32 SCIENCE NEWS | March 13, 2021SCIENCE VISUALIZEDEach year in California, wildfires ravage
hundreds of thousands of hectares of land. Deci-
phering how well large swaths of vegetation
recover over time can be tough from the ground.
Radar maps now reveal the patchwork of plant
destruction and regrowth in the wake of more
than a decade of fires near Los Angeles.
A NASA research plane equipped with radar
instruments flew over Angeles National Forest
many times from 2009 to 2020 to produce a
detailed view (shown) of the terrain. The radar
pulses are sensitive to moisture and changes
in physical features, says Yunling Lou , a radar
engineer at NASA’s Jet Propulsion Laboratory
in Pasadena, Calif. The resulting maps distin-
guish bare earth from trees and shrubs.
Lou and colleagues are color-coding maps
by year to monitor the recovery of forests and
shrubland after wildfires. Red denotes areas
with vegetation in 2010, green is 2017 and blue
is 2020. When maps for those three years are
laid atop each other, they tell a story of loss and
regrowth. After fires in 2014 and 2016, vegeta-
tion had not grown back by 2017 or 2020, so
those areas appear red. The bright yellow tract
shows the area affected by the 2020 Bobcat
Fire , where vegetation was present only in 2010
and 2017 (red and green make yellow ). Green
and blue regions show areas with more plant
growth in recent years.
The color-coding could allow researchers to
identify factors, such as vegetation and soil type,
that explain why areas regenerate at different
speeds. Such maps could also potentially be
used to identify burned regions without vegeta-
tion that are at risk for landslides. — Jack J. LeeA colorful story of
wildfire recoveryJOSHUA STEVENS/NASA EARTH OBSERVATORY
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