Describing interactive growth using vector universalities

The Phenomenological Universalities are a formal way to classify growth. We apply this concept to investigate interactive growth phenomena in biological and ecological systems. Using a vector formulation of these Universalities without any ad hoc assumptions on the nature of the interactions, we are able to characterize the joint growth of two or more interacting organisms and assess the direct mutual influences between them, as well as the indirect influences that operate through environment modifications. Various interactions, such as cooperation, parasitism, and mutual hindrance can be suitably described. We present several illustrative examples, including an examination of the growth dynamics in a mixed-species plantation and compare the predictions of our method with the conclusions obtained by biologists through direct observation.