Scientists Dig into Wildfire Predictions, Long-Term Impacts

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, Santos 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.”