Characterizing Fire-on-Fire Interactions in Three Large Wilderness Areas

Fire Ecology

Table 2 Fire occurrence information and Natural Fire Rotations (NFR) in years for each of the study areas for the time period 1984–2007.

		Bob Marshall	Selway-Bitterroot	Frank Church
Number of years with large fires (yr)		13	15	23
Total number of fires (n)		59	81	187
Burnable area within study area (ha)		1 630 026	876 118	2 365 449
Area burned	Proportion of study area burned (%)	24.4	15.3	53.9
Area burned	NFR (yr)	98	157	44
Area burned only once	Proportion of study area burned (%)	23.5	14.3	46.7
Area burned only once	NFR (yr)	102	168	51
Area burned more than once	Proportion of study area burned (%)	0.9	1	7.3
Area burned more than once	NFR (yr)	2429	2353	331
Area burned in large fire years	Proportion of study area burned (%)	17.9	9.1*	42.4
Area burned in large fire years	NFR (yr)	134	263	57
Area burned in non-large fire years	Proportion of study area burned (%)	6.5	6.2*	11.5
Area burned in non-large fire years	NFR (yr)	368	386	208
Area re-burned in large fire years	Proportion of study area burned (%)	0.7	0.8*	6.5
Area re-burned in large fire years	NFR (yr)	3685	3139	371
Large fire years (>40 500 ha; ranked by most acreage burned)	Year 1	2003	2007*	2007
	Year 2	1988	1988*	2000
	Year 3	2007	2003*	1994
	Year 4			1988
	Year 5			2006

^* In the Selway-Bitterroot Wilderness Area, the 3 years with the highest annual area burned were used since more than 40 500 ha were not burned in any single year.