Reanalysis invalidates 1,500 percent willow growth claim after Yellowstone wolf recovery

The critique identifies three core flaws: the volume model used plant height both to compute and to predict the same variable; the height-volume relationship calibrated on unbrowsed plants was applied to heavily hedged willows whose growth forms violate model assumptions; and 2001-2020 plot comparisons mixed different locations, conflating spatial variation with temporal change. These issues alone render the reported trophic cascade magnitude statistically unsupported. MacNulty's team concludes the data instead show modest, hydrology-dependent responses confined to specific sites rather than park-wide release from browsing.

Simplified trophic cascade narratives have shaped both public perception and management targets, including expanded wolf recovery goals and reduced emphasis on elk hunting or beaver restoration. Yet non-equilibrium conditions, legacy effects of 70 years without wolves, and unmeasured factors such as human harvest outside park boundaries make equilibrium-based comparisons to other systems inappropriate. The reanalysis aligns with earlier cautions from Hobbs et al. that predator effects in Yellowstone remain context-dependent and spatially heterogeneous.

Future work requires repeated measures on identical plots, independent validation of allometric models against harvested biomass, and explicit inclusion of hydrologic and anthropogenic covariates. Until such designs are implemented, claims of dramatic ecosystem engineering by wolves should be treated as hypotheses rather than established fact for policy.