Trees in UW Arboretum
If you’ve opened social media or listened to the news lately, you’ve probably heard about ‘exploding trees’ due to cold temperatures.
A TikTok video from Muskego arborist Jonathan Roberts explains what’s really going on. “When the temperatures drop quicker than normal, the moisture in the sap contracts a lot quicker,” says Roberts. “That can cause a cracking or pop-like sound in the tree.”
Bill McNee is a Forest Health Specialist with the Wisconsin Department of Natural Resources. “Freezing and expansion puts tremendous pressure on the inside of the tree, and if that’s more than the tree can handle, that pressure gets relieved through formation of a frost crack,” McNee says.
And McNee adds that cracking can occasionally be loud. “It might be a small crack and there’s no sound, or it might be a very large noticeable crack in the tree or a larger branch. And these can often give off a very large cracking sound that resembles a gunshot.”
Certain tree species are more likely to experience frost cracking, according to McNee. “Maple trees are generally the most susceptible, but they can occur in any other hardwood tree that loses its leaves in the fall. Or if the conditions are right, it could happen in a conifer such as a pine tree or a spruce tree.”
McNee says some frost cracks may be severe, so have an arborist look at the tree to determine if it’s a safety hazard.
Audio credit Fox 6 Milwaukee, WTAQ Green Bay