Study: Trees with thicker bark are more resistant to fire

PRINCETON, N.J., Jan. 11 (UPI) -- New research suggests thicker bark helps trees survive wildfires. Scientists found trees in fire-prone regions tend to have much thicker bark than trees in wetter climes, like tropical rainforests.

"We found large-scale evidence that bark thickness is a fire-tolerance trait, and we showed this is the case not just in a particular biome such as a savanna, but across different types of forests, across regions and across continents," Adam Pellegrini, now a research fellow at Stanford University, explained in a news release.

Pellegrini led the investigation into tree bark thickness and wildfire vulnerability while a graduate student at Princeton University.

Researchers looked at the bark thickness of 572 tree species in different types of forests. They also measured how quickly different types of forests tend to recover from fire. The data suggests savannas and forests with seasonal rain -- all with thicker-barked trees -- tend to be more resilient.

The new study, published in the journal Ecology Letters, also suggests bark thickness is an evolutionary adaptation inspired by the threat of fire. Further analysis of tree lineages showed bark thickness among closely related species is dictated by the wildfire frequency within a species' natural habitat.

Though the findings link tree bark thickness with fire resilience, it's not clear whether the protective layer will be able to adapt to climate change. As temperatures rise and extreme drought becomes a more common phenomenon, scientists expect the risk of wildfire to increase in many parts of the world.

"Trees from regions that burn frequently could still become vulnerable if the risk of fire increases," Pellegrini said. "The open question is whether the bark is thick enough to help trees survive."