STUDY OF THE TEMPORAL STABILITY OF SPATIA L STRUCTURES BY ANALYZING SERIES OF TOTALLY PAIRED FAUNISTIC TABLES

In this paper, we investigate the potential of partial triadic analysi s (PTA), already introduced in ecology by THIOULOUSE and CHESSEL (1987 ). The principle of the method is presented in a simplified way to fac ilitate its use by ecologists. This method allows the simultaneous pri ncipal components analyses (PCA) of several species composition tables corresponding to the collection of organisms in various locations at different occasions to be coordinated. In this case, PTA permits to fi nd a spatial structure common to every table (i.e., sampling occasion) and to study its temporal stability Therefore, PTA starts by searchin g an average table called compromise Then, the compromise table is ana lysed and its reproductibility by each initial table is finally invest igated. Using the same sampling design, we also present the analysis o f a series of contingency tables (FOUCART, 1978) which represents a di fferent approach since it considers the frequency distribution of spec ies rather than their abundance. We illustrate these two K-set methods by an example in stream ecology We demonstrate the power of these met hods for depicting the temporal evolution of the spatial structures.