Redwoods and Wildfires

Old-growth redwood with fire scars.

A school group investigates a living old-growth redwood with major fire scars in Big Basin Redwoods State Park. Photo by Mike Kahn/Sempervirens Fund

With our terrible year of wildfires here in California, many people have been concerned about how vulnerable redwoods are to fire. We are very fortunate that redwoods are incredibly resilient trees, a fact that helps them live to over two thousand years old (redwood tree facts) and one of the characteristics of identifying old-growth redwoods are signs of fire scarring. Here are key features that help redwoods survive fires:

  • Tannin – Coast redwoods contain a significant amount of the chemical tannin in their bark and in their heartwood. Tannin does not burn easily – a natural flame retardant. It’s the tannin that gives redwoods their reddish color and also protects them against disease, fungi, and insects. Redwoods also have little resin or pitch, which are highly flammable, and lead other types of trees like tanoaks, firs, and pines to burn much quicker.
  • Bark – The bark of mature redwood trees can grow at least a foot thick, creating a great protective shield from fires. This helps prevent fire from getting to the more easily burned sapwood behind the bark. This bark has high water content, which also helps prevent it from burning easily.
  • Height – Redwoods are the tallest trees in the world. Being so tall helps prevent most wildfires from spreading up into the tops of the trees, where their needles soak in sunlight and moisture to keep the tree alive.
  • Needles – Redwoods have needles that are broader and flatter than most conifers, allowing them to catch fog and creating fog drip that reaches down to the forest floor. The fog drip is not only essential for many of the understory plants, but also helps keep areas more moist during typically dry summer months on the coast, reducing fire ignition, spread, and intensity.

Young redwoods that do not yet have thick bark and aren’t as tall are much more susceptible to dying in wildfires. However, this allows for the larger, older redwoods that do survive to have more space and light to grow bigger.

Despite the resiliency of redwoods, there are many factors that are increasing fire dangers and putting communities and forests at greater risk. Hotter, dryer conditions, more dead trees due to sudden oak death, and fire suppression that leaves more fuels on the ground all lead to more intense wildfires. With more intense fires, even large mature redwoods can be killed more easily with the great heat and more potential for flames to get into the upper reaches of the trees.

Controlled burn at San Vicente Redwoods.

Cal Fire performs a prescribed burn at San Vicente Redwoods to increase fire safety. Photo by Mike Kahn/Sempervirens Fund

Sempervirens Fund works with Cal Fire, local Fire Safe Councils, and other agencies and organizations to help mitigate fire risks on our properties and throughout the Santa Cruz Mountains. Creating fuel breaks by removing undergrowth, performing carefully managed prescribed burns and other forms of vegetation management, and maintaining and supporting critical fire infrastructure (roads, water tanks, etc) are important techniques used for fire safety. Sempervirens Fund is also initiating restoration forestry projects to thin forests that have become overcrowded as a result of past clear-cut logging and historic fire suppression. For all property owners living in or near forested areas, clearing land around structures to create a defensible space is also critical.

We are grateful for our donors’ support without which none of this work would be possible.

Additional Resources