Walnuts trees face climate obstacles

Walnut trees are not designed to withstand warmer, drier climates, a U.S. researcher said. Walnut trees -- which are economically significant in Indiana for lumber and furniture making, and in other areas for their nuts -- are especially sensitive to particular climates, research by Douglass Jacobs, a professor of forestry and natural resources at Purdue University, and former doctoral student Martin-Michel Gauthier, now a research scientist in the Ministry of Natural Resources in Quebec, Canada, suggest. "Walnut is really restricted to sites not too wet or dry. It has an extremely narrow range," Jacobs said Monday in a release. Jacobs, whose findings were published in the December issue of Annals of Forest Science, said there could be a decline in the species due to climate change, particularly drought. "Changes in moisture could restrict its ability to survive without irrigation," Jacobs said. "Almost all climate change models predict that climates will become drier." Purdue's Hardwood Tree Improvement and Regeneration Center has a walnut breeding program that is attempting to identify trees that can be used in different climates. Walnuts were a $1 billion a year industry in California in 2010, while black walnut timber accounts for about 15 percent of the logs sold in Indiana at a value of $11 million, Purdue said.