Modelling dominant height growth of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) in Portugal

Abstract

The first plantations of the North-West American conifer Douglas-fir were established in Portugal in 1904. Investigations into growth and yield patterns were started in 1969. Since then others have carried out further studies. This study includes data from the previous studies and covers the whole range of site conditions where Douglas-fir grows in Portugal. Dominant height data from 87 stem analysis trees from 12 sites were used to model dominant height growth of Douglas-fir using the McDill-Amateis, Chapman-Richards and Lundqvist-Korf growth functions. The Chapman-Richards and Lundqvist-Korf growth functions were used in their integral and difference forms. For the evaluation of the candidate growth models' performance, three steps were adopted: