Soils of the Amazon region and their ecological stability

Abstract

The data for this paper were collected during studies in the eastern Brazilian part of the Amazon region, on a Brazilian forest inventory programme, and on an FAO scheme for land evaluation in the region as a whole. The well-drained upland soils (orthic to xanthic ferralsols, and ferric to orthic Acrisols) support high forest, as do those with concretionary laterite or ironstone. The forest re-establishes itself after occasional agricultural occupation, unless the fallow period becomes too short. Substantial level areas exist with imperfectly drained soils (plinthic Acrisols or gleyic Podzols) that support only savannah forest or savannah vegetation. Agricultural occupation, accompanied by large-scale burning and drainage, may change some of these areas irreversibly into bare white sand plains or poor grassy plains with indurated laterite.