Cold Snap, Crackle, Pop…

cold snapsThis winter, there seems to be a pattern of one serious cold snap per month, and it looks like March will be no exception. Forecasts are calling for temperatures around zero degrees this weekend. Our home is about 600 feet higher in elevation than town-proper, meaning that the mercury dips lower for us. In December, we had a reading of -10, and one January morning found us at -16 degrees. Brrrrr!
During these cold snaps, we’ve also noticed strange popping noises emanating from the otherwise silent forest around our home. The sounds have been akin to that of a golf ball striking a hard surface, but certainly no one is playing a round in the dark amongst the hemlock and cedar.
It turns out, the trees are making the noise.
As everyone knows, when water freezes, it expands – including the water content in trees. Thankfully, sap is not pure water; it contains sugar, which acts as antifreeze. The higher the sugar content, the lower the freezing point. This protects the trees from the ravages of Old Man Winter. However, there comes a point when the sugary sap must finally succumb to the frigid temperatures…and it does so with a POP!

This is the sound of a rupture. In most cases, these ruptures are harmless to trees, and come spring and early summer (when trees do most of their growing), they will compartmentalize the wound. Some ruptures are more difficult to heal around, though. This can create two problems for a tree (along with the tree owner who has structures nearby): One is that a rupture that leads to an open wound allows pathogens to enter, thus compromising the health, stability, and longevity of the tree. The other problem is that the rupture may have generated cracks in the trunk of the tree, weakening it structurally. With a strong wind or a heavy snow, the tree could come down.

Native trees have many defense mechanisms for cold, and even with a little popping this winter, they should be just fine come spring. If you’d like to learn more about what trees do at a cellular level to survive cold, the Science Questions With Surprising Answers site has a good explanation. And if you have concerns about a specific tree exhibiting cracks or ruptured bark, don’t hesitate to contact us for a risk assessment.
In the meantime, stay warm!