A MODEL SIMULATING ABOVEGROUND AND BELOWGROUND TREE ARCHITECTURE WITHAGROFORESTRY APPLICATIONS

Modelling plant growth and architecture requires two consecutive and c omplementary approaches. The first is a qualitative botanical analysis , in which the development sequence of a tree is studied by the identi fication of various levels of organisation and of homogeneous subunits . All of these - architectural unit, axis, growth unit - follow partic ular growth processes which can be described by using the second appro ach, the quantitative analysis. Modelling of the functioning of merist ems based upon stochastic processes has been carried out since 1980, i n combination with a large amount of experimental work on temperate an d tropical plants. Calculations involved in tree simulations from fiel d data are based upon the probabilistic Monte Carlo method for the top ological part and on analytical geometry for the morphological part. C omputer graphics methods are then used to visualise the computed plant . Several sectors in agroforestry are concerned with application of su ch plant architecture modelling: tree growth and yield, radiative tran sfers, timber quality and mechanics, simulation of competition, intera ction between plant morphology and physiology.