A new study undertaken by a team of Brazilian and British scientists has discovered that extreme wind and water deficiency are the main causes of tree death in the southern Amazon.
The research which was published this week in the Journal of Ecology is the first to evaluate large-scale causes of tree mortality across the southern Amazon rainforest using tree-by-tree data.
The study showed that more than 70% of all trees dying at the edge of the Amazon rainforest already had severely broken and damaged crowns due to climate change years before they died, a significantly higher percentage than other regions in the Amazon.
Read also: Over 200 nations approve UN report on accelerating climate change impact
Additionally, the study showed that the proportion of trees that die broken in this area is more than anywhere else in the Amazon—roughly 54%.
To undertake the study, researchers from the University of Leeds, University of Oxford and State University of Mato Grosso (UNEMAT) in Brazil investigated the death of almost 15,000 trees from 19 study plots distributed across remaining forests at the southern edge of the Amazon.
According to the study, the region is the driest, hottest, and most fragmented in the Amazon and has recently experienced several severe droughts.
Co-author of the study, professor Oliver Phillips from the University of Leeds School of Geography said, “Individual trees with low wood density have the greatest risk of dying, but such species-level properties do not explain the extreme mortality these forests experience as a whole.
Speaking further, he said, “Rather, the damage caused by climate extremes—especially wind and drought—places exceptional stress on southern Amazon trees.”
The lead author of the study, Dr Simone Matias Reis from UNEMAT said, “Crown breakage hugely increases the risk of tree death. Once broken, the risk of death is much higher, especially when a large part of the tree canopy is broken.
He noted that the growth of broken trees is also affected, as these trees lose the capacity to photosynthesize and so take up less carbon, which in turn increases the risk of death.
Researchers are of the view that the significant impact of climatic water deficits on mortality raises concerns because of climate modelling studies predicting more intense and prolonged seasonality for the Amazon jungle, which may result in high and unprecedented mortality rates for trees of the Southern edge region.
Story was adapted from Phys.Org.
