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Chapter 5. Natural Systems Under Stress: From Grassland to Desert
One tenth of the earth’s land surface is cropland, but an area four times this size is rangeland—land that is too dry, too steeply sloping, or not fertile enough to sustain crop production. This area—two fifths of the earth’s land surface, most of it semiarid—supports the majority of the world’s 3.3 billion cattle, sheep, and goats. These livestock are ruminants, animals with complex digestive systems that enable them to digest roughage, converting it into beef, mutton, and milk. 37
An estimated 200 million people worldwide make their living as pastoralists tending cattle, sheep, and goats. Many countries in Africa depend heavily on their livestock economies for food and employment. The same is true for large populations in the Middle East, Central Asia, Mongolia, and northwest China. Since most land is held in common in these pastoral societies, controlling overgrazing is difficult. 38
In other parts of the world, rangelands are owned by individual ranchers. Australia, whose land mass is dominated by rangeland, has a flock of 100 million sheep, five times its human population. Grass-based livestock economies also predominate in Argentina, Brazil, Mexico, and Uruguay. And in the Great Plains of North America, semiarid lands that are not suited to growing wheat are devoted to grazing cattle. 39
The same ruminants that are uniquely efficient at converting roughage into food also supply leather and wool. The world’s leather goods and woolen industries, the livelihood of millions, depend on rangelands for raw materials.
Although public attention often focuses on the role of feedlots in beef production, the share of the world’s cattle in feedlots is a tiny fraction of the vast numbers feeding on grass. Even in the United States, which has most of the world’s feedlots, the typical steer is in a feedlot for only a matter of months.
Worldwide, almost half of all grasslands are lightly to moderately degraded and 5 percent are severely degraded. The problem is highly visible throughout Africa, the Middle East, Central Asia, and India, where the growth in livestock numbers tracks that in human numbers. In 1950, 238 million Africans relied on 273 million livestock. By 2006, there were nearly 926 million people and 738 million livestock. Demands of the livestock industry now often exceed grassland carrying capacity by half or more. 40
Iran —with 71 million people—illustrates the pressures facing the Middle East. With 9 million cattle and 80 million sheep and goats—the source of wool for its fabled rug-making industry— Iran’s rangelands are deteriorating from overstocking. 41
China faces similarly difficult challenges. After the economic reforms in 1978 that shifted the responsibility for farming from state-organized production teams to farm families, the government lost control of livestock numbers. As a result, China’s cattle, sheep, and goat populations spiraled upward. While the United States, a country with comparable grazing capacity, has 97 million cattle, China has a slightly larger herd of 115 million. But while the United States has only 9 million sheep and goats, China has 366 million. Concentrated in China’s western and northern provinces, sheep and goats are destroying the land’s protective vegetation. The wind then does the rest, removing the soil and converting productive rangeland into desert. 42
Fodder needs of livestock in nearly all developing countries now exceed the sustainable yield of rangelands and other forage resources. In India, the demand for fodder greatly outpaces the supply, leaving millions of emaciated, unproductive cattle. 43
Land degradation from overgrazing is taking a heavy economic toll in lost livestock production. In the early stages of overgrazing, the costs show up in lower land productivity. But as the process continues, it destroys vegetation, leading to erosion and the eventual creation of wasteland and desert. At some point, growth in the livestock population begins to shrink the biologically productive area and thus the earth’s capacity to sustain civilization. 44
37. Land area estimate from Stanley Wood, Kate Sebastian, and Sara J. Scherr, Pilot Analysis of Global Ecosystems: Agroecosystems (Washington, DC: International Food Policy Research Institute and WRI, 2000), p. 3; livestock counts from FAO, op. cit. note 30.
38. Number of pastoralists from FAO, The State of Food Insecurity in the World 2003 (Rome 2003), p.15; FAO, op. cit. note 30.
39. FAO, op. cit. note 30; U.N. Population Division, op. cit. note 19.
40. Robin P. White, Siobhan Murray, and Mark Rohweder, Pilot Analysis of Global Ecosystems: Grassland Ecosystems (Washington, DC: WRI, 2000); FAO, op. cit. note 30; U.N. Population Fund (UNFPA), State of World Population 2006 (New York: 2006), p. 98; Southern African Development Coordination Conference, SADCC Agriculture: Toward 2000 (Rome: FAO, 1984).
41. U.N. Population Division, op. cit. note 19; FAO, op. cit. note 30.
42. FAO, op. cit. note 30.
43. B. S. Sathe, “Dairy/Milk Production,” in Livestock Investment Opportunities in India, FAO Web site, at www.fao.org/DOCREP/ ARTICLE/AGRIPPA/657_en00.htm, viewed 9 September 2005.
44. H. Dregne et al., “A New Assessment of the World Status of Desertification,” Desertification Control Bulletin, no. 20, 1991.
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