Coarse woody debris (CWD) refers to the downed wood on the ground in the forest.
Measurement of CWD may be important for total biomass estimates or to calculate
potential fuel loads and the potential for fire. Most of the techniques designed to
measure CWD were designed to predict fire potential.

Fixed Area Technique

In this method the length and diameter of all stems within a fixed area
are measured, and the formula for a cylinder (or other appropriate
geometric form), is used to calculate the volume of the wood. To obtain
biomass a representative subsample is dried and the dry mass to volume
ratio is used to calculate the overall dry mass. Note: The dry mass to
volume ratio may vary depending upon the degree of decomposition of
the sample.

The line intercept formula has the advantage of not needing a
measurement of length of the wood. This can make the method
much faster than the fixed area plot model. It is important, however,
that a sufficiently long line is sampled and that the lines are randomly
aligned within the forest.