Large wildfires can sometimes help forests regenerate better, new research from Brigham Young University suggests, challenging assumptions that all fire suppression is beneficial. The study, published in the journal Fire in August, shows that megafires — fires larger than 100,000 acres — can trigger pulses of tree regeneration that outpace browsing by deer, elk and livestock in multiple forest types.
“The Smokey the Bear fire suppression campaign has actually been problematic,” said Sam St. Clair, a BYU plant and wildlife professor and the study’s lead investigator. “We should be encouraging more fires in forests that are fire‑adapted.”
Researchers monitored regeneration for three years after the 2019 Pole Creek megafire in northern Utah, sampling 34 burned and unburned sites across a mosaic of high-elevation aspen-fir, mid-elevation maple-oak, and low-elevation pinyon-juniper communities. At each site, the team recorded seedling density, seedling height and rates of browsing by wild and domestic herbivores.
Initially, herbivore browsing suppressed recruitment of some species. By year three, however, all measured tree species showed positive recovery, with overall regeneration increases that exceeded observed browsing pressure. “We found that when a fire is large enough and burns with mixed severity, the resulting surge of tree regeneration across forest types exceeds what the animals can consume,” St. Clair said.
Species that resprout from surviving roots — notably aspen and oak — responded most strongly. Aspen, in particular, produced dense, rapid regrowth and increased leaf chemical defences, which reduced palatability to browsers, helping establish a recovery trajectory that supports broader understory and wildlife habitats. “Aspen trees are pioneer species that set the stage for the rest of the forest after fire; they should ideally be burning every 50–70 years,” St. Clair said.
The authors argue that in landscapes with elevated herbivore populations and long histories of fire suppression, appropriately sized and mixed-severity fires can be a strategic tool for restoring forest resilience. They caution that benefits come with clear trade-offs: short-term canopy loss and smoky air versus longer-term gains in species diversity and structural recovery.
An independent fire ecologist not involved in the study said the results add useful nuance to fire‑management debates. “This study shows megafires can create opportunities for regeneration that smaller burns cannot, but managers still need to weigh risks to communities, air quality and infrastructure when planning treatments,” the ecologist said.
The research team plans to revisit the Pole Creek plots to track longer-term outcomes for canopy structure, understory composition, and ecosystem functions such as decomposition and soil microbial activity.
For further information, visit “Regeneration and Herbivory Across Multiple Forest Types Within a Megafire Burn Scar,” which appears in Fire (2025). DOI: 10.3390/fire8080323. Co‑authors include former BYU students Devri Tanner, Kordan Kildew and Noelle Zenger, and BYU professors Benjamin Abbott, Neil Hansen and Richard Gill.
