Amazon Rainforest More Drought Resistant than Believed, Researchers Say

The Amazon rainforest may be more resistant to drought than previously believed, according to researchers at the University of Exeter and Colorado State University, whose new computer simulation factors in previously unaccounted for elements that suggest the rainforest is more resilient than previous models made it out to be.

Prior Amazon drought models did not take into account that the rainforest can recycle its own moisture in times of need. For their study, the researchers, who published their work in the Journal of Climate, eliminated unrealistic water stress variables, finding that the moisture that is recycled by the forest can sufficiently reduce the intensity of drought conditions.

"This study suggests that forests are not only more able to withstand droughts than we had previously thought, but it is the response of the forest itself that can reduce the intensity or length of the drought," said Anna Harper from the University of Exeter. "Moisture recycling works best in large areas of undisturbed forest so it is essential that measures to protect the Amazon rain forest are in place to ensure that that this natural process can be maintained in what may be a drier climate in the future."

The rainforest recycles its own moisture as a natural effect of the rain cycle; soil moisture evaporates to water vapor and then turns back into rain. How much moisture can be recycled depends on the water evaporating from the ground and also what is moving through the plants from the roots to the leaves.
"Moisture recycling is an important source of rainfall over the Amazon forest; about one-third of the annual rainfall in the southern Amazon forest can originate from moisture recycling," the University of Exeter said in a news release.

In many of the previous Amazon drought models, the point at which drought is reached is modeled too soon, not accounting for the moisture recycling that takes place, the researchers said.

The Amazon rainforest is a constant topic of study, as what happens there will very likely affect many other parts of the world.

In another recent study, researchers from Princeton University reported that deforestation in the Amazon can lead to reduced rain and snowfall in the western United States.