ABSTRACT
The prevailing easterly air flow along the Caribbean coast of the South American continent produces atmospheric divergence and subsidence that makes a near desert of much of the immediate littoral of Venezuela and Colombia. Unlike the savanna landscapes of Africa, Australia, Brazil, and the Guiana highlands, the plains in northern South America are built up from new outwash from the youthful Andes. Only since the arrival of Europeans has grazing by domestic livestock been a significant factor in the ecology of tropical American savannas. The introduction and spread of African grasses into the American tropics has been a seldom recognized but important component of the ongoing biotic interchange between the Old World and the New World. The Venezuelan llanos initially offered little attraction to the Spaniards. The other principal savanna landscape of northern South America is the north-coastal plain of Colombia. Pre-Columbian man showed great ingenuity in dealing with the intransigent lowlands of alternating extremes of water scarcity and abundance.
