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A new using fire-scarred trees in the Proceedings of the National Academy of Sciences (PNAS) journal has documented extensive fire management practices by Western Apache people that significantly reduced the climate’s influence on fire activity across their homeland.

The research, led by Íæż½ã½ãfire scientist Christopher Roos, analyzed 649 fire-scarred trees from 34 sites in Western Apache traditional territory in central and eastern Arizona and compared them to several thousand trees from the broader Southwest region. The findings reveal that despite being a small, mobile population, Western Apache communities had significant control over fire patterns across the landscape at different times of the year, much more than scientists previously thought possible.

Fires were mainly asynchronous and occurred independently of climate drivers, contradicting previous assumptions that abundant lightning and climate conditions drove fire patterns throughout the region.

Notably, more frequent fires occurred in Apache territory than elsewhere in the region for centuries before the establishment of Indian reservations. Most fires occurred disproportionately in late April and May, when Apache people devoted significant time to subsistence activities in pine forests.

"The fire frequencies were so different in Western Apache homelands that they stood out like a neon light," Roos said. "But the fires were also really small, and they were happening at different times of the year, and they were buffering the influence of climate as a result. This was a small group of foragers who were basically taking control of the fire regime. And we were able to show this clearly through tree rings.”

Íæż½ã½ãenvironmental archaeologist Christopher Roos has spent two decades studying human-fire interactions across the the southwestern United States, directing interdisciplinary research that reveals how Indigenous communities shaped wildfire patterns through traditional burning practices.

Fire Management Approaches

The study builds on Roos’s previous research that examines cultural burning practices across the Southwest, including work in Pueblo communities and Navajo country. The Western Apache data came from unpublished fire history work conducted 25 years ago, including research commissioned for the San Carlos Apache Tribe.

Roos points out that the findings challenge common assumptions about Indigenous fire management, which often focus on larger, more sedentary populations. The Western Apache were primarily mobile forager-gardeners who practiced limited gardening. Yet, the tree ring evidence shows they maintained systematic control over fire patterns across the landscape.

According to the study, the Apache fire management created reinforcing cycles of landscape stewardship. Areas they called "farm sites" served as anchors for movement across the territory. Burning in these areas improved forage for game animals. It also enhanced wild plant resources, which brought people back to these locations and led to additional burning cycles.

The research has implications for current fire management approaches. Rather than conducting extensive burns to meet acreage goals, the study suggests that many small, fragmented burns create more effective firebreaks and reduce hazards near human communities.

“Our work supports the need to include Indigenous fire knowledge in contemporary fire management discussions and is a testament to the long histories of environmental stewardship by Native populations,” said Roos.

Other authors involved with the study include J. Mark Kaib, U.S. Fish and Wildlife Service and University of Arizona; Nicholas C. Laluk, University of California, Berkeley and the White Mountain Apache Tribe; Melinda M. Adams, University of Kansas and the San Carlos Apache Tribe; Christopher H. Guiterman, University of Colorado Boulder and NOAA’s National Centers for Environmental Information; Christopher H. Baisan, Kiyomi Morino, and Thomas W. Swetnam, University of Arizona.