A cautionary note regarding the use of cumulative burnt areas for the determination of fire danger index breakpoints
Document Type: Journal
Author(s): Francois Pimont ; Julien Ruffault ; Nicolas K. Martin-StPaul ; Jean-Luc Dupuy
Publication Year: 2019

Cataloging Information

  • fire activity
  • fire danger index
  • France
  • live fuel moisture content
  • International
Record Maintained By:
Record Last Modified: March 20, 2019
FRAMES Record Number: 57481


Identifying the links between fire danger metrics and fire activity is critical in various operational and research fields. A common methodology consists in analysing the relationship between cumulative burnt areas and fire danger metrics. Building on this approach, it has been proposed that fuel moisture content (FMC) drives fire activity in some ecosystems through between one and three breakpoints corresponding to the onset or saturation of fire activity. We demonstrate, through two different approaches, that this methodology is incorrect, because it is biased by the frequency distribution of FMC values. From comparison with a neutral fire distribution and correction for the frequency bias, we show that cumulative burnt area breakpoints are spurious: an upper breakpoint might exist (but would be higher than expected), while no evidence of reduced fire danger was detected for the lowest values of FMC (on the contrary, a secondary increase was detected). Our findings clearly suggest that previous breakpoints resulting from this methodology should be considered with caution, as erroneous conclusions regarding fire danger breakpoints could have major consequences for both fire safety and science outcomes. Finally, we discuss widespread confusion between fire danger breakpoints and fire danger levels, which explains most previous erroneous conclusions.

Online Link(s):
Pimont, Francois; Ruffault, Julien; Martin-StPaul, Nicolas K.; Dupuy, Jean-Luc. 2019. A cautionary note regarding the use of cumulative burnt areas for the determination of fire danger index breakpoints. International Journal of Wildland Fire 28(3):254-258.