Extreme Cold and ‘Exploding Trees’: What’s Really Happening?
John Seiler, a tree physiology specialist at Virginia Tech, recently observed a curious sight on campus: a cherry tree bearing a striking, jagged scar. This wasn’t the result of damage, but a phenomenon gaining attention online – dubbed “tree explosions.” As a massive winter storm threatens much of the United States, understanding these events is more important than ever.
Are Trees Actually Exploding?
While the term “exploding trees” is dramatic, Seiler clarifies that trees aren’t actually detonating. What’s happening is a process scientists call “frost cracks.” These cracks occur when temperatures plummet rapidly, and the sap or water within the tree doesn’t have time to adjust to the sudden cold.
The Science of Frost Cracks
As water freezes, it expands. This expansion creates immense pressure within the tree’s bark and wood. Doug Aubrey, a professor at the University of Georgia’s Warnell School of Forestry and Natural Resources, explains, “That water expands as it freezes, and it can happen usually under very, very drastic drops in temperature.” This pressure can cause the bark to crack or split with a loud, gunshot-like sound – hence the “explosion” moniker.
Seiler offers a relatable analogy: “It’s like when you put a can of Coke in the freezer and forget about it. The can splits open? That’s what’s happening with the tree.”
Historical Precedence and Risks
The National Forest Foundation notes numerous historical and current observations of trees experiencing this phenomenon due to extreme cold. While the sound can be startling, it’s generally not dangerous to people nearby. “It’s going to be loud, but it’s not dangerous. Wood doesn’t go flying through the area,” Seiler assures.
However, frost cracks can leave trees vulnerable. The exposed wood can become susceptible to insect infestations or fungal/bacterial infections. The extent of the damage depends on where the freezing occurs. Aubrey notes that freezing at the base of a stem could kill the entire tree, while freezing in a branch might only affect that portion. Many trees, however, can recover by growing new stems from underground buds.
The Greater Threat: Ice and Snow Weight
While frost cracks are interesting, experts emphasize a more immediate danger during winter storms: the weight of ice and snow. Heavy accumulation can cause branches to break and fall, posing a significant risk to people and property. Aubrey warns, “Tree size factors into the types of impacts that you can have.”
Different tree species are also affected differently. Longleaf pines, with their longer needles, tend to accumulate more ice than loblolly pines. Open-grown trees with larger branches are also more susceptible to breakage than those in dense forests.
Seiler stresses the importance of caution: “If there’s a heavy ice accumulation and wet snow accumulation, you don’t want to have a branch fall on your head. That’s extremely, extremely dangerous.”
Preparing for the Winter Storm
As a powerful winter storm approaches, it’s crucial to be prepared. Stay informed about weather forecasts, avoid walking under trees during heavy ice or snow, and be aware of the potential for falling branches. Prioritize safety and take precautions to protect yourself and your property.
Source: CNN
