Site index research: a literature review

Abstract

The purpose of this paper was to review literature covering the topic of site index with particular emphasis on Scots pine, the most important forest-forming species in Poland. We discuss the history of the site index, research on various tree species, statistical modelling methods, the spatial application of site index and age impact assessment. The history of research on the site index of forest species is long and dates back to the 18th century. Many researchers thought that determining the quality of the habitat is very important from the point of view of rational forest management. The site index, as a measure of the potential of the habitat on which the forest grows, is one of the most important characteristics of forest stands. The site index depends on the selected model, but is most often expressed as the average or top height of trees of a given species at a certain age. In our review, we point out several insufficiencies of studies on the site index, external influences and the connection of the site index with spatial conditions. Furthermore, research conducted so far has not explicitly confirmed that there is a relationship between the site index of pine stands and their geographical location in Poland. More research on the site index, especially in regard with climate change, is needed.

Currently Available Site Index Equations That Use On-Site Tree Measurements for Naturally Regenerated Longleaf Pine in Its Historical Range

“…304-305)). Site index is used across the world [16][17][18]. Conceptually, for a particular species, site index is a collective influence of soil factors and climatic conditions, and when excluding extremes, site index is thought to be independent of stand density ( [13,14] and [15] (p. 303)).…”

Drivers of site productivity for oak in Poland

“…Ważyński (1967) found that the determination of the SI of pine stands up to 10 years old using height is inaccurate, because the height of young stands is not as strongly dependent on the environmental conditions as in later periods. Likewise, it is impossible to determine the site productivity by phytocentric methods for non-forest areas (Vanclay, 1994;Skovsgaard & Vanclay, 2008a;Weiskittel et al, 2011;Kędziora et al, 2020;Tymińska-Czabańska et al, 2021). Furthermore, a limitation of phytocentric methods is that they limit the possibility of identification of individual biological determinants of growth, precluding continuous mapping of SI across the landscape, or direct predictions based on environmental variables.…”

“…Furthermore, a limitation of phytocentric methods is that they limit the possibility of identification of individual biological determinants of growth, precluding continuous mapping of SI across the landscape, or direct predictions based on environmental variables. To solve these problems, for direct site productivity modelling the geocentric method is used, in which SI is predicted from multiple environmental factors (Skovsgaard & Vanclay, 2008b;Weiskittel et al, 2011;West, 2014West, , 2015Kędziora et al, 2020).…”