A NEW HEIGHT GROWTH-MODEL FOR DOMINANT AND CODOMINANT TREES

A model was developed to predict height growth for dominant and codomi nant trees, using asymptotic tree height, and tree height at the age o f maximum height growth as principal characteristics to express the in fluence of site on tree height. The proposed model has many desirable attributes: it (1) produces polymorphic site-index curves, (2) contain s an inflection point, (3) asymptotically approaches maximum tree heig ht as age increases, (4) is mathematically defined at the point of ori gin, and (5) has a theoretical base (pipe model theory) for height gro wth, Model performance was evaluated with stem analysis data taken fro m naturally regenerated forest stands of mature to overmature balsam f ir (Abies balsamea [L.] Mill.) and black spruce (Picea mariana Mill.) growing in two separate regions within New Brunswich, Canada, The mode l was also evaluated by analyzing its ability to reproduce existing si te index curves for red pine (Pinus resinosa Ait.). The results indica te that the proposed model performs slightly better than an existing 5 -parameter model based on the Richards' growth function.