Journal of Tropical Ecology



Fire as a large-scale edge effect in Amazonian forests


Mark A. Cochrane  a1 and William F. Laurance  a2 a3 c1
a1 Basic Science and Remote Sensing Initiative, Michigan State University, East Lansing, MI 48823, USA (Email: cochrane@bsrsi.msu.edu)
a2 Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panamá
a3 Biological Dynamics of Forest Fragments Project, National Institute for Amazonian Research (INPA), C.P. 478, Manaus, AM 69011-970, Brazil

Abstract

Amazonian forests are being rapidly cleared, and the remaining forest fragments appear unusually vulnerable to fire. This occurs because forest remnants have dry, fire-prone edges, are juxtaposed with frequently burned pastures, and are often degraded by selective logging, which increases forest desiccation and fuel loading. Here we demonstrate that in eastern Amazonia, fires are operating as a large-scale edge effect in the sense that most fires originate outside fragments and penetrate considerable distances into forest interiors. Multi-temporal analyses of satellite imagery from two frontier areas reveal that fire frequency over 12-14-y periods was substantially elevated within at least 2400 m of forest margins. Application of these data with a mathematical core-area model suggests that even large forest remnants (up to several hundred thousand ha in area) could be vulnerable to edge-related fires. The synergistic interactions of forest fragmentation, logging and human-ignited fires pose critical threats to Amazonian forests, particularly in more seasonal areas of the basin.

(Accepted July 14 2001)


Key Words: Amazon; Brazil; conservation; carbon emissions; deforestation; drought; fire; habitat fragmentation; logging; rain forest; remote sensing; tropical forest.

Correspondence:
c1 Corresponding author. Smithsonian Tropical Research Institute, Apartado 2072, Balboa, Republic of Panamá. Email: laurancew@tivoli.si.edu