MODELING TREES USING AN OBJECT-ORIENTED SCHEME

Object-oriented modelling techniques are used to construct a conceptua l framework which defines the hierarchical levels and structures of a tree and connects processes from the different levels. At the tree lev el, combining functions with structure is a logical step towards a bet ter understanding of growth dynamics. A generic tree growth simulation system conforming to the conceptual object framework is constructed. The essential part of the system is a tree, which consists of a large number of relatively simple structural units corresponding to shoots, buds and branch whorls. The development of the tree is driven by basic ecophysiological processes such as photosynthesis and respiration and controlled by principles of functional balance and pipe model theory. The application interface allows changes to the parameter values and the forms of the basic functions. In principle, the system can thus mo del the development of different tree species and different circumstan ces. The present implementation models the growth of young Scots pine; it is programmed using the C++ language. The basic units of the tree are linked together using list structures. They also carry the topolog y of the tree, which is visible in the interface of the application. T he available methodologies for object-oriented modelling are promising for ecological projects, but the present lack of integrated tools cov ering analysis, design, and programming prevents their straightforward adoption.