Snap, crackle and, sometimes, a giant pop.
While many trees are dormant these months — and will remain so until their leaves and flowers burst through in the springtime — they sure can create a cacophony in the still of winter.
With temperatures plummeting across a large section of the United States, many trees face possible injuries, and the sound of their pain can echo across the land.
Does that mean trees will explode into a mess of sap and leaves? Not exactly.
The vessels that carry water and nutrients throughout the tree — known as phloem and xylem — freeze and expand, leading to vertical “frost cracks” in the trunk, experts say. Those are not generally fatal.
“These cracks tend to happen at a previous weak spot in the bark,” said Eric Otto, a forest health specialist at the Minnesota Department of Natural Resources.
He said that some trees are more prone to frost cracks, especially thin-barked varieties, like maples, lindens and birches. But the cracks can appear on many species.
“Native trees can get frost cracks, but nonnative trees can be more susceptible if they are not adapted to the area,” Dr. Otto said. “I suspect that in areas that don’t typically have below-zero temperatures, those trees would also be more prone to frost cracks.”
The rapid expansion and contraction of the outer and inner layers of the bark pulls and pushes the wood to separate and crack. That’s the snapping and crackling that people hear. It’s somewhat akin to pipes freezing and bursting in a very cold home.
Sometimes, the burst can sound like the pop of a gunshot. Those bursts are not fatal. “But the tree is more prone to decay, insect activity and canker pathogens” after the minor explosion, Dr. Otto said.
Most cracks will open and close, in sync with fluctuating temperatures. He noted that only in extreme cases — as a result of drastic temperature swings — would a crack not heal, seriously compromising the health of the tree.
A tree has thousands of vessels, or pipes, so if one bursts, the tree can continue to function. Many trees do plenty of advance preparation for the cold, including by draining most of their water ahead of winter to enter a dehydrated, dormant state.
While Minnesota will face among the coldest temperatures during this weekend’s sprawling storm system, its trees will remain relatively pain-free and quiet.
“This isn’t a concern in Minnesota,” Dr. Otto said. “Our trees are adapted to our weather.”
Adeel Hassan, a New York-based reporter for The Times, covers breaking news and other topics.
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