Giant sequoias have coexisted and thrived with low-intensity fire for thousands of years and are uniquely adapted to survive moderate flames.
Spongy bark insulates the cambium and branches grow high above the forest floor to escape flames, however this is becoming less effective as running crown fire becomes more common (Stephenson, 2020).
Giant Sequoia cones are serotinous and the heat from fires releases seeds from cones. Seedlings then have increased access to nutrients from fire ash and increased availability of sunlight as the ground level of the forest is cleared (Tweed, 2016).
Starting in 2015, a tipping point may have been breached as higher-severity fires have killed large giant sequoias in an unprecedented fashion.
The Castle, Windy, and KNP Complex Fires in 2020 and 2021 alone have led to the death of 13% to 19% of all Giant Sequoias (Shive, 2021).
The severe California drought of 2012 to 2016 likely caused sequoias extreme stress as this was the hottest and driest period in recorded California history (Low, 2021). It is also thought that this may have been the most intense drought California has experienced in 1200 years (Low, 2021).
Lack of frequent fire for past century in most groves combined with the impacts of a warming climate have made some wildfires extremely deadly for sequoias.
From the Windy and KNP Complex fires alone, the NPS estimates that 2,261 to 3,637 large sequoias will die as a result of these fires (“2021 fire impacts” – NPS). This accounts for 3 to 5% of all Giant Sequoias, an immense loss after the destructive 2020 Castle Fire.
