Disturbance-mediated apparent competition across boreal landscapes: the role of primary productivity.

Context: Disturbance-mediated apparent competition (DMAC) links landscape disturbance, alternative prey, and predator dynamics in ways that can reduce caribou recruitment and survival. Although DMAC underpins national recovery planning for boreal caribou ( Objectives: We tested the hypothesis that net primary productivity (NPP) governs the strength of DMAC by influencing predator-prey assemblages and shaping patterns of disturbance. Our objective was to determine how these NPP-linked factors influence caribou recruitment and adult female survival at a continental scale. Methods: Using data on caribou recruitment (40 study areas) and survival (30 study areas) from across Canada, along with maps of NPP, disturbance footprints, estimates of moose density, and species richness, we assessed how NPP influences DMAC's effects on caribou. Results: Many of the explanatory variables were strongly correlated. Recruitment and survival declined with increasing NPP, anthropogenic disturbance, predator richness, prey richness, and moose density. Higher NPP increased disturbance, which in turn increased prey and predator richness and decreased caribou recruitment. For survival, NPP increased moose density and ultimately decreased caribou survival. Conclusions: At a continental scale, DMAC diminishes as a potential limiting factor to caribou as NPP declines. Anthropogenic disturbance is concentrated in high-NPP portions of the landscape. High-NPP regions support greater predator and alternative prey species, increasing predation risk for caribou calves. Recognizing the role of NPP in concentrating anthropogenic disturbances and altering trophic interactions is essential for conservation strategies. Supplementary Information: The online version contains supplementary material available at 10.1007/s10980-026-02336-9.