creased attention will be the ability to share with resource-poor areas the institutional capacity, field research methodologies, and scientifically trained human resources of the IARCs, which had been developed primarily for agriculture on resource-rich lands.

The ability of areas with high-quality soil and water resources in Asia to absorb more people engaged in agriculture is limited. These lands have been cleared and settled for many years, even centuries, often predating colonialism. Labor use levels are stable after the increases caused by the green revolution technologies of the 1960s and 1970s. Food production is increasing, but often at a rate not sufficient to keep up with national demand. The few remaining forest areas on these high-potential soils are unique in their genetic diversity and require extreme measures for protection. For the most part, the presence of these few remaining forests is testimony to the effectiveness of protection policies.

In the Americas and in Africa, significant forest areas remain. As roads are built, however, these areas are increasingly threatened with the possibility of land conversion. The short-term economic benefits of logging and the subsequent availability of these highly productive soils make the prospect of further agricultural expansion almost inevitable.

Shifting cultivation is one of the most widespread farming systems in the humid tropics, and it is often labeled as the most serious land use problem in the tropical world (Grandstaff, 1981). Shifting cultivation is usually defined as an agricultural system in which temporary clearings are planted for a few years with annual or short-term perennial crops, and then allowed to remain fallow for a period longer than they were cropped (Christanty, 1986). Conditions that limit crop yields, such as soil fertility losses, weeds, or pest outbreaks, are overcome during the fallow time, and after a certain number of years the area is ready to be cleared again for cropping (Sanchez, 1976).

While most shifting cultivation consists of various slash-and-burn methods, areas with high amounts of rainfall can use a slash-and-mulch system, which has less adverse effects on the environment. In warm wet conditions, relatively rapid decomposition of the mulch provides nutrient recycling benefits unavailable through burning, while

Front Matter (R1-R16)

Executive Summary (1-18)

Part One (19-20)

1 Agriculture and the Environment in the Humid Tropics (21-65)

2 Sustainable Land Use Options (66-137)

3 Technological Imperatives for Change (138-158)

4 Policy-Related Imperatives for Change (159-191)

References (192-214)

Appendix: Emissions of Greenhouse Gases from Tropical Deforestation and Subsequent Uses of the Land (215-260)

Part Two: Country Profiles (261-264)

Brazil (265-351)

C te d (352-392)

Indonesia (393-439)

Malaysia (440-482)

Mexico (483-548)

The Philippines (549-624)

Zaire (625-658)

Glossary (659-674)

Authors (675-678)

Index (679-704)