We summed species from each plot as species richness (S).
The Shannon index (Shannon 1948) was used to describe tree
diversity and Pielou’s evenness (J) index (Pielou 1969) was
used to describe tree species evenness. When assessing associations
between richness, evenness and tree carbon storage
under different environmental factors, the soil data from the
three layers were averaged to single plot values. Plot disturbance
was estimated as the number of stumps recorded in a
plot, in relation to the sum of all stumps in all plots from
a particular vegetation type. All predictors were standardized
to zero-skewness and unit variance before the analyses
because they had different measurement scale, and checked
for collinearity using variance inflation factor (VIF
≤
3) as an
indicator