require large areas of wilderness undisturbed by humans. Clearly,

human influences in national parks are a factor in their decline. More important, the parks may be too small to support grizzlies. Fortunately, grizzly bears have survived in sustainable numbers in Alaska and Canada.

National Parks are also affected by human activities beyond their borders. Pollution doesn't respect park boundaries. Also, parks are increasingly becoming islands of natural habitat surrounded by human development. Development on the borders of national parks limits the area in which wildlife may range, forcing wildlife into isolated populations. Ecologists have found that, when environmental stresses occur, several small "island" populations are more likely to become threatened than a single large population occupying a sizable range.