A Plantation Timber Production and Utilization System (PLATIPUS) is currently being developed for Queensland's three major plantation species. The growth model will predict not only the volume of timber produced, but also the nature, location and size of defects. It will simulate the effect of silvicultural options such as site preparation, fertilizing, weed control, pruning, thinning and fire. The conversion model will initially comprise submodels for bucking, sawing and grading, but will ultimately also predict veneer, chip, bark and waste outturn. Thus PLATIPUS will allow objective appraisal of the impact of any silvicultural option on both the volume and value of the processed timber in the market place. The paper describes the design criteria, the structure of the system, and discusses the functional relationships required
