On the behavior of some proposed goal functions for ecosystem development

Abstract

Abstract In recent years a number of “goal functions” for quantification of the state of development of ecosystems have been proposed, but studies of their behavior have been sparse. One reason for this has been a lack of published quantified ecosystem models that could be used for studies of the goal function behavior. This situation has recently been alleviated and here 41 newly published static ecosystem models are being used to describe the behavior of two goal functions, ascendency and exergy, and some of their derivatives. It is found that ascendency is mostly influenced by the energy throughput in the system, and also that a ranking of the ecosystems after ascendency does not correlate significantly with an independent ranking of the ecosystems after ecosystem maturity, as quantified from seven ecosystem attributes following Eugene P. Odum's description of maturity. Relative ascendency correlates very strongly, though negatively with the ecosystem maturity ranking, showing a promising behavior. The exergy is found to be a function of the total system biomass while no significant correlation was found for exergy and ecosystem maturity. It is concluded that quantification of exergy is problematic and should be reconsidered; a similar conclusion is reached for the structural element of exergy.