Ecologists make models of habitats and ecosystems to study questions that would be impossible, impractical or unethical to answer by testing actual ecosystems. Instead, ecologists concoct complicated mathematical programs that should react in similar fashion to real ecosystems when faced with similar stimuli. According to an article in BioScience, models often produce surprising and unexpected results.
For example, an ecologist may create a model that tries to determine how the energy flows through a small pond ecosystem. Accordingly, the scientist would have to design the model to account for all the various ways energy enters the ecosystem, such as the sun, creatures traveling to the water and plant matter sinking in the pond. Additionally, the ecologist would have to ensure the model accounts for all the ways energy leaves the ecosystem, such as when animals leave the pond.
Models are not perfect recreations of the natural world, and sometimes they produce results that are later demonstrated to be false. This causes many ecologists to tweak their models periodically in pursuit of a model that accurately reflects the real world. Because models are used so extensively in ecology, the National Career Services in the United Kingdom recommends that prospective ecologists have a working knowledge of computers.