Comments on: What's wrong with our Christmas tree?

Question: What's wrong with our Christmas tree?

killy willy — Mon, 10 Dec 2007 20:55:08 -0800

Is that the fire crackling? Nope, it's the Christmas tree!

We bought a Douglas fir on Saturday and tonight it has started making faint crackling sounds. Like Rice Krispies (tm). The tree is not on fire, it has plenty of water and it's not the lights making the sounds. What is it? Is the tree going to asplode? Or is it just a hive of insects that will take over my home once they're done with the tree? Please hope me!

By: lilywing13

lilywing13 — Mon, 10 Dec 2007 22:48:29 -0800

Perhaps it's just settling.
No matter how much water you give it, it's still a dead thing now.
(I'm not judging, as I love the smell of fresh greenery.)

By: hjo3

hjo3 — Mon, 10 Dec 2007 23:43:01 -0800

My guess is that it's just drying out. Like lilywing said, a bowl of water is no substitute for the tree's natural state. As various bits lose moisture, they become less able to bear stress and snap. Sometimes audibly.

By: katie

katie — Tue, 11 Dec 2007 04:12:15 -0800

Once when I was a kid our tree was crackling and we couldn't figure out what was going on. Then, every morning parts of our edible decorations were eaten away - namely, popcorn garland and gingerbread men. We had a mouse living in our tree!

By: man on the run

man on the run — Tue, 11 Dec 2007 06:32:15 -0800

Pine beetles make crackling sounds when they are eating away at the bark of trees. That would be my guess.

By: ssg

ssg — Tue, 11 Dec 2007 08:51:30 -0800

man on the run: The tree is a Douglas fir, so pine beetle is pretty unlikely.
My guess would be drying out as well. Is the faint crackling constant or occasional?

By: jamjam

jamjam — Tue, 11 Dec 2007 10:59:43 -0800

I'm going with drying, too, but with a particular mechanism for generating the sound.

The needles are still alive, I think, and they're continuing to transpire, meaning that water is being lost from their tiny pores (stomata). But this lost water can no longer be replaced even if you have water in a holder (because water vessels are damaged in cutting and sap congeals on exposure to air, blocking flow), and when enough water is lost, a tiny bubble appears with an audible pop in one of the water supplying tubes-- a process called cavitation. Apparently, insects can use the sound of cavitation to home in on plants made vulnerable by water stress:

Higher plant surface temperatures, leaf yellowing, increased infrared reflectance, biochemical changes, and possibly stress-induced cavitation acoustic emissions, may all be positive signals to insects of host vulnerability.

As I recall, stomata close at night, so if cavitation is responsible for the sound, it should at least be louder when the light is brightest than in the middle of the night with the decorations off.

By: iguanapolitico

iguanapolitico — Tue, 11 Dec 2007 12:21:27 -0800

I'd take comfort in knowing that you're not the only one. (Just search for "crackling" on the page.)