2. In the case that the plot has many trees (i.e. dense stands), a sub-plot may be defined to be used for these surveys. The size of the sub-plot at the time of the installation of the plot should be large enough to give reliable estimates
for these surveys for a minimum of 20 years, preferably throughout the life of the stand. A minimum of at least 20 trees in the sub-plot should be available in this period.
1. At each sample point, sample trees should be selected according to a stringently defined, objective and unbiased procedure (e.g., four point cross cluster orientated along the main compass directions with corner points at 25 m distance
from the grid point using a six-tree sampling process on each subplot or sample trees chosen following a spiral from the plot centre).
