During this active wildfire season in California, concerns have been raised about the possibility of damage to giant sequoia groves. These trees, the largest (though not tallest) in the world, are native to the western slope of the Sierra Nevada Range and are found primarily in 68 groves, all at elevations above 4500 feet. Giant sequoias may exceed 300 feet in height and 50 feet in diameter though most never reach those extremes.
Despite public concerns, these giants, which can live for more than 3000 years, have long relied on wildfires for their survival. Each mature tree harbors thousands of green cones which contribute to photosynthesis for up to 20 years or more before drying out and releasing their seeds; heat from wildfires is the primary trigger that opens the cones though beetles and Douglas squirrels also play a role. Fibrous bark, up to three feet thick, protects the lower trunk of giant sequoias and wildfires may damage but rarely kill these trees; the risk of damage rises when fires are fueled by large amounts of dead wood, the result of repeated fire suppression. Wildfire, which clears the understory and enriches the soil, is also vital to the germination and growth of sequoia seedlings.
Indeed, the primary threat to giant sequoias is regional human habitation which fuels a policy of fire suppression. Fortunately, many of the largest groves are protected within National Parks and Monuments where natural wildfires and prescribed burns foster conditions that favor the survival of these majestic trees.
