About sapwood

Sapwood, also known as alburnum, is the outer, living layers of a tree's secondary xylem, lying just beneath the bark. It functions primarily in the transport of water and nutrients from the roots to the leaves and other growing parts of the tree. Sapwood is generally lighter in color than the heartwood, which is the older, non-living inner layers of wood that provide structural support. Over time, sapwood transitions to heartwood as new layers of sapwood are formed. This transformation is accompanied by the deposition of various substances, such as resins and tannins, which help to protect the tree from decay and insect attacks. The width of the sapwood can vary widely among different tree species and is influenced by environmental conditions.