Global Tropical Tree Ring Study Shows No Correlation W. 150 Yrs Atmospheric C, Tree Growth Rates

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But after analyzing tens of thousands of tree rings taken from tropical forests in Bolivia, Cameroon and Thailand, an international team of scientists is calling this assumption into question. Their research, published yesterday in the journal Nature Geoscience, found no correlation between increased atmospheric carbon dioxide concentrations over the past 150 years and forest growth as evidenced in trees' rings.

Tropical forests "are very important carbon stocks," said lead author Peter van der Sleen of Wageningen University's Forest Ecology and Management Group in Wageningen, Netherlands. But, van der Sleen said, his research does call into question tropical forests' capacity to mitigate climate change. This finding has the potential to change our climate predictions, explained Lucas Cernusak of the College of Marine and Environmental Sciences at James Cook University in Cairns, Australia.

"Current model formulations predict increasing tropical forest biomass through this century," Cernusak, who was not involved in the study, wrote in an email. "If this does not occur, the atmospheric CO2 growth rate will increase, and global warming will accelerate."

It's likely that the new study came to a different conclusion because of differences in research methods. Earlier studies were based on analysis of biomass material contained in small forest plots rather than a random sampling from trees throughout a forest as with van der Sleen's study. Also, without the long-term data provided in tree rings, earlier experiments looked at tree growth on a shorter time scale.

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http://www.scientificamerican.com/article/as-carbon-dioxide-grows-tropical-trees-do-not/