Christopher Roos

This is a great job if you have the right skills. I am looking at you archaeometry-types. www.facebook.com/share/1PXdkz...

Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest | PNAS Identifying the influence of low-density Indigenous populations in paleofire records has been methodologically challenging. In the Southwest United...

Many thanks to Steve Pyne @sjpyne.bsky.social for his thoughtful comments on our latest paper.
www.pnas.org/doi/10.1073/...

Roos et al. have managed to find information where it was thought implausible…[in] this seminal publication. We have a lot of fire in our future. But then we have had a lot of fire for all of our past. It is there to learn from if we choose to look for it.
www.pnas.org/doi/10.1073/...

A 1940 Western Apache (Ndee) farm site with two wickiups in a ponderosa pine forest. CREDIT: Lee Russell/Library of Congress

Tree-ring fire records from 649 pine trees in central and eastern Arizona show that fires occurred more often in the territory of the Western Apache, or Ndee, than in other regions between 1600–1870, suggesting a culturally controlled fire regime. In PNAS: www.pnas.org/doi/10.1073/...

New research on fire-scarred trees reveals Western Apache communities had far greater control over landscape fire patterns than scientists previously thought possible. Picture of wildfire in forest.

A new study led by SMU fire scientist Christopher Roos reveals that Western Apache communities had far greater control over fire patterns across Arizona than scientists previously believed possible. 🧪🌎 www.smu.edu/news/researc...

The western North American forestland carbon sink: will our climate commitments go up in smoke? Pathways to achieving net-zero and net-negative greenhouse-gas (GHG) emission targets rely on land-based contributions to carbon (C) sequestration. However, projections of future contributions neglec...

The western North American forestland carbon sink: will our climate commitments go up in smoke? esajournals.onlinelibrary.wiley.com/doi/10.1002/...

Chart with header: California has been seeing more large wildfires While the annual number of large wildfires (those over 10,000 acres) varies year to year with the dryness of the state, the trend has been rising. The chart shows a spiky line from 1950 to 2020, with big spikes in the past 15 years and an accelerating upward 10-year moving average

#Wildfire season is starting weeks earlier in California (up to 2.5 months in some mountainous regions) and large fires have grown more frequent, according to a new analysis of 30 years of fire data. Hotter temperatures and dryer atmospheric conditions are responsible buff.ly/zlitNPA #ClimateSky

Tunnel 5 Fire in the Columbia River Gorge, Washington, July 2023.

Wildfire activity worldwide was higher in 2023 and 2024 than in any year since monitoring began in 2001. Tropical forests are seeing particularly high rates of forest loss. Some forest systems may be approaching tipping points of ecosystem change. In PNAS: www.pnas.org/doi/10.1073/...

‘Unprecedented’ wildfire burns area size of Paris in southern France Advancing blaze scorches 16,000 hectares near Spanish border, destroying homes and forcing people to flee

‘Unprecedented’ wildfire burns area size of Paris in southern France.
www.theguardian.com/world/2025/a...

New studies tie unrecognized deaths and health problems to Maui and LA wildfires Three new studies highlight the severe health impacts of recent wildfires on Maui and in Los Angeles.

Wildfire devastation doesn't stop when the fires are out.
#Climate
apnews.com/article/maui...

How do fire managers use information? Presenters from University of Arizona discuss how wildland fire managers use decision support tools and how those weather and climate tools can be revised or reinvented to better fit managers’ needs.

#ICYMI Webinar Recording Now Available: "How do Fire Managers use Information?: Developing Practical and Usable Weather and Climate Information for Southwest Wildfire Management"
www.swfireconsortium.org/2025/06/10/h...

Depression, suicides, overdoses: broad impacts of US wildfires revealed in study Fallout goes beyond deaths and injuries, including lung damage and deaths caused by healthcare disruptions

From fire survivors, to people far away breathing wildfire smoke, the physiological, psychological and economic consequences of climate-fueled fires are huge, and growing.

www.theguardian.com/us-news/2025...

Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest www.pnas.org/doi/10.1073/...

Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest | PNAS Identifying the influence of low-density Indigenous populations in paleofire records has been methodologically challenging. In the Southwest United...

Fine work that both extends our knowledge of the past and has implications for today. Ndee (Western Apache) land management did a remarkable job controlling forest fires, even in drought-heavy eras like ours. It defies belief to think today's fire-torn SW has nothing to learn from those guys.

Reconsidering space-for-time substitution in climate change ecology - Nature Climate Change Ecologists often leverage patterns observed across spatial climate gradients to predict the impacts of climate change (space-for-time substitution). We highlight evidence that this can be misleading n...

New paper out on the dangers of using patterns across spatial climate gradients to predict what will happen with changing climate. That includes species distribution modeling. Space-for-time substitution can be misleading in sign, not just the magnitude of effects.
www.nature.com/articles/s41...

6/Tree-rings reveal that these patterns persisted for centuries. We need to learn more from Indigenous knowledge and experience built over centuries to millennia to better understand our current wildfire problems and how we can get out of them.

5/Altogether, this meant that climate had much less influence on fire patterns within Ndee landscapes than in the rest of the region.

4/And based on within-ring fire-scar positioning, there was a bias towards greater fire occurrence in late April or May (early earlywood scars), which is when Western Apache (Ndee) people moved back into pine forests each year as part of their seasonal mobility patterns.

3/And by looking at ratios of the fire return intervals of widespread vs. all fires, we were able to show that fires were overwhelmingly small compared to the rest of the region.

2/Using 649 tree-ring samples from across ~48,800 km2 of Western Apache homelands, we show that mean fire intervals were unusually short in Apacheria compared to 3,880 tree-ring samples from across Arizona and New Mexico outside of Apacheria. All samples from dry conifer forests.

1/New Open Access paper in PNAS with an outstanding team of collaborators:
Tree rings reveal persistent Western Apache (Ndee) fire stewardship and niche construction in the American Southwest.
www.pnas.org/doi/10.1073/...

Burning with purpose: Restoring grasslands the traditional way — TANKA FUND Prescribed fire has long been used by Indigenous communities to renew grasslands and support the animals and people who depend on them. At Tanka Fund, Range Ecologist Janét Moore works with ranchers...

#BuffaloRestoration burns can get intense: “Combating woody encroachment means hotter burns. That requires wider firebreaks, more suppression equipment, and good coordination.”

www.tankafund.org/our-stories/...

On Controlling Fire, New Lessons from a Deep Indigenous Past For centuries, the Native people of North America used controlled burns to manage the continent's forests. In an e360 interview, ecologist Lori Daniels talks about the long history of Indigenous burni...

“There’s a school of thought that you can just put a fence around a forest and keep people out, and it will be protected, which is a very old-school view, a very colonial view. It comes from this idea that we came to a land that was ‘empty’ and there for the taking.”

I'm back home with my dad and have thoughts about being an Indigenous scientist and academic. I'm writing this in real time so it might get disrupted and will have typos.

I am fairly successful by academic standards. I have a tenure track job, wrote papers, have grant funding, mentor students.

low severity surface fire burning through a ponderosa pine forest

The Turkeyfeather Fire in the Gila Wilderness, NM has burned as a low-severity fire over about 24,000 acres (so far). This is a continuation of a fire regime that existed for millennia before the 20th century. This 🧵reviews the fire history of the Gila, as my colleagues and I have studied it. 1/18