Application of Stand Density Index to Irregularly Structured Stands

Abstract

Today's silviculturists face the challenge of having to produce and sustain a variety of stand structures to meet diverse objectives involving, for example, ecological restoration, aesthetics, and wildlife habitat. To manage these stands, we must be concerned with all of the elements of structure, including density. Simple stand measures such as basal area and mean diameter, which may be adequate when used to describe even-aged stands, only partly describe stand density and do very little to characterize stand structure. We require a measure that accurately describes density and is also sensitive to diameter classes distribution. When the appropriate method of calculation is used, Reineke's stand density index (SDI) (Reineke 1933) is capable of meeting this need. Stage (1968) showed that SDI for a stand can be partitioned to individual trees. This property gives great flexibility in allocating growing space to desired diameter classes, regardless of structure. In this article, I will address two points: (1) SDI distinguishes between stands with similar basal area but different diameter distributions, and (2) there is a "best" method of calculating SDI, which differs from Reineke's method (the method commonly presented in textbooks).