Immediate Changes

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Fire Severity Amount of Change Following Fire
(Percent Combusted)

• Immediate Changes
• Carbon Emissions, Tree Mortality
• Short Term Changes
• Erosion, Water Quality, Nutrient Availability
• Long Term Changes
• Future Flammability, Animal Browse

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Fire Severity Amount of Change Following Fire
(Percent Combusted)

• Reconstructed Organic Matter (CN) Pools
• Plot Scale Quantitative EffortHigh
• Composite Burn Index (CBI)
• Plot Scale Semi Quantitative EffortMedium
• Normalized Burn Ratio (NBR)
• Remote Sensing Semi Quantitative EffortLow

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Fire Severity Amount of Change Following Fire
(Percent Combusted)
How do we measure something that burned away?
4
Biomass Reconstruction

• Adventitious roots on black spruce trees grow at
  the surface of the organic soil
• Roots are still visible after fire
• Post-fire measurements can reconstruct pre-fire
  organic soil depth and C and N pools
• Aboveground tree measurements, visual estimates,
  plus allometric equations used to reconstruct
  canopy

green moss dead moss fibric humic
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Organic Soil Reconstruction
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Organic Soil Reconstruction

• Measure depth horizons of remaining post-fire
  organic soil
• Adventitious root collar height above burn
  (correct for deeper burning under trees)
• soil core samples analyzed by horizon for bulk
  density, C and N
• (burned layers reconstructed from soil
  measurements in unburned)

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Canopy Reconstruction

• Measure tree density and basal area
• Visually estimate Combustion for needles, fine
  branches, coarse branches and cones
• Black spruce allometric equations used to
  estimate quantity of canopy fine fuels
• 50 C
• 0.4 - 1 N

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Composite Burn Index (CBI)

• A scaled index to visually
• quantify and standardize
• fire effects over large
• areas.
• Five strata
• CBI scale
• Low (0.5-1)
• Moderate (1.0-2.0)
• High (2.0-3.0)

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How does CBI compare to combustion estimates?

• Mean combustion was 64

• CBI significantly
• positively related to
• mass combustion

• CBI better correlated with organic soil
  combustion

10
How does CBI compare to C emissions?

• mean canopy and soil C emissions were 0.4 and
  1.5 kg/m2

• CBI significantly
• positively related to
• C lost

• CBI better correlated
• with organic soil C emissions

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How well does CBI correlate with our fire
severity estimates?
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Summary

• Adventitious root method is a good proxy for
  pre-fire organic soil height
• Correct adventitious root measurements for deeper
  burning at tree, and for offset between root and
  organic soil surface height
• CBI is a great estimator of mass lost, and
  pretty good for C emissions
• CBI is a better predictor for organic soil mass
  and C emissions, explaining from 45-64 of the
  variation

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2 Upland Black Spruce Burns

• Yukon Charley 1999
• Fire start mid-June
• NBR 9-Sept
• CBI-NBR trend
• R2 0.81, n32
• R2 0.64, n47

• Boundary 2004
• Fire start mid-June
• NBR 6-Sept
• CBI-NBR trend
• R2 0.30, n32
• R2 0.43, n28
• R2 0.29, n73

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dNBR 797
dNBR 672
dNBR 913
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Lessons Learned

• Remote sensing estimates best across wide range
  of severity
• Unreliable to estimates at high fire severity
• Estimates should be calibrated by vegetation type
  
• Solar elevation/topography problems

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Field Estimates CBI (0 to 3)
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How do we measure something that burned away?
Using the adventitious root method to measure
fire severity
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Measurementsat burned sites understory
Measurementsat unburned sites understory

• Depth of post-fire organic soil including
  horizons
• adventitious root collar height above burn
• soil core samples analyzed by horizon for bulk
  density, C and N

Adventitious root offset Distance between high
adventitious root and green moss
1. Dead moss
2. Fibric
3. Humic
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1. Green moss
2. Brown moss
3. Fibric
4. Humic
unburned sites four horizons
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Does the adventitious root method work?

• Root collar height corresponds to organic soil
  height
• add 3.2 cm
• pre-fire organic soil
• depth post-fire depth Root collar height
  Root Collar offset

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Adventitious root height

• Adventitious roots on black spruce trees grow at
  the surface of the organic soil
• Roots are still visible after fire
• We can reconstruct pre-fire organic soil depth
  and C and N pools

Adventitious roots
Moss
Adventitious root height Depth of post-fire
soil organic layer Pre-fire soil organic layer
depth
Fibric
Humic
Mineral soil