Non‐parametric multivariate analyses of changes in community structure¶
Why this mattered¶
TBD
Abstract¶
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. (1982). 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. 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’. Statistical assumptions about the data are thus minimized and the resulting non‐parametric techniques will be of very general applicability. 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). Techniques are described that bring such a framework into place, and areas in which problems remain are identified. Accumulated practical experience with these methods is discussed, in particular applications to marine benthos, and it is concluded that they have much to offer practitioners of environmental impact studies on communities.
Related¶
- cite → Bootstrap Methods: Another Look at the Jackknife — The community-structure paper uses bootstrap-style resampling logic to assess significance in non-parametric multivariate tests.
- cite → An Ordination of the Upland Forest Communities of Southern Wisconsin — Bray and Curtis's Wisconsin forest ordination provides the ecological dissimilarity and ordination tradition underlying community-structure comparisons.
- enables ← Bootstrap Methods: Another Look at the Jackknife — Efron's bootstrap enables the 1993 community-structure paper by providing resampling-based significance tests for nonparametric multivariate change.
- enables ← An Ordination of the Upland Forest Communities of Southern Wisconsin — Bray and Curtis's Wisconsin forest ordination enables the 1993 analysis through the ecological dissimilarity and ordination tradition used to compare communities.