Density and the growth of even-aged stands

Abstract

This study develops a density-driven module and combines it with conventional growth equations, making the resulting model applicable to managed stands. The relationship between the diameter increment of an average tree and density evolves from the analysis of amount of light coming to the unshaded (upper) part of the crown, distribution of foliage along the stem, proportion of light transmitted through the crown, probability of shading the lower part of the crown, and other processes. The density module contains seven parameters, all of which can be assessed from existing knowledge. One of the parameters quantifies phenotypic adaptation, which mitigates competition stress. The entire model starts and ends with basic measurable variables: number of trees per unit area and their average diameter. The growth processes are evoked only to connect the current and future values of stand variables.