All dead potential standing and down trees must be tallied. Standing or windfall trees with grey or no needles will be considered dead trees. For net merchantable volume compilation, dead potential stems will have the highest Risk Group factor for that particular species. The 50 percent or more firmwood rule is the key consideration. Decay should be determined at various intervals on the tree.
Tables are available to estimate cross-sectional area of decay.
For example, the outer one-third of a tree represents one half the volume. Also, the bottom third of a tree contains approximately one half of its volume. Other tables are available which show the percentage of volume of the tree in each 10 m log. By estimating percent firmwood in each 10 m log, the firmwood percent of the tree can be determined. Before sounding, look for overhead hazards that may be dislodged.