Techniques are described that bring such a framework into place, and areas in which problems remain are identified. From such a starting point, a unified framework needs to encompass: (i) the display of community patterns through clustering and ordination of samples (ii) identification of species principally responsible for determining sample groupings (iii) statistical tests for differences in space and time (multivariate analogues of analysis of variance, based on rank similarities) and (iv) the linking of community differences to patterns in the physical and chemical environment (the latter also dictated by rank similarities between samples). Statistical assumptions about the data are thus minimized and the resulting non-parametric techniques will be of very general applicability.
The pivotal concept has proved to be that of a biologically-relevant definition of similarity of two samples, and its utilization mainly in simple rank form, for example ‘sample A is more similar to sample B than it is to sample C’.
A decade on, it is instructive to: (i) identify which elements of this often-quoted strategy have proved most useful in practical assessment of community change resulting from pollution impact and (ii) ask to what extent evolution of techniques in the intervening years has added self-consistency and comprehensiveness to the approach. Abstract: In the early 1980s, a strategy for graphical representation of multivariate (multi-species) abundance data was introduced into marine ecology by, among others, Field, et al.
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