Stand structure as the basis of diversity index

Abstract

Abundance of tree species and variation in tree size, age and genetic composition are the most relevant components of diversity in a forest stand. The aim of this study was to develop a within-stand diversity index and classification for between-stand diversity to meet these requirements. This, what may be called LLNS diversity index, was assessed by using the following indicator variables: stem distribution of live trees by tree species (stems ha −1), standing and fallen dead trees by tree species (m 3 ha −1), occurrence of special trees (number/significance) and charred wood (m 3 ha −1). The index was introduced as a scoring table for field use and as a mathematical formula for research and computerisation use. In the test material, this index served to differentiate the development classes of forest stands and site-types fairly well. The value of the index was at its highest in unmanaged, old-growth stands dominated by Norway spruce ( Picea abies (L.) Karst.). In single-tree selection stands, regularly all-sized stand structure resulted in a high diversity index values whereas low thinning, by evening out stand structure, reduced diversity. Classification of between-stand diversity was based on within-stand diversity scores, which were allocated to four quality levels (Excellent, Good, Satisfactory, Poor) by site-type.