AR-News: 'Pristine' Amazonian rainforests are changing
unclewolf at olypen.com
Thu Mar 11 08:09:09 EST 2004
'Pristine' Amazonian rainforests are changing
18:00 10 March 04
NewScientist.com news service
Changes to apparently pristine parts of the Amazonian rainforests have been revealed by a survey of trees. Tall, fast-growing trees are doing better than those that grow slowly.
The changes - possibly the result of increasing levels of carbon dioxide in the atmosphere - threaten to reduce the Amazon basin's crucial ability to store excess CO2.
The discovery comes from a study of 18 undisturbed plots in the heart of the Brazilian Amazon that researchers have been monitoring since the 1980s. Tropical ecologist Bill Laurance, of the Smithsonian Tropical Research Institute in Balboa, Panama, and his colleagues combed through census records of the plots to see how their trees have changed over time.
Of 115 tree genera, they found that two became significantly more common and 14 became significantly rarer over the 15 years of the study. The winners tended to be tall, relatively fast-growing canopy trees, while the losers tended to be slower-growing trees that live their whole lives in the dim depths of the forest below the canopy.
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