ISSN: 2578-4994
Authors: Heiderman R and Kimsey M*
Stand Density Index (SDI) is a common metric used in forestry to normalize comparisons of disparate size-density relationships and evaluate a stand’s relative density to some maximum. Relative density to some maximum is often used to develop thinning prescriptions for maintaining a forest’s resilience and productivity. However, evaluation of the size-density relationship is fraught with potential for miscommunication given reliance on often differential diameter definitions (size) and common truncation of high density stands (density) with small diameters, depending on the objective of the forest biometrician. The objective of this paper is to highlight commonly used methods for defining a stand’s mean diameter and the multiple approaches to computing stand density index. We explore the traditional definitions of mean diameter and their impact on the computation of SDI: 1) arithmetic, 2) quadratic, 3) Reineke’s diameter by summation, and 4) Reineke’s diameter with Taylor expansion, as a function of differing diameter truncation methods. Our analysis summarizes the strengths and weaknesses of the varying definitional approaches to SDI and emphasizes the need to communicate the objectives for which a particular suite of diameter truncation methods and SDI equations are selected.
Keywords: Reineke’s Diameter; Basal Area; Diameters; Forest Biometrician; Equivalent
