The relationship between dominant height and age is the base of site index, the most widely used measure of site quality. In applying the site index concept, one typically assumes that height development is not affected by stand density or thinning treatment. This assumption has been challenged by recent studies on loblolly pine. A detailed data set with initial densities ranging from 6,730 to 750 trees/ha and covering ages 1...

An approach to simultaneously estimate parameters of an annual tree growth model was developed, in which the sum of log-likelihood functions for tree survival and diameter growth was maximized. Four methods for acquiring interim values of stand density were evaluated: (1) Updating Attributes, in which individual tree values were summarized at the end of each year within the growth period to predict interim stand-level attribut...

The generalized algebraic difference approach (GADA) uses both: two-dimensional functions of explicit time and two-dimensional functions of explicit site to derive a single dynamic equation that is a three-dimensional function of explicit time and implicit site. In 2004 Cieszewski advanced dynamic site equations with polymorphism, and variable asymptotes (Cieszewski, C.J. 2004. GADA derivation of dynamic site equations with po...

We discuss here methods of comparing various approaches to site-dependent height–age model-parameter estimation. The discussion emphasis is on proper analysis of the varying parameter (VP) method versus several variants of the algebraic difference methods including one with the error in variable (EIV) theory adaptation. The study has demonstrated that, when properly considered, the VP method consistently outperforms all the ot...

Using an example of averaged growth series data of Scots pine (Pinus sylvestris L.), we examine several approaches to site-dependent height-age model derivation. We consider several renowned base models (two-dimensional equations, such as Y = f(t)) and derive from them anamorphic and polymorphic dynamic site equations (three-dimensional site-height-age models, such as Y = f(t, t 0, y 0)) of different complexities. The consider...

Using eight hypothetical data points (four growth series with two observations each) the difference between two site index curve parameter estimation methods, the base–age invariant stochastic regression approach (BAI) and the method of all base ages (BAA), is illustrated. The anamorphic form of the Schumacher log-transform height–age equation is used for the comparison. The two estimation techniques are equivalent for the lin...