A team of researchers has found that trees in areas with frequent forest fires tend to have thicker bark. This adaptation makes them more resistant to fire damage, a real danger as climate change continues to increase the number of forest fires. The findings are in a paper that was just published in the most recent journal of Ecology Letters.
Forest fires serve an important ecological purpose by removing non-native plants and undergrowth, allowing new plants and trees to gain access to sunlight. This makes it possible for trees and native plants to gain a foothold in an ecosystem that might otherwise become dominated by invasive plants and weeds. Fires also change the soil chemistry, making it even easier for young trees to grow. Severe forest fires, such as accidental fires caused by human activity, can damage the entire forest. Although mature trees can handle the occasional small fire, a severe fire can kill even the largest trees. When these types of fires happen regularly, it can be difficult for the forest to recover. Serious forest fires can also be dangerous to nearby human settlements. Scientists have found that climate change is responsible for the recent increase in severe forest fires. This has led researchers to begin studying the possible effects of repeated fires in forests around the globe.
Scientists from Princeton University investigated the features of 572 tree species in different regions of the world. The team examined bark thickness to see if trees from specific areas were more likely to have thicker bark. They found that trees in areas with frequent fires, such as savannas and seasonal forests, had thicker bark on average. Trees that lived in areas such as rainforests, where fires are very rare, had much thinner bark. This shows that thicker bark has evolved as an adaptation against forest fires, potentially protecting a mature tree from fire damage.
The team’s findings will help scientists determine which tree populations are most at risk as forest fires become more common globally. Many researchers are concerned about rainforests—their delicate ecosystems are now experiencing droughts, which can lead to fires. Since the trees there haven’t developed any kind of protection, they may be more vulnerable to fire damage.
Pellegrini et al. Convergence of bark investment according to fire and climate structures ecosystem vulnerability to future change. Ecology Letters (2017).