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chapter Environmental Interrelationships 1 CHAPTER OUTLINE 环境交叉关系The Important Role of Wolves in Yellowstone

1.1 The Nature of Environmental Science 1.2 Emerging Global Issues GOING GREEN: Individual Decisions Matter 5 FOCUS ON: Campus Sustainability Initiative 6 SCIENCE, POLITICS, & POLICY: National Security Policy and Climate Change 13 ISSUES & ANALYSIS: Government Regulation and Personal Property 14

本章概要

黄石国家公园狼的重要作用 ..................环境科学的特性 ..................新兴的全球问题走向绿色：个体的决定.... 关注：推动可持续发展校园活动.... 科学、政治与政策：国家安全政策与气候变化...... 问题与分析：政府法规与个人财产......

Environmental science is the study of interrelationships between humans and the natural world. This farmer in Uganda has cleared a portion of the original forest to create this small farm, which supplies food and income for the family.

环境科学是研究人与自然世界相互关系的学科。乌干达农民砍掉一片原始森林建成小农场，以为家庭提供食物和收入。

OBJECTIVES

After reading this chapter, you should be able to:

. Recognize that the field of environmental science includes social, political, and economic aspects in addition to science. . Describe examples that illustrate the interrelated nature of environmental science. . Understand why most social and political decisions are made with respect to political jurisdictions but environmental problems do not necessarily coincide with these human-made boundaries. 学习目标

阅读完本章后，你应该能够：

. Understand the concept of sustainability. . Recognize that human population growth contributes to environmental problems. . Recognize that people rely on the services provided by ecosystems. . Understand that food security is an issue for many people in the less-developed world. . Recognize that there are governance issues that make it difficult to solve environmental problems.....认识到环境科学涉及社会、政治和经济等方面，而不仅仅是科学问题 ....列举体现环境科学交叉关系特性的实例 ....了解为什么大多数社会及政治决策是基于政治权限做出的，但是环境问题 并不一定与这些人为的边界相符合 ....了解..可持续性..概念 ....认识到人口增长会引发环境问题 . Recognize that the quality of the environment has an important impact on human health. . Understand that personal security incorporates economic, political, cultural, social, and environmental aspects. . Describe environmental impacts of globalization. . Recognize the central role energy use has on environmental problems. ....认识人类依靠生态系统提供的服务 ....了解食品安全是欠发达地区很多人面临的问题 ....认识到政府管理问题会造成解决环境问题的困难 ....认识到环境质量对人类健康有重要影响 ....了解安全涉及经济、政治、文化、社会和环境等方面 ..叙述全球化的环境影响 ....认识到能源利用对环境问题的重要作用1

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The Important Role of Wolves in Yellowstone

Early explorers of the lands west of the Mississippi River told of a place with fantastic geysers, mud pots, and other thermal features. They also told of abundant wildlife and rivers filled with fish. After several official government expeditions confirmed these tales, Yellowstone National Park was established as the world’s first national park in 1872. As more people settled in the west and ranches and farms were established, there was pressure from farmers and ranchers as well as hunters to reduce the number of predator species on public lands in the west. It was also a generally held idea that predators reduced the numbers of elk, deer, and other species preferred by hunters. Thus the U.S. Congress in 1914 provided funding to eliminate wolves and other predators on public lands including national parks. By 1926 wolves had been eliminated from Yellowstone. The lack of wolves led to a cascade of unintended consequences:

. Since hunting of species other than predators was prohibited in the park, the population of elk increased. In addition, coyotes, which are normally killed by wolves, increased greatly. By 1935, park managers felt that overgrazing by the large population of elk was beginning to destroy the park’s habitat. Therefore, a program of harvesting elk, bison, and pronghorns was instituted to protect the habitat. This program was discontinued in the 1960s as better knowledge of the habitat indicated that it was not overgrazed. . Coyotes greatly reduced the number of small mammal species such as mice, squirrels, and rabbits. . The number of pronghorn antelope also decreased because coyotes killed newborn pronghorns. . Populations of cottonwood and willows along streams declined substantially due to browsing by elk. Eventually, as park managers and biologists began to understand the profound changes caused by the elimination of wolves, the decision was made to reintroduced wolves to Yellowstone National Park. The initial introduction of 31 wolves in 1995 and 1996 has resulted

in a current population of about 100 wolves. Several changes to the Yellowstone ecosystem can be directly attributed to the alterations brought about by the return of wolves:

. Wolves kill and eat elk. This has resulted in a significant reduction in the size of the elk herd from about 19,000 prior to wolf reintroduction to less than 4,000 now. . The presence of wolves also has modified the behavior of elk. Because they must be more vigilant and move about more because of the predatory behavior of wolves, elk spend less time feeding on willow, cottonwood, and aspen. Both the change in behavior and the reduced size of the elk herd have allowed the regeneration of stands of cottonwood and willow along rivers. This has in turn resulted in increased numbers of beavers that use these streamside trees for food. The dams built by beavers tend to slow the flow of water and increase the recharge of groundwater. Furthermore, the stands of willow along the banks of streams cool the water and improve fish habitat. The stands of willow also provide needed habitat for some songbirds. . Wolves directly compete with coyotes and kill them if they have the opportunity. Thus, since the reintroduction of wolves the coyote population has fallen significantly. There is evidence that the populations of the prey of coyotes—voles, mice, and other rodents—have increased. The increased availability of this food source has resulted in an increase in the number of foxes, hawks, and owls. Thus, it is fair to say that the reintroduction of the wolf has changed how water flows through the landscape and has led to increased populations of many organisms—willow, cottonwood, beaver, songbirds, foxes, certain rodents, hawks, and owls; and to the decline in the population of other organisms—coyote and elk. Truly this is a story that illustrates the point made by the early naturalist John Muir (1838–1914)—Tug on anything at all and you’ll find it connected to everything else in the universe.

Wolves reintroduced Elk decline Willows increase Beavers increase

CHAPTER 1

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