John Libbey Eurotext

Science et changements planétaires / Sécheresse


Grazing in arid North America: A biogeographical approach Volume 17, issue 1, Janvier-Juin 2006


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Department of Environmental Science, Policy, and Management, 10 Hilgard Hall, University of California, Berkeley California 94720-3114 United States of America, Department of Geography, 201 Mackay Science/154 University of Nevada, Reno, Nevada 89557-0048 United States of America
  • Key words: animal production, rangelands, arid and semiarid zone, livestock, Mexico, Canada, United States
  • Page(s) : 219-33
  • Published in: 2006

More than one-third of the North American continent, about one billion hectares of the United States, Canada, and Mexico, can be considered arid and semiarid. Since the sixteenth century livestock grazing has been the dominant use of non-arable, “marginal” lands, but in recent decades competition from other uses, and large-scale production of cereal and forage crops, has had major impacts on forms of rangeland production. Poverty and subsistence ranching influence rangeland use and condition in Mexico more than in the other countries. Approximately 28 million beef cows, 4 million ewes, and 5 million goats graze arid North America, with livestock densities increasing from north to south. A transect running west to east across the western continent illustrates the geographical diversity of resources, landownerships, and land uses. The major rangeland types and livestock production characteristics for eight ecological regions are described. In the United States, growing demand for goat meat has stimulated an increase in production, while sheep numbers steadily decline due to consumer preferences and vulnerability to predators and dogs. Interest in the use of goats and other livestock for vegetation management, and in “natural” meats, may influence future livestock grazing patterns on rangelands.