Fire History, Burn Severity and Monitoring

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Fire History, Burn Severity and Monitoring

• Arctic Network
• Jennifer Allen / Chuck Racine / Brian Sorbel

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Fire in the Arctic Network

• 1,222,000 acres burned in the ARCN from
  1955-2004.
• Fire occurrences vary between the parks and among
  years
• Fire occurs in a variety of community types
• Landscape and site changes

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Total acres burned by parks
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Fire Statistics by Park
PARK Avg acres/yr Avg fires/yr Largest Fire Yr (acres)
BELA 5,911 0.73 1977
CAKR 87 0.10 1987
GAAR 6,402 2.92 1969
KOVA 4,126 1.18 1971
NOAT 8,413 2.43 1977
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Vegetation community types affected
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Burn Severity GIS Products

• A more complete depiction of fires effect on a
  landscape
• Captures the mosaic nature of burn scars
• Applications
• Updating fuel model and vegetation layers
• Research and modeling

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The Normalized Burn Ratio (NBR)

• Developed by Carl Key (USGS) and Nate Benson (NPS
  FMPC)
• Compares pre-fire and post-fire Landsat scenes to
  generate a continuous index of burn severity

Range (-1000 to 1000)
Delta NBR Prefire NBR Postfire NBR
Range (-2000 to 2000)
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Landsat Pre and Postfire Views of the Herron
River Fire, DENA 2001
Pre-fire Landsat 7 6-23-01
Post-fire Landsat 7 6-17-02
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Final Perimeter Delineation Landscape Level
Burn Severity Determination
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Field Verification through the Composite Burn
Index (CBI)
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Burn severity Remote vs Ground Truth Boreal
Forests and Tundra
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Burn severity mapping

• Baseline information that can be used for
  management, monitoring, modeling and research.
• The severity of fires plays a role in vegetation
  succession, permafrost degradation, nutrient
  cycling, and water quality parameters
• Can also be used to assess the effects of climate
  changes over time.

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VEGETATION CHANGE FOLLOWING A 1977 TUNDRA FIRE AT
BELA

• Charles Racine
• Randi Jandt
• John Dennis
• Randy Meyers

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Sites 1-5 Tussock-shrub tundra
Site 8 wet sedge
Sites 6-7 Dwarf shrub tundra
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NIMROD HILL PROFILE
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NIMROD HILL MONITORING TIMES
Fire
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1 year (July 20, 1978)
6 years (July 20, 1983)
24 years (Aug 12, 2001)
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Site 3 - Footslope Tussock-Shrub Tundra
1978 (1 year)
1983 (6 years)
2001 (24 years)
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FOOTSLOPE TUSSOCK TUNDRA CHANGE IN GROWTH FORMS
(A) Sites 1, 2, and 3 EVERGREEN SHRUB (Ledum)
INCREASE
(B) Sites 4 and 5 DECIDUOUS SHRUB (Salix and
Betula) INCREASE
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Well-drained Backslope - Dwarf Shrub Tundra-
Sites 6-7
1973 Site 6
Site 6 Before Fire (1973)
1 Year After Fire (1978)
24 Years (2001)
6 Years (1983) Sedge Meadow
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Well-drained Backslope - Dwarf Shrub Tundra Site
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1 Year (1978)
2 Years (1979) Bryophyte
3 Years (1980)
6 Years (1983) Sedge Meadow
24 Years (2001)
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Back slope Dwarf Tundra
Sites 6 and 7
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BACKSLOPE DWARF SHRUB TUNDRA SPECIES CHANGES
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ARCTIC TUNDRA FIRES

• Fire produces rapid changes in physical, chemical
  and biological conditions (i.e. light, soil
  temp.and thaw, nutrients, species).
• Changes depend on the severity and frequency of
  fire.
• Other effects smoke and haze, thermokarst,
  reindeer, ORV impacts, suppression costs, fire
  lines

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Conclusions

• Tundra wildfire is a landscape-scale disturbance
  and driver in tussock and dwarf shrub tundra in
  NW Alaska.
• Fire return interval at the regional scale is
  long (250-450 years)
• Succession during past 25 years may interact with
  climate warming to accelerate change.