Giant sequoia trees continue to smolder for up to two years from past wildfires

Three Fires, giant sequoia trees
Three fires in two years that killed giant sequoia trees. The darker green areas represent groves of giant sequoias.

The U.S. Forest Service distributed information yesterday saying there are areas still burning in giant sequoia groves after wildfires that occurred in the Castle and Windy Fires of 2020 and 2021.

From the Sequoia National Forest, July 23, 2022:


Three fires were discovered this week, still smoldering inside the 2020 Castle and 2021 Windy Fires. Firefighters from Sequoia National Forest quickly reached two, and the third could not be reached safely due to the dense stand of fire-killed trees surrounding it.

The 1-acre Cougar Fire was found burning in the Red Hill Giant Sequoia Grove near the Tule River Indian Reservation boundary. Less than a half mile away, the ¼-acre Crawford Fire was reported by fire personnel responding to the Cougar Fire. Both were caused by a smoldering giant sequoia tree leftover from last summer’s Windy Fire.

Burning area in giant sequoia grove
Burning area in giant sequoia grove. US Forest Service. Photo distributed July 23, 2022. (Date of the photo and name of fire not provided)

Fireline was constructed by hand to stop each fire from spreading further. Heavy material: treetops, limbs, and trunks of previous fallen trees continue to smolder underneath these still-standing sequoia trees, weakened by the fire burning inside them. Fire personnel will continue to mop up and extinguish what they can without jeopardizing their safety by having to work under a burning giant sequoia tree. Neither the Cougar nor Crawford Fires pose an immediate risk to nearby communities.

On Thursday, a third fire was reported southeast of Camp Nelson in the Belknap Giant Sequoia Grove. Helicopter personnel located this fire deep inside the burned area of the 2020 Castle Fire. Due to its remote location, numerous standing hazard trees endangering fire personnel, and minimal chance of escape, this fire will be monitored from a distance and by air.

There have been several instances of smoldering trees, most of them large diameter giant sequoias, observed and reported in both the Castle and Windy Fire burned areas. These are likely to continue as dry conditions persist. Firefighter safety is a priority when determining how best to extinguish these types of fires. They may have to be monitored until the trees fall on their own and can be managed safely on the ground.

Thanks and a tip of the hat go out to Bob.

Photos and video from the Windy Fire in Sequoia National Forest

Numerous giant sequoias were killed in the fire

Windy Fire giant sequoias
Windy Fire. Image from the Mike McMillan video. 2021.

In 2021 the Windy Fire burned more than 97,000 acres in the Sequoia National Forest and the Tule River Reservation in California. It killed numerous giant sequoia trees which can live for up to 3,000 years. Mike McMillan of Spot Fire Images shot this video and still photos as the fire was burning. He served as a public information officer at the fire September 17-24, 2021.

In a two year period 13 to 19 percent of all large sequoias in their natural range were killed by fires

If a sequoia is lucky, it can live for up to 3,000 years

burned Sequoia grove in Sequoia and Kings Canyon NP
Sequoia grove in Sequoia and Kings Canyon NP, November, 2021. NPS photo by Daniel Jeffcoach.

In 2020, 10 to 14 percent of the entire Sierra Nevada population of giant sequoia trees over 4 feet in diameter were killed in the Castle Fire. Early estimates expect that on two fires in 2021, the KNP Complex and the Windy Fire, 2,261 to 3,637 sequoias over four feet in diameter have already been killed or will die within the next three to five years. These losses make up an estimated additional 3-5% of the entire Sierra Nevada sequoia population over four feet in diameter.

In a two year period 13 to 19 percent of all giant sequoias in their natural range over four feet in diameter were killed or will die in the next few years.

These trees can live for up to 3,000 years. However, climate change, inadequate fuel management in the sequoia groves over previous decades, possible regeneration failure following the fires, and a shortage of firefighters while the blazes were burning have led to a significant threat to the persistence of the species.

Three Fires, giant sequoia trees
Three fires in two years that killed giant sequoia trees. The darker green areas represent groves of giant sequoias.

The burn severity in the 2021 fires was variable, from low severity which was beneficial, to high, which killed most of the trees and could make natural regeneration difficult or impossible. Areas that had been previously treated with prescribed fire or mechanical thinning reduced the mortality during the fires and allowed crews opportunities to safely fight fire more effectively.

Funds have been requested for the hundreds of acres, at least, that need to be replanted by hand.

