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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. - PowerPoint PPT Presentation
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• Immediate Changes
Carbon Emissions, Tree Mortality
• Short Term Changes
Erosion, Water Quality, Nutrient Availability
• Long Term Changes
Future Flammability, Animal Browse
• Immediate Changes
Carbon Emissions, Tree Mortality
• Short Term Changes
Erosion, Water Quality, Nutrient Availability
• Long Term Changes
Future Flammability, Animal Browse
Fire Severity: Amount of Change Following Fire (Percent Combusted)
• Reconstructed Organic Matter (C&N) Pools
Plot Scale; Quantitative; Effort=High
• Composite Burn Index (CBI)
Plot Scale; Semi Quantitative; Effort=Medium
• Normalized Burn Ratio (NBR)
Remote Sensing; Semi Quantitative; Effort=Low
• Reconstructed Organic Matter (C&N) Pools
Plot Scale; Quantitative; Effort=High
• Composite Burn Index (CBI)
Plot Scale; Semi Quantitative; Effort=Medium
• Normalized Burn Ratio (NBR)
Remote Sensing; Semi Quantitative; Effort=Low
Fire Severity: Amount of Change Following Fire (Percent Combusted)
How do we measure something that burned away?
Fire Severity: Amount of Change Following Fire (Percent Combusted)
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 mossdead mossfibric humic
Mean offset between adv. root
and moss surface = 3.2 ± 0.3 cm
Adventitious root
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)
Organic Soil 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
Canopy Reconstruction
• A scaled index to visuallyquantify and standardizefire effects over largeareas.
• Five strata
• CBI scale: Low (0.5-1)Moderate (1.0-2.0)High (2.0-3.0)
Composite Burn Index (CBI)
How does CBI compare to
%combustion estimates?
Organic soil Canopy
R2= 0.63, P<0.001R2= 0.14, P<0.02
• Mean combustion was 64%
• CBI better correlated with organic soil combustion
0
20
40
60
80
100
1 1.5 2 2.5 3
%m
ass
com
bu
stio
n
Total CBI scores
• CBI significantlypositively related to % mass combustion
How does CBI compare to C emissions?
• CBI significantlypositively related to % C lost
• CBI better correlatedwith organic soil C emissions
• mean canopy and soil C emissions were 0.4 and 1.5 kg/m2
0
2
4
6
8
1 1.5 2 2.5 3
C e
mis
sion
s kg
/m2
Total CBI score
Organic soil
Canopy R2= 0.44, P<0.001
R2= 0.14, P<0.03
How well does CBI correlate with our fire severity estimates?
measurement CBI Equation R2 P- value Organic soil % mass combustion Total -39.7 + 45.0 (CBI- Tot) 0.63 <.0001 Understory (U) -13.0 + 34.7 * (CBI - U) 0.63 <.0001
% C combustion Total -66.3 + 52.56 * (CBI- Tot ) 0.54 <.0001
Understory (U) -36.6 + 41.1 * (CBI - U) 0.56 <.0001 C emissions (kg/m2) Total -3.0 + 2.60 * (CBI- Tot) 0.44 <.0001 Understory (U) -1.42 + 1.97 * (CBI - U) 0.43 <.0001 Tree canopy fine % mass combustion Total 34.3 + 16.51 * (CBI- Tot) 0.14 0.02 fuels Overstory (O) 9.6 + 2.83 * (CBI- O) 0.44 <.0001 (branches, needles, % C combustion Total 48.6 + 14.15 * (CBI- Tot) 0.15 0.02 cones) Overstory (O) 8.39 + 28.7 * (CBI- O) 0.44 <.0001 C emissions (kg/m2) Total -0.25 + 0.28 * (CBI Tot) 0.14 0.03 Overstory (O) -0.74 + 0.45 * (CBI - O) 0.27 0.002 Ecosystem % mass combustion Total -37.0 + 43.9 *(CBI – Tot) 0.64 <.0001 % C combustion Total -61.1 + 50.6 * (CBI - Tot) 0.56 <.0001 C emissions (kg/m2) Total -3.26 + 2.85 * (CBI - Tot) 0.45 <.0001
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
2 Upland Black Spruce Burns
Yukon Charley 1999
• Fire start mid-June• NBR 9-Sept
CBI-NBR trend:• R2 = 0.81, n=32• R2 = 0.64, n=47
Boundary 2004
• Fire start mid-June• NBR 6-Sept
CBI-NBR trend:• R2 = 0.30, n=32• R2 = 0.43, n=28• R2 = 0.29, n=73
dNBR = 797dNBR = 672
dNBR = 913
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
Field Estimates : CBI (0 to 3)
Using the adventitious root method to measure fire severity
How do we measure something that burned away?
MeasurementsMeasurementsat burned sites: at burned sites:
understoryunderstory• 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]
1. Dead moss1. Dead moss
2. Fibric2. Fibric
3. Humic3. Humic
MeasurementsMeasurementsat unburned sites: understoryat unburned sites: understory
Root collar height
Adventitious root offset:Adventitious root offset: Distance between high Distance between high adventitious root andadventitious root and green mossgreen moss
Mineral Mineral soilsoil
unburned sitesunburned sitesfour horizons:four horizons:
3. Fibric3. Fibric
4. Humic4. Humic
2. Brown moss2. Brown moss
1.1. Green mossGreen moss
• Root collar height corresponds to organic soil height
• add 3.2 cm
• pre-fire organic soildepth= post-fire depth + Root collar height + Root Collar offset
> 0 0
<0
to -
1
<-1
to -
2
<-2
to -
3
<-3
to -
4
<-4
to -
5
<-5
to -
6
<-6
to 0
2
4
6
8
Frequ
ency
Root collar offset values (cm)
Does the adventitious root method work?
+Adventitious root height
+ Depth of post-fire soil organic layer
= Pre-fire soil organic layer depth
Moss
Fibric
HumicMineral
soil
Adventitious root height
Adventitious roots
Brown Moss
FibricHumicMineral
soil
Green Moss
• 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