Flawed analysis invalidates claim of a strong Yellowstone trophic cascade after wolf reintroduction: A comment on Ripple et al. (2025)

Daniel MacNulty, David Cooper, Michael Procko, Tyler J Clark-Wolf

Ripple et al. (2025) recently argued that large carnivore recovery in Yellowstone National Park triggered one of the world’s strongest trophic cascades, citing a ~1500% increase in willow crown volume derived from plant height data. In this comment, we show that their conclusion is invalid due to fundamental methodological flaws. These include use of a tautological volume model, violations of key modeling assumptions, comparisons across unmatched plots, and the misapplication of equilibrium-based metrics in a non-equilibrium system. Additionally, Ripple et al. rely on selectively framed photographic evidence and omit critical drivers such as human hunting in their causal attribution. These shortcomings explain the apparent conflict with Hobbs et al. (2024), who found evidence for a relatively weak trophic cascade based on the same height data and a long-term factorial field experiment. Our critique underscores the importance of analytical rigor and ecological context for understanding trophic cascade strength in complex ecosystems like Yellowstone.