An assessment of Alberta's strategy for controlling mountain pine beetle outbreaks

Abstract Managing forest pests at landscape scales presents one of the greatest challenges in applied ecology. Since 2004, the Canadian province of Alberta spent more than 500 million dollars managing mountain pine beetle (MPB) populations—primarily by detecting and burning infested trees—yet the effectiveness of this intervention remains uncertain. Using a statistical modelling framework coupled with long‐term field data, we examined how direct control measures, severe winters and host‐tree depletion shaped the trajectory of Alberta's MPB outbreak between 2009 and 2020. Control efforts reduced cumulative tree mortality by 79% (95% predictive interval: 55%–89%), preventing approximately 1.8 (0.77–3.8) trees per hectare from being killed during the study period. Cold winters had minimal direct impact on tree mortality, but worked synergistically with control efforts to collapse beetle populations around 2020. Host‐tree depletion played a negligible role. Each infestation that was removed (cost: 320 CAD) prevented the loss of approximately seven additional trees in the long term (95% predictive interval: 2.4–14), demonstrating potential cost‐effectiveness. Model projections show high uncertainty in future outbreak severity, with potential tree mortality ranging from 0.37 to 8.6 trees per hectare over an 11‐year period under a no‐control scenario, and an alternative model suggesting even wider variation (~1–40 trees per hectare). Synthesis and applications. Our findings tentatively support a ‘wait it out’ management strategy for forest pests with strong Allee effects, where small populations face experience negative growth. Moderate but sustained control efforts prevent explosive population growth until extreme winter conditions deliver a final blow, offering a cost‐effective approach that enables complete outbreak suppression without indefinite intervention.