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An Ordination Study of a Chalk Grassland Community

M. P. Austin
Journal of Ecology
Vol. 56, No. 3 (Nov., 1968), pp. 739-757
DOI: 10.2307/2258104
Stable URL: http://www.jstor.org/stable/2258104
Page Count: 19
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An Ordination Study of a Chalk Grassland Community
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Abstract

Some aspects of the use of ordination techniques are discussed. It is proposed that ordinations based on vegetation variables be termed vegetational ordinations, while those based on environmental variables be termed environmental ordinations. It is suggested that environmental ordinations are inherently inefficient and that either principal component analyses of a matrix of weighted similarity coefficients between stands or of correlation coefficients between species is likely to be the most satisfactory technique at present available. A comparison of vegetational and environmental ordinations on data from a relatively homogeneous community type is made. It is concluded that a vegetational ordination provides the greatest information but the environmental ordination may provide additional information. Hypotheses regarding the environmental factors associated with major vegetational variation within the community type are put forward. The most important cause of variation was the competitive effect of the `dominant' species, Zerna erecta. Variation in a soil property correlated with soil depth, available phosphorus and exchangeable calcium and in a factor related to aspect and the ratio of calcium to potassium were suggested as other important associated environmental factors. A canonical correlation analysis was also undertaken but the results were found to be unsatisfactory.

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