February 13, 2023

Researchers say changes in plant moisture content and carbon cycles need to be considered in wildfire forecasting

Hannah Grover

Fall colors are seen north of Chama

A paper published in the journal New Phytologist in January emphasizes the need to understand seasonal and drought related changes in plants and how vegetation dynamics influences wildfire. 

Los Alamos National Laboratory plant ecophysiologist Turin Dickman is the lead author on the paper, which includes more than three dozen authors from multiple countries.

The western United States has been experiencing record-breaking wildfires at a regular frequency. While some of the intensity is due to past forest management decisions, climate change is leading to longer fire seasons and more dry conditions that make fires more likely to occur. 

The researchers don’t mince words, starting the paper with a statement that wildfires are a global crisis and that the current fire models are not integrating the changes to vegetation that are happening as a result of climate change.

“The goal of the paper was to really suggest that we need to consider vegetation and we need to consider physiology,” Dickman said.

She said that the topic is still in the research-development phase and that scientists are still exploring its importance.

Using remotely-sensed estimates of the water and carbon dynamics within plants, the authors say fire models can be fine-tuned to improve wildfire forecasting.

Considering the fuel moisture content and the plant seasonal changes could help forest managers as they plan prescribed burns and reduce the likelihood of a prescribed burn getting out of control like New Mexico experienced last year.

As an ecophysiologist, Dickman studies the interactions between plants and the plant communities. She said she has researched how plants respond to climate change and drought.

“Recently, we’ve had some big fires here in our backyard,” she said.

She said her husband’s experience as a wildland firefighter was one of the factors that got her thinking about how climate change is impacting plants and how that may influence wildfires.

In the paper, the authors discuss current models as well as previous research into how plant changes impact wildfires. 

One study cited in the paper involves the pre-budburst, which happens in early June. This study was published in 2016 in the journal Forest Ecology and Management. A team led by U.S. Forest Service ecologist Matt Jolly that included Los Alamos scientists, looked into what is known as the spring dip in moisture content in conifer needles focusing on two types of pines—the red pine and the jack pine. Those pines grow in Wisconsin. The spring dip is when the moisture content in the foliage decreases before new needles come in. 

The moisture content in the needles decreased significantly during three weeks as starch accumulated in the old foliage, the team found. Once the new needles grow in, the starch moves from the old foliage to the new growth.

The seasonal change in foliage comes with an increase in flammability.

Dickman said that is important to note as climate change could push the pre-budburst time period earlier in the year, which could impact when forests are more likely to burn.

The research team concluded their paper by noting the increasing wealth of information about plant physiology—or the chemical and physical changes within a plant—and how it influences fire conditions. Along with that research, there are new sensors being deployed and “next-generation models.” The paper’s authors conclude “we are finally poised to tackle the problem of providing a dynamic and mechanistic description of fire behavior and effects through vegetation processes. Doing so will better equip us and the ecosystems we depend on to survive and thrive in a future made uncertain by global change.”