Abstract
Even though the site index is a popular method for describing forest productivity, its use is limited in uneven-aged multispecies forests. Accordingly, the site form (SF) is an alternative measure of productivity to the site index based on the tree height-diameter relationship. Our study aims to evaluate SF as a measure of productivity in the temperate uneven-aged multispecies forests of Durango, Mexico, applying three methods to estimate SF: (i) as the mean height of dominant trees at a reference diameter (SF(H-D)); (ii) as the expected mean height of dominant trees at a reference mean diameter (SF(MH-MD)), and (iii) as the expected height at a reference diameter for a given site (SF(h-dbh)). We assess the effectiveness of the SF based on two hypotheses: (i) the SF correlates to the total volume production, and (ii) the SF is independent of stand density. The SF(H-D) and the SF(h-dbh) showed a high correlation with productivity. However, they also did so with density. Contrary to this, the SF(MH-MD) had a weak correlation with density and productivity. We conclude that the SF is a suitable approach to describe site quality. Nonetheless, its effectiveness as a site quality indicator may be affected according to the method used.