CHAPTER NINETEEN

Figure 19.2. Schematic diagram of the interrelationships between tropical land cover changes and forest fires (Cochrane 2003). Arrows indicate forcing of each node upon others in the system. Blue arrows directly affect forest fire occurrence, black arrows indirectly influence forest fire occurrence.

•  Road building results in forest access that is strongly associated with deforestation (Laurance et al. 2001).

•  Deforestation fragments the remaining forests creating increasing amounts of edge (Skole and Tucker 1993, Laurance et al. 1997).

•  Road building and paving provide greater access to the forest to loggers and directly affect the transportation costs and area of economic accessibility (Veríssimo et al. 2002).

•  Logging directly results in limited amounts of deforestation for roads and log landings. Post-logging colonization frequently leads to settlement and deforestation (Veríssimo et al. 1995).

•  Forest edges are subject to biomass collapse and microclimate changes (Laurance et al. 1997) that make them very susceptible to frequent fires (Cochrane 2001a).

•  Repeated forest fires, especially in previously logged forests, can lead to unintentional deforestation. Accidental deforestation can cause half of the total deforestation in some regions (Cochrane et al. 1999).

•  Both deforestation fires and pasture/land maintenance fires result in many accidental forest fires (Cochrane 2001b) that predominate along forest edges (Cochrane 2001a).

•  Logging degrades the forest and can lead to increased susceptibility to fire (Uhl and Buschbacher 1985, Holdsworth and Uhl 1997). This can lead to extensive fires even several years after the logging operations (Siegert et al. 2001).

•  Forest fires can create a positive feedback cycle where recurrent fires become more likely and more severe with each occurrence (Cochrane et al. 1999).

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