Is There a Difference Between Sapwood & Heartwood?
Sapwood is the outermost, living portion of a woody branch or stem, while the heartwood is the inner, dead wood which usually includes the bulk of a stem’s cross-section. You can always distinguish sapwood from heartwood by its brighter color. Get in touch with a local arborist if you need help identifying your trees.
Though, color in wood can be quite misleading. All dark wood is heartwood, and not all heartwood is dark.
The qualified amounts of heartwood and sapwood in any stem can differ tremendously among species, growing conditions, and individuals. So, for a less credible and more accurate distinction, we need a more comprehensive understanding of what wood is and how both heartwood and sapwood form. An arborist can help you identify parts of your trees if you’re curious.
The Essentials of Sapwood and Heartwood
All wood begins as sapwood. It is shaped just below the bark by a thin layer of living cells called the cambium, which make bark cells to the outside and wood cells to the inside. Tree stems grow in girth during each year of growth since a new layer of wood cells is adjoined inside the cambium. In positive growing years, this new layer of wood can be numerous cells thick. In poor years, it’s comparatively thin.
It doesn’t matter the thickness when any growth happens; the cambium moves outward to adapt to the new layers of wood developing inside. Sapwood contains a host of cell types, most of which are physiologically active and alive. This sapwood is where dissolved minerals and water are carried between the crown of the tree and the roots which is where energy reserves are saved.
In young parts of older trees and young trees, all the wood in the stem is sapwood. However, as the tree gets older and its trunk grows in diameter, changes occur. No longer is the whole cross-section of the trunk needed for managing sap. This, combined with an enhanced need for structural support, brings significant changes in the wood. The cells near the center of the trunk die, but remain intact.
As the sapwood cells get older and die, they convert to heartwood. That is, they are altered to adapt to a shift in function. As deposits of the forming living cells and added chemicals from elsewhere in the plant amass in the heartwood, those cells stop transporting water or storing energy reserves.