Releve ranking based on a sum of squares criterion

Summary When a very large number of phytosociological types have to be compared, a reduction of the number of relevés is desirable. In this paper a method of relevé selection from given phytosociological tables is suggested. The method is based on a sum of squares criterion. The advantage, in comparison with other selection procedures, is that this method provides a means on the basis of which the efficiency of a relevé selection can be objectively measured.Contribution from the Working Group for Data-Processing in Phytosociology, International Society for Vegetation Science.The work was completed at the Department of Plant Sciences of the University of Western Ontario, London, Canada. We wish to thank Prof. L. Orlóci for the hospitality and the helpful discussions. The work was supported by Italian C.N.R., within the project Promozione qualità dell'ambiente subproject Metodologie matematiche e basi di dati.