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 moss dead moss fibric 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 % N Canopy Reconstruction

A scaled index to visually quantify and standardize fire effects over large areas. Five strata CBI scale: Low (0.5-1) Moderate ( ) High ( ) Composite Burn Index (CBI)

How does CBI compare to % combustion estimates ? Organic soil Canopy R 2 = 0.63, P<0.001 R 2 = 0.14, P<0.02 Mean combustion was 64% CBI better correlated with organic soil combustion %mass combustion Total CBI scores CBI significantly positively related to % mass combustion

How does CBI compare to C emissions? CBI significantly positively related to % C lost CBI better correlated with organic soil C emissions mean canopy and soil C emissions were 0.4 and 1.5 kg/m 2 Organic soil Canopy R 2 = 0.44, P<0.001 R 2 = 0.14, P<0.03

How well does CBI correlate with our fire severity esti mates?

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: R 2 = 0.81, n=32 R 2 = 0.64, n=47 Boundary 2004 Fire start mid-June NBR 6-Sept CBI-NBR trend: R 2 = 0.30, n=32 R 2 = 0.43, n=28 R 2 = 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?

Measurements at burned 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] 1. Dead moss 2. Fibric 3. Humic Measurements at unburned sites: understory Root collar height Adventitious root offset: Distance between high Distance between high adventitious root and adventitious root and green moss green moss

Mineral soil unburned sites four horizons: 3. Fibric 4. Humic 2. Brown moss 1.Green moss 1. Green moss

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 > 0 0 <0 to -1 <-1 to -2<-2 to -3<-3 to -4 <-4 to -5 <-5 to -6 <-6 to Frequency 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 Humic Mineral soil Adventitious root height Adventitious roots Brown Moss Fibric Humic Mineral 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