Red Flag Warnings and wind gusts of 50 to 69 mph have led to preemptive power shutoffs in Southern California on Thanksgiving day.
Southern California Edison reported at 10:25 a.m. Thursday that 1.1 percent, or 63,835 of their customers, have had their electrical power turned off as a preemptive measure to prevent wildfires if the strong winds blow down power lines. An additional 156,000 customers are in areas where power shutoffs are under consideration.
At 9:38 a.m. Thursday 44 weather stations had wind gusts that exceeded 50 mph, with the highest being 69 mph at Cloudland Cutoff. At that time 380 stations recorded conditions meeting Red Flag Warning criteria, and another 307 were flirting with the status. Most had relative humidity in the low teens.
The strong winds out of the northeast are expected to decrease Thursday afternoon and by 8 p.m. will be less than 7 mph in most areas. But the extremely low relative humidity in the single digits or teens will continue through Monday.
As this is being written at 10:30 a.m. PST Thursday there have been no reports of large fires during this wind event.
Red Flag Warnings, Southern California, Nov. 25, 2021
Firefighters on the North Complex, Plumas NF, Sept. 9, 2020. USFS photo by Kari Greer.
National Public Radio produced a four-minute feature on All Things Considered in which they interviewed wildland firefighters about the effects of the forthcoming pay raise. They talked with firefighters Dave Carman and Patrick Benson, as well as retired US Forest Service Fire Chief Riva Duncan who is now with Grassroots Wildland Firefighters.
If a sequoia is lucky, it can live for up to 3,000 years
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 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, 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.
Eight percent higher than the average of the previous 10 years
Updated Feb. 2, 2022
The number of acres that burned in the United States in 2021 according to the annual report from the National Interagency Fire Center, was more than the average of the previous 10 years. The 6,872,286 acres in the lower 49 states is 8 percent higher than the average of the previous 10 years, and 33 percent above the average in the decade before that, 2001 – 2010.
This is contrary to statements from some fire officials in December who said fewer than average acres had burned. That is only correct if Alaska is counted. When it is, the numbers can be misleading. Alaska is a huge state with a very low population for its size. Many fires there burn far from any structures or private property and are not suppressed. On some fires the only action taken is “point protection,” just keeping a small village or single cabin from burning. A fire can burn hundreds of thousands of acres over a period of months with few if any firefighters assigned.
The burned area in Alaska varies wildly from year to year, for example, about 62,000 acres in 2008 and more than 5,000,000 in 2015. In 2015 more acres burned there than in the other 9 geographic areas combined. (Alaska is it’s own geographic area. Map.) However, so far this year, Alaska has ranked only third in number of acres burned in geographic areas, outranking only the Rocky Mountain and Eastern Areas. Including the Alaska numbers in a calculation of fire activity in the 50 states is misleading and can radically skew statistics.
Fires continue to grow larger
The average size of fires 2021 was the fifth largest in the last 36 years. Since 1984 the six years with the highest average size have all occurred in the last 11 years, according to the available reliable data from the National Interagency Fire Center after 1984.
The total number of fires is on a downward trend
The number of fires in 2021 was the sixth lowest in the last 36 years.
All of the statistics for 2021 are from the annual report for 2021 published by the National Interagency Fire Center. Data from previous years also came from NIFC.
The U.S. Forest Service produced this video about the 2021 wildfire season of a fire crew based on the Six Rivers National Forest in Northern California — the Smith River Interagency Hotshots.
John Hawkins, retired CAL FIRE Unit Chief and County Fire Chief, sent us a .pdf copy of the publication, Forest Fire Fighting Fundamentals, which I had not seen in many years. It may have been considered part of basic training for wildland firefighters, written by the US Forest Service and the agency then known as California Department of Forestry (CDF).
I’m not sure when the 58-page document was first published. As you can see above, it was received on the Medicine Bow National Forest in 1953. The National Museum of Forest Service History says it was published around 1945 (“1945 ca.”), but I wonder if there were multiple editions throughout a couple of decades.
Forest Fire Fighting Fundamentals, p. 23
There are many hand-drawn illustrations, many of which are attention-grabbing or funny, which may have made it easier to retain the lesson being taught.
Forest Fire Fighting Fundamentals, p. 32
There are no chain saws or air tankers, but you will see a dozer and a very early model helicopter. Numerous times it mentions “men” being used to fight fire, “Only physically fit men should be used,” for example.
Forest Fire Fighting Fundamentals, p. 40
It mentions aggressive initial attack, saying that when using direct attack, “You either ‘hit the head’ (point of most rapid spread) or start at the rear and work forward on both sides (flanks) at the fire edge and thus pinch out and control the head.”
Forest Fire Fighting Fundamentals, illustration on page 39
It is very out of date in many respects, but the physics of fire and general principles of fire suppression and firefighter safety remain basically the same. It has been a while since I looked at what rookies are shown in basic firefighter training, S-130/190, but it would not hurt to let them peruse this document to help reinforce some fundamentals.
