Stand structural diversity is useful in forecasting growth and can be indic
ative of overall biodiversity. Many variables that indicate structural dive
rsity can be measured. However, species, diameter, and height are commonly
measured and indicate changes in vertical and horizontal stand structure. I
ndices based on the distribution of basal area per hectare by diameter, hei
ght, and species were derived and evaluated by applying them to simulated a
nd actual data sets with a wide variety of stand structures. Extending the
Shannon index of diversity to proportions by species, diameter, and height
resulted in reasonable results with more diverse structures having higher v
alues. However, diameter and height ranges must be divided into classes to
use these indices. A new index based on the variances of the target stand,
relative to the variance of a uniformly distribution stand, showed similar
diversity measures to that of the Shannon index, without the need for divid
ing the diameter and height data into classes. Examination of these indices
for use in growth and yield modelling of complex stands is needed.