NASA Studies True Colors of Evergreen Rain Forests

Ruth Dasso Marlaire
NASA Ames Research Center, Moffett Field, Calif. March 12,
2007
650-604-4709
rmarlaire@xxxxxxxxxxxxxxxxx

Kira Edler
Boston University, Boston, Mass.
617-358-1240
kedler@xxxxxx

RELEASE: 07-11AR

NASA STUDIES TRUE COLORS OF EVERGREEN RAIN FORESTS

NASA satellites reveal that Amazon forests are neither evergreen nor
dependent on constant rain, and are capable of manufacturing their
seasons.

Researchers report a 25 percent increase in the amount of green leaf
area
during the dry season when the skies are relatively clear. They found
that
the rain forests are more dependent on light than rain, enduring
several
months of dry season by tapping water deep in the soil with their
long
roots. The results of this NASA-funded research will appear in the
March 20
issue of the Proceedings of the National Academy of Sciences.

"Our finding is similar to the discovery of a large green continent,
nearly
a third the size of South America, appearing and disappearing each
year,"
explained Ranga Myneni, professor of geography and environment at
Boston
University, the lead author of this study. "This has very important
consequences for weather, atmospheric carbon, water and nutrient
cycling,
given that leaves are the air purifiers and food factories of our
planet,"
Myneni added.

The Amazon rain forest covers an area equivalent to more than half of
the
continental United States and is home to more than one-third of all
living
species on Earth.

Scientists used satellite images to study the amount and dynamics of
green
leaf area of Amazon rain forests. This study was made possible by more
than
five years of daily estimates of leaf area over the entire Amazon
basin at
one- kilometer resolution with the Moderate Resolution Imaging
Spectroradiometer aboard the NASA Terra satellite, by a team of 27
individuals from 15 different institutions.

The researchers report that the rain forests sprout new leaves in
anticipation of the coming dry season. The greener forests capture
more
sunlight, absorb more carbon dioxide and evaporate more water during
the
dry season compared to the wet season, according to scientists. By
gradually humidifying the atmosphere, the forests play an integral
role in
the onset of the wet season, scientists observed.

"This work is an important outcome of over 10 years of NASA's
investments
and teamwork to develop, build and launch state-of-the art sensors
and
processing algorithms enabling the discovery of hitherto unknown
vegetation
dynamics on Earth," added Rama Nemani, a co-author of the paper at
NASA
Ames Research Center, Moffett Field, Calif.

This work was made possible through funding by NASA as part of a long-
term
research program dedicated to understanding how human-induced and
natural
changes affect our global environment.

For more information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/home

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