Surprising finding from most extensive land-based study of drought in Amazon rainforests

As with all life forests are incredibly adaptive -- provided they're not overwhelmed by the need to adapt. Where's the tipping point?   

Drought stalls tree growth and shuts down Amazon carbon sink, researchers find

July 6, 2016

Source: University of Exeter

Science Daily

A recent drought completely shut down the Amazon Basin's carbon sink, by killing trees and slowing their growth, a ground-breaking study led by researchers at the Universities of Exeter and Leeds has found. Previous research has suggested that the Amazon -- the most extensive tropical forest on Earth and one of the "green lungs" of the planet -- may be gradually losing its capacity to take carbon from the atmosphere. This new study, the most extensive land-based study of the effect of drought on Amazonian rainforests to date, paints a more complex picture, with forests responding dynamically to an increasingly variable climate.

The study made use of two large-scale droughts occurring just five years apart, in 2005 and 2010, to improve understanding of how drought affects tree growth, and therefore the rate of uptake by trees of carbon dioxide from the atmosphere. In the first basin-wide study of the impact of the 2010 drought and its interaction with previous droughts, the international team of researchers found that tree growth was markedly slowed by drought across the vast forests of the Amazon.

By using long-term measurements from the RAINFOR network spanning nearly a hundred locations across the Amazon Basin, the team was able to examine the responses of trees. In both the first drought and the second the Amazon temporarily lost biomass. But while both droughts killed many trees, the 2010 drought also had the effect of slowing the growth rates of the survivors, suggesting that many trees were adversely affected but not to the point of death.

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