Writing and photographs by Kirsten Khire, University Communications, and Tyler Gibson, Office of the Duke Forest.
Three universities. Three distinct research studies. One extraordinary Forest.
The Duke Forest, Duke University’s largest outdoor teaching and research laboratory, is more than just a beautiful landscape—it is a dynamic hub for scientific discovery. Spanning 7,000 acres, it serves as a vital resource for researchers from across the region and beyond who study pressing environmental challenges, from climate change to urbanization. On Feb. 1, the 2025 Research Tour showcased the Forest’s vital role in unlocking scientific knowledge, featuring three researchers whose work explores the drivers and impacts of our changing environment.
Terrestrial laser scanning to build a digital forest
Researcher Tong Qiu from Duke University’s Nicholas School of the Environment is interested in how climate and habitat change drive biodiversity shifts. His current research quantifies the regeneration potential of global forests and their role in supporting biodiversity, at a time when there is global forest dieback and tree cover loss over the past several decades. One specific way he is conducting this research is by observing and estimating seed production of forests.
“I’m interested in how many seeds a tree can produce,” Qiu said, adding that the patterns and drivers of global tree seed supply are not well understood. Qiu said the phenology, the timing of activities such as leafing and flowering, is the “footprint” of global warming and could influence seed production.
“When the temperature is warmer, leafing happens sooner,” Qiu said. “With earlier bud burst, photosynthesis starts sooner, extending the growing season and thus might increase seed production. However, if a late frost occurs, the young leaves can suffer damage.”
“Climate isn’t the only factor influencing plant growth—nutrients play a crucial role as well,” Qiu said. “for example, nutrient-demanding trees species have lower seed production because resources might be allocated for plant growth,” he explained, adding that seeds are essential for forest regeneration and also food for animals. “These changes impact other animal species, like squirrels and birds, which rely on seeds as a key food source in the ecosystem.”
Qiu and his team quantify seed production on trees in several ways, with the hardest way being the most low-tech way: binoculars. Now, Qiu is experimenting with computer vision to measure seeds on trees. During the research tour, Qiu and his Ph.D. student Yu Wei demonstrated a high-powered instrument – one owned by only six universities nationwide – that creates a “digital forest,” a 360-degree scan of the forest at a resolution of 5 mm that allows the research team to zoom in on individual branches and even distinguish seeds from surrounding leaves.
Beyond measuring seed production, the digital forest has broader applications. The instrument can scan the forest up to 800 meters to create a digital map, producing detailed spatial maps. These digital reconstructions can help scientists study everything from habitat complexity to how trees allocate resources for growth and reproduction.
Like a forensic scientist, Qiu is now able to have an in-depth look at a scene – in his case: the Forest.
Investigating radiative forcing due to CO2 and aerosols in urban areas
From North Carolina Central University, researcher Zhiming Yang featured his research on radiative forcing, when the amount of energy that enters the Earth’s atmosphere is different from the amount of energy that leaves it. In today’s world, more heat is coming in than going out. Human activity affects radiative forcing, in part by adding small particles called aerosols to the air, from smokestacks, airplanes, and car exhaust.
Car exhaust releases tiny particles called black carbon, which absorbs heat and leads to warming. Black carbon, commonly known as soot, is a component of air pollution consisting of particles with a diameter of 2.5 micrometers or less (PM2.5). These are tiny particles that can be inhaled and can penetrate deep into the lungs and body. Yang is measuring levels of black carbon, associated with respiratory disease, cardiovascular disease, cancer, and other health impacts.
For the past several years, Yang has been comparing black carbon levels in urban areas and in the Forest. Using a black carbon instrument, a particle counter, and a weather meter, Yang and his students take readings each week at several sites, including a parking lot of NCCU and the Duke Forest Durham Division near Couch Mountain. With undergraduate student Donovan Banks demonstrating the equipment at the tour, Yang talked about the data he has examined to date.
“Car exhaust contributes to black carbon, and the measurements of black carbon are higher in the parking lot than the Forest,” Yang said. “Also, local roads are more polluted with black carbon than highways, because of the need to slow down and speed up.”
While Yang has found that the Forest has lower black carbon readings, there are seasonal differences.
“In the summer, there is higher black carbon in the Forest when the temperatures are higher,” Yang said.
Looking ahead, Yang wants to gather more data to assess climate trends.
Studying pathogens infecting wild plants
Charles Mitchell of the University of North Carolina at Chapel Hill is interested in why there is so much disease in the world, not only with humans, but also with plants.
“Just as humans have a flu season each year, plants have their own type of flu season too. Plant diseases can be seasonal,” Mitchell said.
At the Duke Forest, just beyond the perimeter of the Duke Campus Farm, Mitchell’s team has set up dozens of small greenhouse chambers to study, under warmer temperatures, a typical field grass: tall fescue (Lolium arundinaceum).
Mitchell explained that there are multiple reasons his team works on tall fescue. It’s a common grass, it has agricultural importance in pastures and in hay production, and finally, it has a lot of diseases. A plant with a long, smooth, round stem and ridges on leaves, one attendee described the scratchy feel as a “cat’s tongue.”
Mitchell and his team taught tour attendees how to identify fescue and other plants in the Forest, collect fescue for data collection, and identify plant diseases.
At one station, Ph.D. student Liz Troy guided a small group of attendees to practice hands-on data collection. Each person experienced taking a field sample with a hole punch and collecting the sample in a vial. The research team takes vials regularly back to the lab, where they clean and cool the fescue, until it is time for DNA extraction and sequencing of the leaf microbiome.
Nearby, lab manager Susan Cleary showed attendees how to look for plant disease on fescue. She threw a pin flag at the nearest fescue tiller, or plant. She extracted the plant, which had three long leaves. She identified for the group the youngest to oldest leaves, and assessed the leaf for disease or damage. She said the research team repeats this process hundreds of times in the Forest to assess disease incidence.
Back in the midst of the chambers, Mitchell knelt at a square patch of ground surrounded by cement blocks. He helped attendees identify all of the plants within the small square – not only fescue, but also foxtail grass, blackberry plant, horse nettle, and more. Then, he demonstrated how the research team quantifies the healthy fescue growth – estimating the percentage of the plot area covered by fescue. Mitchell and his team will continue to collect data in the Forest as the temperatures warm. The chambers were set up in May 2024, so the team is looking forward to comparing data in the months ahead from last year.
Learn more about research and upcoming events in the Duke Forest.
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