A theory to link relationships of stand volume, density, mean diameter and height in forestry data

In this study, a geometric model of a growing forest stand has been explored. The basic relationships considered link stand volume and stand density, diameter at breast height (DBH), mean DBH and mean height. The model provides simple formulas connecting the exponents of all the relationships. Application of the formulas to real forestry data provided a high level of predictions of an exponent from two others measured through regressions from empirical data. The Pinus sylvestris L. data were of a static nature, a collection of individual stands, while the Pseudotsuga menziesii (Mirb.) Franco data were dynamic, representing forest stand development over time. The ability of the model to predict exponents in the empirical data implies, on the one hand, a substantial level of similarity between the model and the forestry data. And, on the other hand, the model gives an example in which parameters of one relationship may be linked to parameters of another. Supposedly this kind of ‘relationship between relationships’ may be observed in forest stands undergoing active growth and competition-induced self-thinning.