Posts By Christopher Roos

What impact has fire suppression had on wildfire intensities?

Pinyon, juniper, and ponderosa pine trees killed by the 2012 San Juan prescribed burn at the archaeological site of Wabakwa in northern New Mexico. Photo by C. Roos.

Many tree-ring and charcoal studies indicate that the period of fire suppression (the last 120+ years) is unique for its paucity of fire over multi-century to multi-millennial timescales in dry forests across the Western US. Nevertheless, there are still some scholars and environmentalists who suggest that fire behaviors (for example, fire intensity, or temperature for a given area) and impacts (for example, fire severity, or the degree of above ground biomass consumption or mortality) in modern fires that follow that fire free period are within the historical range of variability for the West. Tree ring and charcoal methods are generally unable to get at fire intensities of the past to evaluate the uniqueness of fire intensities from fire suppression and fuel accumulation today.

With colleagues at Utah State University, the University of Arizona, the US Geological Survey, Southern Methodist University, and Harvard University, I have just published an innovative application of archaeological luminescence dating to assess the consequences of fire suppression and fuel accumulation on fire intensity relative to a millennium or more of frequent surface fires. By using the heat sensitive luminescence signal from archaeological ceramics exposed to historical surface fires (documented in tree-ring records) and those exposed to a 2012 prescribed burn under mild weather conditions, we were able to isolate the impact of fire suppression-generated fuel buildup on fire intensity. All ceramics burned in the 2012 fire with modern fuels had their luminescence signal reset, indicating that they were heated high enough and long enough to free electrons from crystaline traps and reset the luminescence clock. In contrast, none of the ceramics exposed to at least 14 historically documented surface fires had any evidence of resetting, indicating that fire intensities (and duration) in modern fuels had no precedent since at least before the site was established roughly 900 years ago.

Add climate change to the scenario and the combustible situation with modern fuels requires urgent action.

This paper was published in the open access journal Fire. You can find the article here or here.

Roos, Christopher I., Tammy M. Rittenour, Thomas W. Swetnam, Rachel A. Loehman, Kacy L. Hollenback, Matthew J. Liebmann, and Dana Drake Rosenstein
2020    Fire Suppression Impacts on Fuels and Fire Intensity in the Western US: Insights from Archaeological Luminescence Dating in Northern New Mexico. Fire 3:32.

Is Anthropogenic Pyrodiversity Invisible in Paleofire Records?



Around the globe, anthropogenic burning regimes often involve burning very small patches at relatively high frequencies. This creates a fine-grained mosaic of post-fire succession communities that benefits many species and often promotes biodiversity. This anthropogenic pyrodiversity is often difficult to identify in the historical ecology of environments that already experience frequent fires. Is this a weakness of paleofire methods? Is it an inherent problem in identifying fire regime differences that are relatively low-contrast?

In a recent paper with Grant Williamson and David Bowman in the journal Fire, I explore these issues with a simple cellular model of varying fire regimes and simulated fire-scar tree-ring records. Although anthropogenic pyrodiversity is not necessarily invisible in paleofire records, it is much easier to identify when paleofire and cultural information are integrated.

You can find the paper here or on my publications page.

Roos, Christopher I., Grant W. Williamson, and David M.J.S. Bowman (2019) Is Anthropogenic Pyrodiversity Invisible in Paleofire Records? Fire, 2, 42.

Native Fire: Prescribed Fire through Traditional Ecological Knowledge

Tribal communities and their traditional wisdom play an important role in fire management of our forests and rangelands today and into the future.

Jemez Pueblo offers centuries of valuable fire lessons

In the wake of the devastating 2018 fire season in California, I penned a guest column for the Albuquerque Journal on the lessons from the past to coexist with wildfire today. Ancestors of Native American residents of Jemez Pueblo lived sustainably in fire-prone Southwestern Ponderosa Pine forests for centuries. I have been fortunate to work with tribal members from Jemez Pueblo in an interdisciplinary research project to document fire and human history in their ancestral landscape.

We tend to treat our contemporary fire problems as uniquely modern ones. This overlooks the thousands of years of experience that indigenous communities have with fire on their lands. We have a lot to learn from the past. We should look to interdisciplinary environmental archaeology and the traditional ecological knowledge still held in these native communities today to help us make better decisions as our forests and communities are transformed by fire risk on a warming planet.

https://www.abqjournal.com/1260496

Fire, Climate, and Society at the Archaeology Cafe

This is a Throwback Thursday post to share the video of a public talk I gave as part of the Archaeology Southwest Archaeology Cafe series in Tucson in 2016. Here I talk about my work in Arizona documenting the benefits of indigenous burning on the long-term resilience of Southwestern forests.

