where H is dominant height at the age A1, SI the site index, i.e.
the dominant height at the reference age Aref, k and r are again
model parameters. In order to parameterize this model, for each
plot the site index has to be known. In this study, it was gained
through linear interpolation between the two ages that comprised
the reference age. Many authors favoured the reference
age of 15 years for C. lusitanica (e.g. Teshome and Petty, 2000;
Ngugi et al., 2000; Matu, 1983 quoted in Teshome and Petty,
2000). It was as well suitable for this