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Conservation Science for a Healthy Planet

Drought-affected trees die from water transport failure and carbon starvation

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Posted: 07 Aug 2017 08:15 AM PDT  read full article at Science Daily

Drought-caused tree deaths are produced by a combination of hydraulic failure [cannot transport water from the roots to the leaves] and carbon starvation [closing pores in response to drought], shows new research. The finding, based on a meta-analysis by 62 scientists from across the world, will improve predictive models of how trees die in response to heat, drought, and other climate stresses...

As the number of hot droughts increases globally, scientists are looking to make more consistent predictions of what will happen to plants and vegetation in the future.

This matters for models used to predict climate change because plants take up a big portion of the carbon dioxide humans pump in the atmosphere. Therefore, the effect of tree death and die-off, as observed globally in recent decades, could affect the rate at which climate changes.

…Trees respond to the stress of drought by closing those pores that let in carbon dioxide. At that point, they need to rely on their stored sugars and starches to stay alive, and could die from carbon starvation if they run out before the drought is over.

On the other hand, if the tree loses too much water too quickly, an air bubble (embolism) will form and the tree has hydraulic failure, it cannot transport water from the roots to the leaves, which becomes lethal as the whole tree dries out…

Adams et al. A multi-species synthesis of physiological mechanisms in drought-induced tree mortality. Nature Ecology & Evolution, 2017; DOI: 10.1038/s41559-017-0248-x

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