Fall Insider 2021: Fire Season

Fire: From Friend to Foe pg 2 Particulate-ly Damaging pg 3 Damage on Unseen Organisms pg 4

FIRE SEASON Saltman Quarterly | Volume 17 | Fall 2021

SQ INSIDER wildfires from burning as intensely.

Before the colonization of North America, native people successfully managed large areas of land with such intentional burns; however, the marginalization of these tribes after colonization buried years : y nb writte NDU of knowledge about managing A J N A SIMR wildfires. Margo Robbins, a : y b ated r t N s member of the Yurok tribe A lu I il K SARA of California, explains that native people were forbidden from conducting prescribed burns, which were an important cultural practice for their tribe. Furthermore, in 1911, the U.S. In just minutes, Forest Service prioritized the very opposite entire homes are ravaged of prescribed burning: preventing fires of and innocent lives are turned upside any kind. This idea prompted a series of down by a single culprit, which leaves federal policies that allowed forests to grow behind just ashes. The name of this criminal denser, increasing the risk of wildfires and remains plastered in news headlines year- further villainizing fires in the public eye. round: “Relentless Wildfires Continues to More importantly, the U.S. Forest Service took on a reactive approach rather than a Scorch the West.”

The criminal nature of wildfires is likely proactive one.

Contrary to the U.S. Forest Service’s obvious to people in our modern society. belief, fires play an important role in Every year, people are forced to face the facilitating ecological balance. As described harmful effects of fires: smoke inhalation, massive financial damage, homelessness, in a paper published in the Ecological and devastating deaths. Unfortunately, Society of America, fires increase plant the frequency of wildfires in the United biodiversity through evolutionary and States continues to increase each year, and ecological processes. When fires take place, the U.S. Forest Service projects that the they create new habitats for plant species dangers posed by climate change will only with increased resources and decreased competition with other species. Forcing exacerbate these wildfires in the future.

Throughout California, firefighters these species to adapt to new habitats work tirelessly to prevent and contain this allows them to evolve over time in order beast. According to the U.S. Forest Service to survive in the conditions created by the guidelines, firefighters use fire retardant to fires. Ecologically, fires create large, open reduce the intensity and rate of wildfires spaces by burning vegetation, which creates as well as hand tools to dig fire lines. With open ecosystems. In open ecosystems, plant the death and destruction that wildfires cause, there seems to be no question that uncontained fires have the capacity to cause harm. However, Indigenous tribes in California hold a different perspective; they view fire as an ally, a powerful force that can be compromised with. These tribes take advantage of the vital role that fires play in our ecosystem by proposing a different solution to containing wildfires: fighting fire with fire.

Indigenous tribes employ a practice called “prescribed burning,” a technique in which small, contained fires are intentionally set in areas prone to wildfires in order to reduce surface fuel levels and vegetation, according to a paper in the Ecological Applications journal. Surface fuels include natural materials found in forests, such as dry grass and twigs, which allow fires to easily ignite and spread.

Prescribed burns expend these surface fuels, consequently preventing future

G N I N TUR FROM FIRE OE TO A F RIEND AF

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species can interact more dynamically with different organisms and even relocate to conditions that are more environmentally suited to their development. Therefore, it is important to recognize the crucial role that fires play in the life cycle of forest ecosystems.

The rapidly worsening wildfire conditions in California prompted CALFIRE, the state’s department of forest and fire protection, to seek the fire management expertise of Indigenous people. In 2013, the Yurok tribe collaborated with CALFIRE to execute a small prescribed burn on Yurok ancestral lands. This collaboration was an important stepping stone to further the efficacy of sanctioned fire management.

By 2014, a training program that brought together firefighters and members of the Yurok tribe was created to establish the legal requirements necessary to regularly practice prescribed fires. Joining forces can not only consolidate traditional and modern knowledge about fires, but also allow the Indigenous people of California to reclaim prescribed fires as an important part of their culture.

Continuing to incorporate the expertise of Indigenous fire experts into modern day fire management techniques may just be the key to improving current wildfire control tactics. According to a PBS news article, CALFIRE is now committed to burning a half-million acres in California by 2025 in anticipation of future wildfires. Wildfires are rapidly increasing and resources to stop them are depleting, so there is still much work to be done. However, if the collaboration between state organizations and native tribes continues, we can gradually turn fire from a foe into a friend.

