During January, enormous fires have swept over parts of Los Angeles in western USA, and destroyed more than 16,000 buildings – primarily residences.
A contributing factor to the fires, often overlooked, is the significance of invasive species, reports Wired. California's landscape is undergoing a change, from the traditional scrubland to one consisting solely of invasive species.
One of the biggest questions in southern California right now – aside from people's burned-down homes – is the transformation from a scrubland with a diversity of species to a devastated landscape of non-native species – primarily grass, says Hugh Safford, who studies fire ecology at the University of California in Davis.
Sea of invasive grass
Most of the grass spreading in western USA is not American. It is species from the Mediterranean region and the Middle East, which followed the colonizers. When an area with invasive grass, primarily cheatgrass, and native scrub has burned, everything dies.
The scrub cannot come back. But cheatgrass can. Its seeds start germinating immediately and take over the entire area. So much of Nevada, western Utah, and eastern California is starting to look like a sea of this invasive grass.
Before colonization, plants grew more sparsely, with desert sand in between. If a fire started in one place, it did not spread.
But the grass fills in these areas. It's like a continuous, dry fuel bed. It's like gasoline, you light a match and it explodes into flames, says Safford.
The native grass species in California are perennial, staying green longer. The invasive species live only one year, grow rapidly, and turn yellow already in early summer.
It's a highly flammable landscape. And fire moves so fast in grass. There's no doubt that both the Palisades fire and the Eaton fire started in grass.
Fire-prone eucalyptus
Another problematic species is the beautiful eucalyptus trees, which were planted worldwide after Europeans discovered them in Australia. The oily leaves burn easily, and glowing bark can fly far in the wind. Eucalyptus can catch fire in seconds, and flames can reach twice as high as the tree. In the Oakland Hills fire in 1991, it was pointed out as a culprit in the drama.
Many homes burned down and people were killed, and it was largely due to eucalyptus fields, says Safford.
The fires broke out on the outskirts of Los Angeles on January 7 and spread quickly to populated areas.
At least 29 people have died and more than 16,000 buildings have been destroyed. It is the fire incident that has caused the most devastation in Los Angeles history.
The three main fires (Eaton, Palisades, and Hughes) have burned on an area of over 23,000 hectares. After a few days of rain last weekend, the fires are more or less under control.
Sources: WWA, Los Angeles Times.
