Synthesis: Growth Models for Tropical Forests: A Synthesis of Models and Methods

Abstract

Tropical forests may have many species, indeterminate ages, and a wide range of growth habits and stem sizes, and thus require special modeling techniques. But technique contributes only part of model quality, and much depends on the quality of calibration data. Whole stand models have limited utility in these forests, as it is hard to describe the forest adequately with few stand-level variables. Stand table projection may to be useful where summarized stand data are available and computer resources are limited, but the many classes required detract from the method. Matrix methods are suitable where stand density and silvicultural practices remain within a narrow range, but are untenable for general conditions. Tree list models offer greater flexibility, enable projections under a wide range of conditions and provide diverse information. Increment equations may predict growth or yield of basal area or diameter but should ensure reliable predictions over all tree sizes, sites and stand conditions. Mortality may be modelled with logistic functions fitted to individual tree data. Regeneration models are complex where there are many species, and two-stage recruitment models may be more practical. The value of a model is in the use to which it is put, so models should be easy to use, well documented and readily available.