Remote Sensing Tools for

Post-fire Assessments

Jay Miller

US Forest Service

Pacific Southwest Region

Fire and Aviation Mgmt.

What are we mapping?

“Severity”

“The degree to which a site has been

altered or disrupted by fire; loosely, a

product of fire intensity and

residence time.” -- National Wildfire Coordinating Group

The particular metric measured is dependent

upon the resource of interest, e.g. fauna

flora, soils, cultural, etc.

Parsons, A., Robichaud, P.R., Lewis, S.A., Napper, C. and Clark,

J.T. (2010). Field guide for mapping post-fire soil burn severity.

USDA Forest Service, Rocky Mountain Research Station, Fort

Collins, CO. General Technical Report. RMRS-GTR-243.

• Little to no effective ground cover remaining after fire (less than 20%). All or most litter and duff has been consumed, only ash or bare soil (ash blown away) remain. Little to no potential for leaf- or needle-cast.

• Soil surface black, brown, or reddish beneath ash.

• Soil structure weakened due to consumption of fine roots and organics.

• Canopy foliage scorched but

generally not completely

consumed. Needles or leaves

remain on trees (significant

potential for needle-cast to

provide mulch).

fire (conversion of forest to non-forest) is perceived to be “ ” severity

“Stand-replacement fire regime (applies to forests, woodlands, shrublands, and grasslands) - Fire kills aboveground parts of the dominant vegetation, changing the aboveground structure substantially.”

Brown, J.K. & Smith, J.K. (Eds.) (2000). Wildland fire in ecosystems: effects of fire on flora, RMRS-GTR-42-vol. 2. Ogden, UT: USDA Forest Service, Rocky Mountain Research Station.

• But, is grassland or sprouting shrub stand-replacing fire high or low severity? It depends on how you define “severity”.

• Primary Satellite has been Landsat 5 – Wavelengths used (bands 4 & 7) are

primarily sensitive to changes in

, , , and

– Pixel size is – 16 day revisit schedule

NOTE: Landsat 5 was launched in 1984. TM sensor

experienced a fatal failure in Nov 2011. Landsat 8 to be

launched in January 2013 (planned).

May not detect

effects due to low

intensity surface fire

under dense tree

canopies.

Effects are averaged

over 30m pixels which

can lead to “mixed”

effects

Unable to distinguish

between overstory

and understory

effects in areas of

open tree canopies.

Prefire NBR – Postfire NBR =

• Correlated to the amount of live pre-fire biomass

(Soil Burn Severity)

• May need to be calibrated for each fire –categorical data are often a result of an analyst examining the image without any knowledge of ground conditions

= -

= dNBR/sqrt(Prefire)

• Better for showing in heterogeneous

landscapes (stand-replacing fire will be classed as high severity regardless of stand density)

• Calibrations – Based upon data from California

• Severity maps derived from dNBR and RdNBR will be similar when pre-fire cover is relatively homogeneous.

The three national level

severity mapping programs

USDA Forest Service

Remote Sensing Applications Center (RSAC)

Salt Lake City, UT

USGS

Center for Earth Resources Observation and Science (EROS)

Sioux Falls, SD

– Primarily an assessment of soil effects

assessments – Must be completed within 2 weeks of containment

• Images may be acquired while smoke is in the air

– Satellites other than Landsat may be used • May use different combination of wavelengths

• Pixel size may be larger than 30m

is usually used to derive categorical data • BARC – Burned Area Reflectance Classification

– Categories – visually interpreted by an analyst

– Continuous 0-256 can be recoded by BAER team to match severity observed in the field

http://www.fs.fed.us/eng/rsac/baer/

– Forest Service only, supports reforestation planning

– Fires >1000 ac of forested land burned

• National: 2007 through present

• FS Pacific SW Region: 2000 through present

assessments: Objective is to provide data within 30 days after containment

based products

• Categorical and continuous, calibrated to CBI, % change in

canopy cover, and % change in Basal Area (BA)

• Summary statistics: >50 % change in BA stratified by

vegetation type

– National program uses Landfire vegetation

– FS Pacific SW Region - CALVEG

http://www.fs.fed.us/postfirevegcondition/index.shtml

– Fires >1000 ac in western US, 500 ac in eastern US 1984 through present

– Primarily assessments (1 year post-fire)

– Grasslands, non-sprouting shrublands are mapped with initial assessments

– Categorical data are derived using same methods as BAER

• Analyst interpreted categories

– Continuous data are available, both dNBR and RdNBR

http://mtbs.gov/

“Subsequent to dNBR derivation, the process of developing fire severity

and perimeter maps becomes much more dependent on analyst

interpretation.”

