Tree-rings reveal the legacy of Indigenous cultural burning in the Southwest USA скачать в хорошем качестве

Tree-rings reveal the legacy of Indigenous cultural burning in the Southwest USA

Summary: This webinar demonstrates how population size, culture, and economic organization were not limiting variables on the influence of Indigenous populations on fire regimes and that new methodological approaches may offer new insights into long histories of Indigenous fire stewardship. Recorded on Nov 5, 2025 Description: Studying the influence of Indigenous people on ancient and historical fire regimes 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. In this webinar Dr. Christopher Roos uses published and unpublished tree-ring fire history records from pine forests in Arizona and New Mexico to demonstrate that Indigenous foragers, pastoralists, and farmers influenced southwestern fire regimes in similar ways. This research shows that population size, culture, and economic organization were not limiting variables on the influence of Indigenous populations on fire regimes and that new methodological approaches may offer new insights into long histories of Indigenous fire stewardship that can contribute to discourse on contemporary fire management, fire-co-management, and restoration of traditional fire management practices. Presenter: Dr. Christopher Roos, Professor of Anthropology and Earth Sciences, SMU Chapters 0:00 Introduction of presenter and topic 1:28 Beginning of presentation 2:39 Geographic region studied 5:31 Research questions 6:39 Question 1: Could foragers influence historical fire regimes? 8:20 Question 2: Could cultural burning even be visible with so much lightning? 10:00 Question 3: Could cultural burning influence future land use for mobile populations? 12:19 Question 4: Could cultural burning mitigate the impacts of climate on fire activity? 15:35 How dendrochronology works 18:36 Western Apache history and fire use 22:27 Study sites and fire use 28:14 Lightning ignition vs human ignition 30:08 Fire size 30:46 Seasonality of fires 32:08 Fire and climate associations 27:28 Answers to the four questions 40:36 Conclusion 41:10 Q&A Additional resources: Relevant publications by Dr. Roos and contributors: Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest, 2025: https://doi.org/10.1073/pnas.2509169122 Indigenous land use and fire resilience of southwest USA ponderosa pine forests, 2023: https://www.taylorfrancis.com/chapter... Indigenous fire management and cross-scale fire-climate relationships in the Southwest United States from 1500 to 1900 CE, 2022: https://doi.org/10.1126/sciadv.abq3221 The "I don't have time to watch the full webinar" CHATGPT Video Summary This webinar explores how Indigenous cultural burning shaped fire regimes across the Apache homeland and the broader U.S. Southwest. Using dendrochronological fire-scar records, the study investigated whether mobile foraging groups like the Apache significantly influenced fire frequency and patterns over centuries, despite their small population density. Key Findings -Seasonality of Fires Analysis of fire-scar locations within tree rings revealed that most fires occurred late April–May. This timing aligns with when Apache groups moved from lowland winter areas to higher elevations for farming and hunting. Because this period experiences minimal lightning activity, the surplus of spring fires is attributed to human ignitions rather than natural causes. This strongly indicates intentional or incidental cultural burning by Apache communities. -Fire–Climate Associations Results showed weak correlations between fire activity and climate in Apache territories compared to surrounding regions. Only about 25% of Apache sites showed significant climate associations, versus roughly 50% regionally. This pattern mirrors earlier research across Hemez, Navajo, and other Apache landscapes, showing that during periods of intensive Indigenous land use, fires were less driven by climate and more by human activity. When Indigenous management decreased—due to colonial displacement or warfare—fire occurrence became more climate-dependent, with larger, climate-synchronized wildfires. This demonstrates that frequent, small-scale Indigenous burning fragmented fuels, reducing large fire spread and weakening the top-down control of climate on wildfire occurrence. Conclusion The study demonstrates that Indigenous fire stewardship, even among mobile populations, was a dominant ecological force. Reviving similar small-scale burning patterns today could strengthen ecosystem resilience to modern climate extremes.