Reviving Fire Management: Insights from Wildfire Archaeology
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Chapter 1: Understanding Wildfire Dynamics
At this moment, over 100 destructive wildfires are raging across the American West, with many achieving record sizes and intensities. Some fires, notably in Colorado, have been so fierce that they've spawned their own thunderstorms. Scientific data indicates that the severity of wildfires has escalated significantly over recent decades. This raises critical questions: Are climate change and human development encroaching on previously untouched forests the main culprits? Or could it be that federal wildfire suppression strategies are contributing to this escalating crisis?
Fire management policies in the United States trace back to the 1880s, shortly after the establishment of Yellowstone National Park in 1872. Following a period of allowing certain wildfires to burn naturally, the U.S. Forest Service adopted the "10 a.m. policy" in 1935, mandating that all wildfires be extinguished by the next morning. To engage the public in these fire suppression efforts, the U.S. Forest Service introduced Smokey Bear in 1944, who has since become a beloved symbol, famously declaring, "Only YOU can prevent forest fires!" However, this notion rests on a flawed assumption that all forest fires are detrimental to both people and the environment.
Contrary to this belief, many Native American tribes have traditionally regarded fire as an essential tool for land management. In recent years, the U.S. Forest Service has begun to recognize this perspective, advocating for prescribed burns to restore forest health.
Innovative archaeological research in New Mexico supports this view, revealing that the forests of the American West are critically out of ecological balance, in part due to federal fire suppression policies. But how have these archaeologists substantiated their claims?
Section 1.1: The Wabakwa Archaeological Site
The inquiry begins at Wabakwa, an archaeological site in northern New Mexico that flourished between A.D. 1140 and A.D. 1470. This expansive village, with 800 to 1,000 rooms, was situated on a ridge in a fire-prone ponderosa pine forest in the Jemez Mountains. Its inhabitants, the Ancestral Puebloans, cultivated maize and other crops, hunted, and gathered wild plants. Their descendants now reside in Walatowa (the Pueblo of Jemez) and other northern New Mexico communities.
Archaeologist Christopher Roos, specializing in human pyrogeography, found Wabakwa to be an ideal location for investigating the unintended repercussions of fire suppression. Roos's research focuses on ancient fire regimes, which reveal historical patterns and frequencies of fires to understand the role Native Americans played in forest management over time. In a recent study, Roos and his team analyzed how different fire management approaches have influenced the health of the Wabakwa ecosystem over the past 900 years.
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Using dendochronology, or tree-ring dating, the team examined fire-scarred trees around Wabakwa, identifying three distinct fire patterns. From A.D. 1100 to A.D. 1650, small, patchy fires were prevalent, likely set by the inhabitants for subsistence and cultural practices. These fires would have facilitated the management of plant resources and enhanced agricultural yields. Scientists collected tree-ring samples from fire-scarred ponderosa pines to accurately date past wildfires.
Once the Native Americans vacated the area, these small fires ceased, allowing nature to reclaim dominance. Between the late 1600s and around 1880, the team observed widespread, low-intensity wildfires that impacted greater numbers of ponderosa pines, consistent with the natural fire cycles seen in other North American ponderosa pine forests.
However, from the late 19th century onward, coinciding with federal fire suppression, livestock grazing, and logging activities, the team found substantial alterations to the forest structure. The absence of low-intensity fires led to denser, overgrown forests, with many trees sprouting since the last recorded wildfire in 1893. The accumulation of combustible materials, termed "fuel load," significantly increased due to these fire suppression practices.
Section 1.2: The 2012 Prescribed Burn
In 2012, after 119 years of fire suppression in the Jemez Mountains, the U.S. Forest Service permitted a fire to traverse Wabakwa once more. This prescribed burn was part of the Jemez Mountain Restoration Project, aimed at alleviating the excessive fuel loads that had accumulated since the 1890s.
Roos and his team had the perfect conditions to test their hypotheses regarding fire management styles. They employed a groundbreaking dating technique for pottery shards, known as optically stimulated luminescence (OSL) dating. This technique, while complex, offers fascinating insights.
OSL dating is applied to pottery and other objects containing specific sediments. The quartz sand grains within these sediments preserve a record of their last exposure to intense heat or light. When subjected to ionizing radiation, stray electrons become trapped in the quartz's crystalline structure. This accumulation continues until a burst of energy, such as a fire, allows the electrons to escape, resetting the quartz crystal's internal clock.
Roos's team utilized OSL dating to ascertain the last time a fire in the vicinity of Wabakwa was intense enough to reset the quartz clocks of the pottery fragments they recovered. They collected 32 pottery shards, dividing them into three groups: one-third had been exposed to intense heat during the 2012 burn, another third had been through earlier wildfires but not the recent one, and the final third had remained buried since their manufacture.
Upon testing these samples, the results aligned with their predictions: the quartz clocks of the shards from the 2012 burn had been reset, while those from earlier wildfires and the buried pieces remained unchanged. This indicated that the prescribed burn was indeed more intense than any fire in the area over the last 900 years, largely due to the buildup of fuel from federal fire suppression policies.
Chapter 2: The Ecological Consequences
Reflecting on a television commercial from 1970, which emphasized that "matches don't start forest fires. People do," I now recognize the irony and unintended consequences of over a century of fire suppression in the American West. The work conducted by archaeologists at Wabakwa provides compelling evidence that once well-managed ponderosa pine forests have transformed into highly flammable environments.
Addressing this ecological imbalance will be challenging. However, collaborative efforts among federal agencies, universities, and Native American tribes suggest that reviving Indigenous fire management practices could effectively alleviate our current crisis. We must act swiftly to avoid further degradation.
Stephen E. Nash is a historian and archaeologist at the Denver Museum of Nature & Science. He has authored several books, including Stories in Stone and An Anthropologist's Arrival: A Memoir. Residing in Denver with his family, he shares insights on Twitter @nash_dr.
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