How they differ
In many species heartwood is darker than sapwood, and the boundary can be seen on a stump or a cut round. In others the difference is faint. Sapwood is the working part of the trunk and stays alive near the cambium; heartwood is chemically changed and holds the tree up. A tree is not like an animal. It can lose much of its heartwood to decay and keep growing, because the working wood is on the outside.
That is why a hollow trunk is not necessarily a dead one, and why the question becomes how much sound wood remains in the wall. See cavity.
Why it matters in Northern Nevada
Many valley trees are old and have lost heartwood to decay, and the trees may still look green and healthy. Cottonwoods, willows and Siberian elms are common examples. Firewood is the other place this shows up: heartwood and sapwood season and burn differently, and different species dry at different rates; see how to season and stack firewood.
For junipers and cedars the heartwood is rot-resistant and the sapwood is not, which affects how long a fence post or a dead standing tree lasts.
What an arborist does about it
The arborist assesses how much sound wood is left, using what is visible: the shape of the trunk, a conk, a crack, tapping, and sometimes specialist tests. CODIT explains how a tree walls off decay to protect the sapwood. The result is a judgement on whether a tree with inner decay can stay, with or without support. Call 775.232.8243 for a free estimate. Do not let anyone tell you from the street that a hollow tree is fine, or that it must go; the answer sits in the sound wood that remains and in what the tree could hit.
Sources
- International Society of Arboriculture, Trees Are Good: Recognizing Tree Risk (brochure) (read October 17, 2026)