CLUSTER-ANALYSIS OF ASSOCIATIONS OF TESTATE AMEBA (RHIZOPODA, TESTACEA) IN SPHAGNUM

A quantitative study of the Testacea of 189 samples of Sphagnum from 12 bog and fen sites and isolated Sphagnum swards was made. The upper and lower sections of the Sphagnum plants were analysed separately. Active and encysted individuals as well as empty shells were distinguished. Taking into account the vertical distribution, a new method is proposed to determine the minimal sample size (Gruppenminimalareal GMA) for Testacea in Sphagnum. The classification of Testacean associations was carried out by cluster analyses. An UWPG algorithm (McCammon and Wenninger 1970) was used (Figs. 2-6, Table 2). The faunistic similarity between samples was computed as percent similarity of dominants (Renkonen number) because no satisfactory results were obtained with presence/absence data. The analysis differentiated 25 associations of Testacea, characterized by their dominants. fig. 7 gives the position of clusters in the space of the three factors humidity class, zone of Sphagnum stem and type of habitat (bog or fen). Some of the associations are restricted to single sample sites. The highest number of associations is found in Sphagnum swards of medium moisture content. Coenotic variability is too great to be explained by the variability of abiotic habitat conditions some of the associations match the types proposed by Schönborn (1963), but the total number is much higher and will increase significantly with more and different sites being surveyed with Similar methods. © 1979, VEB Gustav Fischer Verlag Jena. All rights reserved.