Wildfires in California Are The End of Giant Sequoias

Every year, giant sequoias are threatened by wildfires in California.

Usually, it’s not a huge problem. Despite the constant threat of wildfires, these huge trees live for over a thousand years, and often live for over two thousand.

Well, until now. In the recent years, several wildfires in California have destroyed hundreds of giant sequoias. Just last year, one wildfire destroyed about ten thousand sequoias. And in this past week alone, the Washburn Fire came awfully close to burning down Mariposa Grove, the largest giant sequoia grove in Yosemite National Park.

Considering how few giant sequoias there are already, at this rate, wildfires will spell the end of the sequoias.

Why?

First, giant sequoias only grow in an area that is at high-risk for wildfires. Second, wildfires in California are getting worse due to climate change.

Giant Sequoia Distribution

Like the coastal redwood to the north, the giant sequoia has a very limited distribution. With only around sixty-three groves total, giant sequoias only grow on the west side of the Sierra Nevadas, in between 4,000- and 8,000-feet elevation.

This leaves only a 250-mile strip where giant sequoias will naturally grow. Even then, you won’t find any giant sequoia forests. If you explore the 250-mile strip where sequoias grow, you will find pockets here and there; small clumps of trees mixed in with the more common firs, pines, and cedars. The smallest grove, at the north end of the sequoia’s habitat, contains only six sequoias.

Because the giant sequoia’s distribution is so limited, that makes sequoias especially vulnerable to wildfires in California. Most of the areas where the sequoias grow are at high risk for wildfires.

Resistance to Wildfires

Despite the giant sequoia’s limited distribution, it is designed to be resistant to fire. Giant sequoias have bark that is about two feet thick, forming a highly effective shield against fire. Because the bark is almost impregnable, the fire has to consume the crown to completely kill it. However, considering that these trees typically stand over two hundred feet, it is extremely rare for a wildfire to reach a mature giant sequoia’s crown. Typically the crown extends far beyond the reach of fire, and wildfires do nothing more than scar the bark.

But once the crown is burned, the tree dies. The sequoia will not grow from the base, and the torched trees are useless.

Not only are giant sequoias naturally fire resistant, but they need fires in order to reproduce. They only reproduce by seed…and their cones will only release seeds after a fire. Without any forest fires, there would be no new sequoia growth. Thus, fire is essential to the giant sequoia life cycle.

In a study by Thomas Swetnam, ninety dead trees from five different giant sequoia groves were sampled to examine the fire history of the grove. Each of the trees was over 1500 years old. Swetnam found that “an average of 63.8 fire dates was recorded per sample tree.” 

In other words, these trees had survived an average of about sixty-four fires in their lifespan.

So why are the giant sequoias dying now? If they are so fire resistant, what changed?

Well, to put it simply, the climate did.

Wildfires in California Are Getting Worse

As a native of the east coast, I never paid much attention to wildfires in California until 2020, when my aunt went to work at a fire camp in Ukiah. The Ukiah camp served as the fire support headquarters for the August Complex, which broke the record for California’s largest wildfire, growing to the size of 1,032,648 acres.

Yes, that’s right. Over a million acres burned up.

While the August Complex was spreading out of control and breaking records, another wildfire was also spreading at a rapid pace. This incident, known as the Castle Fire, was south of Sequoia National Park. It tore through the Sequoia National Forest and destroyed around ten thousand giant sequoias, burning them completely. Entire groves were scorched.

Of the thousands of giant sequoias destroyed by the Castle Fire, the National Park Service estimated that at least 7,500 were large sequoias, meaning they had a diameter of over four feet. In their lifetime, these trees had survived dozens of fires. One more fire should not have been a problem.

Yet that wasn’t the case.

“10 to 14% of all large sequoias in the natural sequoia groves of the Sierra Nevada died in the Castle Fire.” - National Park Service

The fire burned so hot that in many areas even the seeds were scorched and failed to germinate, eliminating the hope that the groves would repopulate.

"I am very concerned that some areas will not have sequoias. All the adults are killed and there will not be enough seedlings to repopulate." - Christy Brigham, head of resource management and science for Sequoia and Kings Canyon National Parks.

The following year, the Windy Fire tore through the Sequoia National Forest, just south of where the Castle Fire had been the year before. The Windy Fire burned hundreds of giant sequoias in eleven different groves. 2021 was also the year of the KNP Complex, another wildfire that destroyed large sections of the Sequoia National Forest.

Then, of course, in 2022 the Washburn Fire burned right next to Yosemite’s Mariposa Grove. Firefighters use sprinklers and wrapped trees in foil to prevent the sequoias from burning, but without the large preventative measures, the Mariposa Grove could have gone up in smoke like so many other groves.

Sadly, with hotter temperatures and severe drought in California, the wildfires in California are burning hotter and higher. The year of 2020, with its devastating combo of the August Complex and the Castle Fire, was unprecedented. But, rather than being a once-in-a-lifetime occurrence, the next year brought on the KNP Complex and Windy Fire.

Even the naysayers are beginning to grudgingly accept that wildfires in California have never been this bad. If climate change continues to worsen, California wildfires may completely destroy our giant sequoias in the upcoming years.

Interested in learning more? The giant sequoias are not the only trees to be affected by climate change. Click here to read about climate change in the Pacific Northwest.