Sap stays through the winter
![[Corel] Sap stays in the tree during the winter.](2002-03-13-tree.jpg) Q: What happens to the sap in a tree in winter? If a tree is cut down in the winter will there be less sap
in the tree so that the wood will dry out more quickly than if the tree is cut down other times of the
year? -Ira
A: "Tree sap doesn't go away in the winter," says Robert Miller, forestry professor at the University of
Wisconsin. In the winter, the watery sap in the tree's live cells contains a natural antifreeze (dissolved organic
and inorganic chemicals). Consequently, the sap in sapwood rarely freezes.
[Corel] Sap stays in the tree during the winter.
The tree also contains free water in its long vertical cells that move water up the tree to the leaves. It also has
water bound to the wood fibers. All this water can and does freeze in very cold weather as "...anyone who has
ever split green wood in the winter can tell you," says Miller. However, freezing doesn't harm the tree
because this water is in the tree's dead wood.
So, cutting a tree in the winter won't reduce the amount of sap and the cut wood won't dry any quicker. Proper drying, though, is the key
to a good fire. If the wood is split and stacked, it'll dry out in about six months. Cover the top to keep rain from wetting it but leave the
sides open to encourage good ventilation.
The only tree that burns well when first cut is the heart of an ash tree because its heartwood dries while the tree is alive. Its sapwood,
though, is wet.
(Answered by April Holladay, science correspondent, Mar. 13, 2002)
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