Abundance Biomass Comparison Method

Abstract

The ‘abundance biomass comparison’ (ABC) method is a means of detecting the effects of anthropogenic perturbations on assemblages of organisms that is underpinned by the r- and K-selection theory. It involves the plotting of separate k-dominance curves for species abundances and species biomasses on the same graph and comparing the forms of the two curves relative to each other. In undisturbed assemblages the biomass curve is elevated relative to the abundance curve throughout its length. In perturbed assemblages the abundance curve lies above the biomass curve and under moderate perturbation the biomass and abundance curves are closely coincident and may cross over each other one or more times. The contention is that these three conditions (unperturbed, moderately perturbed, or grossly perturbed) should be recognizable without reference control samples in time or space, the two curves acting as an internal control against each other and providing a snapshot of the condition of the assemblage at any one time or place. The plots can be reduced to a single summary statistic (W), the standardized sum of the biomass minus abundance values across the ranks.