Dynamical implications of the variability representation in site-index modelling

Abstract

Issues in the development and formulation of forest site-index models are examined, linking the forestry terminology and methods to standard mathematical concepts. Variability complicates interpretation. Three sources of variation are distinguished: between sites, within sites, and observation error, with the article focusing mainly on the second one. Two site-index definitions arising from different views about the variability are contrasted. Modelling based on algebraic difference equations (ADE's) is analyzed in detail, relating it to concepts of state space flows used in modern dynamical systems theory. It is shown that, given a stand current state, ADE's predict growth rates that are independent of site quality. © 2010 The Author(s).