Tree moisture content?

[Qweaver]

I remember reading on this forum that moisture content in trees does not change from winter to summer.  That seems to be illogical.  If so, why do sugar maples only make sugar in the spring?  I'm not arguing...just want to understand.  A friend just said to me that he wanted to fell trees before the sap begin to raise.  I had no logical way to tell him that it did not?  I know next to nothing about how trees work.

[bluthum]

 Since no one has provided any science I'll venture a guess.I do not know this for a scientific fact so fwiw.
I'd guess a log, practically speaking, would weigh the same winter or summer. Same volume of liquids inside. But those liquids would vary a lot from winter to summer in their chemistry.

Now, maybe having extended my neck with a guess someone will provide some facts.

[WDH]

In the case of maple, "sap" is water and sugar being transported in the inner bark to ready the tree for growth when the tree leafs out.  It has nothing to do with the moisture content of the wood, which is not inner bark and does not transport sugars to the roots.  "Sap rising" and moisture content of the tree are different beasts. The tree, like us, is a living organism, and our moisture content does not change much day to night or winter to summer.  The bark is called phloem and the wood is called xylem.  Two different functions, and two different beasts. 

[Catenaut]

Tree moisture content (MC) is a topic that occasionally stirs debate in the paper mills, pellet mills, etc. so there is a massive body of literature on the subject, but to save time, a few facts from my experience:

- MC depends on soil type and region. A pine forest in NC will have a different MC profile than a pine forest in Mississippi

- Obviously MC depends on species, but I thought I'd mention it just to make sure

- For pine trees we generally see an average of 48% MC but it can get down in the high 30's during a real hot dry summer and up in the low 50's during a soaking wet winter. No idea why, but that's a fact that numerous paper mills and decades of meticulous data collection have proven every time this question's asked

- For hardwood it varies. We've had some tupelo gum show up with nearly 70% MC