Thursday, August 03, 2023

Scientists dig into wildfire predictions, long-term impacts

DOE/OAK RIDGE NATIONAL LABORATORY

Fernanda Santos soil sampling — IMAGE: ORNL’S FERNANDA SANTOS EXAMINES A SOIL SAMPLE AT AN NGEE ARCTIC FIELD SITE IN THE ALASKAN TUNDRA IN JUNE 2022. view more
CREDIT: AMY BREEN, UNIVERSITY OF ALASKA FAIRBANKS

Wildfires are an ancient force shaping the environment, but they have grown in frequency, range and intensity in response to a changing climate. At the Department of Energy’s Oak Ridge National Laboratory, scientists are working on several fronts to better understand and predict these events and what they mean for the carbon cycle and biodiversity.

Two months into the 2023 peak summer fire season from June through August, Canadian wildfires had burned more than 25 million acres of land, disrupted the lives of millions and spread beyond the traditional confines of western Canada east to Nova Scotia. The phenomenon attracted renewed attention as smoke drifted to heavily populated regions, turning the New York City skyline orange and drifting across the Atlantic Ocean to Europe by late June.

Understanding the many risks and impacts of wildfires is at the heart of several projects at ORNL. Henriette “Yetta” Jager, an ORNL scientist whose research sits at the intersection of energy and ecology, has studied how selective forest thinning can both remove fuel for wildfires and provide plant material for conversion into biofuels.

“It’s a complex topic,” Jager said. “The science is showing that although it may be difficult to remove undergrowth and thin trees in some roadless areas, simply leaving old growth forest alone may cause more harm than good. For at-risk species such as spotted owls, letting fuel build up can cause larger and more widespread fires that can be worse in the long run.”

Jager has worked with colleagues to build a framework that can support decision-making around forest-thinning practices, landscape patterns and even spatial firefighting tactics. Results of their work could be used to protect terrestrial and aquatic species that need safe passage to move away from wildfire and then return later.

“Wildfire disturbance is a part of nature, and species are adapted to it, but we’re in a different situation now with climate change,” Jager said. “There are going to be big shifts in when these fires happen, their size and severity, which will cause big shifts in vegetation and new impacts on animal species.

“By continuing our research, we can help forest managers plan for these shifts.”

Unearthing data in the carbon-rich Arctic tundra

Advancing the understanding of wildfire effects on the carbon cycle is a focus for ORNL scientist Fernanda Santos. She studies not only single events, but also repeated wildfires over decades. She examines what these fires portend for the land’s ability to lock away carbon. And, conversely, her work evaluates how fires can become a source of carbon emissions during wildfires and potentially intensify the warming cycle. The world’s soils hold more than 3 gigatons of carbon — triple the amount in the atmosphere — and roughly 70% of the top layer of all soils has been exposed to fire at some point.

Her research illuminates the anticipated changes as the land evolves in response to fire. “A lot of people think of evolution as something that happens over centuries,” Santos said. “But the idea of rapid evolution, including how plants and soil microbiomes rapidly adapt to increased fires, is relatively new. Will we see more or less biodiversity after repeated fires? Ultimately, we want to know how fire affects these environments, including belowground.”

Fire affects plant functional traits as well as the diversity and function of microbes and other organisms in and around the soil that can alter plant and soil quality, Fernanda and colleagues said in a special issue of Functional Ecology examining knowledge gaps in the study of wildfire evolutionary impacts. Changes in wildfire regimes related to a hotter climate, like greater recurrence and severity, have been reported to accelerate the transition from tree- to shrub-dominated ecosystems, for instance. Fire’s evolutionary influence can be seen in the selection of plants with traits such as thicker bark and fast germination and resprouting and can result in less plant diversity.

The scientists also pointed to the need for more research into how fire may affect plant-fungal interactions in forests. More severe and repeated wildfire may also impact the sensory cues that animals, including insects, pollinators and herbivores, typically use to avoid fire and result in additional implications for biodiversity in a changing climate, the scientists said.

At ORNL, Santos works on projects like the DOE Next-Generation Ecosystem Experiments Arctic, or NGEE Arctic, performing experiments and collecting observational data to better understand changes happening in Arctic ecosystems. She concentrates on disturbance ecology — what events such as wildfires and pest outbreaks mean for the environment and future climate feedbacks. She examines the organic and inorganic chemistry of the Arctic topsoil, which helps insulate the tundra’s carbon-rich permafrost layer.

Refining large-scale climate simulations

Santos is also helping refine large-scale simulations of the Earth’s climate, such as DOE’s Energy Exascale Earth System Model, to better represent different forms of carbon like charred biomass — soot and charcoal — that result from wildfire. E3SM is supported by the DOE Office of Science’s Biological and Environmental Research Program and spans eight national labs, including ORNL. The model runs on the world’s fastest supercomputers, providing highly advanced simulations to better predict environmental change that could affect the energy sector.

All of that work depends on the quality and quantity of observational and experimental data. To enhance wildfire- related datasets, Santos and ORNL colleague Jiafu Mao have launched a Fire Community Database Network to encourage scientists and land managers to submit environmental data on burned areas to a central repository. Sharing such information can not only improve research, but also inform land management practices, the scientists said.

Wildfires consume not only the biomass of plants and trees, but can also result in the release of carbon that has been stored in soils for years or centuries, Santos said. “Our work in the Arctic is focused on a better understanding of what may happen in these carbon-rich soils in higher latitudes like Alaska and Canada. We model and predict the land carbon cycle, and I’m focused on helping decrease the uncertainty in those models with field data about historical fires.”

