PREDICTING SPACING EFFECTS ON GROWTH AND OPTIMAL ROTATIONS OF TROPICAL MULTIPURPOSE TREES

In order to improve our ability to analyze growth of tropical fast-gro wing trees, we developed a simple model (MPTGro) to predict developmen t of even-aged stands from allometric equations of leaf area and total biomass, and a competition index based on wood production per unit le af area, or net assimilation rate (E). In this study we (1) tested the model assumption that our competition index is valid across plant spa cings, (2) tested the performance of MPTGro on two species of tropical multipurpose trees, and (3) applied the model to optimize rotations b ased on tree size, biomass allocation, or annual biomass increment. Me asurements of E and stand leaf area index (LAI) at three-month interva ls in spacing trials of Acacia auriculiformis and Leucaena diversifoli a supported the assumption that a single relationship between E and LA I would explain growth at a variety of planting densities. Increasing plant density in the simulations decreased time until maximum mean ann ual increment (MAI) and diameter at maximum MAI, but increased leaf:wo od biomass ratio al maximum MAI.