Eat all the walnut treats you can this holiday season. They might not be so plentiful in coming years.
Commercially grown walnut trees (Juglans nigra and Juglans regia) are very particular about their growing conditions and drought or untimely frosts can crack the walnut tree's defenses.
"Walnut is really restricted to sites not too wet or dry. It has an extremely narrow range," said Douglass Jacobs, professor of forestry and natural resources at Purdue University, in a press release.
"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," said Jacobs, whose research was published in the Annals of Forest Science.
"Changes in moisture could restrict its ability to survive without irrigation," Jacobs said. "Almost all climate change models predict that climates will become drier."
Walnut species thrive in the tropics, but in temperate areas, they are cautious about frost. To avoid the chilly danger, they don't even sprout leaves until nearly a month after other trees.
As climate patterns also become less predictable, a late frost or other extreme weather event could also cause black days for the black walnut and other varieties.
"That, on top of the increase in temperatures, would be a problem for walnut," study co-author Martin-Michel Gauthier said in a press release. "The trees would basically shut down."
Loss of the walnut's high quality wood and delicious nuts would have economic consequences across the U.S., from California's $1 billion per year nut farms to Indiana's $11 million per year walnut lumber industry, warned the authors.
Walnuts ready to be cracked (P.J.L Laurens, Wikimedia Commons)
Walnut still on the tree (Wikimedia Commons)