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BYU study: megafire reshapes understory and early tree regeneration; non‑native plants increase in burned pinyon‑juniper
Summary
A BYU Ph.D. study of the 2018 Pole Creek megafire found that understory responses varied by forest type: burned aspen–fir lost native forb richness, oak–maple showed limited change, and pinyon‑juniper saw increased non‑native richness and cover, raising concerns about cheatgrass expansion.
A researcher reporting BYU Ph.D. results said the 2018 Pole Creek megafire’s effects on understory plant communities and sapling regeneration depended on forest type, with burned pinyon‑juniper showing a marked rise in non‑native species.
Devry (Ph.D. researcher, Brigham Young University) summarized field work across aspen‑fir, oak‑maple and pinyon‑juniper forest types within the megafire footprint. Teams sampled paired transects in burned and unburned patches and recorded species richness, percent cover and sapling browse and density for three years post‑fire (2019–2021).
Key results: in aspen‑fir stands, burned plots showed decreased native forb richness and lower native species cover; oak‑maple showed only modest negative changes. Burned pinyon‑juniper sites had higher total forb richness but that increase was driven by non‑native species — eight of the top ten cover species in burned pinyon‑juniper were non‑native, including a notable presence of cheatgrass, which can increase fire spread risk.
Devry also measured sapling regeneration and herbivory. Woody species regenerating vegetatively (e.g., oak clones) increased after fire, while seed‑regenerating conifers and pinyon had lower sapling density in burned areas early on. Herbivory on broadleaf saplings was higher the first year post‑fire but generally declined in subsequent years and did not exceed threshold levels the researcher cited for long‑term regeneration loss.
On aquatic consequences, conference presenters from BYU‑linked teams reported that a heavy storm immediately after the megafire moved large pulses of sediment and particulate carbon and nitrogen into downstream systems — one study cited a ~2,000‑fold rise in sediment flux and ~6,000‑fold increase in particulate C and N during the storm — with implications for reservoirs and the Great Salt Lake catchment.
Devry’s takeaway: megafires can produce divergent ecological responses across forest types. Managers should expect increased invasion risk at lower elevation pinyon‑juniper sites and prioritize post‑fire monitoring and targeted restoration (e.g., native seedings and cheatgrass control) where non‑natives threaten recovery.
