Vicious circle of drought and forest loss in the Amazon.
If dry seasons intensify with human-caused climate change, the risk for self-amplified forest loss would increase even more, an international team of scientists finds.
To detect such non-linear behavior, the researchers apply a novel complex network analysis of water fluxes.
"We already know that on the one hand, reduced rainfall increases the risk of forest dieback, and on the other hand, forest loss can intensify regional droughts.
Our study provides new insight into this issue, highlighting the risk of self-amplifying forest loss which comes on top of the forest loss directly caused by the rainfall reduction."
"The Amazon water cycle is of course pure physics and biology, but it is also one of nature’s great wonders," says co-author Henrique M.J. Barbosa from the Universidade de Sao Paulo, Brazil.
Even if average rainfall might not drastically change, extended drought events might tip parts of the Amazon forest into self-amplifying forest loss, eventually turning them into a savanna.
Diversity has the potential to decrease the effects of self-amplified forest loss.
"Since every species has a different way of reacting to stress, having a great variety of them can be a means for ecosystem resilience," says Marina Hirota from the Federal University of Santa Catarina, Brazil.
Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks.

Researchers at the German Potsdam Institute for Climate Impact Research (PIK) found the Amazon rainforest could be exposed to higher risks of dieback if dry seasons intensify and rainfall decreases. This could lead to a vicious dieback circle, they said in a study published in Nature Communications. “The Amazon rainforest is one of the tipping elements in the Earth system,” said lead-author Delphine Clara Zemp, who conducted the study at PIK. “We already know that on the one hand, reduced rainfall increases the risk of forest dieback, and on the other hand, forest loss can intensify regional droughts,” she said. “So, more droughts can lead to less forest leading to more droughts and so on. Yet the consequences of this feedback between the plants on the ground and the atmosphere above them so far was not clear.” The researchers found the close relationship between deforestation and drought could put the Amazon further at risk. When it rains, trees absorb water through their roots and then release it back into the atmosphere. Tropical forests produce most of the water they need themselves: they pump moisture which then rains back to them. Yet logging and warmer air – due to greenhouse gas emissions – reduce precipitation and hinder the moisture transport from one forest area to the other, affecting even remote areas. ‘Vicious circle’ “Then happens what we call the ‘cascading forest loss,'” said co-author Anja Rammig from the Technical University of Munich, who is currently working as a guest scientist at Potsdam Institute for Climate Impact…

Researchers have identified a climate feedback mechanism that could have catastrophic consequences for one of the world’s great rainforests. They report that a dangerous mix of human-induced devastation and cyclic drought in the Amazon could launch a vicious circle of forest dieback. The drought that killed the trees could intensify because of the intricate relationship between the rainforest and the rainfall, in which trees play a role in maintaining a pattern of precipitation by pumping fallen water back into the atmosphere. “We already know that, on the one hand, reduced rainfall increases the risk of forest dieback, and, on the other hand, forest loss can intensify regional droughts. So more droughts can lead to less forest, leading to more droughts, and so on,” says Delphine Clara Zemp, of Germany’s Potsdam Institute for Climate Impact Research, who led the international team of scientists behind the finding. Amazon forest loss “Yet the consequences of this feedback between the plants on the ground and the atmosphere above them so far was not clear. Our study provides new insight into this issue, highlighting the risk of self-amplifying forest loss, which comes on top of the forest loss directly caused by the rainfall reduction.” Dr Zemp and other scientists from Germany, the Netherlands, Sweden and Brazil report in Nature Communications that their results suggest frequent extreme drought events in…