Stability and reactivity of food webs with trophic interactions

Ecosystems are increasingly vulnerable to species extinctions and functional disruptions driven by climate change and anthropogenic pressures. Although significant progress has been made in understanding the stability and reactivity of ecosystems, the influence of functionally distinct species groups remains underexplored. Here, we develop a food web model that incorporates producers, consumers, decomposers, and detritus, effectively capturing key characteristics of real food webs. By simulating ecologically realistic perturbations-including species loss, interaction loss, and changes in interaction strength-we examine how trophic structure shapes the stability and reactivity of food webs. We demonstrate that stability and reactivity are not determined solely by species richness or network connectivity, but are critically influenced by the functional roles of species. Shifts in interaction strength can trigger phase transitions in food webs. Our results reveal that, compared to other taxa, variations in the interaction strength of consumer taxa pose a greater threat to the overall state of food webs, increasing the likelihood of reactive or unstable dynamics. Finally, we propose that enhancing self-regulation and managing species abundances can promote ecosystem resilience and mitigate large-scale species loss under persistent disturbances. This work offers a functional perspective on ecosystem stability and reactivity, and provides new insights for the conservation and restoration of food webs.