Influence analysis in vegetation

Abstract

Species incidence data from Mount Rescue National Park heath, South Australia, were analysed by a single-classification technique, and then according to an alternative strategy, which classifies samples in terms separately of independent nodes of interactions resultant in them, as consequences of influences. This strategy expresses the degrees of interaction in a node, as between two poles, and hence classifies vegetation samples into linear gradients.

This advantage is developed by constructing, for each influence (independent node of interactions), lines on a map which demarcate areas where the outcome or consequence of the influence is the same (isotel map). These maps are similar in appearance to contour or isohyet maps, and depict the disposition, directions, and strengths of an influence. The identity of each influence may then be sought directly by determining what varies over the area as do the isotels.

This strategy is relevant in plant ecology to the analysis of species incidence data by contingency tables, and is so discussed, together with comments on its broader implications.