Category: Ecology

Summary: Finding the omnivory level where the dominant reactive mode in a layered food-web model leaves a basal refuge-supported state and shifts upward into transient amplification.

Ecological community matrices can show strong transient amplification even when long-run growth is damped, and refuges can concentrate that activity in protected basal layers. This experiment asks how much omnivory is required before the top reactive mode escapes that refuge-supported structure and becomes concentrated in middle or upper trophic levels instead.

The model builds dense layered operators with refuges, trophic asymmetry, competition, and omnivory, then uses GPU eigensolves with iterative deepening and bisection on omnivory strength. The threshold is defined by localization and mass-balance criteria that detect when the dominant symmetric reactive mode is no longer refuge-centered.

That target goes beyond asking whether the system is reactive at all. It looks for a structural transition in where amplification lives inside the food web, which is a finer question than standard stability or persistence sweeps usually address.

Method: GPU dense symmetric eigensolves with iterative deepening and bisection on omnivory strength in a layered refuge food-web operator.

What is measured: Reactive-mode presence, localization score, refuge mass, middle-layer mass, top-layer mass, and the critical omnivory threshold.