Preliminary Estimates of Sequoia Mortality in the 2020 Castle Fire

Portions of a report from the Sequoia & Kings Canyon National Parks:

Although some giant sequoia trees have stood for thousands of years and are adapted to withstand frequent low and mixed severity fires, preliminary estimates suggest that the 2020 Castle Fire 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. These estimates may change as we acquire new data.

Why Did This Happen?

A combination of one hundred years of fire suppression along with climate change driven hotter droughts has resulted in a denser forest with unprecedented levels of fuel loading. These conditions have changed how wildfire burns in the southern Sierra Nevada, resulting in large areas of high severity fire effects and mass fire events that generate their own weather. The Castle Fire of 2020 was one of these megafires.

What Steps Can Be Taken to Protect the Sequoia Groves?

In order to reduce fuels and restore wildfire resilience, we will need all available tools in the toolbox. Prescribed burning remains one of the most important management tools to reduce fuels in sequoia groves, favor regeneration, and increase resilience of these groves to climate change and wildfires. However, smaller burn windows and massive fuel accumulation means that prescribed fire is not able to keep up with the treatment needed and some areas cannot be safely treated with fire. Restorative thinning is an additional too that can be used to help protect the sequoia groves.

3 thoughts on “Preliminary Estimates of Sequoia Mortality in the 2020 Castle Fire”

  1. It is certainly a sad story.

    I thought some prescribed burning was already being applied in Sequoia and King’s canyon NPs, or was that only in some areas of Yosemite NP? It would be interesting to see a chronological history of any prescribed burns that have been implemented within the impacted areas and the effect.

    Of course, thinking that thinning followed by prescribed burns can solve all the problems of climate change in vulnerable forests is way too short-sighted, even if they are recommended ingredients in a complete solution; Sequoias (and other species) are facing a broad array of compounding impacts.

    “The hotter drought of 2012-2016 appears to have been a tipping point for giant sequoias and other Sierra Nevada mixed-conifer forests. In hotter droughts, unusually high temperatures worsen the effects of low precipitation, resulting in greater water loss from trees and lower water availability. This is an emerging climate change threat to our forests.”

    The following newly observed phenomena in giant sequoia should also be factored into the equation:

    Native bark beetles killing giant sequoias, and

    Widespread giant sequoia foliage dieback (primarily 2014) due to extreme heat and drought conditions.

    The heavy impact from human use is also an important influence and constraining factor to take into consideration.

    • This grove is privately-owned, and changed hands last year when the Save the Redwoods League bought it with money from fundraising. They intended to do fire safety work, thinning and development of recreational facilities before selling it off to the Forest Service, down the road.

  2. Well, I guess the Save the Redwoods League has its work cut out for it, even more. They spent 17 million for it all. They did recognize the need to reduce fuels, but they were just too late in implementation. It’s a wake-up call, for sure.


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