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Recent Observations of Fire Behaviour

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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

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ISI

MPB  Red-­‐attack  observations

MPB  Grey-­‐attack  observations

MPB  Old  attack  observation

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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

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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