ABSTRACT
Clearly the ecosystem has been a key concept in the development of modem ecology, whose history shows, however, that ecologists did not share a common understanding of this concept (Franzle 1998, Golley 1993). Indeed, from the viewpoint of theory building, the history of the ecosystem concept offers examples for conjectures, refutations, revised conjectures and additional refutations or, as Popper (41972: 215) had it with regard to science in general, it can be seen as The repeated overthrow of scientific theories and their replacement by better or more satisfactory ones’. It is the purpose of the following contribution to outline the role of ecosystem research in the sequential refinement of ecosystem theories which is particularly well reflected in model building. These range from empirical models for practical purposes to rather abstract ones, aiming at qualitative general insights. At one end o f this spectrum there is a detailed and mechanistic description of specific systems such as soil horizons or precisely defined adsorbents in interaction with one or a few pure chemicals in aqueous solutions. At the opposite end of the spectrum are relatively general models which have to sacrifice numerical precision for the sake of general principles. Such conceptual models need not correspond in detail to any single Teal world’ process, but aim to provide a framework for the discussion of broad classes of phenomena or simply of contentious issues. Rationally handled, these different approaches mutually reinforce each other, thus providing reciprocally new and deeper insights.
