AN INFORMATIONAL SYNTHESIS OF ECOSYSTEM STRUCTURE AND FUNCTION

The mechanistic view of ecosystem dynamics, being inherently reversibl e, seems ill-suited to describe directional behavior, such as ecosyste m succession. A more conservative approach, such as one that involves probabilities, seems warranted. Work involving conditional probabiliti es has led to the development of a systems property called the ascende ncy, the increase of which appears to incorporate many of the changes that characterize the successional process. Ascendency originally was formulated entirely in terms of systems transactions. Hence, it did no t address the crux of system dynamics, which is the connection between the stocks of taxa and the trophic flows between these populations. O ne may, however, expand the definition of system ascendency in a perfe ctly natural and consistent way to include compartmental biomasses. Th e principle of increasing ascendency, recast in terms of the new defin ition, provides a whole-system context for hitherto unexplained elemen ts of traditional ecology. For example, the allometric trend during su ccession towards larger organisms with slower turnover times and the t ime-honored 'Liebig's law of the minimum' both can be derived from the revised principle. Furthermore, the same derivational techniques prov ide us with an entirely new criterion for identifying the limiting nut rient linkages within an ecosystem. Such a theoretical 'prediction' mi ght augur the beginnings of a robust theoretical systems ecology. (C) 1997 Elsevier Science B.V.