Analyzing ecotones to predict biotic productivity

Abstract

A technique for predicting the potential biotic productivities of areas is presented. The simple method uses maps or other techniques of remote imagery in comparing adjacent terrestrial and/or littoral areas for investigations when ground reconnaissance is not feasible. Theedge index, the statistical basis for comparison, is calculated as the ratio of the length of a particular ecotone (for example, timberline or shoreline) that would be affected by a proposed development to the affected land area. In similar habitats an unbiased comparison results at the ordinal level of measurement. The method predicts that a higher edge index will correspond to a higher productivity. But because it is not established whether or not the relationship is somehow scalar, the method is not recommended for comparing greatly dissimilar or far distant areas.

It has long been observed that ecotones (edges) where two biotic communities meet often produce more game than pure stands of either community. The reasons for this edge effect are reviewed. The demonstrably higher productivity of ecotones is partially explained in terms of the mechanisms that also account for diversity of species.

An attempt is made to reconcile theoretical treatments of species diversity with the pragmatic methods for reaching conclusions, which are employed by specialists in resource management.