Maui Fires: What Makes a Plant Fireproof?

Maui Fires: What Makes a Plant Fireproof?

The 2023 Maui wildfire was primarily ignited by a combination of factors. Prolonged drought conditions, which had plagued the region for several months, had left the vegetation exceptionally dry and prone to combustion. Additionally, strong winds that swept through the island played a significant role in the rapid spread of the fire. Authorities suspect that the initial spark may have come from a downed power line, although the exact cause is still under investigation.

Fire Proof?

It is not unusual for some trees to remain standing in the aftermath of a fire while surrounding buildings and vehicles burn. While I don’t want to paint a picture of fire proof foliage, there are some species that were able to take the heat.

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 like water content inside and on the surface of the plants itself. You also have to take into account the way the fire propagates through an area.

Why Some Plants and Not Others?

Dense tree trunks filled with water will not catch fire easily. Having a lot of water means some trees and plants have high heat capacity allowing it to absorb a lot of heat before increasing much in temperature. Wild fires usually are the most powerful at ground level due to the presence of dry grass and shrubs that act as a quick “high burn” fuel. Any tree branches that aren’t low to the ground (like a well-groomed tree or a palm tree) won’t be directly exposed to the flames. That doesn’t necessarily mean that flying embers can’t fly into the canopy, but even so, without the quick burn fuel of dried grass and leaves, it’s harder for embers to take hold.

It's also important to account for species that have evolved in high fire risk areas. Any species that has lived and grown for thousands of years will be able to change its own traits to handle frequent fire exposure. For example, the Ponderosa Pine Trees that are older than four or five years develop thicker bark that can protect them against low intensity fires. Some plant species native to Hawaii including the Acacia Koa Tree shows some tolerance of fire and can regenerate after it experiences burning.

The Future of Maui and Invasive Plants

The Hawaii Invasive Species Council lists no fewer than 79 non-native plants that were brought to the islands as early as 1793. These plants were brought over for a variety of reasons (some utility, some accidently). According to the U.S. Department of Agriculture, there are 18 species that contribute to Hawaii’s wildfire risk, including Buffel Grass, Molasses Grass, and Guinea Grass. When invasive species are brought in, the native plants receive new competition for space and water that they can’t compete with. The native plants die out, the new fire hazard plants take over, and the island of Maui is set up for disaster.

While the future of Maui is not saved by native plants alone, local authorities can take charge of the local flora and fauna by removing invasive species in order for the island to begin its healing process. There is also needs to be an improved fire safety system, improved electrical grid, and a full reset to the people put in charge of the local government. The state of Hawaii is known for having a difficult and corrupted government that do little to protect their people. But, that is an article for a different time.


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