Fires in tropical forests with closed canopies tend to occur infrequently (hundreds of years) and with low intensity (Goldammer 1990). With increased logging, forest fires in Amazonia and southeast Asia now occur more frequently and with greater intensity (Cochrane 1999; Stolle 2004).
1. Closed canopy tropical rainforest with infrequent, low intensity fires.
2. Fragmented forest, open canopies and frequent high intensity fires. Can possibly lead to scrub or savanna.
Logging and associated road building opens up the forest canopy, with some forest being converted to agricultural land. The forest becomes fragmented, increasing edge effects and susceptibility to fires (through microclimate changes and biomass dieback) (Cochrane 2001). The frequency of fires can increase in this remaining forest, through burning for pasture in agricultural land. High intensity fires are more likely in drier years (Stolle 2004).
A positivefeedback loop is set up, where repeated fires lead to further deforestation and fragmentation, which then lead to more fires (Cochrane 1999). The probability of a fire is greater after a first burn because dieback and regrowth cause fuel loads to increase, providing fuel for subsequent higher intensity fires.
There appears to be a threshold of canopy opening, at which the landscape undergoes rapid fire-driven change towards a new state, with the original forest largely disappearing (du Toit et al. 2004).
Contact
Jacqui Meyers
Email
jacqui.meyers@csiro.au
CSIRO Sustainable Ecosystems,
PO Box 284,
Canberra ACT 2601
Keywords
adaptive management, empirical data, tropics, forests, thresholds, resilience, land-use, fire, Indonesia, Tanzania, Africa, Zimbabwe, fire, forest, deforestation, Amazon, Brazil, clearing, rainforest, empirical data
