Climate Change

Data on plant ‘sweat’ might help predict wildfire severity

NASA studies data from space station instrument; Water-stressed plants help identify areas with greater fire risk

 
By DTE Staff
Published: Monday 08 August 2022
Smoke rises from the Bobcat Fire, which burned more than 115,000 acres (46,539 hectares) in Southern California’s San Gabriel Mountains in 2020. In the months before the fire, NASA’s ECOSTRESS passed over the area aboard the International Space Station, c
Smoke rises from the Bobcat Fire, which burned more than 115,000 acres (46,539 hectares) in Southern California’s San Gabriel Mountains in 2020. In the months before the fire, NASA’s ECOSTRESS passed over the area aboard the International Space Station, collecting data on plant water use. Photo: NASA Smoke rises from the Bobcat Fire, which burned more than 115,000 acres (46,539 hectares) in Southern California’s San Gabriel Mountains in 2020. In the months before the fire, NASA’s ECOSTRESS passed over the area aboard the International Space Station, collecting data on plant water use. Photo: NASA

A study by the United States space agency, National Aeronautics and Space Administration (NASA), might help us understand why wildfires affect certain areas more than others. The rate at which plants release water, or “sweat”, can help predict the intensity of subsequent wildfires.

Several parts of the US have reported massive wildfires, but not all areas face the same degree of wildfire risk. Many American states have critical weather conditions with scorching temperatures and dry fuels, according to the National Interagency Fire Center, a fire management programme. Red flag warnings are in effect for parts of Oregon, Washington and northern California.

The study used data from ECOsystem and Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument aboard NASA’s space station. The data helped the researchers better understand why some parts of a wildfire burn more intensely than others.


Read more: Smoke from wildfires may have added over 700 COVID-19 deaths to US toll


ECOSTRESS measures the temperature of the ground, which is hotter than the air temperature during the daytime. The primary mission of the instrument is to identify plants’ thresholds for water use and water stress, giving insight into their ability to adapt to a warming climate.

The study found relationships between the intensity of a wildfire and the water stress in plants. It wasn’t just a matter of dry plants burning more than hydrated ones; some areas where vegetation had sufficient water burned more severely, possibly because fires had more fuel to consume.

Researchers compared ECOSTRESS data with separate postfire satellite imagery. They found that the rate of plant “sweating”, or evapotranspiration, and how efficiently they use water for photosynthesis can help predict the intensity of subsequent wildfires.

The paper found that water-stress-related variables and elevation were dominant predictors of burn severity in areas struck by three southern California wildfires in 2020: The Bobcat Fire in the Angeles National Forest, the Apple and El Dorado fires in the San Bernardino National Forest.

Like humans, plants struggle to function when they’re too hot. And in much the same way that sweating helps humans stay cool, plants rely on evapotranspiration to regulate their temperature. 

Evapotranspiration and efficient use of water for photosynthesis indicate whether a plant community is getting enough water or is under stress from lack of it.

The research was led by NASA’s Jet Propulsion Laboratory in Southern California, which used NASA’s Jet Propulsion Laboratory in Southern California. Researchers focused on data collected during portions of 2019 and early 2020 over six areas — three in Southern California mountains and three in the Sierra Nevada – that were subsequently scorched by wildfires.


Read more: NASA releases first pieces of the multispectral maps of Mars


Other research has shown that wildfire season across the Western US is starting earlier in the year and increasing in length and severity, NASA said. 

California has 33 million acres (13 million hectares) of forests, much of it managed by federal, state, and local agencies. Detailed insights on the relationship between wildfire and water availability to vegetation could help fire-management officials identify areas at risk and how serious the damage can be.

“We are in an intense megadrought — the worst in 1,200 years — and it’s creating conditions for more catastrophic fires,” said Christine Lee, a study co-author at the lab. “Data sets like those from ECOSTRESS will be critical for advancing science and can provide information to support those responding to climate-change crises.”

“We were trying to understand what drives differences in why some areas have severe burns and other areas don’t,” said Madeleine Pascolini-Campbell, a water and ecosystems scientist at JPL and lead author of the paper. 

“The results show how crucial water stress is for predicting which areas burn the most and why it’s important to monitor vegetation in these regions,” she added.

In general, slower evapotranspiration and lower efficiency signal that plants are water-stressed. Higher values indicate that plants are getting enough water, NASA said. 

The paper was published in Global Ecology and Biogeography. The study comes as NASA is ramping up efforts to mobilize its technology, expertise, and resources to study wildfires. 

Subscribe to Daily Newsletter :

Comments are moderated and will be published only after the site moderator’s approval. Please use a genuine email ID and provide your name. Selected comments may also be used in the ‘Letters’ section of the Down To Earth print edition.