Category: Ecology

Summary: Finding the omnivory leakage level where a refuge-supported persistence mode in a layered food web escapes its basal refuge without disappearing entirely.

Refuges can protect persistence in food webs, but omnivory creates extra feeding pathways that may leak dynamical support out of the protected zone. This experiment asks when those additional links pull the leading mode away from a refuge-supported basal band while the system still remains persistent overall.

The model constructs dense layered food-web Jacobians with trophic structure, competition, and a basal refuge boost. It then bisects omnivory strength while increasing system size, tracking whether the dominant mode stays concentrated in the refuge or spreads upward through the network.

That distinction separates loss of localization from total collapse. The result is a threshold map for when omnivory turns a protected persistence pattern into a more diffuse and potentially less robust one.

Method: Dense non-symmetric eigensolve with iterative deepening and bisection on omnivory leakage in layered food-web Jacobians.

What is measured: Critical omnivory threshold, refuge mass, upper-layer mass, persistence level, leading-mode localization, and bracket width.