PARTICULATE-LY DAMAGING: WILDFIRES & LUNG HEALTH written by: KATELYN NGUYEN

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any of us remember the feeling of rising apprehension each October as year after year, weather broadcasts relay reports of wildfires devastating our western coastline.

Stepping outside and expecting to see the grey of overcast autumn skies and instead watching ashes rain down from above is truly jarring—the perpetually orange haze painting a dystopian portrait of the California we know and love. Even prior to the COVID-19 pandemic, residents of Northern California were masking up with N95 respirator masks—not because of any viral threat, but because of the risk of smoke inhalation and the dangers that come with it.

To fully understand the hazardous impact of wildfire smoke on the human respiratory tract, it is essential to dissect the smoke’s molecular makeup. Fine particulate matter equal to or less than 2.5 micromolar in diameter (PM2.5) are heavily implicated in adverse lung health.

These aerosols are incredibly small in size, measuring up to at least 20 times smaller than the width of a human hair.

Particulate matter has the ability to breach the filtration provided by nose hairs, allowing access to the respiratory tract. Its large surface-area-to-volume ratio allows more and more PM2.5 to touch the lung epithelia—the barrier between inhaled air and the blood stream. As described by Yu-Fei Xing of Soochow University, such contact permits these particles to diffuse into other parts of the body during gas exchange, a normal event in respiration allowing oxygen and carbon dioxide to circulate between the alveoli and capillaries.

According to a Scientific Reports study, PM2.5 can present itself in diverse sizes, shapes, chemical compositions, and toxicities. For example, the materials burned in wildfires carry a greater proportion of polar organic compounds— high in carbon—including wood, plants, and plastic. In fact, recent animal toxicological studies published in Nature Communications have established that PM2.5 generated by wildfire smoke contains more carbon than other sources

photo by: SAM ZIBERMAN

such as road dust, sea spray aerosols, and ammonium nitrate.

Sathrugnan Karthikeyan of the National University of Singapore describes how this carbonaceous combustion generates reactive oxidative species (ROS), which are oxygen-containing molecules that are highly unstable and readily react with other molecules. In particular, free radical ROS—molecules with unpaired electrons—can cause significant tissue damage as a result of oxidative stress, wherein largescale chemical chain reactions occur throughout the body. This poses severe consequences for human health and homeostatic balance, including cardiovascular disease, neurodegenerative impairment, and cancer.

PM2.5 produced by wildfire smoke contains molecules with high oxidative potential, and when inhaled, forces a homeostatic imbalance of calcium that results in excessive inflammation and tissue injury. ROS causes massive cell oxidation and inserts holes in the lipids that comprise cellular membranes.

This increases the ability of molecules— including calcium—to enter and exit the cells. According to a study published in the American Journal of Physiology, high calcium homeostatic imbalance also can induce cell death. This is because as a key factor in inflammation, calcium plays an integral role in the mediation of cellular function. When cell membranes become porous as in the case of oxidative stress, more calcium enters the cell. This, in turn, activates a positive feedback loop that generates even more ROS free radicals. Macrophages, which digest and destroy foreign particles, are particularly reliant upon calcium regulation. Thus, as described by Siamon Gordon of the University of Oxford, these overactivated macrophages go on to trigger inflammatory injuries in the lungs and other organs.

With the progression of climate change and rising global temperatures, the risk of lung cancers and other respiratory health

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conditions is also growing. In particular, the United States EPA warns of the positive correlation between PM2.5 inhalation and the incidence or exacerbation of respiratory conditions such as asthma, chronic obstructive pulmonary disease, pneumonia, and lung cancer. Researchers around the world have been developing filters that mitigate the risk of inhaling small particles, an endeavor accelerated by the COVID-19 pandemic as described in a review published in Science Partner Journal. These new mask technologies include electrospun nanofibers, metalorganic frameworks, and of course, N95 respirator masks.

Though the dangers of airborne microbial infection highlight the importance of protective masks, they should not be the only reason we resort to using them. As infectious diseases continue to threaten humanity, so will wildfires. It is important to note that while the COVID-19 pandemic might be an isolated event, global temperatures will continue to rise. Smoke inhalation presents a major concern to public health.

One of the most practical ways to protect ourselves from these wildfires is assuming similar masking practices as the ones we’ve adopted in the past year.

