Fire in Amazonian selectively logged rain forest and the potential for fire reduction

• Published in: Ecological applications 1997-05, Vol.7 (2), p.713-725
• Main Authors: Holdsworth, Andrew R., Uhl, Christopher
• Format: Article
• Language: English
• Subjects: Amazonian rain forest and selective logging; APROVECHAMIENTO DE LA MADERA; fire damage and tree mortality; fire reduction in selectively logged forests; fire susceptibility, effects of logging methods on; Forest canopy; Forest ecology; FOREST FIRES; forest fragmentation, fire-induced; Forest regeneration; gap size and fuel moisture in logged forests; hemispheric canopy photography; INCENDIE DE FORET; INCENDIOS FORESTALES; LOGGING; LOGGING EFFECTS; Old growth forests; photon flux density and forest fuel moisture; Pioneer species; RECOLTE DU BOIS; Timber; tree and vine/liana regeneration after fire; Trees; Tropical rain forests
• ISSN: 1051-0761; 1939-5582
• DOI: 10.1890/1051-0761(1997)007[0713:FIASLR]2.0.CO;2

Approximately 8000 km$^2$ of Brazilian Amazon forest are selectively logged each year. Although virgin forest in eastern Amazonia is generally immune to fire, selectively logged forests are susceptible to fire. In eastern Amazonia we employed permanent-plot studies, forest fuel moisture measurements, and hemispheric canopy photographs to study the impacts of fire on a selectively logged forest, the microclimatic conditions that foster forest fires, and the measures that loggers might take to reduce fire incidence. Significant tree mortality followed a typical ground fire in a selectively logged forest. Forty-four percent of all trees $\geq$ 10 cm in diameter at breast height died in a burned plot while only 3% died in an unburned plot. In large logging gaps the density of regenerating pioneer species increased by $>$60% in burned plots 15 mo after the fire, while it decreased by $>$40% in unburned plots. The rate of fuel drying in selectively logged forest was influenced by photon flux density (PFD), time since logging, and logging techniques. There was a significant $(P = 0.005)$ negative correlation between PFD and the number of days fuel sticks required to reach the point where fire could spread. In a recently logged forest, large logging gaps ($>700$ m$^2)$ reached fire susceptible after 6 d, and medium-sized logging gaps ($\approx$ 200-700 m$^2$) reached fire susceptibility after 15 d. But fires susceptibility declines over time as logging gaps become densely packed with saplings; fuel moisture conditions in large gaps of forest selectively logged 4 yr earlier were similar to those found in virgin forest, thus reducing the likelihood of fire. Careful logging also can reduce the likelihood of fire. Special low-impact logging techniques remove the same amount of timber as do the more typical high-impact logging techniques, but fire is significantly less likely because the more careful operation avoids the creation of large logging gaps, the most fire susceptible areas.