There are other trees with thick barks which act as heat shields to protect the vital sapwood that transports nutrients and water throughout the tree.

Eight of the 13 samples were narrowed down to be dated between 40 and 60 A.D., using the sapwood present.

Individual ash can also be girdled to make a so-called trap tree: the bark is removed all the way around the trunk, drawing borers in the vicinity with the promise of exposed sapwood.

An outer sapwood layer holds vessels called xylem tubes that siphon water and minerals up the plant.

The evaluation assesses the tree’s vigor, the thickness of its sapwood shell, its disease stresses, the state of the roots and the like.