Nature performs valuable, practical, measurable functions, without which the human economy could not exist. Many experts contend that, as human activity gradually consumes or destroys this natural capital, the monetary value of the ecosystem to the economy must be calculated and considered. Thirteen economists, ecologists, and geographers studied 16 different biomes (ecological areas such as lakes…
For millennia humans have left their mark on the world's forests, although it was difficult to see. By the twenty-first century, however, forests that humans once thought were endless are shrinking before their eyes. Forests are not only a source of timber; they perform a wide range of social and ecological functions. They provide a livelihood for forest dwellers, protect and enrich soils, …
The United States has 747 million acres of forested lands; they comprise roughly one-third of the nation's total land area. (See Figure 9.1.) Forests are valued for a variety of ecological and economical reasons. In their natural state they provide vital habitat for wildlife and play an important role in the carbon cycle. (See Figure 2.10 in Chapter 2.) Forests are also a source of recreati…
The GAO reported in 2001 that the federal government managed just over 680 million acres or about 29 percent of the nation's total land surface. Of these lands, 96 percent are managed by four agencies—the National Park Service, the Fish and Wildlife Service, the Bureau of Land Management, and the Forest Service. Most public lands are located in western states. In much of the West ran…
Marshes, swamps, bogs, estuaries, and bottomlands comprise about 5 to 9 percent of the 48 contiguous states and about 40 percent of Alaska. Although these terms refer to specific biosystems with sometimes very distinctive characteristics, they are commonly grouped together under the name "wetlands." Wetlands provide a vivid example of the dynamic, yet fragile interactions that creat…
Mountains are one of Earth's most important features. They span one-fifth of the landscape and house one-tenth of Earth's population. Roughly two billion people live downstream from mountains and depend on the water, hydropower, grassland, timber, and mineral resources generated by those mountains. A mountain is a landmass that projects conspicuously above its surroundings and is hig…
Erosion is the process in which the materials of the Earth's crust are worn and carried away by wind, water, and other natural forces. The destruction of forests and native grasses has allowed water and wind greater opportunity to erode the soil. Changes in river flow and seepage from human technology have shifted the runoff patterns of water and the sediment load of rivers that, in turn, d…
Human beings have survived in deserts or arid areas only because they have been able to increase the quantity of water available to meet their needs. An elaborate system of dams, reservoirs, irrigation pipelines, aqueducts, and canals allows residents of the American West, for example—especially California—to ignore the fact that they live in a naturally dry climate. That fact has ma…
Biological diversity, or biodiversity, refers to the full range of plant, animal, and microbial life and the ecosystems that house them. Environmentalists began using the term during the 1980s when biologists increasingly warned that human activities were causing a loss of plant and animal species. Studies of deforestation have supported the concerns about declining biodiversity, showing that trop…
The loss of habitats, the contamination of water and food supplies, poaching, and indiscriminate hunting and fishing have depleted the population of many species. Most scientists agree that prospects for the survival of many species of wildlife, and hence biodiversity, are worsening. The expansion of human development into wildlife habitats has resulted in some animals being squeezed into cities a…
Materials extracted from the Earth are needed to provide humans with food, clothing, and housing and to continually upgrade the standard of living. Some of the materials needed are renewable resources, such as agricultural and forestry products, while others are nonrenewable, such as minerals. The USGS reported in Materials Flow and Sustainability (1998) that a significant trend is the decreasing …
The indebtedness and poverty of many developing countries reduce opportunities for conservation. Local, national, and international efforts must be linked to deal effectively with the underlying pressures on the ecosystems that support biological diversity. Some international efforts include "debt-for-nature" programs and ecotourism (travel oriented around natural sites, native speci…
Every year the Gallup Organization conducts a comprehensive poll of Americans on environmental issues. The latest poll was conducted in March 2004. Poll participants were asked to express their level of TABLE 9.2 Public concern about loss of tropical rain forests, 2004 PLEASE TELL ME IF YOU PERSONALLY WORRY ABOUT THIS PROBLEM A GREAT DEAL, A FAIR AMOUNT, ONLY A LITTLE, OR NOT AT ALL. THE LOS…
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