2025-08-04 アリゾナ大学
＜関連情報＞
- https://news.arizona.edu/news/tree-ring-study-reveals-western-apache-fire-management-practices-buffered-climate-effects
- https://www.pnas.org/doi/10.1073/pnas.2509169122
- https://www.science.org/doi/10.1126/sciadv.abq3221
樹輪は、アメリカ南西部における西部アパッチ族（Ndee）の持続的な火災管理とニッチ構築を明らかにする Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest
Christopher I. Roos, J. Mark Kaib, Nicholas C. Laluk, +4 , and Thomas W. Swetnam
Proceedings of the National Academy of Sciences Published:August 4, 2025
DOI:https://doi.org/10.1073/pnas.2509169122
Significance
Indigenous fire stewardship—the practice of using controlled fire to achieve cultural goals—was well documented in contemporary communities and in the ethnographic record but has often been undetected in historical fire records. Here, we use well-replicated tree-ring records from Western Apache homelands in Arizona to show that fire regimes here were structured by Indigenous fire stewardship for centuries even as many fire regimes elsewhere in the region were driven primarily by lightning ignitions and climate over the last few millennia. Western Apache fire stewardship persisted on the San Carlos Reservation well into the 20th Century and provides an alternative model to current institutional prescribed burning for restoring cultural fire regimes and resilience to Southwestern dry forests.
Abstract
Identifying the influence of low-density Indigenous populations in paleofire records has been methodologically challenging. In the Southwest United States, well-replicated fire histories suggest that abundant lightning and suitable climate conditions drove frequent low-severity wildfires in dry pine forests independent of human activities even as ethnography provided hints that highly mobile indigenous populations used fire in myriad land use contexts. Here, we leverage published and unpublished tree-ring fire history records from pine forests in Western Apache (Ndee) traditional territory in central and eastern Arizona (N = 34 sites, N = 649 trees) to demonstrate that historical fire regimes were overwhelmingly influenced by Ndee cultural burning. Our tree-ring synthesis shows significantly more frequent fires in Ndee territory than elsewhere in the region for centuries before the establishment of reservations (1600–1870 CE). Despite the heightened fire activity, fires were largely small and asynchronous, occurred disproportionately in late April and May, when Ndee invested significant subsistence activities in these pine forests, and occurred independent of climate drivers. This suggests that Ndee fire stewardship created a patchwork of nearly annual small, spring fires that inhibited natural fire spread and limited the influence of drought on fire activity. Our work shows that even relatively small, highly mobile populations of forager-gardeners had significant influence on some pre-Euroamerican fire regimes despite abundant natural ignitions. Our study shows clearly that Indigenous fire management impacted fire-size distributions, fire frequencies, and fire seasonality in ways that cannot be explained by seasonal and annual lightning densities.
1500年から1900年までのアメリカ南西部における先住民の火災管理と、火災と気候のクロススケール関係 Indigenous fire management and cross-scale fire-climate relationships in the Southwest United States from 1500 to 1900 CE
Christopher I. Roos , Christopher H. Guiterman, Ellis Q. Margolis, Thomas W. Swetnam, […] , and Lionel Whitehair
Science Advances Published:7 Dec 2022
DOI:https://doi.org/10.1126/sciadv.abq3221
Abstract
Prior research suggests that Indigenous fire management buffers climate influences on wildfires, but it is unclear whether these benefits accrue across geographic scales. We use a network of 4824 fire-scarred trees in Southwest United States dry forests to analyze up to 400 years of fire-climate relationships at local, landscape, and regional scales for traditional territories of three different Indigenous cultures. Comparison of fire-year and prior climate conditions for periods of intensive cultural use and less-intensive use indicates that Indigenous fire management weakened fire-climate relationships at local and landscape scales. This effect did not scale up across the entire region because land use was spatially and temporally heterogeneous at that scale. Restoring or emulating Indigenous fire practices could buffer climate impacts at local scales but would need to be repeatedly implemented at broad scales for broader regional benefits.
