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5 December 2013 11:26 am ,
Vol. 342 ,
An animal rights group known as the Nonhuman Rights Project filed lawsuits in three New York courts this week in an...
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Breeze Keeps Trees Apart
9 August 2000 5:30 pm
SNOWBIRD, UTAH--The wind whispering through the pines may sound romantic to human ears, but it's a headache for the trees. According to a study presented here 8 August at the Ecological Society of America's annual meeting, even a mild breeze whips the treetops around with such force that they easily collide and can break. The researchers say this may be one reason why in many tree species, the canopies do not grow close enough to touch neighbors.
The distance between tree canopies has been called "crown shyness." Scientists speculated that if the canopies touched, too little light would filter down to the lower branches. But researchers from the University of Alberta in Edmonton, Canada, thought that wind damage might be an important force keeping trees to themselves.
Mark Rudnicki and his colleagues attached tiltmeters to 10 trees in a natural cluster of close-growing lodgepole pines (Pinus contorta latifolia) in Alberta. These devices recorded how the 15-meter-tall trees swayed whenever the wind speed averaged 5 meters per second for more than 3 minutes. Then the scientists plotted the treetops' trajectories as they were buffeted by the wind, an experiment never done for a whole set of trees.
The treetops, they found, moved as much as 5 meters from side to side. "These trees are really moving--and they're moving fast," Rudnicki says. For some pairs of neighboring trees the crowns' paths sometimes overlapped as much as 24%. The team watched trees collide up to 70 times a minute, often tearing off branch tips. Such damage probably prevents neighboring trees from growing too close for comfort, Rudnicki argues.
The finding is "a real advance," says Charles Canham, a forest ecologist at the Institute for Ecosystem Studies in Millbrook, New York, who has long been puzzled by crown shyness. Tracking 10 trees at a time is a technical feat too, he says. "I was impressed with the sophistication of the study."