More detail on ORNL’s modeling and simulation work around wildfire is available in this recent article.

Support for the projects comes from the DOE BER program, the DOE Office of Energy Efficiency & Renewable Energy’s Bioenergy Technologies Office, and ORNL Laboratory Directed Research and Development.

UT-Battelle manages ORNL for DOE’s Office of Science, the single largest supporter of basic research in the physical sciences in the United States. The Office of Science is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.

A NASA satellite image from June 8, 2022, reflects smoke and red “hot spots” of wildfire resulting from more than a dozen active fires in southwest Alaska, as the largest tundra fire on record at the time burned hundreds of thousands of acres in the Yukon Delta.

CREDIT

NASA MODIS

JOURNAL

Functional Ecology

DOI

10.1111/1365-2435.14387

METHOD OF RESEARCH

Commentary/editorial

SUBJECT OF RESEARCH

Not applicable

ARTICLE TITLE

The eco-evolutionary role of fire in shaping terrestrial ecosystems

ARTICLE PUBLICATION DATE

2-Aug-2023

Sea urchins are struggling to ‘get a grip’ as climate change alters ecosystems

Syracuse University researchers explore how excess freshwater from climate change-associated events such as increased torrential rainstorms are impacting sea urchin survival

Peer-Reviewed Publication

SYRACUSE UNIVERSITY

When driving through a rainstorm, traction is key. If your tires lack sufficient tread, your vehicle will slip and slide and you won’t have the grip needed to maneuver safely. When torrential rains hit nearshore, shallow water ecosystems, sea urchins experience a similar challenge. Heavy precipitation can alter the concentration of salt in the ocean waters causing lower salinity levels. Even a slight change in salinity can affect the ability of sea urchins to securely attach their tube feet to their surroundings – like tires gripping the road. This becomes a matter of life and death for the small spiny creatures, as they rely on their adhesive structures to move in the wave-battered rocky area near the seashore.

Syracuse University biologists co-authored a study exploring how sea urchin adhesive abilities are affected by differing levels of water salinity.

The survival of sea urchins is vital for maintaining balance within marine ecosystems. Sea urchins are responsible for grazing around 45% of algae on coral reefs. Without sea urchins, coral reefs can become overgrown with macroalgae, which can limit the growth of corals. With the importance of coral reefs for coastal protection and preservation of biodiversity, it is critical to safeguard the sea urchin population.

As global climate change causes weather extremes ranging from heat waves and droughts to heavy rains and flooding, the large amounts of freshwater pouring into nearshore ecosystems are altering habitats. A team of biologists, led by Austin Garner, assistant professor in the College of Arts and Sciences’ Department of Biology, studied the impacts of low salinity and how it alters sea urchins’ ability to grip and move within their habitat. Garner, who is a member of Syracuse University’s BioInspired Institute, studies how animals attach to surfaces in variable environments from the perspective of both the life and physical sciences.

The team’s study, recently published in the Journal of Experimental Biology, sought to understand how sea urchin populations will be affected by future extreme climatic events.

“While many marine animals can regulate the amount of water and salts in their bodies, sea urchins are not as effective at this,” says Garner. “As a result, they tend to be restricted to a narrow range of salinity levels. Torrential precipitation can cause massive amounts of freshwater to be dumped into the ocean along the coastline causing rapid reductions in the concentration of salt in seawater.”

The group’s research was conducted at the University of Washington’s Friday Harbor Laboratories (FHL). The study’s lead author, Andrew Moura, who is a graduate student in Garner’s lab at Syracuse, traveled to FHL along with Garner and researchers from Villanova University to conduct experiments with live green sea urchins. They worked alongside former FHL postdoctoral scholar Carla Narvaez, who is now an assistant professor of biology at Rhode Island College, and Villanova University professors Alyssa Stark and Michael Russell.

At FHL, the researchers separated sea urchins into 10 groups based on differing salinity levels within each tank, from normal to very low salt content. Among each group, they tested metrics including righting response (the ability for sea urchins to flip themselves over), locomotion (speed from one point to another) and adhesion (force at which their tube feet detach from a surface). In Garner’s lab at Syracuse, he and Moura completed data analysis to compare each metric.

The team found that sea urchin righting response, movement, and adhesive ability were all negatively impacted by low salinity conditions. Interestingly, though, sea urchin adhesive ability was not severely impacted until very low salinity levels, indicating that sea urchins may be able to remain attached in challenging nearshore environmental conditions even though activities that require greater coordination of tube feet (righting and movement) may not be possible.

“When we see this decrease in performance under very low salinity, we might start seeing shifts in where sea urchins might be living as a consequence of their inability to remain stuck in certain areas that experience low salinity,” explains Moura. “That could change how much sea urchin grazing is happening and could have profound ecosystem effects.”

Their work provides critical data that enhances researchers’ ability to predict how important animals like sea urchins will fare in a changing world. The adhesion principles Garner and his team are exploring could also come in handy for human-designed adhesive materials – work that aligns with the Syracuse University BioInspired Institute’s mission of addressing global challenges through innovative research.

“If we can learn the fundamental principles and molecular mechanisms that allow sea urchins to secrete a permanent adhesive and use it for temporary attachment, we could harness that power into the design challenges or our adhesives today,” says Garner. “Imagine being able to have an adhesive that is otherwise permanent, but then you add another component, and it breaks it down and you can go stick it again somewhere else. It’s a perfect example of how biology can be used to enhance the everyday products around us.”

Syracuse University biology professor Austin Garner holding a sea urchin.