Los Angeles: That’s why the fire destroys houses, but not trees

“What kind of investors have plans here?” “Warm demolition?” With these words, many social media users comment on images of the damage caused by the catastrophic fires in Los Angeles – especially those that show houses burned to the ground, while the trees next to them appear to be unscathed are remainers.

According to users, the recordings suggest that the forest fires might not be doing the right things. A claim that has already appeared in previous forest fires: for example in the devastating forest fires in Canada in 2023. At that time speculatedthe fires were caused by energy weapons. Just like after the forest fires in Hawaii that same year. At that time some people said: “Something’s wrong here.”

The claims are false. There are various reasons why houses and trees survive fires differently. “There is a physical explanation why trunks and large branches of trees don’t burn, but houses do,” Ernesto Alvarado of the University of Washington’s Department of Environmental and Forestry Sciences told the news agency after the Hawaii wildfires AFP.

First of all: In California, not only buildings burned and burned, but also vegetation. There is plenty of visual evidence of this – both in the media and on social media. Trees, bushes and hedges have also fallen victim to the flames in the last few days.

How well the plants resist the flames depends on their art. Tropical trees, for example, often had a very high water content. This means “even in dry conditions they burn less easily than grass and all the dry wooden houses and buildings from which they are built,” Camille Stevens-Rumann of the Colorado Forest Restoration Institute told AFP.

According to the Americans National Forest Foundation and the non-profit organization American forests Some trees – especially in the western United States – have adapted to the conditions as a result of the recurring forest fires: They have developed thicker bark. This doesn’t catch fire so quickly. “It also protects the interior of the trunk, the living tissue that transports water and nutrients, from heat damage.” It takes an enormous amount of heat over a long period of time to burn directly through a trunk, according to US biologist David Peterson -Ministry of Agriculture Scientificalert.com.

Fires produce glowing sparks that fall onto roofs, patios or other flammable surfaces and start new fires. Homes with dry materials are more susceptible to this. Houses offer “many nooks and crannies from the roof to the foundation where wind-borne embers – burning pieces of wood and plants – can land and ignite,” Courtney Peterson, a climate adaptation specialist at Colorado State University, told AFP. These could fly for kilometers. However, trees had fewer flat surfaces for sparks to land and burn.

Many of the homes that have now fallen victim to the fire in California are made of wood that was dry, unlike the trees around them. In addition, buildings often contain highly flammable materials such as wood, plastic, insulation and roofing felt.

“With American construction, a spark is often enough for houses,” says fire ecologist Johann Georg Goldammer from the Global Fire Monitoring Center in Freiburg (D). Bild.de. “The houses are often sealed off with plastic. It burns quickly.” There are also numerous combustible materials inside.

In addition, oxygen can enter the house through windows, doors and cracks, which further fuels the fire. What’s more, “Man-made structures have lots of little holes through which embers can fly or be sucked into the house, and then it’s all over,” says Marlon.