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Acta Amazonica

Print version ISSN 0044-5967On-line version ISSN 1809-4392

Acta Amaz. vol.12 no.3 Manaus July/Sept. 1982

https://doi.org/10.1590/1809-43921982123579 

ECOLOGIA

Desmatamento na Amazônia Brasileira: Com que intensidade vem ocorrendo? *

Philip M. Fearnside** 

**Instituto Nacional de Pesquisas da Amazônia, Manaus.


Resumo

O desmatamento na Amazônia brasileira está ocorrendo a uma taxa inédita. Uma série de imagens de satélite LANDSAT de áreas de colonização em Rondônia, de 1973 até 1978, indicam que as tendências de desmatamento podem ser exponenciais, porém dados são escassos demais para conclusões firmes. Informações disponíveis de imagens LANDSAT de 1975 e 1978. com cobertura de todos os 5 x 106 km2 da Amazônia Legal brasileira, possibilitam o cálculo do que aconteceria se o desmatamento ocorresse exponencialmente nas taxas indicadas pelas imagens destas duas ditas. A não homogeneidade das taxas de desmatamento resultaria em que algumas áreas seriam desmatadas mais cedo e outras, mais tarde; se as taxas de desmatamento permanecessem constantes, dentro de cada Estado ou Território, estes seriam desmatados em datas que variam desde 1988 para Rondônia até 2159 para Amapá. Esclareça-se que nenhum destes cálculos representa uma previsão do que está esperado a acontecer, mas apenas cenários hipotéticos do que aconteceria, caso estas taxas fossem sustentadas ao longo do tempo. O desmatamento é um processo complexo demais para ser adequadamente representado por equações simples.

Summary

Deforestation in the Brazilian Amazon is proceeding at an unprecedented rate. Felling intensity is very uneven, being concentrated in certain parts of the region. A series of LANDSAT satellite images from settlement areas in Rondônia, from 1973 through 1978. indicate that clearing trends may be exponential, but information is too scant for firm conclusions. Available information from LANDSAT images from 1975 and 1978 covering all of Brazil's 5 x 106 km2 Legal Amazon indicate that if clearing were to proceed exponentially at the rate implied by the images at these two dates, the entire region would be cleared by 1991. The unevenness of clearing rates would result in some areas being cleared sooner and others later; if clearing rates within each state or territory were to remain constant, they would be cleared at dates ranging from 1988 for Rondônia to 2159 for Amapá. It is emphasized that none of these calculations represent forecasts of what is expected to happen, but only hypothetical scenarios of what would happen were these rates to continue. Deforestation is far too complex a process to be adequately represented by simple equations.

Forces leading to continued exponential growth of cleared areas include a probable positive feedback relationship between roadbuilding aid deforestation. Many government policies have potential effects on clearing rates, including highway construction and improvement programs, agriculture and ranching incentives, and policies affecting population size, distribution of income, land tenure, and agricultural mechanization both in the Amazon and in source areas of migrants. Brazil's Forest Policy draft law, to cover many aspects of development policy in Amazonia, is a major unknown factor in future deforestation trends.

More important than the precise time remaining for the bulk of Amazonia's rainforests are the designation and defense of areas to be left in forest, and the establishment in present and future cleared areas of agroecosystems which are agronomically and socially sustainable, limitation of concentration of income and land tenure, retriction of total consumption, and maintenance of human population levels below carrying capacity, defined to include an adequate and sufficiently certain standard of living.

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*— Versão original inglesa publicada em Interciencia, 7 (2): 82-88, 1982.

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