4. Functional ecology and ecosystem models

Moving to the ecosystem level naturally brings problems of matter and energy flows to the fore, and only a few salient aspects of biomathematical and computational approaches will be mentioned here.

In the 1970s and 1980s, one of the most significant quantitative approaches was the construction of ecosystem models, notably as part of the "international biological program" . These models, made up of huge systems of difference equations, often with a time step of one day, represent the flows of matter (carbon, nitrogen, phosphorus) within an ecosystem divided into compartments: soil proper, soil microbes, root compartment, epigeous part of plants, herbivores... The complexity...