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close this bookThe Fragile Tropics of Latin America: Sustainable Management of Changing Environments (UNU, 1995)
close this folderPart 1 : The ecological outlook
close this folderRich and poor ecosystems of Amazonia: an approach to management
View the document(introductory text...)
View the document1 Introduction
View the document2 Characterization of the oligotrophic environment
View the document3 Characterization of eutrophic forests
View the document4 Management of oligotrophic areas
View the document5 Management of eutrophic areas
View the document6 Conclusions
View the documentAcknowledgements
View the documentReferences

5 Management of eutrophic areas

By contrast, management of the eutrophic areas of terra firme offers the challenge of diversity. This was handled by native populations by creation of "islands of resources." They concentrated species of economic interest within close proximity to soils favourable for horticulture and favourable in locational factors, such as ease of river transportation, well-drained areas for habitational sites, and cool breezes to provide comfort and freedom from insects.

The creation of anthropogenic forests and soils solves two of the commonly mentioned problems posed by Amazonia:poor soils and species dispersal. This process need not have been conscious. The behaviour of ancestors could very well have been certified in myths and descendants continued traditions found to be favourable to their lifestyle.

For agriculture, the preferred areas were the vine forests, because of their association to alfisols. Near the villages, the population concentrated further resources by creating palm forests, bamboo forests, food/fruit-rich forests and the garbage from their settlements built up over time anthropogenic soils which would serve in the future as usable soils in previously inferior areas from an agronomic viewpoint. This is equivalent to the population creating ecotones, or transitional areas, to favour high productivity.

In eutrophic areas, cultivation of grains and other nutrient-demanding plants is possible, although this will shorten the time before fertilisation will be required. On the other hand, it makes no sense to build cities on top of these superb soils (as has been done in recent years, for example, at Tucumã, Pará) or to put them into the production of export and tree crops (as was the case in Rondônia, with cacao). Agricultural zoning of these areas will need to achieve particularly high levels of sophistication, matching the quality of the soils to the products developed. Unfortunately, much of this will have more to do with market forces than with the micro-ecological characteristics of the areas.

The eutrophic areas of terra firme can be put to intensive use. Doing so should begin with attention to the processes of environmental modification undertaken by indigenous populations, and build on these efforts. The better soils can withstand cultivation for prolonged periods of time because of their fine structure and high initial cation exchange capacity. However, fertilisation will be required for any form of continuous and intensive cultivation. The viability of continuous cultivation in these areas of terra firme is not an environmental issue per se but, rather, a political and economic one, of the government providing the conditions for access to fertilizers at competitive prices and of matching market demand to the products supplied by the areas put under cultivation. So far, for most of Amazonia, this has been poorly done. One of the few success stories has been the Japanese colony at the favourably located Tome-Açú, in which the inhabitants identified a low-weight/high-value crop early on, and which invested in technical and human resources from the outset.