Below is the “executive summary” of a report recently released about the effects of this year’s wildfires on the giant sequoia groves.


The 2021 fire season included two large wildfires (both started by the same lightning storm in early September) that burned into a large number of giant sequoia groves. This species has a limited distribution, covering just ~28,000 acres in ~70 groves on the western slopes of the Sierra Nevada mountains. Given the impacts of the 2020 Castle Fire to sequoia groves, where losses were estimated at 10-14% of the entire Sierra Nevada population of sequoia trees over 4 feet in diameter, there is significant concern by sequoia managers and the public regarding the impacts of these new fires. This report summarizes potential impacts to groves that were burned in the 2021 fire season, in the KNP Complex Fire and Windy Fire, including number of groves burned, amount of grove area burned at differing vegetation severity (RAVG-composite burn index), estimated number of large sequoias killed based on a preliminary analysis, the percentage of the entire population this loss represents, potential for regeneration failure, and potential for loss of seed source due to erosion (for KNP only). All of the data, data analysis, maps and modeling contained in this report are excerpted from the Burned Area Emergency Response Plan for the KNP Complex produced by an interagency team and submitted by the National Park Service. Some additional explanatory text and structure has been added to make this a standalone report. Because of this emphasis, there is more detail and analysis for KNP Complex sequoia groves than those burned in the Windy Fire.

Grove-level Estimates

  • In total 27 sequoia groves are fully or partially within the fire perimeters of the KNP Complex Fire and the Windy Fire.
    • 16 groves burned in the KNP Complex Fire.
    • 11 groves burned in the Windy Fire.
    • For both fires combined, 6,109 acres of giant sequoia groves were burned. This estimate is based on updated grove boundaries provided by the NPS and the USFS Region 5 Remote Sensing Laboratory.
      • KNP: 4,374 acres
      • Windy: at least 1,735 acres (Note: this estimate does not include two groves on the Tule River Reservation for which there is not publicly available spatial data)

Sequoia Grove Vegetation Burn Severity Analysis Using Composite Burn Index (CBI)

Fire severity was assessed using the USFS Rapid Assessment of Vegetation Condition after Wildfire (RAVG) four class Composite Burn Index product (CBI4) (details on the severity maps can be found on the RAVG website https://fsapps.nwcg.gov/ravg/). This analysis contains four categories of vegetation change: undetected change, low, moderate, and high, where high severity has been associated with 95% tree mortality (Miller et al., 2009). The acreage burned by severity class for each fire is:

KNP Complex (all ownerships):

  • Undetected change: 1,169 acres
  • Low: 1,849 acres
  • Moderate: 740 acres
  • High: 616 acres

Windy Fire (all ownerships):

  • Undetected change: 228 acres
  • Low: 659 acres
  • Moderate: 437 acres
  • High: 411 acres

Large Sequoia Mortality Estimates

For the KNP Complex we estimate that between 1,330-2,380 sequoias over four feet in diameter have already been killed or will die within the next three to five years. This estimate is based on RAVG satellite analysis combined with mortality rates from surveys in other sequoia groves that burned in three previous fires (similar methodology to Stephenson and Brigham 2021).

For the Windy Fire, we estimate that between 931-1,257 sequoias over four feet in diameter have already been killed or will die within the next three to five years.

The combined impact of these two fires is estimated to be 2,261-3,637 sequoias over four feet in diameter that have already been killed or will die within the next three to five years. These losses make up an estimated 3-5% of the entire Sierra Nevada sequoia population over four feet in diameter. On top of the 10-14% of large sequoias lost in the 2020 Castle fire, these fire impacts represent a significant threat to large sequoia persistence.

Dead sequoias killed fire
Dead sequoias, November, 2021. NPS photo.

Potential for Regeneration Failure

The least understood impacts of these wildfires are impacts to sequoia regeneration in high severity areas. Sequoias generally regenerate well after wildfire, though reports of inadequate regeneration in high severity areas are raising concerns. Regeneration failures could potentially occur if the cones and/or seeds were incinerated during crown fire, seeds did not survive the smoldering fire, or seeds washed away due to surface erosion. In these cases, regeneration would be dependent on proximity to live tree seed sources.

