WEST LAFAYETTE, Ind. - Warmer, drier summers and extreme weather events considered possible as the climate changes would be especially troublesome - possibly fatal - for walnut trees, according to research at Purdue University.
Over five years, Douglass Jacobs, a professor of forestry and natural resources, and Martin-Michel Gauthier, a former doctoral student under Jacobs who is now a research scientist in the Ministry of Natural Resources in Quebec, studied the physiology of walnut trees, which are economically significant in Indiana for their lumber and veneer, and in other areas for their nuts. They found that the trees are especially sensitive to particular climates.
"Walnut is really restricted to sites not too wet or dry. It has an extremely narrow range," said Jacobs, whose findings were published in the December issue of Annals of Forest Science. "We suspect and predict that climate change is going to have a real impact on walnuts. We may see some type of decline of the species."
Specifically, walnuts would have difficulty tolerating droughts that could be associated with a changing climate.
"Changes in moisture could restrict its ability to survive without irrigation," Jacobs said. "Almost all climate change models predict that climates will become drier."
Walnuts are also sensitive to cold, so much so that they have developed a defense mechanism against late frosts. Jacobs said walnut trees don't begin sprouting leaves until almost a month after other trees in the spring.
That defense mechanism could be compromised by extreme weather events associated with climate change scenarios. Late spring frosts after walnuts have developed leaves could kill trees.
"That, on top of the increase in temperatures, would be a problem for walnut," Gauthier said. "The trees would basically shut down."
In California, more than 500,000 tons of walnuts were sold for more than $1 billion
|Contact: Brian Wallheimer|