PE&RS February 2015 - page 143

Vegetation Burn Severity Mapping Using
Landsat-8 and WorldView-2
Zhuoting Wu, Barry Middleton, Robert Hetzler, John Vogel, and Dennis Dye
We used remotely sensed data from the Landsat-8 and
WorldView-2 satellites to estimate vegetation burn severity of
the Creek Fire on the San Carlos Apache Reservation, where
wildfire occurrences affect the Tribe’s crucial livestock and
logging industries. Accurate pre- and post-fire canopy maps
at high (0.5-meter) resolution were created from World-
View-2 data to generate canopy loss maps, and multiple
indices from pre- and post-fire Landsat-8 images were used
to evaluate vegetation burn severity. Normalized difference
vegetation index based vegetation burn severity map had the
highest correlation coefficients with canopy loss map from
WorldView-2. Two distinct approaches - canopy loss map-
ping from WorldView-2 and spectral index differencing from
Landsat-8 - agreed well with the field-based burn severity
estimates and are both effective for vegetation burn severity
mapping. Canopy loss maps created with WorldView-2 im-
agery add to a short list of accurate vegetation burn severity
mapping techniques that can help guide effective manage-
ment of forest resources on the San Carlos Apache Reserva-
tion, and the broader fire-prone regions of the Southwest.
The more frequent and severe droughts projected for the
arid and semi-arid southwestern United States (US) over the
coming decades (Overpeck and Udall, 2010; Seager
et al
2007) put the vast carbon stocks of the southwestern forests
and woodlands at risk (Breshears
et al
., 2005; Wu
et al
., 2011)
and may trigger a potential, positive feedback that contrib-
utes to further, ongoing climate change (Cox
et al
., 2000).
The increasing vulnerability of the region to major wildfires
is a major factor in the ecosystem-climate interactions that
underlie these changes. Due to variability in abiotic and biotic
conditions, wildfires usually burn across the landscapes
heterogeneously, therefore creating areas and patches with
various burn severities (Krawchuk
et al
., 2006; Turner
et al
1999; Turner and Romme, 1994). Pinyon - juniper woodlands
and ponderosa pine forests are the most prevalent forest types
in the southwestern US (Hicke
et al
., 2007), and can serve as
model systems to understand the effects of fire and interac-
tions of land management decisions.
Historically, fire regimes of the southwestern US were low
intensity surface fires (Swetnam and Baisan 1996). Human ac-
tivities such as livestock grazing, fire suppression, and logging
have dramatically altered the forest conditions in the South-
west (Allen
et al
., 2002), rendering these forests susceptible to
large and destructive crown fires with significant consequenc-
es for ecological and human communities (Covington and
Moore, 1994). The southwestern US is expected to experience
further warming and drying as a result of changing climatic
conditions (Seager
et al
., 2007). Increasing aridity is likely to
lead to increasing moisture stress in plants and more frequent
fire events (Fischlin
et al
., 2007), and elevated temperatures
will further exacerbate this problem (Westerling and Bryant,
2008). Fire consumes vegetation biomass, facilitates grassland
expansion, and therefore has major short-term impacts at the
regional scale. Large fires were associated with dry years pre-
ceded by one or more wet years (Swetnam and Baisan, 1996),
and the timing of the monsoon rainfall drives grass biomass
and fuel accumulation in the semi-arid southwestern US. Fire
and climate change can act together causing shifts in regional
vegetation distribution, species composition, and land cover
type conversions, with ecological and economic consequences.
For example, loss of grassland as a result of fire suppression
has great economic and ecological implications due to their
function in soil conservation, wildlife, and livestock produc-
tion (Moir
et al
., 2000; Whitford, 1997). In addition, land man-
agement practices, especially fire suppression, shape landscape
homogeneity, thereby changing the ecosystem structure.
On the San Carlos Apache Reservation in east-central Ari-
zona, as across much of the western US, fire suppression and
other factors have led to overstocked forests and woodlands,
and woodland encroachment into grasslands. In an effort to
retain traditional relationships with the land, the San Carlos
Apache Tribe is working to restore the land to approximate
pre-European settlement conditions using a combination of
mechanical thinning and prescribed burning. Prescribed fire
and managed wildland fires are cost-effective treatments,
but successful outcomes depend on many biotic and abiotic
factors that change over time and space. Restoring the historic
fire return interval in forests and woodlands with the current
unnaturally high fuel loads in times of prolonged drought is a
challenge on the San Carlos Apache Reservation. Thus, timely
and accurate fire burn severity mapping can help highlight
vulnerable areas that were subjected to high burn severity,
and therefore direct restoration efforts, and monitoring of
post-fire recovery at the landscape scale.
Burn severity describes the biomass consumption from fire,
and sometimes is subdivided into vegetation burn severity
Zhuoting Wu is with the US Geological Survey, Western Geo-
graphic Science Center, Flagstaff, AZ; and the Merriam-Pow-
ell Center for Environmental Research, Northern Arizona
University, Flagstaff, AZ 86001 (
Barry Middleton, John Vogel, and Dennis Dye are with the
US Geological Survey, Western Geographic Science Center,
Flagstaff, AZ 86001.
Robert Hetzler is with the Bureau of Indian Affairs, San Carlos
Agency, San Carlos, AZ.
Photogrammetric Engineering & Remote Sensing
Vol. 81, No. 2, February 2015, pp. 143–154.
© 2014 American Society for Photogrammetry
and Remote Sensing
doi: 10.14358/PERS.81.2.143
February 2015
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