Forests, Fires, and the Future of the American Landscape

With wildfires making headlines on an increasingly frequent basis—such as the ones that ravaged Los Angeles in January—the need to understand how and why these blazes happen is greater than ever. 

Alongside her team of student researchers, Helen Poulos studies the impacts of wildfires and climate change on forests. Her classroom teachings and her field research in the Southwest region of the United States make critical strides in addressing the damage wreaked by fires on landscapes as we know them today.

“A lot of my work is being a barometer of environmental change,” said Poulos, Distinguished Associate Professor of the Bailey College of the Environment and Earth and Environmental Sciences, who has been teaching at Wesleyan since 2008.

Poulos’s research centers around two core questions: How are forests changing in response to climate change and increasing wildfire activity, and what can forest managers do to promote healthy forests into the future? Her fire ecology class takes students into the long history of wildfires, delves into strategies relating to fire management in forests, and examines the effects of climate change, all while contextualizing how fire shapes vegetation patterns across landscapes. The class draws on the many elements of Poulos’s work, especially since she partners with forest managers to test techniques to give forests a stronger chance against climate change and fire.

Poulos has a network of long-term forest monitoring plots scattered across the Southwest. She estimates that she’s wrapped a measuring tape around more than 100,000 trees to measure their growth in response to wildfire and drought and compare the changes they experience over time. Over the two-and-a-half decades of her research, she has seen most, if not all, of her plots experience either severe wildfire or drought—sometimes both.

For Maya Lopransi ’25, Poulos’s classes and the subsequent trip she took to the Sky Islands as a research assistant changed her outlook on the effects of fires. Before moving to college, she had to evacuate her home in Utah as wildfires swept the area, so she had some firsthand prior experience to apply to her studies. Still, what she witnessed on a two-week voyage last summer to measure the effects of the 2021 South Rim 4 Fire on the Chisos Mountains in Big Bend National Park left a lasting impression.

“The trees just looked barren, and there were a lot of tree scars, and it was very patchy. So you'd walk from a decently dense area to a kind of forest-scape that it had just gone right through,” Lopransi said.

The Southwest saw few fires in the past century thanks to both passive and active fire suppression techniques. According to Poulos, these strategies include national fire suppression policies dating back to the early 1900s and cattle grazing that has removed fine fuels for moving fires across landscapes since the late 1800s. More than a century without wildfire has resulted in fuel buildup—the accumulation of dry vegetation and other natural materials that make landscapes more flammable. Now, climate change bears responsibility for the higher severity fires that have swept the region in recent years, killing most above-ground vegetation.

“Today’s fires are burning bigger and hotter than they ever did in over centuries in the past, and the plants actually don't have the evolutionary mechanisms to survive, regenerate, and grow in the wake of high-severity fire, so the fires that are coming back are sparking dramatically different post-fire outcomes after wildfire,” she explained.

Poulos’s work aims to help mitigate the damage. She works with forest managers to lower high-severity fire risk through techniques such as prescribed burning and forest thinning.

Water plays a large role in her work as well, since plants with lower moisture levels are largely more susceptible to catch fire. In one NASA-funded project she’s conducting in Arizona, Poulos uses tree measurements to examine how forest management strategies impact the way plants cycle water. Her research also takes her to Texas, where she’s focusing on freshwater springs, thanks to funding from the National Parks Service. The project centers not just around the scientific value of water but also the significance it holds to humans.

“Texas is really interesting because it has a lot of aquifers and it has a lot of groundwater,” she said. “Those are really vital cultural resources to people and also to wildlife.

Combining her on-the-ground measurements with satellite data allows Poulos to then predict how much water the springs produce, namely ones where there aren’t mechanisms in place to gather data. Around a dozen undergrads have worked with her on this endeavor. “Now we know that moisture balance is really important. So places that are really dry and have heavy fuel loadings are going to burn really hot,” Poulos said. “That's kind of the takeaway of this across a bunch of different fires, so we can then use that predictively. Like with spring pulse, if I actually could figure out how to detect how much water is coming out of the ground from space, how cool would that be for water managers?”

Anya Le ’25 participated in this project the summer after she took Poulos’s fire ecology course. As a research assistant, Le also traveled to Arizona with Poulos and said that her experiences have shaped the path she intends to pursue.

“I was interested in ecology, but I feel like I might not have gotten into fire ecology, and also all of the significance in planning human communities and how urban environments are built and constructed, especially in places that burn frequently,” said Le, who now began working at the Smithsonian Conservation Biology Institute after graduating in the spring.

Fueled not just by her research but also the opportunity to collaborate with others throughout the process, Poulos relishes seeing how her students take what they’ve learned in her classes and on her trips and then apply their interests in the world beyond Wesleyan.

“It's the multiplier effect. You get these students that come back to you and they're telling you all these amazing things they did to save the environment that have nothing to do with the way I would ever envision saving the environment,” she said.

This, for Poulos, is what it all comes down to—protecting the planet we all call home. “That's one of the fundamental problems with the environment. People discount the value of a resource and of having a resource in the future, so they want to extract it now,” she said. “They want to profit on it now; saving it for someone else later is not a priority.”