An ecosystem model can be very simple or very complex depending on the questions being examined. For example, a graphical model like the one below can be very useful to help us figure out what the various components are in an ecosystem and how they are related, but they are not very useful in predicting future conditions. Much more complex models are needed to attempt to predict what will happen to an ecosystem under different conditions. Even the relatively complex carbon cycle illustrated below is probably not detailed enough to actually predict future conditions if one part of the ecosystem changed. In order to do that, you need to not only know which compartments are linked, but what factors control the flow of nutrients of energy among the various ecosystem components.