Figure 1. Diagram illustrating four methods for reducing complexity of natural systems. Centre figure shows a hypothetical system with the true interactions and variables. Functional groups/trophospecies illustrates the idea of grouping species by trophic/functional similarity and treating each group as one component. Modules represent sub-groups of mostly mutually interacting species which can be modelled independently. Modules can also be linked to each other. General functions can define interactions between individuals based on traits (e.g., size), rather than between species. Latent variables are used to represent the variability caused by unknown factors (e.g., species or environmental variables).