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Ordination of Vegetation Samples by Gaussian Species Distributions
Author(s) -
Gauch Hugh G.,
Chase Gene B.,
Whittaker Robert H.
Publication year - 1974
Publication title -
ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.144
H-Index - 294
eISSN - 1939-9170
pISSN - 0012-9658
DOI - 10.2307/1935466
Subject(s) - ordination , gaussian , gradient analysis , sample (material) , mathematics , gaussian network model , vegetation (pathology) , ecology , statistics , chemistry , biology , medicine , pathology , computational chemistry , chromatography
Direct gradient analysis has shown that along many environmental gradients species distributions show bell—shaped forms, overlap broadly, and have their centers and limits scattered. This finding is the basis of a technique called “Gaussian ordination” presented here, which arranges samples by maximizing the fit of Gaussian curves to the individual species' distributions. Ordination proceeds by (1) a first—guess arrangement of samples, (2) sorting of species for relative usefulness in ordination, and (3) fitting of least—squares Gaussian curves to the individual species, followed by (4) iterative fitting that changes the ordination values to produce an optimal Gaussian fit for all species together. Gaussian ordination is appropriate for sample sets with a major axis of environmental and community variation. The technique has produced successful ordinations of simulated and field data. Because Gaussian ordination is based on an explicit model of vegetation structure and computes the species and sample parameters for this model, the technique represents a convergence of research in direct and indirect ordination.