Do Species Assemblages Ever Recur?

Abstract

Ecology suffers from the affliction that arguments often happen in the absence of data. Eventually the controversy dies down, and everyone thinks that the issue has been settled, though it is not agreed how, since in fact no test has ever been made. So it is with the question of whether the same assemblage of species (i.e. 'association) can be found at different sites ('association' is used in this paper for a local assemblage of species, with no other implications). The question 'Does any association recur?' strikes at the basis for recognizing and naming community types (e.g. Rodwell 1991-95). It can be seen as the critical test between the two major concepts of community structure, in the words of Gleason (1939), either: