5 perrakis - mpb recent obs - wfc2012wildfire/2012/pdfs/dan perrakis.pdf · 3 current mpb outbreak...
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Recent Observations of Fire Behaviour
IN
Dan Perrakis, WMB Dana Hicks, WMB Rick Lanoville, FBS Steve Taylor, NRCan, Can. For. Serv. Nathalie Lavoie, QC MRNF Mike Pritchard, WMB Rick Kubian, Parks Canada Agency
Mountain Pine Beetle- Affected Stands
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Overview • Current MPB outbreak status • Recent observations study – Rate of Spread model
• Inferences regarding Headfire Intensity
• Questions and discussion
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Current MPB Outbreak • BC: 18.1 - 20 million ha affected (2012)
• 53% of pine volume killed (2011) • Projected to reach 60 % by 2021
• AB: 6 million ha ‘at risk’ (2010) • Millions of ha in US (WA, CO, WY, etc.) • (BC) Outbreak extent decreasing from 2005-2007 peak
• Current outbreak front is NE/NW (BC), boreal (AB and rest of Canada)
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Peak Year of MPB Attack:
-Also shows where red- attack is still present
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The
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• What about fire?
• Example of extreme fire behaviour in old grey-attack long ago:
• Sleeping Child Fire (1961, Montana), burning in lodgepole pine stands affected by MPB attacks in 1928-1932.
• “In spite of rapid initial attack”, lightning fire grew to 3640 ha within 24 hours.
• credit: M. Alexander – photo in Jenkins et al. (2012)
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Recent Observations Study – 15 observations (14 modeled) • BC air attack photos (photo-interp. by R. Lanoville) – 9 fire runs • Wildfire monitoring/observation (S. Harvey & D. Hicks) – 3 runs • Experimental burns (Carrott Lake, Kootenay Nat. Park) – 3 runs
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12 wildfire ROS observations 3 PB ROS obs.
9 G40100 (2005)
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Repeated evidence for continuous crown fires in red/grey attack lodgepole pine & pine/spruce, <1 to 6 years post-MPB
C20650 (2009)
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cISIbeaROS )1( )( ×−−×=(FCFDG 1992)
⎥⎦
⎤⎢⎣
⎡
×+××= −
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31.5138.005039.0
1093.419.91208.0 meeISI mW
(Van Wagner 1987)
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ROS (m
/min)
ISI
MPB Red-‐attack observations
MPB Grey-‐attack observations
MPB Old attack observation
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ROS (m
/min)
ISI
MPB Red-‐attack observations
MPB Grey-‐attack observations
MPB Old attack observation
• MPB-attacked stands ~2.7 times faster ROS than C-3 • r2 = 0.394 • No clear pattern suggesting faster ROS in red-attack vs grey-attack • Crowning threshold of ISI ≥ 7 suggested • Somewhat similar to M-3 (60%DF) at ISI < 30
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C-3 fuel type
C-2 fuel type
• Compare with C-2, C-3 scatter plots...
• Observed vs Predicted compared with C-3 model
• Also 2 photo-interp. points in green conifer fuels (C-2, C-3)
• Suggests ok methodology
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Observed (m
/min)
Predicted (m/min)
MPB obs.
C-‐2/C-‐3 obs.
Model 1
Obs=Pred
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Headfire Intensity (kW/m
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Initial Spread Index (ISI)
FBP Fuel Type (FT):
FT Modifier (M):(if applicable)
FT:
M:
FT:
M:
FT:
M:
%Con, %cur, or %DF %C, c, DF %C, c, DF %C, c, DFGFL: t/ha
FMC: %
C6 CBH: m
• Headfire intensity?? • HFI = 300 x TFC x ROS • Compare between fuel types • M-3 (60%DF) likely ‘first guess’?
Lush green herbaceous understory
(Lower fire risk)
Absent understory (Possibly surface fire only – depends on remaining green
pines or other conifers)
Conifer understory (fast rate of spread,
high spotting potential, high intensity)
Importance of Understory Structure (Grey)
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• Legacy in BC will be grey- and old grey-attack MPB-killed stands
• e.g. Greer Creek fire (2010) • High intensity, lower ROS?
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• In sum: • ROS in 0-6 year post-MPB Pl 2.7 x faster than C-3
• No consistent difference between ROS of red- & grey-attack (but check understory, remnant live overstory)
• Crowning threshold ~ ISI 7 • No new HFI findings, but likely closer to M-3 (60%DF) than C-3
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