There is little doubt that the ecosystem model can be of great use in improving our understanding of individual habitats and the biosphere (Jones, 1983). However, applying the ecosystem concept to real-life situations is difficult. If the ecosystem concept is applied at the 'black- box' level then little by way of real understanding of how the habitat functions can be achieved.
On the other hand, to work at 'white-box' level demands a small team of research workers, sophisticated computer capabilities (massive computer storage and an ability to write the necessary programmes) a time span of perhaps a decade and finance to support the research effort.
It is appropriate to apply the concept of 'successive approximation' as developed by Poore (1964) to the study of ecosystem. Poore, op. cit., suggested that when working with vegetation community analysis it would be necessary to begin at the simplest level and to gradually increase the intensity of study so that greater understanding of the community could be obtained.
A similar process of 'successive approximation' is directly applicable to ecosystem studies. Initial work would be made at the black box level. Gradually, and with increasing experience, a move towards grey-box level could be made. Eventually, and for a small selection of ecosystems, it should be possible to work at white box level.