For the KNP complex we analyzed high severity areas within sequoia groves that were over 100 meters from an intact sequoia grove area with live sequoia trees (represented by areas of undetected change, low or moderate severity). In total 436 acres were identified that may be vulnerable to total sequoia loss if regeneration from seeds that survived the fire is inadequate. Of the 436 acres >100m from live sequoia forests, 335 acres are on NPS lands. The Burned Area Rehabilitation Plan recommends reforesting these 350 acres with giant sequoias if adequate regeneration is not present based on subsequent field surveys.

Erosion modeling suggests that the high severity areas identified for potential restoration are also at high risk of losing any seeds that did survive the fire due to surface erosion.

Other Key Points

In several places that burned during this event, previous prescribed fire work appears to have reduced fire severity (portions of Redwood Mountain Grove, Giant Forest). In other areas previous prescribed fire and mechanical thinning treatments, as well as preparation for upcoming burn units, allowed fire crews opportunities to safely fight fire more effectively (prescribed burn preparations at Lost Grove and Park Ridge Fire Lookout area were used during suppression operations on the KNP complex).

Although we are seeing some significant high and moderate severity areas in sequoia groves where we expect impacts to large giant sequoias to be detrimental, much of the grove area in the KNP Complex burned at low severity and we expect beneficial results for giant sequoias in these areas. These beneficial effects include fuel reduction, small canopy openings ideal for regeneration, and removal of litter and generation of ash – also ideal conditions for giant sequoia seedlings.

Other areas not classified as high severity may have also had beneficial effects, but the effects will likely be more mixed. In areas classified as “undetected change,” there will likely be a mix of completely unburned areas and areas that had a light surface fire that is similar to low severity fire effects. The fire effects in moderate severity will be the most variable, with some areas having beneficial effects and others being more severe.

Thanks and a tip of the hat go out to Ben.

Officials estimate hundreds of giant sequoias were killed in the Windy Fire

Giant sequoia trees can live for up to 3,000 years

Three Fires, giant sequoia trees
Three fires in two years that killed giant sequoia trees. The darker green areas represent groves of giant sequoias.

11:30 a.m. PDT Nov. 4, 2021

Giant sequoia trees can live for up to 3,000 years, but in 2020, 10 to 14 percent of all giant sequoias in the Sierra Nevada that were at least four feet diameter were killed in the Castle Fire in the Sequoia National Forest. When post-fire surveys of the 2021 fires are complete that number will probably increase substantially. It will be many months before detailed surveys are complete, but the sequoia mortality can be estimated from how severely the fire burned.

The lightning-caused 97,528-acre Windy Fire just south of the Castle Fire (see map above) burned into eleven giant sequoia groves in September and October, 2021. The Forest Service is working to determine the impacts of the fire in the groves managed by the Forest Service. The agency said on November 2 that initial assessments based on observations by resource advisors and burn severity analysis indicate the fire killed hundreds of giant sequoias. Many more were heavily torched and may or may not survive.

A report released June 25, 2021 about the 2020 Castle Fire found that areas which burned with high intensity killed many giant sequoias. The data showed 97.3 percent mortality of the trees in high fire severity areas, and 55.1 percent in moderate severity locations.

Preliminary fire severity data is now available for a portion of one of the two 2021 fires that burned through groves of giant sequoias, in this case, Giant Sequoia National Monument in the Windy Fire.

Burn severity, giant sequoia groves, Windy Fire
Burn severity in Giant Sequoia National Monument in the Windy Fire, Oct. 2021.

Using the fire severity data for the portion of the Windy Fire in Giant Sequoia National Monument, if there was only one giant sequoia per acre before the fire, approximately 1,142 were likely killed. However, there were probably far more than one per acre.

While numerous fires were burning in 2021 in California there was a shortage of firefighters due to unfilled positions in the US Forest Service, COVID-19 restrictions keeping some on the sidelines, and competition for resources among the fires. The limited numbers that were available worked on suppressing the spread of the fires, and on the Windy and KNP Complex they also took actions to protect the huge sequoias as personnel were available.

giant sequoia Windy Fire
Firefighter Curtis Wayka (arrow) stands beneath giant sequoia on the Windy Fire. Photo by Nick Lacey, Oct. 2021.

In some areas, they constructed firelines surrounding a grove or individual groups of trees, set up sprinkler systems, and removed ladder fuels from around individual trees in advance of the fire. After the fire burned through, additional efforts were made to further reduce the fire’s impact on giant sequoia trees by extinguishing hot spots in and around the trees, again, as personnel were available.

