Each site series in each BEC unit was assigned to a site class (Figure 4.2). There were four site classes (I, II, III, IV). For each class, the available SI data were shown in box plots. Where enough data were available, box plots were given for Ba, Cw, Fd, Hw, and Ss.
For a given species, the box plot showed the minimum, maximum, and median SI in the site class. The median SI was the line in the middle of the box. The box indicated the range in which the middle 50% of the SI data was located.
To obtain SI for a species on a site series, the surveyor determined which site class the site series was in, and then read the median SI out of the appropriate box plot.
Section 6.3 of the Vancouver Forest Region eco-guide provides more information on these SI estimates.
Given the following site series, use the old Vancouver Forest Region format for the BEC method to determine SI: