Analysis of Forest Fire Disturbance in the Western US Using Landsat Time Series Images: 1985-2005
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Analysis of Forest Fire Disturbance in the Western US Using Landsat Time Series Images: 1985-2005. Haley Wicklein Advisors: Jim Collatz and Jeff Masek, Goddard Space Flight Center, NASA Research and Discover Program 2008. Motivation. • Forest carbon sink: ~ 270 ± 130 Mt C / yr

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Analysis of Forest Fire Disturbance in the Western US Using Landsat Time Series Images: 1985-2005

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Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Analysis of Forest Fire Disturbance in the Western US Using Landsat Time Series Images: 1985-2005

Haley Wicklein

Advisors: Jim Collatz and Jeff Masek,

Goddard Space Flight Center, NASA

Research and Discover Program 2008


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Motivation

• Forest carbon sink:

~ 270 ± 130 Mt C / yr

• Debate about relative importance of causal factors (disturbance, land use, climate change, etc)

• Future of sink is highly uncertain

• Landsat is an important tool for environmental monitoring

The First State of the Carbon Cycle Report (2007)

King, Dilling, many others


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Objectives

  • Compare two disturbance products, identify fraction of disturbance that is fire

  • Use products to understand meteorological drivers of fire

  • Examine regrowth dynamics for fire vs. other types of disturbance


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Objective 1: Two Disturbance Maps

Monitoring Trends in

Burn Severity (MTBS)

North American Forest

Dynamics Project (NAFD)

Joint project by USGS and USFS

Maps burn severity and fire perimeter across the United States

Uses before and after Landsat images to determine severity for all fires > 1000 acres

Currently available for Pacific Northwest, CA, and parts of the Southwest

Joint project by Goddard, UMD, and USFS

Landsat based data cubes (30m res)

Annual record of forest disturbance events (logging, fire, insects, etc) from 1984-2005

Don’t distinguish between different types of disturbance

Year since disturbance

Oregon Landsat cube

Fire severity


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Disagreement between MTBS and NAFD

High

3%

Moderate

Disagreement

33%

6%

Low

8%

Unburned - Low

Agreement

67%

16%

Hash Rock Fire (2000)

MTBS

Ex: Oregon

(1985-2005)

NAFD disturbance map


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Cube Statistics


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Forest Disturbance Trends

Total Area Disturbed

Area Burned


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Objective 2: Climate Correlations

Westerling et al. (2006) found

Occurrence of Western wildfires largely governed by climate

Attributed fire to:

Warmer spring and summer temperature

Reduced precipitation

Reduced snowpack/ earlier spring snowmelt

All lead to…

Longer, drier summer fire season


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Fire Trends Correlate with Aridity Index

1=dry, 0=wet

1- (Precip/ PET)

Fire


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Objective 3:

Regrowth dynamics


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Spectral Indices: NBR and NDVI

Normalized Burn Ratio (NBR)

NIR – MIR

=

NIR + MIR

[MTBS uses dNBR = pre NBR – post NBR]

VIS

NIR

MIR

WAVELENGTH

NIR – VIS

From: rangeview.arizona.edu

=

NIR + VIS

Normalized Difference Vegetation Index (NDVI)

NBR values range from -1 (bare soil) to 1 (very green)

NDVI values range from 0 (bare soil) to 1 (very green)


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

NBR and NDVI by Severity Class

Severity Class

High

Moderate

Low

Unburned to Low

Jefferson Fire, 1996

Oregon (p45r29)

3922 acres

NBR

NDVI

*NBR and NDVI values from NAFD maps


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Spectral Recovery from Fire and Logging Disturbance

Jefferson Fire

Oregon (p45r29)

1996

3922 acres

Fire

Logging

Logging disturbance 1985


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Do NBR and NDVI Provide Useful Ecological Information?

1995 (year before fire)

1996 (year of fire)

2005(from: google earth)


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Conclusions

  • Only 7-30% of total disturbance in Western US is fire

  • Hot and dry conditions necessary, but not sufficient for fire activity

  • NDVI and NBR are good measures of timing and magnitude of disturbance, but canopy structure and height data (ex: LIDAR) is needed for useful information on ecological variables.


Analysis of forest fire disturbance in the western us using landsat time series images 1985 2005

Questions?

Special Thanks to:

Jim Collatz

Jeff Masek

Chris Williams

The Research and Discover Program


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