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No. 73: Jan-Feb 1991

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Killer Trees That Talk Among Themselves

"Acacia trees pass on an 'alarm signal' to other trees when antelope browse on their leaves, according to a zoologist from Pretoria University. Wouter Van Hoven says that acacias nibbled by antelope produce leaf tannin in quantities lethal to the brows ers, and emit ethylene into the air which can travel up to 50 yards. The ethylene warns other trees of impending danger, which then step up their own production of leaf tannin within just five to ten minutes."
(Hughes, Sylvia; "Antelope Activate the Acacia's Alarm System," New Scientist, p. 19, September 29, 1990.)

Free-ranging antelope can always find unwarned acacias with low levels of tannin to browse on, but on some South African game ranges, they are forced to consume high tannin leaves. Too much tannin inactivates the antelopes' liver enzymes, and they die in about two weeks. Hundreds may perish in a very dry season. (Vincent, Catherine; "Les Arbres Communiquent entre Eux," Le Monde, p. 11, September 14, 1990. Cr. C. Mauge)

From Science Frontiers #73, JAN-FEB 1991. 1991-2000 William R. Corliss