Modeling forest growth II. Biomass partitioning in Scots pine

Biomass budgets of Scots pine (Pinus sylvestris) are analyzed with a canonical S-system model. The model is constructed with standardized methods of power-law representation, and a complete set of parameter values is derived from experimentally measured compartment sizes, fluxes and nitrogen contents. None of the typical assumptions about growth rates, relationships between roots and shoots, or allometry are made. All these phenomena are produced by the model as outputs. Specifically, the model correctly predicts the different long-term growth patterns of leaves, stems, and roots; relationships between these compartments, biomass production, and growth rates; and relationships that constitute the concept of functional balance. The model also predicts allocation patterns for biomass under different fertilization regimens and during the ageing of a stand. These latter predictions are more complicated than expected but appear reasonable, though definitive data for validation are lacking.