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Vol. 17 | Fall 2021 | 3

SQ INSIDER

LONG LASTING DAMAGE OF WILDFIRES ON UNSEEN ORGANISMS written by : JOEY TRUONG

photo by: ANDREA FARRELL

rom expansive blackouts in California to enormous wildfires in Australia, it seems that wildfires are becoming a more prominent issue around the world.

The Environmental Protection Agency (EPA) has been tracking wildfire data since the early 1980s and lists wildfires as a climate change indicator. According to the EPA, there has been an increase in acres burned due to wildfires. From 1985 to 2020, the number of acres burned annually has tripled, with 10 million acres burned in 2020 alone in the United States. While it’s apparent that wildfires destroy trees and animals present in forests, what do they do to unseen organisms? The damage these intense fires cause to microbes is difficult to understand. Could increasing wildfires permanently damage the soil microbiome necessary for sustaining a healthy ecosystem?

The intense heat of wildfires drastically changes the nutritional characteristics of forest soil. Boreal forests are vast stretches of forests all along Canada and other northern regions with low precipitation throughout the year. The soil nutrients are extremely important to the diversity of microbes living in the soil; when the proper nutrients are available, a diverse microbiome essential for boreal forest ecosystems can form. Some soil nutrients and properties that are crucial to the microbiome are pH, carbon, nitrogen, and phosphorus. In boreal forests, although soil pH levels remain relatively normal after a fire, the topsoil layer has “significantly lower amounts of [carbon] even 42 years after disturbance,” with carbon levels recovering significantly 60 years after the fire (Koster). This long-term reduction of carbon largely affects microbes that rely on C sources for energy. Fortunately, the effects of wildfires on nitrogen and phosphate are largely temporary, with both nutrient levels recovering in under a year (Certini).

When the properties of the soil change, the microbiome within that soil also changes to adapt to the new conditions.

After a wildfire, a majority of the microbes present in the soil die from the heat of the burn, and those that do survive the initial burn are often incapable of living in the new soil conditions. According to Dr. Holden’s analysis of forest disturbances, soil biomass reduced 52%–56% after a fire. However, soil is enriched with ‘fire response’ microbe families, such as Acidobacteria and Betaproteobacteria, one year post-fire that help restore the ecosystem. These microbes are adapted to thrive in a low pH environment and slowly remediate the soil’s nutrients.

For example, Betaproteobacteria can be photoautotrophic, gaining carbon from environmental sources and using

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ions from the soil for energy. As seen in Chinese boreal forests, once the soil conditions become closer to pre-burn conditions, the ‘fire response’ bacterial community numbers will resemble prefire conditions; however, this process takes time (Xiang). In Xiang’s paper, researchers observed a fully restored forest 11 years after the burn, with the diversity of microbes returning to the pre-fire state.

Additionally, it has been observed that a coniferous forest can take up to 12 years to recover to its pre-burn biomass (Fritze).

This leads to another issue: since recovery takes at least a few years, what happens if another catastrophic fire takes place within that time frame?

Wildfires are becoming more intense: will there be enough time for the soil microbiome to recolonize after each burn?

Forests are taking longer to recover from the effects of wildfires (Stevens-Rumann).

A major player in microbe recolonization is the spread of microbes from non-burnt areas to burnt areas. They identify that a key reason for this delay is a lack of water, but also attribute some of the lesser forest recoveries towards changes of soil species.

One reason for the lack of water is the lack of plants. With the loss of plants, humidity control decreases, and soil microbiomes struggle to recover. Plants and microbes work together to recover a forest, and due to climate change and wildfires, there is less water. For these reasons, forests are having a tougher time recovering from wildfires.

Not only are wildfires becoming larger, but forests are also taking longer to grow back. This is partially due to longer microbial remediation times to prepare the soil for plant regrowth, and the most significant reason for this is climate change.

Climate change contributes to the greater severity of wildfires and decreased amount of water in these forests, in turn causing a slower recovery of microbial communities and plants in forests. Slower recovery of forests may lead to further devastating effects that could prevent forests from ever recovering. A longer period of unrestored forest may lead to large scale erosion, harming the ecosystem further. Wildfires pose an enormous threat to forests as we know them. A solution must be found to preserve our forests and to reduce the effects of climate change.

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