‘Included sapwood’ in redcedar
Eastern redcedar (Juniperus virginiana) is a common tree species in Tennessee. The wood is valued for its beauty, workability and pleasing odor. It is often used for fence posts and outdoor furniture because of its natural resistance to rot and insect attack. It is also commonly used as animal bedding.
As with all naturally durable woods, only the heartwood of Eastern redcedar contains the chemicals that protect the wood against fungi and termites. The sapwood (light colored ring of wood under the bark) is not resistant and is often cut away from wood that will be exposed outdoors. The familiar reddish purple color (and characteristic odor) of the heartwood indicates the presence of the protective chemicals. In addition to the dark colored heartwood and the light colored sapwood surrounding it, there are often streaks of pale wood running through the red heartwood portion. This is called “included sapwood” or “white ring.” It is not clear what causes this abnormal wood to form but it is very common in eastern redcedar.
The properties of included sapwood are intermediate between sapwood and heartwood: included sapwood is less resistant to rot fungi and termites, and shrinks more, than heartwood. However, included sapwood is more resistant to mold fungi than normal sapwood (as resistant as heartwood). Because of the low rot resistance of included sapwood, it is often beginning to rot when the tree is harvested. Many manufacturers who work with eastern redcedar will reject pieces that contain any included sapwood or associated incipient decay. However, normal red colored heartwood of eastern redcedar is very rot resistant and a few small streaks of included sapwood will not lessen the lifespan of most cedar products.