Indigenous Land Use and Fire Resilience of Southwest USA Ponderosa Pine Forests

The inability of many dry conifer forests in western North America to recover from modern wildfires has highlighted the impacts of land-use history (fire suppression, logging, overgrazing) and climate change on the resilience of these otherwise fire-adapted forests. Although spatially and temporally variable, Indigenous populations could have influenced historical fire regimes for centuries to millennia, even when those influences were subtle enough to be nearly indistinguishable from lightning-only fire regimes in the paleoecological record. Here, we combine archaeology, paleoecology, and paleoclimate records to show that Indigenous land use in at least two regions of the Southwest US improved the fire resilience of dry ponderosa pine (Pinus ponderosa) forests relative to spatially distant lightning-dominated landscapes. Native American fire management that involved high frequency, small patch burning in environments that already experienced frequent lightning ignitions helped to limit the risk to severe fires in variable climates, suggesting that we can similarly reduce the risk of future high-severity fires by applying similar strategies today.