Aim of the study To develop a site index model for Quercus faginea Lam. stands. Area of study Spain Material and methods Data from 81 growth series collected in plots where Q. faginea was the main species were used for modelling. Different generalized algebraic difference equations (GADA) were fitted from traditionally used models. Richards model was selected and used to expand the parameters with environmental variables. Research highlights Winter rainfall (WR), annual potential evapotranspiration (PET) and pH were introduced increasing the prediction ability of the GADA. It is strongly recommended to apply the model with ages lower than 80 years because the lack of data above that age makes bias increase and efficiency decrease. © 2014 Ministerio de Agricultura Pesca y Alimentacion. All rights reserved.

Peer reviewed