Magazine article Science News

Most Trees a Sip Away from Death: Plants' Plumbing Systems Often on the Brink of Failure

Magazine article Science News

Most Trees a Sip Away from Death: Plants' Plumbing Systems Often on the Brink of Failure

Article excerpt

Trees in most forests, even wet ones, live perilously close to the limits of their inner plumbing systems, a global survey finds.

Seventy percent of 226 woody species in forests around the world routinely function near the point where a serious drought would stop sufficient water transport from their roots to their leaves, says plant physiologist Brendan Choat of the University of Western Sydney in Richmond, Australia. Even trees in moist, lush places operate with only a slim safety margin separating them from 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. He and his colleagues report their findings in the Nov. 29 Nature.

"I think this is a really big deal," says David Breshears of the University of Arizona in Tucson. As forest researchers confronting climate change, "we've been trying to be careful as a community not to be alarmist," he says. But the new paper adds yet more worrisome data. "They all keep pointing to: 'Whoa, our forests are really vulnerable.'"

Trees don't have hearts to pump vital fluids. Instead, evaporation from tiny pores in the leaves pulls water up from the roots through masses of microscopic tubes. …

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