Does the sap of a tree rise in the spring?

by Mike on March 19, 2010

That the sap of a tree rises in the spring -and goes down in the fall is a common but ‘erroneous notion. In the spring there is an increased circulation of liquids through the tissues of the tree and the food materials stored in the trunk and branches are dissolved and carried to the buds and root tips where first growth begins. It is this increased activity preceding the bursting of the buds and the development of visible growing parts that is so often taken for the rise of -sap. In sugar maple trees the circulation of liquid through the stem in the spring is attended by considerable pressure. If one of these trees is bruised in the spring it “bleeds” more freely than if it is bruised in any other season and this is taken by many as positive proof that there is more moisture in the tree in the spring than at any other time. It is also accepted as evidence that the-sap goes up -in- the-1 spring:and-down in the fall. As stated above, such is not the case. The sap does not go down at any time. At any given point above the ground the moisture content between the inner and outer zones of living wood may vary from month to month and from season to season. A British investigator found that in the fall the center of a tree is very wet, and the outer regions are comparatively dry, while in the spring this condition is reversed. He concluded that if we desire to make our language conform with the fact we should not say that the sap is up in the spring and down in the fall, but that it is out (near the bark) in the spring and in (toward the center) in the fall. Analysis shows that pieces of wood cut from trees in the winter sometimes have a moisture content just as high or even higher than pieces cut in the spring or early summer.

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