By Susan Milius
Trees in most forests, even wet ones, live perilously close to the limits of their inner plumbing systems, a global survey of forests finds.
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Seventy percent of the 226 tree species in forests around the world routinely function near the point where a serious drought would stop water transport from their roots to their leaves, says plant physiologist Brendan Choat of the University of Western Sydney in Richmond, Australia. Trees even in moist, lush places operate with only a slim safety margin between them and a thirsty death.
“This is the first time that we’ve looked across all forest [types] and seen that there’s a convergence on risky behavior,” Choat says.