The US Forest Service said that from initial observations, it was apparent that giant sequoia trees treated before the Windy Fire swept through were more likely to survive. Those with duff and woody debris scraped away from their trunks, especially near burn marks, were less susceptible in most cases. In the Starvation Complex grove, four out of six giant sequoia trees treated before the fire reached them, survived. An estimated 116 trees not accessible before the fire, were killed. Similar conditions were found in the Long Meadow Grove, where more than a decade of fuels reduction efforts helped save the giant sequoia trees along the Trail of 100 Giants.

“Within the high severity burned areas, most of the giant sequoias were burned and killed,” said Forest Ecosystem Manager Gretchen Fitzgerald. “In moderate severity areas, some giant sequoias may survive while those in low severity burned areas are likely to survive the Windy Fire.”

The Sequoia National Forest will be partnering with researchers and local experts to monitor the groves and determine the impacts of the Windy and Castle Fires over the next year.

“Recent fires highlight the need for restoration in the giant sequoia groves,” stated Forest Supervisor Teresa Benson. “By reducing fuels through prescribed burning and other density-reduction treatments, the likelihood of future large, high-severity fires can be reduced. The Giant Sequoia National Monument Management Plan requires protection, preservation, and restoration of giant sequoias through management activities. We will continue to work with our partners, Tule River Indian Reservation, National Park Service, Save the Redwoods League, and CAL FIRE on best management practices to protect and restore our giant sequoia groves.”

Firefighters climb giant sequoias on the Windy Fire

The blaze has burned more than 92,000 acres in California.

9:02 a.m. PDT Oct. 3, 2021

smokejumpers climb giant sequoia tree Windy Fire
Rick Rataj and Tyler Anderson, USFS California Smokejumpers, climb a giant sequoia to investigate an area on the tree that is burning. Windy Fire, Sept. 30, 2021. BIA photo by Laura Scott.

Smokejumpers who usually arrive at a fire by parachute have climbed at least one of the giant sequoia trees on the Windy Fire in California to investigate areas on the tree that were burning. The initial reports were that they would climb an adjacent tree and use a fire hose to apply water onto the burning tree. Smokejumpers are trained to climb trees in order to retrieve hung up chutes, but this is not a common task for them, climbing a tree that is burning. Usually they simply cut it down.

But these huge trees that can live for more than 3,000 years have been suffering during the multi-year drought  and dry windy weather that has caused very low fuel moistures and intense fires that can penetrate the foot-thick bark. Last year the Castle Fire, just to the north (see map below), destroyed an estimated 7,500 to 10,600 large sequoias with trunk diameters of more than four feet, which was 10 to 14 percent of all large sequoias across the tree’s natural range in the Sierra Nevada.

Windy Fire map
The red line on the map was the perimeter of the Windy Fire at 7:30 p.m. Oct. 2, 2021. The black line inside that, was the perimeter about 48 hours before. The darkest green areas are groves of giant sequoias.

The 92,473-acre Windy Fire has not spread as much in the last two days as it did earlier. Most of the additional growth was on the west side in and south of the Tule River Indian Reservation. During the Saturday night mapping flight the only large area with intense heat (dark red area on the map) was on the reservation.

Most of the north one-third of the fire has contained fireline, as do some of the areas around California Hot Springs, Pine Flat, and Sugarloaf Village but there is still work to do west of Fairview, on the Tule River Indian Reservation, and other locations near Sugarloaf Village.

Very dry daytime and nighttime conditions are expected to persist into early next week. On Sunday, the Kern River drainage will be very prone to strong winds, with gusts of 25–30 miles per hour; elsewhere, gusts will be up to 20 miles per hour. The result will be several hours of near-critical to critical fire weather conditions along the Kern River valley and adjacent slopes.

smokejumpers climb giant sequoia tree Windy Fire
Rick Rataj and Tyler Anderson, USFS California Smokejumpers, utilize a “bigshot” to launch ropes into the branches of a giant sequoia tree so they can climb up to investigate heat left by the Windy Fire on September 30, 2021. BIA photo by Laura Scott.
smokejumpers climb giant sequoia tree Windy Fire
Rick Rataj and Tyler Anderson, USFS California Smokejumpers, climb a giant sequoia to investigate an area on the tree that is burning. Windy Fire, Sept. 30, 2021. BIA photo by Laura Scott.
smokejumpers climb giant sequoia tree Windy Fire
Rick Rataj and Tyler Anderson, USFS California Smokejumpers, climb a giant sequoia to investigate an area on the tree that is burning. Windy Fire, Sept. 30, 2021. BIA photo by Laura Scott.

