Several measures of trophic structure applicable to complex food webs

Abstract A continuous measure of “trophic position” is introduced, based on average function of an ecosystem component. Two measures of trophic position variance are defined, and the ideas of trophic specialists and generalists are introduced. The analysis is based on a Markov chain model of energy flows. Along with a number of simple ecosystem structures, the model is also applied to data on the North Sea ecosystem. The model developed in this paper allows for describing in trophic level terms ecosystems which differ substantially from food chains. It is envisioned that such a description would play a useful role in the comparative analysis of ecosystems.