Scientists Simulate Forest and Fire Dynamics to Understand Area Burn of Future Wildfires

Scientists, including Matthew Hurteau in the Department of Biology at The University of New Mexico, are examining more data via simulations of wildfires in the Sierra Nevada to improve their understanding between prior and future wildfires. They hypothesized that prior wildfires and their influence on vegetation, coupled with a changing climate and its influence on vegetation recovery after a wildfire, would likely restrict the size of wildfires in the future.

The research titled Vegetation-fire feedback reduces projected area burned under climate change, was published in Scientific Reports, and was conducted to better understand the climate-wildfire interaction and how that impacts wildfire emissions, and subsequently, air quality in the Sierra Nevada mountain range.

Using a landscape model that simulates forest and fire dynamics, Hurteau and his colleagues conducted simulations where climate was the only influence on area burned (static) and where the interaction of climate and prior fire events on both fuel flammability and availability influenced area burned (dynamic).

“Using an ecosystem model, that included photosynthesis and respiration, we were able to capture how the vegetation would respond to climate and area burned during each decade,” said Hurteau. “We used the ecosystem model output from each decade and a statistical model that accounted for the effects of prior area burned and climate to re-estimate fire size distributions for the subsequent decade and capture the effects of previous wildfires.”

What they found was a little surprising. They had expected that prior fire events and their effect on the amount of fuel available to burn in the forest would impose a large constraint on future area burned. Scientists call it a fuel limitation effect from prior fire events, but they found that it doesn’t last very long and it’s not near as large as they had thought.

“We discovered that compared to the static scenarios, where climate is the only influence on area burned, accounting for the interaction of prior fires and climate on fuel availability and flammability moderates only reduces the cumulative area burned in the Sierra Nevada by about 7.5 percent over the course of this century. This is much lower than we anticipated because enough vegetation was able to recover following a fire that a burned area would be able to support a subsequent fire pretty quickly,” said Hurteau.

As part of the study, Christine Wiedinmyer, an atmospheric chemist and the associate director at the University of Colorado’s Science at Cooperative Institute for Research in Environmental Sciences, built upon the work of Hurteau and others to take it to the level of air pollutant emissions by looking at the smoke release from wildfires in different climates with different types of vegetation.

Wiedinmyer utilized the information from the other researchers to determine how the changes in the amount of vegetation burned impacts the amount of air pollutants emitted from the wildfire smoke. The inclusion of the new vegetation dynamics changed the estimates of wildfire pollutant emissions — which can ultimately impact air quality. The ability to acquire more detailed predictions of vegetation/wildfire/emissions will enable air quality managers to have better predictions of wildfire air quality impacts into the future.

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Source: University of New Mexico. “Scientists simulate forest and fire dynamics to understand area burn of future wildfires.” ScienceDaily. ScienceDaily, 26 February 2019. 

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