Ancient redwood trees showcase surprising resilience as they sprout new life from burnt trunks

California has unfortunately been the victim of many wildfires over the years. Recently, a devastating fire created concerns that the state's iconic redwoods would be ruined forever and be unable to recover. The fire started in California's Big Basin Redwoods State Park due to a lightning strike in August 2020. Redwood trees are known to be resistant to burning. Unfortunately, the fires proved to be so intense that they ended up going through canopies of trees that were over 100 meters in height, effectively incinerating the needles. 

Drew Peltier, an ecophysiologist at Northern Arizona University, shared his concerns with Science Magazine, saying, "It was shocking. It really seemed like most of the trees were going to die." Somehow, despite these damaging fires, many trees survived. Peltier published a paper in the Nature Plants journal along with his colleagues, explaining the mechanism behind their astounding survival. The old redwoods contained energy reserves that had been created from sunlight many decades earlier. They utilized this hidden energy to revitalize dormant buds under the tree bark. 

Adrian Rocha, an ecosystem ecologist, emphasized how Peltier's paper completely changed the way researchers understood tree growth. She said, "It is amazing to learn that carbon taken up decades ago can be used to sustain its growth into the future." This groundbreaking discovery also highlights the potential for redwoods to survive fires that can come about as a result of climate change. However, they are unsure how long the species would survive if it were to be exposed to such catastrophic fire regularly under warmer conditions.

Redwood forests, in general, are no stranger to fires as they are subject to them at least once every decade. The trees possess the ability to prevent themselves from burning up because of their surprisingly thick barks, which can be up to 30 centimeters thick towards the base. Furthermore, the bark contains tannic acids that work against the fire. Also, in most scenarios, their more vulnerable parts, such as branches and needles, are located very high up. The fire in 2020 proved to be different because it was able to go higher and burn the leaves, effectively stopping photosynthesis. 

Photosynthesis is an essential process that trees rely on to get energy to develop and repair damaged parts. Scientists were aware that most trees had energy reserves. But they had no idea that the reserves within redwood trees would be sufficient to actually bring the trees of the Big Basin back to life. Peltier and his colleagues visited the forest a few months after the disaster and discovered that there was fresh growth coming from blackened trunks. According to his calculations, redwood trees were utilizing carbohydrates that were photosynthesized almost six decades back. 

What makes this finding even more interesting is how the sprouts came from buds that were formed centuries ago. Redwoods and similar tree species can create budlike tissue that exists under the bark. Scientists can track the date of these buds and how long they have been there. Peltier found that many of the buds on the redwoods were over 1000 years old. The team maintains an optimistic mindset and hopes that the redwoods recover enough to bring back just as many needles to reach photosynthesis levels before the major fire in 2020 occurred.