System Omnivory Index

Omnivory, intended as the feeding on more than one trophic level, increases the complexity of trophic networks, this latter being an important feature for evaluating stability and maturity of ecosystems. The system omnivory index quantifies the distribution of feeding interactions among trophic levels through the weighted average of omnivory of the network’s consumers. It represents an overall measure of the complexity of a given ecological network, thus allowing for the intercomparison among ecosystems and for assessing their development stage and maturity. Number of links in the web, magnitude of flows and predation on nonadjacent trophic levels, are all influencing the system omnivory index. However, given a trophic network, it is only slightly affected by the aggregation method used. Therefore, the system omnivory index is largely applied as a quantification of the web-like structure of weighted and directed food webs.