Cattle Ranching in the Mojos Savannas of Northeastern Bolivia

CATTLE RANCHING IN THE MOJOS SAVANNAS OF NORTHEASTERN BOLIVIA* William M. Denevan University of Wisconsin The Llanos de Mojos is a seasonally inundated tropical savanna occupying about 90,000 square miles in die Beni Department of northeastern Bolivia. Today the region is undeveloped has a population of only 120,000, and remains isolated from die rest of Bolivia. Cattle ranching has dominated life in Mojos for over two centuries, but cattle have nevertheless been almost worthless until recently. However, since 1950, as a result of die use of meat cargo planes, the Mojos savannas have become die major source of beef for La Paz, and cattle are now die most valuable product of northeastern Bolivia. Both physically and economically die Mojos savannas have much in common widi other large grassy savannas in South America: die lower Orinoco llanos, die Amazon campos, and die vast Pantanal de Mato Grosso. All of diese savannas are seasonally flooded, and all are important livestock raising areas today. Mojos, however, is somewhat unique for die severity of its annual floods, for die past neglect of ranching, and for die partly negative effects of die recent and sudden availability of major markets for beef. An examination of some of die past and present aspects of cattle ranching in die Llanos de Majos therefore seems desirable, with an emphasis on the striking changes which have taken place since ranching was described in the late 1940's and early 1950's.1 Background The Mojos savannas occupy most of die Beni Basin, which is located between the Andes and the western hills of die Brazilian Highlands and is filled with thousands of feet of young sediments washed down from die Andes. This unusually level plain ranges in elevation from roughly 1,000 feet in the south to 600 feet in die north, and die gradient is about one foot per mile. The basin is drained by the Rio Beni, Rio Mamoré, and Rio Guaporé (Itenez) which along widi die Rio Madre de Dios join in an apex near the northern border of Bolivia to form die Rio Madeira, a major tributary of the Amazon. During high water these rivers and their tributaries overflow, and this flooding, combined widi standing rain water, results in as much as 80 per cent of die savannas being under sevenil inches * This paper is part of a study of the historical geography of the Llanos de Mojos for which field work in 1961-1962 was supported by the NAS-NRC Foreign Field Research Program. 1 David Weeks, "Bolivia's Agricultural Frontier," Geographical Review, 36:546S67 (1946). Comisión Ganadera al" Beni, "Informe de la Comisión Ganadera para el Beni," Ministerio de Agricultura, La Paz, 1953. Harold Osborne, Bolivia, A Land Divided, London, 1956, pp. 88-91. 37 Fie. 1.—Map of northeastern Bolivia and the Llanos de Mojos. 38 to several feet of water between December and June. Rainfall averages 60 to 75 inches a year and is concentrated between October and May. Vegetation is directly related to relief and the associated amount of flooding but is also strongly influenced by burning. The lowest ground has sedges (Cyperaceae) where permanently wet, and grasses (Graminae) where seasonally flooded. Higher ground subject to only brief flooding has open scrub savanna dominated by palms (Copemicia, Acrocomia) and species of Tahehuia and CurateUa. Sites seldom or never flooded (islas), such as natural levees, low divides, and low mounds, are usually forested. Rain forest or semi-deciduous tropical forest surrounds die Llanos de Mojos on all sides. The savanna soils consist mainly of acid clay loams with hard pans and low organic content. Because of the low fertility and poor drainage of the grassy savannas, all agriculture today is confined to the better soils of the forested islas. Mojos was one of the legendary El Dorados of South America but remained unexplored until an expedition reached it from Santa Cruz de la Sierra in 1580. The Indian tribes encountered had large, palisaded villages, elaborate crafts, and a total savanna population of probably several hundred thousand. Some of the tribes adapted to the inconveniences of flooding by constructing causeways, mounds, and raised and ditched crop rows. The remnants...