UNH Study Published in Science
Finds Sites in Amazon Forest Are Not Absorbing Carbon as Expected
Contact: David Sims
Institute for the Study of Earth, Oceans, and Space
November 27, 2003
DURHAM, N.H. — New research, published in the Nov. 28 issue
of the journal Science, reports that some old growth forest in the
Brazilian Amazon is not taking up atmospheric carbon dioxide and,
in fact, is emitting a small amount of the greenhouse gas.
The finding is unexpected because, since 1995, reports in scientific
literature have claimed that Amazon forests are important carbon
sinks, which, in fact, might be large enough to offset the amount
of carbon being lost as a result of deforestation in the region.
The new detailed and complex study, the most comprehensive to date
in the Amazon, shows that two sites at that Tapajos National Forest
in the Brazilian Amazon are not taking up carbon.
"Our paper raises significant questions with these claims
for two measurement approaches," says co-author of the study
Michael Keller of the USDA Forest Service and the University of
New Hampshire's Institute for the Study of Earth, Oceans, and Space
(EOS). Patrick Crill of EOS and the UNH Department of Earth Sciences
also co-authored the report. Scott Saleska authored the study under
the direction of Steven Wofsy of Harvard University.
Not only does the study find a counter example to the widely held
"sink" belief, but according to Keller, the paper also
shows why both types of previous measurements might be incorrect.
"Our study points out that eddy covariance (a method of measuring
carbon exchange in and out of a forest system) just doesn't work
very well at night in tropical forests," Keller says.
The second problem, Keller asserts, is that while previous studies
of carbon sinks focus on how much trees grow, "we also estimated
the other critical parts of the forest carbon balance, including
the decomposition of dead wood." Both dead and living trees
have to be taken into account for studies to accurately assess the
carbon balance, Keller says.
Michael Keller can be reached for comments at (603) 862-4193.