44-TV-01
FOR IMMEDIATE RELEASE
OLD-GROWTH AMAZON TROPICAL FORESTS LIVE LONGER, MORE IMPORTANT TO CONTROLLING ATMOSPHERIC CARBON DIOXIDE
Amazon Study May Have Impact on Kyoto Protocol Provisions
Irvine, Calif., March 21, 2001 -- Trees in old-growth tropical forests in the Amazon region of Brazil live longer than previously thought, which adds to their importance in the effort to control increases in atmospheric carbon dioxide, UC Irvine researchers have found.
Jeffrey Chambers and Susan Trumbore of UCI's Department of Earth System Science, working with Brazilian researchers, used a combination of radiocarbon dating and long-term observations of forest growth to study the life cycles of trees in old-growth forests near Manaus, Brazil. A surprising result of their study was that the very large trees in these forests can be more than a thousand years old, far older than expected. A model developed by Chambers determined that because these tropical trees live longer, forests can accumulate carbon for more than a century if increases in atmospheric carbon dioxide promote faster tree growth, as some research suggests. The researchers' results appear in the March 22 issue of Nature.
Faster growth fueled by increases in atmospheric carbon dioxide would cause Amazonian old-growth forests to absorb as much as five percent of the airborne carbon released by worldwide fossil fuel use. Increases in atmospheric carbon dioxide are believed to be the main cause of global warming trends.
"With fossil fuel combustion and land-use activities threatening to double atmospheric carbon dioxide this century, maintaining large forests as carbon reservoirs becomes an additional conservation incentive," Trumbore said. "If elevated carbon dioxide indeed makes these trees grow faster, the potential long-term carbon storage in intact tropical forests is large."
The results of the UCI /Brazilian study disagree with other work based on measurements taken from towers situated above the forest canopy, which directly measure the flow of carbon to and from the atmosphere. These tower studies suggest that old-growth Amazonian forests are absorbing up to a third of fossil fuel-emitted carbon dioxide. The UCI researchers say these measurements are inconsistent with their observations of forest dynamics and likely have methodological flaws.
The UCI/Brazilian findings also may have an impact on Kyoto Protocol provisions, said Trumbore. Under the precepts of the protocol, which has yet to be enacted, each industrialized nation must reduce fossil fuel emissions to below 1990 levels through a combination of cutting emissions and offsetting them by increasing carbon sinks such as forests. Understanding how long trees in tropical forests can live provides much-needed information on the carbon storage capacity of these forests and emphasizes the importance of maintaining them.
"Forests take up enormous amounts of carbon, and protecting old-growth trees in addition to planting new ones can play a factor in eventually meeting Kyoto Protocol standards," Trumbore said.
In addition to Trumbore and Chambers, Niro Higuchi and Edgard Tribuzy of the Brazilian National Institute for Amazonian Research participated in the study. Chambers also is affiliated with the National Center for Ecological Analysis and Synthesis, Santa Barbara, Calif., and the Smithsonian Biological Dynamics of Forest Fragment Project, Manaus, Brazil.
The study is part of the large-scale biosphere-atmosphere experiment in the Amazon, a Brazilian-led multinational research effort, which is also supported by NASA.
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Contact:Tom Vasich(949) 824.6455[email protected]
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