Sequoia Mortality Study Released California

Anyone who cares about trees has surely seen the headlines about the loss of 10-14% of all giant sequoias in the world in a single fire. At long last, the actual study has been released! It includes the data I compiled from months of hard work counting every large sequoia in Alder Creek Grove.

The Castle Fire killed 7,500 to 10,600 large giant sequoias (those with trunk diameters of 4 feet or more).

Starting shortly after the fire tore through and continuing through April of 2021, I hand counted every sequoia approximately six feet or more in diameter in Alder Creek Grove. I recorded the GPS location for each tree, along with its status, indicating if it was dead, heavily damaged (lost top/nearly full brown needles/unsure if living or not), or alive (moderately damaged/lightly damaged/unchanged).

The Castle Fire destroyed 31-42% of all large giant sequoias in its path, the equivalent of 10-14% of their total population.

The counts I collected were plotted by the NPS on a satellite-derived fire severity map. The data set was then used to determine the percentages of sequoias lost for each fire severity area. For example, mortality was nearly 100% in the areas that burned with high severity. These percentages were then applied to the fire severity maps for other groves in order to estimate the numbers of sequoias lost in all areas.

In addition to my data, an aerial assessment and two surveys of past fires were used to accurately estimate the percentage and number of sequoias killed by the fire. This much-needed report provides a solid picture of the fire’s impact.

The Castle Fire burned a whopping 1/3rd (33%) of all sequoia grove acreage.

Besides Alder Creek Grove, I’ve personally visited the following groves post-fire: Freeman Creek Grove, McIntyre Grove, Mountain Home Grove, Garfield–Dillonwood Grove, Forgotten Grove, Homer’s Nose Grove, South Fork Grove, and Board Camp Grove. I have attempted to see into every portion of the forest (not just what’s along a road or trail). My direct experience aligns with the fire severity map as well as the numbers and percentages of sequoias lost that are presented in this study.

Click to see the entire study:

About the Author:
Sue Cag is a musician, artist, writer, photographer, and conservationist.

All photos and video by Sue Cag. All Rights Reserved. Photos and video may not be used without permission.