Transpiration from the Trunk?

vagardener

Hello, I am new to the forum and glad you are here, so thank you!

I saw the most unusual thing happening with an American White Oak in my yard this winter. From the corner of my eye, I noticed the oak looked on fire. "Smoke" was literally billowing out of its trunk one very cold, sunny morning after a heavy February rain. There are no visible large holes or cracks in the bark. It was kind of just pouring out of an area of the trunk that looked like normal bark to me. I've seen this happen on this tree one or two more times this winter, but never have I seen such breath coming out of any other tree.

What I thought in the moment was: it must be hot as a chimney inside there. Then, I wondered if the tree was exhaling. I figure that in some sense it was a kind of breath - water, oxygen, carbon? But, I wonder what was the process that was happening? Why did I see it on this day? Why have I never seen it before in all my years of hanging around trees?

I've been looking around, reading, and trying to remember my biology. I'm just so confused because everything I'm reading indicates that water vapor - evaporation, transpiration - leaves through the leaves or roots and that the trunk is full of cells that are just, well, like plumbing to get the water where it needs to go.

Does what I've described sound like something you might know about? What is the science behind it and where can I read more?

Info:
Richmond VA
American White Oak, probably close to 100 years old, close to 70 feet tall

Thank you so much!

Eric Frei

Well, I'm not sure what you witnessed.

Could it have been gaseous exchange? Could it have been water vapour from the warmer trunk to the cooler air?

Generally transpiration takes place at the leaves when the stomata is open.

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windthrown

Only thing I can think of is that the sap was running and the xylem water temp was way warmer than ambient, so the bark was warm and releasing a lot of water on the bark in the form of vapor. Either that or the sun was warming the bark and the same thing was happening as a result. Tree sweat, as it were. I see that on trees here, but it is more mysty and foggy than smokey. I cannot imagine that it was smoke, or the tree would be burning.

No transpiration from the trunk. Xylem channels water and nutrients up from the roots. That is drawn up by the leaves and leaf stems which are transpiring and releasing moisture into the air via the stoma, and sucking water up the sap wood via capillary action. Trees also send sugars and nutrients from the leaves down to the roots via the phloem (inner bark just outside the vascular cambium). The cambium is the live part of the truck, growing bark on the outside and sap wood on the inside, but there is no tranpiration happening there.

vagardener

Awesome replies, thank you both. I appreciate your thoughts; makes a lot of sense. I just haven't seen trees sweating so profusely. It was actually pretty cool. Thanks, again.