, Volume 117, Issue 4, pp 570–578

A method for analysing spatial scales of variation in composition of assemblages

  • A. J. Underwood
  • M. G. Chapman

DOI: 10.1007/s004420050694

Cite this article as:
Underwood, A. & Chapman, M. Oecologia (1998) 117: 570. doi:10.1007/s004420050694


In several areas of research on ecological assemblages, it is useful to be able to analyse patterns of spatial variation at various scales. Multivariate analyses of dissimilarity or similarity in assemblages of species are limited by problems of non-independence caused by repeated use of the sample-units. Where rank-order procedures are used, no comparative quantitative measurements of dissimilarity at different scales are produced. An alternative method is described that uses the sample's average assemblage (or centroid). These estimates are themselves averaged to give centroids for larger spatial scales. Dissimilarities from the centroids at each scale are then calculated using independent replicates for each scale from those in each sample. The dissimilarity measures can then be examined by analysis of variance to detect spatial scales of differences for each sample at every level of a hierarchy of scales. The method is illustrated using data from mangrove forests and rocky shores, involving up to 97 taxonomic groups (species, other taxa). Differences among assemblages at the scales of sites (tens of meters apart) or locations at shores (hundreds of meters apart) were identified. Consequences of different numbers of replicates are discussed, with some potential problems (and their solutions) in application.

Key words Assemblages Hierarchy Multivariate analyses Spatial scale 

Copyright information

© Springer-Verlag Berlin Heidelberg 1998

Authors and Affiliations

  • A. J. Underwood
    • 1
  • M. G. Chapman
    • 1
  1. 1.Centre for Research on Ecological Impacts of Coastal Cities, Marine Ecology Laboratories, A11, University of Sydney, NSW 2006, Australia e-mail: aju@bio.usyd.edu.au, Fax: +61-2-9351 6713AU

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