In this study, we have attempted to model the budgets of heat. water vapor, and carbon dioxide within three-dimensional vegetation. This model consists of three submodels: a model for turbulent flow within vegetation, a model for radiation transfer within vegetation, and a stomatal conductance model. We adopted our own turbulence model for the flow within vegetation and used Ross's model for radiation transfer within vegetation and a stomatal conductance model by Collatz et at. These three submodels were integrated into the present model, which we applied to a single model tree to investigate how environmental factors affected the budgets of heat, water vapor, and carbon dioxide within a tree. (C) 2004 Elsevier Ltd. All rights reserved.