NPR interview on KERA – Native American fire and bison hunting

Here is some more news coverage of my recent paper in Proceedings of the National Academy of Sciences. I was interviewed by KERA’s Justin Martin, the local host for All Things Considered. You can read a summary and listen to the interview here.

You can access the original paper here or on my Publications page.

Roos, Christopher I., María Nieves Zedeño, Kacy L. Hollenback, and Mary M. H. Erlick (2018) Indigenous Impacts on North American Great Plains Fire Regimes of the Last Millennium. Proceedings of the National Academy of Sciences 115:8143-8148.

CBC interview on ‘Quirks and Quarks’ – Native fire use and bison

I recently had the pleasure to do an interview on a CBC science radio show, ‘Quirks and Quarks’, about our recent paper in Proceedings of the National Academy of Sciences about the sophisticated ways that Native hunters used fire to manage prairies and manipulate bison herds. You can read more and listen to the interview here.

Our work was recently published in the Proceedings of the National Academy of Sciences. You can find a link to the work here and on my Publications page.

Roos, Christopher I., María Nieves Zedeño, Kacy L. Hollenback, and Mary M. H. Erlick (2018) Indigenous Impacts on North American Great Plains Fire Regimes of the Last Millennium. Proceedings of the National Academy of Sciences 115:8143-8148.

 

New paper on fire, bison hunting, and climate

Native bison hunters on the northwestern Great Plains used fire to manipulate bison grazing patterns and increase the success rates of communal hunts. In so doing, they leveraged climate opportunities to burn, ultimately amplifying the effects of climate on prairie fire activity.

Using geoarchaeology and landscape archaeology, my colleagues and I document this sophisticated fire use between 1100 and 1650 CE associated with the use of stone demarcated drive lanes and jumps to harvest bison en masseBison prefer to graze recently burned patches. When climate conditions were right, indigenous hunters burned prairie near the mouth of these drive lanes to lure bison herds in. Once within the gathering basin of a drive line complex, the hunters could initiate a stampede and funnel the bison towards the jump. By using climate conditions in their decision making, Native hunters were amplifying the impact of climate variability on prairie fire activity.

Our work was recently published in the Proceedings of the National Academy of Sciences. You can find a link to the work here and on my Publications page.

Roos, Christopher I., María Nieves Zedeño, Kacy L. Hollenback, and Mary M. H. Erlick (2018) Indigenous Impacts on North American Great Plains Fire Regimes of the Last Millennium. Proceedings of the National Academy of Sciences 115:8143-8148.

What kind of fire can we live with?

We often ask the wrong question: how do we stop wildfires? The real question should be: what kinds of fire can we live with?

Environmental archaeology can be valuable here because we can learn from the successes and failures of past societies to live in fire-prone settings. This is what my colleagues and I have been doing in partnership with the Pueblo of Jemez in northern New Mexico. How did Jemez people live in fire-adapted ponderosa pine forests so successfully for centuries when we are in danger of losing this forest type to mega-fires today?

I recently had an opportunity to chat about these issues with my old schoolmate, Maya Lilly. She has made a video from that chat for her environmentally conscious lifestyle channel, Gungho Eco. Check it out.

New charcoal methods paper published

Contrasting reflectances of charcoal from the 2013 Thompson Ridge Fire. Width of frame ~1mm. Photomicrograph by A. Scott.

I have a new paper out today in the International Journal of WIldland Fire. This paper was a collaboration with geologist Andrew Scott from Royal Holloway University, in which we compare charcoal reflectance between samples from crown and surface fire contexts in northern New Mexico.

Our analysis indicates that charcoal produced by surface fires is statistically distinguishable from charcoal produced by crown fires. This is an important methodological development, as it suggests that reflectance of stratified soil and sedimentary charcoal may be used to infer changes in fire severity over time. 

You can find the article at the journal here or on my publications page.

Roos, Christopher I. and Andrew C. Scott
2018    A Comparison of Charcoal Reflectance between Crown and Surface Fire Contexts in Dry Southwest US Forests.International Journal of Wildland Fire 27:396-406. [PDF] [LINK]

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