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Confronting the Effects of Land Use
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"Current trends in land use allow humans to appropriate an ever-larger fraction of the biosphere's goods and services while simultaneously diminishing the capacity of global ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and mediate infectious diseases. This assertion is supported across a broad range of environmental conditions worldwide, although some (e.g., alpine and marine areas) were not considered here. Nevertheless, the conclusion is clear: Modern land-use practices, while increasing the short-term supplies of material goods, may undermine many ecosystem services in the long run, even on regional and global scales. "Confronting the global environmental challenges of land use will require assessing and managing inherent trade-offs between meeting immediate human needs and maintaining the capacity of ecosystems to provide goods and services in the future. Assessments of trade-offs must recognize that land use provides crucial social and economic benefits, even while leading to possible long-term declines in human welfare through altered ecosystem functioning.
[Here is a] Conceptual framework for comparing land use and trade-offs of ecosystem services.
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Global Consequences of Land Use
"Human alteration of Earth is substantial and growing. Between one-third and one-half of the
land surface has been transformed by human action; the carbon dioxide concentration in the atmosphere
has increased by nearly 30 percent since the beginning of the Industrial Revolution; more atmospheric
nitrogen is fixed by humanity than by all natural terrestrial sources combined; more than half of all
accessible surface fresh water is put to use by humanity; and about one-quarter of the bird species on
Earth have been driven to extinction. By these and other standards, it is clear that we live
on a human-dominated planet.
"All organisms modify their environment, and humans are no exception. As the human population has grown
and the power of technology has expanded, the scope and nature of this modification has changed drastically.
Until recently, the term "human-dominated ecosystems" would have elicited images of agricultural fields,
pastures, or urban landscapes; now it applies with greater or lesser force to all of Earth. Many ecosystems
are dominated directly by humanity, and no ecosystem on Earth's surface is free of pervasive human influence.
"The global consequences of human activity are not something to face in the future,
they are with us now. All of these changes are ongoing, and in many cases accelerating; many of them were
entrained long before their importance was recognized. Moreover, all of these seemingly disparate phenomena
trace to a single cause--the growing scale of the human enterprise. The rates, scales, kinds, and combinations
of changes occurring now are fundamentally different from those at any other time in history; we are changing
Earth more rapidly than we are understanding it. We live on a human-dominated planet--and the momentum of
human population growth, together with the imperative for further economic development in most of the world,
ensures that our dominance will increase.
"Finally, humanity's dominance of Earth means that we cannot escape responsibility for managing the planet.
Our activities are causing rapid, novel, and substantial changes to Earth's ecosystems. Maintaining populations,
species, and ecosystems in the face of those changes, and maintaining the flow of goods and services they provide
humanity (55), will require active management for the foreseeable future. There is no clearer illustration of
the extent of human dominance of Earth than the fact that maintaining the diversity of "wild" species and the
functioning of "wild" ecosystems will require increasing human involvement.
Peter M. Vitousek, Harold A. Mooney, Jane Lubchenco, Jerry M. Melillo
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The Future of Farming and Conservation |
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George Beggs 8/2005 - Feedback is welcome
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