A numerical model to quantify the growth of a canopy for a forest hydrology model

The paper presents a distance-dependent, individual tree growth model, developed to run as a pre-processing unit for a canopy interception model. The two main routines in the model are the logistic equation controlling individual tree growth and zones of influence controlling inter-tree competition. The model has a largely empirical nature, although many of the input parameters are physically measurable. The testing of the model takes the form of a sensitivity analysis and validation testing against a dataset. The sensitivity analysis indicates the importance of size for zones of influence and the mean growth ratio within the model structure. It also indicates the dynamic nature of the model in that the input parameters are affecting the model output by variable amounts at different times. The model has been used to generate a specified age of forest canopy for a hydrological model which makes use of the three-dimensional nature of simulated canopy. (C) 1999 Elsevier Science Ltd. All rights reserved.