Câmara et al.
challenge our assertion that the unprecedented, planned expansion of highways
and other transportation projects in
First, the projections of our models—that 28 to 42% of Brazilian
Amazonia would be deforested by 2020 if all the Avança Brasil projects proceed
immediately—are in fact very plausible and do not differ greatly from simple
extrapolations using the current high rate of forest loss (2). Second, our models incorporated key components of regional
If a new highway penetrates into a large forest tract and promotes spontaneous colonization by farmers, loggers, and ranchers, is the forest loss caused by the highway or the other drivers? Clearly, it is both—but the crucial point is that such transportation projects play a pivotal role in determining where forest destruction occurs. The truly alarming aspect of the Avança Brasil program is that it will criss-cross the Amazon with some 7500 km of paved highways and many other transportation projects that will penetrate deep into the heart of the basin. The net effect will be not only be increased deforestation but also fragmentation of forests on an unprecedented spatial scale (1). Rather than concentrating development in the vast expanses of land that have already been deforested, the projects that promote frontier expansion will do precisely the opposite.
Contrary to the claim by Câmara et al., the dramatic upsurge in Amazonian deforestation in 2002–03
includes many areas associated with highways and roads, including the notorious
1. W. F. Laurance et al., Science 291, 438 (2001).
2. If the deforestation rate in 2002–03 (2.35 million ha year-1) continues indefinitely, then 100 million hectares of forest will have disappeared by the year 2020. This is about 25% of the original forests in Brazilian Amazonia.
3. G. Carvalho, A. C. Barros, P. Moutinho, D. C. Nepstad, Nature 409, 131 (2001).
4. B. Soares-Filho et al., Global Change Biol. 10, 745 (2004).
5. B. Soares-Filho et al., “A spatially explicit
simulation model of deforestation for the
6. A. Alencar et al., Desmatamento na Amazônia: Indo Além da “Emergência Crônica” (Instituto de Pesquisa Ambiental da Amazônia, Belém, Brazil, 2004).