MODELING GROWTH AND OPTIMAL ROTATIONS OF TROPICAL MULTIPURPOSE TREES USING UNIT LEAF RATE AND LEAF-AREA INDEX

A simple model of tree growth in even-aged stands calculated growth rate as the product of unit leaf rate (E) and leaf area per tree. Theoretical analysis showed that decreasing E with increasing leaf area index (LAI) depends on both allometry and current growth rate, which depend on planting density, growth history, and competition. A case study using Eucalyptus saligna grown in Hawaii found that the growth trajectories of four different planting densities can be represented by a single curve of E versus LAI. Using maximum mean annual increment (MAI) as the criterion for optimal rotation length, the model predicts increasing peak MAI from 16.4 to 21.5 t ha-1yr-1 for initial planting densities, varying from 500-2000 trees ha-1. Over this range of initial densities, rotation age decreases from 9.0 to 4.7 yr; at rotation age for these initial densities, trunk diameter decreases from 28 to 14 cm, total biomass decreases from 148 to 102 t ha-1, and LAI decreases from 4.0 to 2.9. -from Authors