At least two dozen giant sequoia trees destroyed in Windy Fire

Smokejumpers climbed one tree to knock down fire in upper limbs

11:33 a.m. PDT Oct. 1, 2021

Windy Fire map 8:45 p.m. PDT Oct. 1, 2021
Windy Fire map at 8:45 p.m. PDT Sept. 30, 2021. The green areas are giant sequoia groves. The black line inside the Windy Fire was the perimeter on Sept. 27, 2021. The “Fawn Fire” should be labeled “French Fire”.

Some of the giant sequoia trees that can live for more than 3,000 years  are being killed in the Windy Fire which has burned about 89,800 acres east of Porterville in Southern California. The huge blaze is burning in Tule River Indian Reservation; the Sequoia National Forest, including the Giant Sequoia National Monument; and Tulare County and state responsibility areas.

The multi-year drought has led to extremely dry fuel moistures which is causing wildfires in California and other areas to burn with unusual intensity, making even some of the giant sequoias with bark up to a foot thick susceptible to wildfires burning under these conditions.

flames fire giant sequoia Windy
Flame spread around large tree on the Windy Fire. Mike McMillan, BIA. Uploaded to InciWeb 9-22-2021.

The giant sequoias are found in groves, seen as green areas on the map above.

CNN is reporting that Garrett Dickman, a wildfire botanist with Yosemite National Park who is leading personnel protecting the big trees, said an early assessment indicates that at least 29 of them have died so far.

From CNN:

While the assessment is just beginning, there’s already grave concern. The center of Long Meadow Grove managed well, thanks to work crews did in preparation for the fire, but moving away from that area, Dickman counted 29 sequoias that were “just incinerated” by the blaze.

“There were four of those that had burned so hot that they’d fallen over,” Dickman said, adding one tree burned so badly that it was nearly reduced to just an outline of a tree on the ground. “The majority of the grove is going to survive,” Dickman said, “but there are portions that burned so hot and those trees won’t make it.”

Elsewhere in the forest, Dickman has seen even more devastation. In Starvation Creek Grove, which he says has no modern fire history, he said he saw only “a couple of trees survived.”

“It was one of the groves where we got a few hours of prep work and those trees that we did the emergency prep work around, from the picture, they are the ones that did survive and all the rest of them — it doesn’t look promising,” Dickman said, adding that he plans to assess the grove in the next few days.

Smokejumpers are firefighters who arrive at a fire by parachute. They are trained to climb trees in order to retrieve chutes hung up in trees. Some of them assigned to the fire are going to climb the iconic Bench Tree in the Trail of 100 Giants and use a fire hose to apply water to an adjacent sequoia that has fire burning in some of the upper limbs. This may be unprecedented, or at the very least, it is very uncommon.

The National Park Service reported that, “…preliminary estimates suggest that the 2020 Castle Fire [just north of the Windy Fire, see, map above] killed between 31% to 42% of large sequoias within the Castle Fire footprint, or 10% to 14% of all large sequoias across the tree’s natural range in the Sierra Nevada. This translates to an estimated loss of 7,500 to 10,600 large sequoias (those with trunk diameters of 4 feet or more).”

The Windy Fire was active Thursday, growing by about 1,800 acres, and is expected to be more so on Friday. On Thursday there was significant spotting on the south and west sides.

Crews have documented 14 residences, 12 outbuildings, and 2 commercial structures that have been destroyed.

Resources assigned to the fire include 71 hand crews, 136 engines, 17 helicopters, 23 dozers, and 12 water tenders for a total of 2,500 personnel.

The top priority continues to be the southwest side where crews are making good progress securing containment lines and providing structure defense around Sugarloaf and Sugarloaf Mountain Park north towards Pine Flat and California Hot Springs.

If weather conditions on the northwest side permit, Friday crews will continue a tactical firing operation to help improve containment lines.

On the east and southeast sides helicopters and the Bombardier CL-515 Super Scooper have been dropping water and retardant on the upper ridge to slow the fire’s movement east towards the Kern River.

Tulare County residents can sign up to receive county emergency notifications by registering at AlertTC.com.

Information about evacuations can be found at the Tulare County website.