The Contrast in Stand Dynamics as Reveated by Comparing Parameter Estimates for a General Stand Growth Model

1988

S. 1479-1485

4 Abb., 2 Tab., 13 Lit. Ang.

Unselbständiges Werk

200038776

A general stand model is fitted to and used to describe the pattern of stand dynamics for six different species of conifers. The speciesconsidered are Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco), lodgepole p ine (Pinus contorta Dougl.), western hemlock (Tsuga heterophylla (Raf.) Sarg.),jack pine (Pinus banksiana Lamb.), white spruce (Picea glauca (Moench) Voss), and red pine (Pinus resinosa Ait.). The model, a causal process model, uses twodifference equations and six species-specific parameters to generate changes i n stand volume and density as a function of volume, density, and site quality. In a simulation framework, the model represents a variable- density, variable-site yield equation. The model's structural equations are invariant from species to species. The differences in species stand dynamics are thus reflected by differences in the species-specific parameter values. The variation in species dynamics is accounted for by variation in only three of the model's parameters. The first of these three parameters reflects the site-determined growth potential of the species, the second reflects the reduction in growth that results from stand crowding, and the third corresponds to a density-independent mortality rate.