VISUAL BASIC

Physiological Principles in Predicting Growth (3-PG)

The 3-PG model was developed to bridge the gap between conventional, mensuration-based growth and yield, and process-based carbon balance models. 3-PG calculates the radiant energy absorbed by forest canopies and converts it into biomass production. The efficiency of radiation conversion is modified by the effects of nutrition, soil drought (the model includes continuous calculation of water balance), atmospheric vapour pressure deficits and stand age. Output includes stem biomass and volume, average stem diameters, stand basal area at any time and the time course of Leaf Area Index.