“The analyst evaluates the dNBR data range and determines where

significant thresholds exist in the data to discriminate between severity

classes.”

“Thresholding dNBR data into thematic class values results in an intuitive

map depicting a manageable number of ecologically significant

classes. There are uncertainties in this approach stemming from analyst

subjectivity and limited or no plot data to guide threshold

selection. Ecological significance is issue dependent and one set of

thresholds cannot be expected to apply equally well to all analysis

objectives and management issues.”

http://mtbs.gov/methods.html August 7, 2012

• Fires 1984 – 2011

– Almost all fires > 1000 ac

that occurred at least

partially on NF lands (some

fires smaller than 1000 ac)

– Perimeters

– RdNBR calibrated to

Composite Burn Index

(CBI)

– % change in canopy cover

or basal area are available

upon request (not online)

http://www.fs.usda.gov/wps/portal/fsinternet/main/r5/landmanagement/gis

Fire still active

in this location

Fire still active

in this location

2002 Hayman August 24, 2001 September 15, 2003

2002 Hayman

MTBS

Published Oct 2010

High Threshold: 480

RdNBR

based upon published thresholds

MTBS

Published April 2012

High Threshold 350

• Keeley, J.E. (2009). Fire intensity, fire severity and burn severity: a brief review and suggested usage.

International Journal of Wildland Fire 18(1): 116-126.

• Key, C.H. (2006). Ecological and sampling constraints on defining landscape fire severity. Fire Ecology 2(2): 34-

59.

• Key, C.H. and Benson, N.C. (2006). Landscape assessment: ground measure of severity, the Composite Burn

Index. FIREMON: Fire Effects Monitoring and Inventory System. D. C. Lutes, Ed. Fort Collins, CO, USDA Forest

Service, Rocky Mountain Research Station. General Technical Report, RMRS-GTR-164-CD: LA8-LA15.

• Key, C.H. and Benson, N.C. (2006). Landscape assessment: remote sensing of severity, the Normalized Burn

Ratio. FIREMON: Fire Effects Monitoring and Inventory System. D. C. Lutes, Ed. Fort Collins, CO, USDA Forest

Service, Rocky Mountain Research Station. General Technical Report, RMRS-GTR-164-CD: LA25-LA41.

• Eidenshink, J., Schwind, B., Brewer, K., Zhu, Z.-L., Quayle, B. and Howard, S. (2007). A project for monitoring

trends in burn severity. Fire Ecology 3(1): 3-21.

• Lentile, L.B., Holden, Z.A., Smith, A.M.S., Falkowski, M.J., Hudak, A.T., Morgan, P., Lewis, S.A., Gessler, P.E.

and Benson, N.C. (2006). Remote sensing techniques to assess active fire characteristics and post-fire effects.

International Journal of Wildland Fire 15(3): 319–345.

• Miller, J.D. and Thode, A.E. (2007). Quantifying burn severity in a heterogeneous landscape with a relative version

of the delta Normalized Burn Ratio (dNBR). Remote Sensing of Environment 109(1): 66-80.

• Miller, J.D., Knapp, E.E., Key, C.H., Skinner, C.N., Isbell, C.J., Creasy, R.M. and Sherlock, J.W. (2009).

Calibration and validation of the relative differenced Normalized Burn Ratio (RdNBR) to three measures of fire

severity in the Sierra Nevada and Klamath Mountains, California, USA. Remote Sensing of Environment 113(3):

645-656.

• Parsons, A., Robichaud, P.R., Lewis, S.A., Napper, C. and Clark, J.T. (2010). Field guide for mapping post-fire soil

burn severity. USDA Forest Service, Rocky Mountain Research Station, Fort Collins, CO. General Technical

Report. RMRS-GTR-243.