Quantifying local fire regimes using the Landsat data-archive: a conceptual framework to derive detailed fire pattern metrics from pixel-level information

Figures & data

Figure 1. Fire sample across the boreal plains ecozone.

Table 1. Physical and biological characteristics of the ecoregions with 30 or more fires within the BP ecozone. Based on the Terrestrial Ecozones of Canada (Wiken 1986).

Ecoregion name	Ecoclimate	Mean temperatures for year/summer/winter (°C)	Precipitation (mm)	Vegetation	Topography	Remarks	N of fires in the sample
Slave River Lowlands (SRL)	Sub humid mid-boreal	−2/13/−17	300–400	Closed stands of trembling aspen, balsam poplar, and jack pine with white and black spruce, and balsam fir in late successional stages. Tamarack and black spruce dominate fens and bogs with ericaceous shrubs and mosses	Flat to gently rolling	50% of the area is peatlands	38
Clear Hills Upland (CHU)	Sub humid mid-boreal	−1/13/−17	400–600	Lodgepole pine with white spruce and fir in the uplands. Black spruce dominates in the poorly drained valley bottoms	Steep to gently rolling	Ecotone between boreal and cordilleran vegetation	30
Mid-Boreal Uplands (MBU)	Sub humid mid-boreal	−1/14/−14	400–550	Closed stands dominated by trembling aspen with balsam poplar with understory of tall shrubs and herbs. White and black spruce, and balsam fir occur in late successional stages. Deciduous stands have and understory of tall shrubs and herbs while coniferous have feathermoss. Tamarack and black spruce dominate fens and bogs	Flat to gently rolling	Accounts for most area burnt in BP (Parisien et al. 2004)	275
Wabasca Lowland (WL)	Sub humid mid-boreal	1/13/−13	350–500	Closed stands of trembling aspen and balsam poplar. White and black spruce, and balsam fir, occur in late successional stages. Tamarack and black spruce dominate fens and bogs	Flat to gently rolling	50% of the area is peatlands	53
Western Alberta Upland (WAU)	Sub humid mid-boreal	1.5/12/−10	450–600	Closed stands dominated by lodgepole pine, trembling aspen and white spruce with some balsam poplar, paper birch and balsam fir. Drier sites are most often covered by stands of aspen or open lodgepole pine forest; while on wet sites tamarack and black spruce are more prevalent. Higher elevations of the foothills are dominated by conifers and lower plains with aspen	Flat to gently rolling	Ecotone between mid-boreal and mid-cordilleran vegetation	35
Mid-Boreal Lowland (MBL)	Sub humid mid-boreal	−1/13/−17	375–625	Closed stands of trembling aspen, balsam poplar, and jack pine with white and black spruce, and balsam fir in late successional stages. Black spruce and willows dominate fens and bogs	Flat	50% wetlands	51

Figure 2. Analysis workflow.

Figure 3. Process to derive a disturbance event.

Notes: The top thumbnail represents the difference between pre- and post-fire composites, where the red channel corresponds to the difference in Landsat NIR band (4 in TM and 5 in OLI), the green channel to the difference in the SWIR 1 band (5 in TM and 6 in OLI) and the blue channel the difference in the SWIR 2 band (7 in TM and OLI). The middle thumbnail represents the three-class mortality map from the RF classifier, where green corresponds to unburned, yellow to partial mortality and red complete mortality. The bottom figure corresponds to the disturbance event by Andison (2012), where red corresponds to disturbed, yellow to IR and dark green to MR (colour online only).

Table 2. Description of the seven fire pattern metrics calculated on the disturbance events. Based on Andison (2012).

Type	Metric [unit]	Acronym	Formula	Interpretation
Event	Event area [ha]	EA	MR + IR + disturbed	Size of the event
	Shape index [no units]	SI	Total perimeter of the disturbance event/perimeter of a square with area of EA	Complexity of the perimeter
Within-event	Percentage of matrix remnants [%]	%MR	(Total area of MR/EA) × 100	Percentage of residuals physically attached to the surrounding matrix of intact forest
	Percentage of island remnants [%]	%IR	(Total area of IR/EA) × 100	Percentage of residuals lying entirely within disturbed patches
	Percentage of total remnants [%]	%TR	((Total area of IR + total area of MR)/EA) × 100	Percentage of vegetation that survives in some form
	Number of disturbed patches [patches]	NDP	Number of patches resulting of the combination of IR and disturbed classes	Total number of disturbed patches per event
	Percentage largest disturbed patch [%]	%LPD	(Area of the LDP/EA) × 100	Size variability of disturbed patches

Figure 4. Number of observations per pixel for the image compositing averaged by individual fires.

Figure 5. Time difference (days) for the image compositing averaged by individual fires.

Notes: ‘Median’ corresponds the distance in days between the selected median pixel and a hypothetical fire occurring the 1st of August of the fire year reported in the fire history databases. ‘Closest’ is the nearest observation in days from a hypothetical fire occurring the 1st of August of the fire year.

Figure 6. Summary of the screening process.

Figure 7. Summary boxplots of the comparison between ecoregions.

Figure 8. Spyder plot grouped by fire pattern metric and significant differences in the cumulative distribution functions by ecoregion pairs (in box).

Notes: The spyder plots are calculated using the median of each metric. The maximum and minimum values for each metric correspond to the maximum and minimum ecoregion values for each metric. EA is event area; SI is the shape index; %TR is the percentage of remnant islands; %IR is percentage of island remnants; %MR is the percentage of matrix remnants; NDP is the number of disturbed patches; and %LDP is the percentage of the largest disturbed patch. ALL stands for all fires combined; MBU for Mid-Boreal Uplands; WL for Wabasca Lowland; MBL for Mid-Boreal Lowlands; SRL for Slave River Lowlands; WAU for Western Alberta Uplands; and CHU for Clear Hills Uplands. The significant differences by the combination of WX and the KS tests at the .01 significance are represented in the box at the right hand side.

Figure 9. Spyder plot by ecoregion.

Notes: The spyder plots are calculated using the median of each metric. The maximum and minimum values for each metric correspond to the maximum and minimum ecoregion values for each metric. EA is event area; SI is the shape index; %TR is the percentage of remnant islands; %IR is the percentage of island remnants; %MR is the percentage of matrix remnants; NDP is the number of disturbed patches; and %LDP is the percentage of the largest disturbed patch.

Wiken, E. B. (comp.). 1986. Terrestrial Ecozones of Canada. Ecological Land Classification Series No. 19. Environment Canada, Hull, QC. 26 p. + map.

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Parisien, M. A., K. G. Hirsch, S. G. Lavoie, J. B. Todd, and V. G. Kafka. 2004. Saskatchewan Fire Regime Analysis. Edmonton, AB: Canadian Forest Service Information Report NOR-X-194.

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Andison, D. W. 2012. “The Influence of Wildfire Boundary Delineation on Our Understanding of Burning Patterns in the Alberta Foothills.” Canadian Journal of Forest Research 42: 1253–1263. doi:10.1139/x2012-074.

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