Chapter Land Degradation

1. Gretchen C. Daily, "Restoring Value to the World's Degraded Lands," Science, 269, pp. 350-354,1995. Reprinted in L. Owen and T Unwin, eds., Environmental Management: Readings and Case Studies, Blackwell, 1997.

Since 1945, soil degradation has affected in excess of 2 billion hectares, or 17 percent of the Earth's vegetated land. Of the degraded lands, 38 percent are lightly degraded, 46 percent are moderately degraded, 15 percent are severely degraded (reclaimable only with major effort), and 0.5 percent are extremely degraded (unreclaimable). In addition, over 4.5 billion hectares of rangelands are degraded and subject to desertification. The breakdown for rangelands is 27 percent lightly degraded, 28 percent moderately degraded, 44 percent severely degraded, and 1.6 percent extremely degraded. To this survey of land degradation we must also add tropical rain forest degradation, which afflicts more than 427 million hectares. The total of land degraded by soil depletion, desertification, and degradation of tropical rainforests comes to more than 5 billion hectares, or more than 43 percent of the Earth's vegetated surface.

2. R.A. Houghton, "The Worldwide Extent of Land Use Change," Bioscience 44(5): pp. 305-313.

4. N. Myers, The Nontimber Values of Tropical Forests, Forestry for Sustainable Development Program, University of Minnesota, November, 1990.

5. Pimentel and Giampietro, Food, Land, Population and the U.S. Economy.

6. David Pimentel et al., "Will Limits of the Earth's Resources Control Human Numbers?," Environment Development and Sustainability, Issue 1,1999.

7. Pimentel and Giampietro, Food, Land, Population and the U.S. Economy.

10. D. Wen, "Soil Erosion and Conservation in China," in Soil Erosion and Conservation, ed. David Pimentel, Cambridge University Press, 1993, pp. 63-86.

11. J. R. Parrington et al., "Asian Dust: Seasonal Transport to the Hawaiian Islands," Science 246:1983, p. 195-197.

12. N. Rome Alexandrotos, World Agriculture: Toward 2010, Food and Agriculture Organization of the United Nations and John Wiley & Sons, 1995.

13. H.E. Dregne, "Erosion and Soil Productivity in Africa," Journal of Soil and Water Conservation, 45,1990, pp. 431-436.

14. M. Simons, "Winds toss Africa's soil, feeding lands far away," New York Times, October 29,1992. pp. Ai, A16.

15. H. E. Dregne, ed., Degradation and Restoration of Arid Lands, Texas Technical University, 1992.

16. R. Lai, "Soil Erosion Impact on Agronomic Productivity and Environment Quality," Critical Reviews in Plant Sciences, 17, 1998, pp. 319-46417. Pimentel and Giampietro, Food, Land, Population and the

20. Pimental and Pimental, Land, Energy and Water.

21. Pimentel and Giampietro, Food, Land, Population and the U.S. Economy.

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