Geography of Giant Sequoias

| |

Giant sequoias (Sequoiadendron giganteum) are behemoths. These incredible trees are nature’s skyscrapers, the tallest of them rising 275 feet above the forest floor.

Giant sequoias inspire awe and admiration from the over one million people who visited Sequoia National Park in 2018 and countless others who have visited before and since.

Largest Single Trees by Volume

Located in 75 groves across the Sierra Nevada Mountains, giant sequoias can grow up to 30 feet in diameter and over 250 tall.

The tallest giant sequoia in the world, nicknamed General Sherman, has a circumference of 102 feet and is 275 feet tall. These trees grow between 5,000-7,000 feet above sea level.

Giant sequoias can be confused with California redwoods, another impressive tree species.

Both of these trees have a similar, red-orange bark color that differentiates them from the gray-brown pines, firs, and other trees that reside in the mixed conifer forests where giant sequoias reside.

Giants of the Forest

Giant sequoias are one of the longest lived tree species, with the oldest giant sequoia living an estimated 3,400 years.

Their incredibly long lives mean that many of these trees have lived through droughts, fires, record snowfall years, and other climate changes that are visible in the tree cores sampled by researchers.

A giant sequoia tree at Yosemite National Park's Mariposa Grove of Big Trees.
A giant sequoia tree at Yosemite National Park’s Mariposa Grove of Big Trees. By volume, giant sequoias are the world’s largest single trees. Photo: Alex Demas, USGS. Public domain.

Their thick bark helps giant sequoias adapt to conditions that threaten the survival of other forest species. Giant sequoia bark can be up to 18 inches thick, insulating them from the heat from wildfires that periodically sweep through their forest environments.

Several giant sequoias on a slope reveal signs of fires that the trees have survived.
Several giant sequoias on a slope reveal signs of fires that the trees have survived. Photo: Nate Stephenson, USGS Western Ecological Research Center. Public domain.

These trees are highly adapted to periodic forest fires, and can heal from serious injuries even if their thick bark fails to protect the live tissue under their bark layer. 

What are Monarch Trees?

The largest trees in a giant sequoia grove are known as monarchs. They are well suited to this regal name- these large trees nurture one another and promote the health of the old growth forest around them.

Extensive logging has reduced the number of giant sequoias in California and impacted old growth stands that offer the most resilience against the effects of climate change. 

Giant Sequoia tree known as the Fallen Monarch Tree which fell about 300 years ago.
This Giant Sequoia tree is known as the Fallen Monarch Tree which fell about 300 years ago. Giant sequoias are resistant to decay due to the high tannin content in their bark. Photo: Alex Demas, USGS. Public domain.

Giant Sequoias and Forest Fires

The Giant Sequoias’ thick bark layer and height allow these trees to be incredibly well adapted to the forest fires that have affected the Sierra Nevada at intervals of 6-35 years in the past.

Logging and forest management practices have suppressed the forests’ natural fire patterns, causing a buildup of dead trees and other brush that provides fuel for the fires that do still sweep through the groves.

Indigenous fire practices and current prescribed burning methods have been shown to be effective ways of managing forest environments to promote the health of the ecosystem.

While forest fires have mostly been viewed as negative events in the United States , they are a natural occurrence and are highly important to the growth and survival of multiple species, including giant sequoias.

A forest fire clears away competing undergrowth and establishes a base of mineral soil that giant sequoia seeds need to thrive.

Using Fire to Germinate

Giant sequoia seeds remain in closed cones for up to 20 years until the heat of the fire dries them out, allowing the cones to open and seeds to fall to the forest floor. While 98% of giant sequoia seeds won’t germinate, the 2% that do allow for the continuation of this species. More miraculously; each giant sequoia seed is the size of a grain of oatmeal.

Climate Change is Causing Wildfires to Burn Hotter and Longer

The extra fuel on the forest floor combined with droughts and climate change are causing some forest fires to burn hotter and longer.

In the Alder Creek grove, numerous giant sequoias were killed by the heat of the fire. In this grove, only two giant sequoia seedlings have been found, causing concerns over the grove’s ability to regenerate new giant sequoias as the mature trees die off. 

The Castle Creek fire also damaged giant sequoias, but burned at a lower temperature than the Alder Creek grove fire did. In the groves affected by the Castle Creek fire, environmental managers are finding hundreds of new seedlings that have sprouted in the wake of the flames. 

The drought and fires that have scorched the Sierra Nevada over the last few years have killed an estimated 10,600 giant sequoias, or approximately 14% of the entire population. These numbers are based on early estimates, and the total number of giant sequoias affected by recent fires may be much higher. 

Climate Change Impacts to Giant Sequoias

Giant sequoias have adapted to a variety of climate conditions in the past, but the current pace of climate change may be their toughest challenge yet. 

Due to their long-lived nature, giant sequoias are massively important for carbon storage.

Old growth forests are one of our most important tools in the effort to combat climate change; forest fires and logging release this carbon back into the atmosphere. 

Giant sequoias with dieback due to drought.
Hotter droughts are causing unprecedented foliage dieback in giant sequoias. Photo: Nathan Stephenson, USGS. Public domain.

Droughts, heat waves, and other environmental conditions exacerbated by climate change can increase the amount of stress that giant sequoias and other trees face, making them more susceptible to infections and bark beetle infestations.

Climate has influenced where giant sequoias have been found in the past, and the future is no different. The coming decades will be hotter, more fire-prone, and giant sequoias may have difficulty adapting to new constraints on where they can grow.

Related: How Climate Change is Affecting the Forests of the Sierra Nevada

Preserving Our Giant Trees

While much climate news is indeed dire, not all hope is lost for the giants of the forest. Groundbreaking partnerships are being made between local tribes, nonprofits, universities, and state and federal agencies that are working together to identify giant sequoia groves that are the most at risk from climate change and forest fires.

These partnerships are working to protect the vital old growth forests where the giant sequoias already are to prevent their loss, in addition to considering how to plan for the future. 

Preserving the remaining giant sequoias is of the utmost importance, not only because of the rarity of these trees in the world, but because of the awe they inspire in all those who have the honor of witnessing them while they are still here. 

References

Szalay, Jessie. “Giant Sequoias and Redwoods: The Largest and Tallest Trees.” Live Science. 4 May, 2017. www.livescience.com/39461-sequoias-redwood-trees.html

“Giant Sequoias.” National Park Service. Accessed 13 October, 2021. www.nps.gov/seki/learn/nature/bigtrees.htm

“Giant Sequoias and Climate.” National Park Service. Accessed 13 October, 2021. www.nps.gov/seki/learn/nature/giant-sequoias-and-climate.htm

Sommer, Lauren. “A Single Fire Killed Thousands of Sequoias. Scientists are Racing to Save the Rest.” NPR. 17 September, 2021. www.npr.org/2021/09/17/1037914390/giant-sequoia-national-park-wildfire-climate-change

“Sequoia and King’s Canyon Park Hosted 1.2 Million Visitors in 2020.” National Park Service. Accessed 13 October, 2021. www.nps.gov/seki/learn/news/sequoia-and-kings-canyon-national-parks-hosted-1-2-million-visitors-in-2020-35-decrease-compared-to-2019.htm

Related

Share:


Enter your email to receive the Geography Realm newsletter: