On the use of landscape surrogates as ecological indicators in fragmented forests

Abstract

Given the potentially negative effects of forest fragmentation on biodiversity, govemments and management agencies have sought generic landscape measures of forest fragmentation to monitor changes in forest cover - measures that also may be informative for decisions relating to changes in biodiversity. In this paper, we discuss issues relating to the evaluation of landscape surrogate measures and their usefulness as ecological indicators. We illustrate some of these points by a detailed examination of statistical relationships among several target responses (defined as the occurrence of particular species), and a selection of landscape surrogate measures in two forest regions of southeastern Australia. There was no evidence in our data that surrogate landscape measures have generic applicability for the conservation of large sets of species. Although landscape surrogates may be useful where the aim is to quantify current landscape patterns from a human perspective or to monitor the extent and rate of change in that pattern over time, they may not have biological and statistical significance for particular elements of the biota. There is a need for a clear definition of units and measures, a need to be aware of redundancy among potential surrogates, and a need for the establishment of a framework for rigorously evaluating ecological indicators.