New York Times: In life’s web, aiding trees can kill them
By Cornelia Dean, Jan. 11, 2008
A few years ago, Todd Palmer, an ecologist at the University of Florida, was walking past a fenced-off research site in Kenya when he noticed something curious: instead of thriving, acacia trees that were protected from leaf-eating elephants and giraffes were withering and dying.
“That struck me as paradoxical,” he said in a telephone interview this week from the site. “If you remove large herbivores, you should see more vigorous trees.”
Dr. Palmer and his colleagues investigated. Their findings, reported in Friday’s issue of the journal Science, add to the mounting evidence that relationships between plant and animal species can be far more complex than had been thought and that even seemingly benign interference can have devastating effects.
The acacias and a species of ant that colonize them live together in an arrangement called mutualism. The ants nest in the trees’ thorns and sip on their nectar; in return, they swarm out ferociously, ready to bite, when a tree is disturbed by an elephant, a giraffe or other grazing animal.
