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wheat cultivation in the Great Plains.The number of cul- trate, high technology, nonlabor-intensive land, and water
tivated hectares doubled during World War I as tractors use can also cause severe degradation.
(for the first time) were employed in the thousands. In Human-induced desertification is not new. Although
Kansas alone the wheat area increased from less than 2 people often focus on the Dust Bowl years of the 1930s
million hectares in 1910 to almost 5 million in 1919. and the current degradation of the Sahel, desertification
After the war wheat cultivation continued apace, helped has been the subject of great interest in the Mediterranean
by the development of the combine harvester and gov- area since classical times. Likewise, some evidence indi-
ernment assistance. Over large areas the tough sod, cates that more than four thousand years ago Mesopota-
which had exasperated earlier homesteaders, had given mia was suffering from chemical degradation of soils and
way to friable (easily crumbled or pulverized) soils of high crop yield reductions as a consequence of the adoption
erosion potential. Drought, acting on damaged soils, cre- and extension of irrigation. Nevertheless, land degrada-
ated the “black blizzards.” tion is not the inevitable consequence of increasing pop-
Dust storms are still a serious problem in parts of the ulation densities and land-use intensification, and many
United States.Thus, for example, in the San Joaquin Val- techniques are available for desert reclamation.
ley of California in 1977 a dust storm caused extensive
Andrew S. Goudie
damage and erosion. More than 22 million metric tons
of soil were stripped from grazing land within a twenty-
four-hour period. Although the combination of drought
Further Reading
and a high wind (as much as 300 kilometers per hour)
Coffey, M. (1978).The dust storms. Natural History, 87, 72–83.
provided the predisposing natural conditions for the
Dregne, H. E. (1986). Desertification of arid lands. In F. El-Baz & M. H.
stripping to occur, overgrazing and the general lack of A. Hassan (Eds.), Physics of desertification (pp. 4–34). Dordrecht,
windbreaks in the agricultural land played a more sig- Netherlands: Nijhoff.
Dregne, H. E., & Tucker, C. J. (1988). Desert encroachment. Desertifi-
nificant role. In addition, broad areas of land had recently cation Control Bulletin, 16, 16–18.
been stripped of vegetation, leveled, or plowed up prior Ehrlich, P. R., & Ehrlich, A. H. (1970). Population, resources, environ-
ment: Issues in human ecology. San Francisco: Freeman.
to planting. Other quantitatively less important factors
Gill, T. E. (1996). Eolian sediments generated by anthropogenic distur-
included stripping of vegetation for urban expansion, bance of playas: Human impacts on the geomorphic system and geo-
extensive denudation of land in the vicinity of oilfields, morphic impacts on the human system. Geomorphology, 17, 207–
228.
and local denudation of land by vehicular recreation. Goudie, A. S. (Ed.). (1990). Desert reclamation. Chichester, UK: Wiley.
Elsewhere in California dust yield has been considerably Goudie,A. S., & Middleton, N. J. (1992).The changing frequency of dust
storms through time. Climatic Change, 20, 197–225.
increased by mining of dry lake beds and by disturbance
Grainger, A. (1990). The threatening desert: Controlling desertification.
of playas (flat-floored bottoms of undrained desert basins London: Earthscan.
that become at times shallow lakes). Grove, A. J., & Rackham, O. (2001). The nature of Mediterranean
Europe: An ecological history. New Haven, CT: Yale University Press.
A comparable acceleration of dust storm activity Helldén,V. (1984). Land degradation and land productivity monitoring
occurred in the former Soviet Union. After the “Virgin —needs for an integrated approach. In A. Hjort (Ed.), Land manage-
ment and survival (pp. 77–87). Uppsala, Sweden: Scandinavian Insti-
Lands” program of agricultural expansion during the
tute of African Studies.
1950s, dust storm frequencies in the southern Omsk Jacobsen, T., & Adams, R. M. (1958). Salt and silt in ancient
region increased on average by a factor of 2.5 and locally Mesopotamian agriculture. Science, 128, 1251–1258.
Mabbutt, J. A. (1984). Desertification of the world’s rangelands. Deser-
by factors of 5 to 6. tification Control Bulletin, 12, 1–11.
Desertification is not restricted to heavily populated Marsh, G. P. (1864). Man and nature. New York: Scribner.
Middleton, N. J., & Thomas, D. S. G. (1997). World atlas of desertifica-
lands with large agricultural and pastoral populations.As
tion (2nd ed.). London: Arnold.
the examples of the U.S. Great Plains and California illus- Nicholson, S. (1978). Climatic variations in the Sahel and other African