Ecological Modelling 191 (2006) 225–242 Dynamic growth model for Scots pine (Pinus sylvestris L.) plantations in Galicia (north-western Spain) Ulises Di´ eguez-Aranda a,∗ , Fernando Castedo Dorado b , Juan Gabriel ´ Alvarez Gonz´ alez a , Alberto Rojo Alboreca a a Departamento de Ingenier´ ıa Agroforestal, Universidad de Santiago de Compostela, Escuela Polit´ ecnica Superior, Campus Universitario, 27002 Lugo, Spain b Departamento de Ingenier´ ıa Agraria, Universidad de Le´ on, Escuela Superior y T´ ecnica de Ingenier´ ıa Agraria, Avenida de Astorga, 24400 Ponferrada (Le´ on), Spain Received 15 October 2004; received in revised form 21 April 2005; accepted 29 April 2005 Available online 24 June 2005 Abstract In this study we developed a dynamic growth model for Scots pine (Pinus sylvestris L.) plantations in Galicia (north-western Spain). The data used to develop the model were obtained from a network of permanent plots, of between 10 and 55-year- old, which the Unidade de Xesti´ on Forestal Sostible (Sustainable Forest Management Unit) of the University of Santiago de Compostela has set up in pure plantations of this species of pine in its area of distribution in Galicia. In this model, the initial stand conditions at any point in time are defined by three state variables (number of trees per hectare, stand basal area and dominant height), and are used to estimate stand volume, classified by commercial classes, for a given projection age. The model uses three transition functions expressed as algebraic difference equations of the three corresponding state variables used to project the stand state at any point in time. In addition, the model incorporates a function for predicting initial stand basal area, which can be used to establish the starting point for the simulation. This alternative should only be used when the stand is not yet established or when no inventory data are available. Once the state variables are known for a specific moment, a distribution function is used to estimate the number of trees in each diameter class, by recovering the parameters of the Weibull function, using the moments of first and second order of the distribution (arithmetic mean diameter and variance, respectively). By using a generalized height–diameter function to estimate the height of the average tree in each diameter class, combined with a taper function that uses the above predicted diameter and height, it is then possible to estimate total or merchantable stand volume. © 2005 Elsevier B.V. All rights reserved. Keywords: Stand growth model; Scots pine; Algebraic difference equations; Weibull function ∗ Corresponding author. Tel.: +34 982 252303; fax: +34 982 285926. E-mail address: udieguez@lugo.usc.es (U. Di´ eguez-Aranda). 1. Introduction Forest growth models predict growth of a target for- est stand using site characteristics and management 0304-3800/$ – see front matter © 2005 Elsevier B.V. All rights reserved. doi:10.1016/j.ecolmodel.2005.04.026