So do scientists it seems. Quoting Gene Wengert again:Daruma wrote:I am still curious why sap in Maple trees only moves in above freezing temperatures.
I think every woodworker should have a moisture meter. It's an essential tool.It is my understanding that turgor pressure refers to the minute action within a cell, but does not account for sap flow itself in a tall tree, especially in a species like sugar maple in the early spring before leaf growth starts. In fact, we need to recognize that virtually all cells in the stem of a tree are dead. Further, the cells of a tree are filled with about half water and half gas... If they were all water, trees or logs would not float, as wood itself is 1.5 times heavier than water. Unfortunately, the literature is full of theories on sap flow that are incorrect when applied to tall trees, but do work for short plants.
In a tree, does water flow up in the sapwood and down in the bark? Or is it the other way? In other words, how do the sugars of photosynthesis get down the tree? Another comment is that wood cells, when first formed in the cambium layers (which was once thought to be a single layer of cells) are full size and do not grow longer or fatter. In fact, soon after creation, most of the cells die... Maybe some ray parenchyma cells remain active.
Joyce Kilmer may have said it best:
I think that I shall never see
A poem lovely as a tree.
A tree whose hungry mouth is prest
Against the earth's sweet flowing breast;
A tree that looks at God all day,
And lifts her leafy arms to pray;
A tree that may in summer wear
A nest of robins in her hair;
Upon whose bosom snow has lain;
Who intimately lives with rain.
Poems are made by fools like me,
But only God can make a tree.