PREDICTION OF STEM PROFILE OF PICEA-ABIES USING A PROCESS-BASED TREE GROWTH-MODEL

We built a simple tree growth model for Norway spruce (Picea abies (L. ) Karst.) that describes the biomass and stem radial growth of one tre e in a stand. Growth is controlled by an external height growth functi on that accounts for site quality. Crown recession is represented by a n empirical function that accounts for the limitation to crown develop ment caused by mechanical contacts with neighboring trees. The model d escribes biomass growth based on carbon budget (photosynthesis, respir ation and senescence) and carbon partitioning between foliage, stem an d root compartments. An internal regulation is introduced based on a f unctional balance between crown and root development. Stem annual grow th is distributed along the stem by means of an empirical rule. Stem p rofile is the final output of the model and can be used to check the o verall consistency of the model and as an aid in wood quality studies. The underlying assumptions of the model are described.