In wake of Maui fires, here’s why some trees survive damage

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It is not unusual for some trees to remain standing in the aftermath of a fire while surrounding buildings and vehicles burn, fire dynamics and environmental experts told Reuters.
Some posts on social media in the wake of the fires on the Hawaiian island of Maui, however, suggested that the fact some trees had remained standing showed proof that the fires were somehow engineered or steered to intentionally burn homes and vehicles, leaving trees unscathed.
One user shared an image of fire wreckage in Maui on Instagram, where buildings were torched to the ground but trees in the surroundings remained standing, with a caption reading, “Cars and homes nearly vaporized yet surrounding trees still standing… something seems fishy with this” (here). Another individual on Facebook said, “Everything is burnt but the trees, but don’t point that out or ur a conspiracy theorist,” alongside a video of a severely burnt area (here).
Not all trees were left unscathed. Reuters photographs and satellite imagery of the Lahaina Banyan Court area produced by Maxar Technologies shows buildings, vehicles and trees damaged following the fires (shorturl.at/bpsTX), (here).
Other trees were more heavily damaged, but remained standing, Reuters pictures show (here), (here).
Regardless, the fact that some trees could remain standing or were less damaged than cars or buildings during a fire is not abnormal. This depends on a variety of factors, fire dynamics and ecology experts told Reuters, ranging from water content on the surface and within a tree itself to the way the fire propagates through an area.
NOT UNIQUE TO MAUI FIRES
Albert Simeoni, Head of the Fire Protection Engineering Department at Worcester Polytechnic Institute, said that it’s “very typical” to have vegetation “unburned inside large communities.”
“It is not uncommon to see burned down homes and cars while also seeing trees and utility poles virtually undamaged,” said Erica Fischer, Assistant Professor at the Department of Wood Science and Engineering at Oregon State University. “We have seen this after many other fires and it is documented within federal reports, such as the 2008 Grass Valley Fire,” viewable (here).
Fischer sent Reuters images she took after the 2020 Labor Day Fires in Oregon (ibb.co/z4cMjbq) and the 2021 Marshall Fire in Colorado (ibb.co/N1c7Cp6) where buildings and structures were torched, but the surrounding trees remained standing.
WHY SOME TREES AND NOT OTHERS?
Dense tree trunks filled with water will not catch fire easily, JB Friday, Extension Forester at the University of Hawaii at Manoa said, with Christopher Baird, Associate Professor of Physics at West Texas A&M University, adding that water has a high heat capacity allowing it to absorb a lot of heat before increasing much in temperature (here).
Wildfires “tend to be most intense at ground level,” Baird said, where dry grass and shrubs known as “fine fuels” can burn easily (here), while trees with no low branches, such as palm trees, have their branches above the most intense parts of the fire.
Certain species of trees can have a higher tolerance to fire than others.
For example, according to the “The Nature Conservatory” nonprofit, ponderosa pine trees that are older than four or five years develop thicker bark that can protect them against low intensity fires (here).
Some plant species native to Hawaii including the acacia koa tree (here) show “some tolerance of fire,” said Katie Kamelamela, Postdoctoral Researcher, Akaka Foundation for Tropical Forests, and it can regenerate after a fire (here), (here).
More on how the introduction of non-native plants has affected fires in Hawaii can be read (here).
HOW FIRE SPREADS
When a fire is within an area where the built-up environment meets a wildland (known as a WUI) (here), embers can be transported over large distances due to high winds, Fischer said, with large surface areas available on houses for embers to land and ignite. Once homes are ignited, they can burn for several hours, creating embers that ignite other areas of the community.
Upon flame contact, the receptiveness of an object to catch fire is “strongly correlated with the size,” James Urban, Assistant Professor of Fire Protection Engineering at Worcester Polytechnic Institute (WPI) said to Reuters, adding that “foliage and twigs will ignite very quickly when in contact with a flame” compared to a larger tree.
Cars can burn more intensely than trees.
For objects like cars or houses to burn, they “must be exposed to a sufficient temperature for a sufficient duration” so that the materials chemically break down in a process known as thermal decomposition (here), Niamh Nic Daeid, Director of the Leverhulme Research Centre for Forensic Science at the University of Dundee, said to Reuters. When this occurs, the materials “release gases which, when mixed with air, can ignite,” she added.
Whether this happens depends on a variety of factors, including moisture content, how they are exposed to the fire and for how long. Once the interior of a car burns, the heat is confined and builds up, making the fire more intense and resulting in greater damage, Nic Daeid said. This differs from burning in the open air, where hot gases rise and dissipate easier around a tree.
VERDICT
Misleading. Trees sometimes survive severe damage during fires due to factors including their water content and the ways a fire spreads.
This article was produced by the Reuters Fact Check team. Read more about our fact-checking work .

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