, Volume 29, Issue 2, pp 89-99

Catenation: Quantitative methods for the definition of coenoclines

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Summary

Catenation is defined as the ordering of elements in continuous sequences that best accounts for local similarities without assuming linear relations. It is thus a non-linear relative of ordination. When applied to phytosociological data it is equivalent to the detection and definition of coenoclines.

Several mathematical methods of catenation are available and potentially useful in phytosociology. One such method, continuity analysis (parametric mapping) has been tested on a variety of simulated and real vegetation data. Despite some computation problems, it usually succeeded in accurately recovering simulated coenoclines which were strongly curved in Euclidean vegetation space. In data from Wisconsin vegetation it defined a first catena which was similar to the ‘continuum’ defined by the leading dominants method; but in one case indicated some modifications and the existence of a second dimension. When applied to other sets of real data, the method detected between one and three catenae or nonlinear dimensions, which were usually closely related to environmental gradients. The relationships of species (or communities) to these catenae tended to be of a bell-shaped form, even though such a form is not explicitly assumed in the method.

Nomenclature of taxa mentioned in examples d and e follows Gleason, 1950, the new Britton and Brown illustrated Flora of the N.E. United States and adjacent Canada.
This was part of the work for a Ph. D. thesis at the Department of Biogeography and Geomorphology, Research School of Pacific Studies of the Australian National University. I am grateful to my supervisors, Donald Walker and Bill Williams, for their advice, to Mike Austin and Mike Dale for useful discussions and to Hugh Gauch and Robert Whittaker for the manuscript of their paper on Gaussian ordination and for the ensuing discussion.