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Inaccurate forest fuel data could fuel B.C. wildfires, study finds


Wildfire suppression and forest management decisions are potentially hampered by inaccurate government data that misrepresents forest fuel loads in the British Columbia Interior, a new study suggests.

The British Columbia government says the provincial wildfire service is working with the study’s lead author and others to fill the data gap, which involves “mismatches” between remote sensing mapping, Forest fuel classifications and field observations.

“These lags make it difficult for fire managers to accurately determine the expected behavior of a fire before an event occurs,” say the researchers in the study published in the peer-reviewed journal Fire Ecology last month.

These disparities could also result in a failure to identify at-risk areas that would benefit from work to mitigate fuel buildup, the paper said.

Understanding the mix of grasses, branches and dead trees fanning flames in the forest is crucial to managing risk, because these fuels are the only factor people can change in the short term to influence fire behavior, says The report.

Researchers from the University of British Columbia and the Canadian Forest Service acknowledge that mapping forest fuels is “notoriously difficult” despite its importance in influencing and predicting wildfire behavior.

Lead author Jen Baron says correcting the data will help officials identify and respond to fire-prone areas, although it will likely require a “tremendous effort.”

“The challenge is that we try to use these fuel type maps to decide where to apply fuel treatments,” she says, referring to measures such as prescribed burning, thinning of dense forests or burning of piles of “slash” after logging.

Improved mapping of fuel types will also help researchers and wildfire managers understand how fuels interact with current environmental conditions and each other to influence fire behavior, Baron says.

“What we really need to do is be able to relate fuel conditions, fire behavior (things like spread rate, intensity, flame length) and weather, so so we can understand how they all work together in different scenarios. .”

The document reveals a “poor match” between field observations and government data, particularly the British Columbia Plant Resource Index and the National Fire Behavior Prediction System.

Researchers identified 76 plots in an area known as the Rocky Mountain Trench separating the Columbia and Rocky Mountain ranges in southeastern British Columbia.

They found “no suitable match” between national system data and field observations in 58 percent of the one-hectare plots. Another 42 percent were “partially fit,” the paper said.

National and provincial forest inventory data comes largely from aerial imagery, and Baron says it “significantly underestimated” the density of undergrowth that serves as a conduit for flames spreading up to the forest canopy. .

The British Columbia Plant Resource Index was designed to estimate “merchantable timber,” that is, trees intended to supply the forestry industry, says Baron, a lecturer in the department of forestry sciences and Conservation at the University of British Columbia.

“There is a lot more fuel on the territory than what is marketable. »

The study also revealed problems with the Canadian fire behavior prediction system when it comes to classifying fuel types in the British Columbia interior, Baron says.

The existing system uses data from a series of experimental burns 60 years ago, when fire conditions and fuel beds were “very different than they are today,” she says.

It was also designed primarily to inform fire suppression in boreal forests and uses 16 fuel types to represent conditions across Canada, Baron says.

“There simply aren’t enough fuel types to represent the diversity of conditions we experience in interior British Columbia. »

An example of a mismatch might be an area with a fuel type listed as mature lodgepole pine forest, but if it had been logged, leaving a buildup of “slash,” Baron says the system might not capture the actual load of fuel and the potential risk.

The provincial wildfire service uses existing fuel type mapping, but officials are aware of its limitations and use their own expertise and observations to make decisions regarding fire suppression and fuel mitigation efforts, she adds.

In an emailed statement, the Ministry of Forests says the BC Wildfire Service is working with Baron and other researchers to improve fuel classification.

This spring, Baron will examine how fire behavior scientists use existing data in combination with local knowledge to “calibrate their predictions,” he says.

The BC government is also working to improve its forest inventory data by acquiring LiDAR mapping for the entire province. Short for “light detection and ranging,” the process of aerial mapping using laser technology.

Still, Baron says researchers will also need field data, more detailed than LiDAR can offer, as well as data on how fires behave under different conditions.

The ministry’s release says the BC Wildfire Service has “expanded the research element” of prescribed burning, and fire behavior observers will accompany front-line crews to collect data on active fires.

Nationally, Baron says work is beginning on the “next generation” of Canada’s fire behavior prediction system, although it will take some time.

The 2023 fire season in Canada was the most destructive on record. It had burned more than 180,000 square kilometers by the end of September, including more than 28,000 square kilometers of land in British Columbia, where hundreds of homes were destroyed in the Okanagan and Shuswap regions.

This report by The Canadian Press was first published March 3, 2024.


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