ABSTRACT
Ecosystems are what is called medium number systems (O ’Neill et al., 1986). They have many components and the components as well as the systems are all unique and different. In a generalising estimation, a typical ecosystem would have in the order of 10151020 components. Some of them may belong to the same species or the same type of non living components, for instance suspended clay particles. The number of species in ecosystems may vary considerably, but will in most ecosystems be o f the order o f 1000 - 100,000. Individuals belonging to the same species may have some characteristic properties in common, but each individual is still different from all the other individuals - for instance they have their own genetic code, which implies that we are dealing with systems of 10151020 components with clearly different properties. This variability is indispensable, as it is the basis for the Darwinian selection and thus a prerequisite for evolution. The conclusion is therefore that it would be an impossible task to analyse and know all the components of an ecosystem in detail, and even if we could gather the detailed knowledge about all the components, it may soon be useless, because the biological components are currently changing as they adapt to the steadily changing conditions.
