known example. Other intensive systems include terrace, mound, and drained-field systems of Africa, Asia, Central and South America, and the Pacific (Wilken, 1987a,b). These systems combine water control for drainage and irrigation through intricate systems of ditches, dikes, and shaping of the land. They provide harvests of high quality and quantity, and they are fairly predictable in their ability to provide consistent harvests from year to year.

Because of their high agricultural potential, resource-rich areas were the first to be developed, with early investment in roads, electricity, irrigation, and other infrastructural features. From the standpoint of national investment, these areas produced the greatest return per dollar. With few exceptions, most had been deforested and converted to high-productivity agriculture by the 1960s. Exceptions include malaria-infested portions of Nepal and Thailand, much of Mindanao in the Philippines, and large areas of inaccessible forestland in Brazil and Central Africa. These remaining areas may still be converted because of their value to agricultural production. Given social and economic pressures, the maintenance of forested areas can probably be justified only on the basis of preserving biodiversity. In most Asian countries, the few forested areas remaining on highly productive soils represent a small portion of total land area.

Internationally supported research and development in the 1960s and 1970s focused on realizing the high-production potential of these resource-rich lands. International agencies perceived an increasingly critical need for food and recognized the potential for existing scientific understanding and research methods to contribute to meeting this need. The international agricultural research centers (IARCs), such as the International Rice Research Institute (IRRI) in the Philippines, Centro Internacional de Agricultura Tropical (CIAT, International Center for Tropical Agriculture) in Colombia, and the International Institute of Tropical Agriculture (IITA) in Nigeria, were purposely situated in high-productivity tropical environments. The crop varieties that were developed had the genetic potential to respond to physical and managerial inputs under favorable soil and water environments. The widespread application of these new agricultural technologies gave rise to the green revolution. The agencies' focus also influenced the selection of areas with high-development potential and the placement of research centers within them (Dahlberg, 1979).

As a result of this concentrated investment in research and development, information and technology are readily available for high-