Vicious circle in the Amazon
International team of scientists analyzes connection between drought and forest loss
Logging that happens today and potential future rainfall reductions in the Amazon could push the region into a vicious dieback circle. 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 with participation from the University of Göttingen has found. If however there is a great variety of tree species in a forest patch, this can significantly strengthen the chance for survival. The study was published in Nature Communications.
“The Amazon rainforest is one of the tipping elements in the Earth system,” says lead-author Dr. Delphine Clara Zemp who conducted the study at the Potsdam Institute for Climate Impact Research and is now working at Göttingen University. “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.” Yet the consequences of this feedback between the plants on the ground and the atmosphere above them so far was not clear.
Applying a complex network analysis of water fluxes, the scientists found out that under a dry-season halving of rainfall, at least ten percent of the forest might be lost due to effects of self-amplification alone, adding to the substantial direct forest losses from reduced water availability. Taking into account the puzzlements of the vegetation-atmosphere-feedback, self-amplified forest dieback could amount to up to 38 percent of the Amazon basin. In combination with the direct effects of the droughts, in fact most of the Amazon forest might eventually be at risk. According to the authors, the uncertainties are still considerable: “Our study cannot provide information about the time scales of the processes. It is rather a sensitivity analysis.”
Interestingly, the more diverse the Amazon vegetation is, the less vulnerable it seems to be. Diversity has the potential to decrease the effects of self-amplified forest loss. “Different tree species will respond differently to a given level of water stress,” says Dr. Vincent Montade from Göttingen University. “A forest with a great variety of them is more resilient. Preserving biodiversity may therefore be a tool to stabilize key elements of the Earth system.”
Original publication: Delphine Clara Zemp et al. Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks. Nature Communications 2017. Doi: 10.1038/NCOMMS14681.
Dr. Clara Zemp
University of Göttingen
Faculty of Forest Sciences and Forest Ecology
Biodiversity, Macroecology and Conservation Biogeography Group
Büsgenweg 1, 37077 Göttingen
Phone +49 551 39-10728
Dr. Vincent Montade
University of Göttingen
Faculty of Biology and Psychology
Department of Palynology and Climate Dynamics
Wilhelm-Weber-Straße 2a, 37073 Göttingen
Phone +49 551 39-10399