Rainforest Trees May Die of Thirst as Climate Change Causes Drought
Droughts may kill off the tallest trees in tropical rainforests in coming decades. Scientists have identified the ecological trigger that brings about the death of tropical rainforest trees during prolonged water shortages.
How trees die from drought has been poorly understood until now. Previous research suggested that a severe lack of water might have prevented trees from making enough sugars to fuel their metabolism, causing them to starve and die.
The researchers carried out fieldwork over a 13-year period to assess the impact of drought on trees in the Amazon. Using a large-scale drought experiment, the scientists monitored growth, sugar levels and the performance of the water transport system in trees.
The researchers found that the amount of sugars stored in trees experiencing drought for more than a decade was similar to those in trees which had normal amounts of water during the same period. Drought-affected trees were found to grow at a normal rate right up until they died, indicating that they had enough sugars to fuel their metabolism and that starvation wasn't the trigger for death.
Instead, the researchers found that it's the breakages in the tree's water transport system that lead to their death rather than starvation. This suggests that the Amazon rainforest is not resistant to intense droughts or to long-term drought.
"Tropical forests play a key role influencing global and regional climate, and understanding the way rainforest trees respond to long-term changes in their environment is essential for improving predictions of the impacts of climate change," said Lucy Rowland, first author of the new study, in a news release.
The findings are published in the journal Nature.
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