ANN ARBOR A new genetic analysis has revealed that many Amazon tree species are likely to survive human-caused climate warming in the coming century, contrary to previous findings that temperature increases would cause them to die out.
However, the authors of the new study warn that extreme drought and forest fires will impact Amazonia as temperatures rise, and the over-exploitation of the region's resources continues to be a major threat to its future. Conservation policy for the Amazon should remain focused on reducing global greenhouse-gas emissions and preventing deforestation, they said.
The study by University of Michigan evolutionary biologist Christopher Dick and his colleagues demonstrates the surprising age of some Amazonian tree species more than 8 million years and thereby shows that they have survived previous periods as warm as many of the global warming scenarios forecast for the year 2100.
The paper is scheduled for online publication Dec. 13 in the journal Ecology and Evolution. The new study is at odds with earlier papers, based on ecological niche-modeling scenarios, which predicted tree species extinctions in response to relatively small increases in global average air temperatures.
"Our paper provides evidence that common Amazon tree species endured climates warmer than the present, implying that in the absence of other major environmental changes they could tolerate near-term future warming under climate change," said Dick, an associate professor of ecology and evolutionary biology and acting director of the U-M Herbarium.
But study co-author Simon Lewis of University College London and the University of Leeds cautioned that "the past cannot be compared directly with the future."
"While tree species seem likely to tolerate higher air temperatures than today, the Amazon forest is being converted for agriculture and mining, and what remains is being degraded by logging and i
|Contact: Jim Erickson|
University of Michigan