Why are California’s redwoods and sequoias so big and tall?

Part 2 of an ongoing series about California’s unique and remarkable trees.

California is a state of superlatives. The oldest living thing lives here. The largest animal in the history of the world swims off our shores. The hottest temperature ever recorded baked visitors at Death Valley’s Furnace Creek back in 1913. California boasts the highest point in the contiguous United States and arguably the tallest waterfall in the country.

We also have the world’s tallest and biggest trees.

California’s giant sequoias and redwoods are nature’s skyscrapers. Redwoods exist in a few narrow pockets in Northern and Central California and into Southern Oregon. Sequoias live exclusively in small groves in central and Northern California with the largest grouping of them found in Sequoia National Park. These two tree species are wonders of the biological world. They are also some of the most magnificent things to behold on the planet.

I have personally climbed the Stagg tree (see photo below), the fifth-largest sequoia in the world, and I will forever remember the experience.

Erik Olsen climbs the Stagg tree, a giant sequoia.
The author climbs the Stagg tree, the fifth-largest tree in the world. (Erik Olsen)

We are lucky to still have our big trees, what’s left of them, anyway. Just a century and a half ago, old-growth redwoods and sequoias were relatively plentiful. People marveled at them, with some early settlers in California spinning unbelievable yarns of trees that rise from the earth “like a great tower“. They also saw them as a bounteous resource, ripe for plunder.

By 1900, nearly all of California’s tall trees had been purchased by private landowners who saw in the trees not beauty, but dollar signs. By 1950, nearly all of the old-growth redwoods and sequoias had been cut down for timber and other purposes. Today, only 5 percent of the old-growth coast redwood forest remains. The largest surviving stands of ancient coast redwoods are found in Humboldt Redwoods State Park, Redwood National and State Parks and Big Basin Redwoods State Park. It’s a wonder and a blessing that there are some left. And even then, they face an uncertain future thanks to climate change.

Professional tree climber Rip Thompkins at the top of the Stagg tree, a giant sequoia.

Sequoias and redwoods are closely related. The primary difference between sequoias and redwoods is their habitat. Redwoods live near the coast, while sequoias live in subalpine regions of California. Redwoods are the tallest trees in the world. Sequoias are the biggest, if measured by circumference and volume. Redwoods can grow over 350 feet (107 m). The tallest tree in the world that we know of is called the Hyperion, and it tickles the sky at 379.7 feet (115.7 m). But it is quite possible another tree out there is taller than Hyperion. Redwoods are growing taller all the time, and many of the tallest trees we know of are in hard to reach areas in Northern California. Hyperion was only discovered about a decade ago, on August 25, 2006, by naturalists Chris Atkins and Michael Taylor. The exact location of Hyperion is a secret to protect the tree from damage.

The giant sequoia (Sequoiadendron giganteum) is Earth’s most massive living organism. While they do not grow as tall as redwoods – the average size of old-growth sequoias is from 125-275 feet – they can be much larger, with diameters of 20–26 feet. Applying some basic Euclidean geometry (remember C = πd?), that means that the average giant sequoia has a circumference of over 85 feet.

Many of the remaining sequoias exist on private land, and in fact, one of the largest remaining stands of Sequoias in the world – the Alder Creek Grove of giant sequoias – was just bought by the Save the Redwoods League conservation group for nearly $16 million

Sequoias grow naturally along the western slope of the Sierra Nevada mountain range at an altitude of between 5,000 and 7,000 feet. They tend to grow further inland where the dry mountain air and elevation provide a comfortable environment for their cones to open and release seeds. They consume vast amounts of runoff from Sierra Nevada snowpack, which provides groves with thousands of gallons of water every day. Many scientists are deeply concerned about how climate change might affect the grand trees, as drought conditions potentially deprive them of water to survive.

General Sherman tree
The General Sherman tree in Sequoia National Park. Wikimedia.

The world’s largest sequoia, thus the world’s largest tree, is General Sherman, in Sequoia National Park. General Sherman is 274.9 feet high and has a diameter at its base of 36 feet, giving it a circumference of 113 feet. Scientists estimate that General Sherman weighs some 642 tons, about as much as 107 elephants. The tree is thought to be 2,300 to 2,700 years old, making it one of the oldest living things on the planet. (To learn more about the oldest thing in the world, also in California, see our recent feature on Bristlecone pines.) Interesting fact: in 1978, a branch broke off General Sherman that was 150 feet long and nearly seven feet thick. Alone it would have been one of the tallest trees east of the Mississippi.

Many sequoias exist on private land. Just last month, one of the largest remaining private stands of Sequoias in the world – the Alder Creek Grove of giant sequoias – was bought by the Save the Redwoods League conservation group for nearly $16 million. The money came from 8,500 contributions from individual donors around the world. The property includes both the Stagg Tree mentioned above and the Waterfall Tree, another gargantuan specimen. The grove is considered “the Crown Jewel” of remaining giant Sequoia forests.

Redwoods (Sequoia sempervirens), also known as coast redwoods, generally live about 500 to 700 years, although some have been documented at more than 2,000 years old. While wood from sequoias was found to be too brittle for most kinds of construction, the redwoods were a godsend for settlers and developers who desperately needed raw material to build homes and city buildings, to lay railroads, and erect bridge trestles. The timber companies who profited from redwoods only began to cut them down in earnest a bit over a century ago. But cut them down they did, with vigor and little regard for the preservation of such an amazing organism. After World War II, California experienced an unprecedented building boom, and the demand for redwood (and Douglas fir) soared. Coastal sawmills more than tripled between 1945 and 1948. By the end of the 1950s, only about 10 percent of the original two-million-acre redwood range remained untouched.

So how did these trees get so big and tall? We don’t know for sure, but some scientists believe it has to do with the climate in which they grow. Sequoias benefit from Californa’s often prodigious snowpack, which seeps into the ground, constantly providing water to the roots of the trees. Redwoods get much of their water from the air, when dense fog rolls in from the coast and is held firm by the redwoods themselves and the steep terrain. The trees’ leaves actually consume water in fog, particularly in their uppermost shoots. According to scientists who study the trees using elaborate climbing mechanisms to reach the treetops, in summer, coast redwoods can get more than half of their moisture from fog. (In fact, fog plays a central role in sustaining several of California’s coastal ecosystems.) The reason is that fog is surprisingly dense with water. One study from scientists Daniel Fernandez of California State University, Monterey Bay, showed that a one-square-meter fog collector could harvest some 39 liters, or nearly 10 gallons, of water from fog in a single day.

Another answer to the redwood’s size may lie in the tree’s unusual, enormous genome. The ongoing Redwood Genome Project has revealed that the tree’s genome is ten times the size of the human genome (27 base pairs compared to three billion in humans), with six copies of its chromosomes (both humans and giant sequoias only have two copies) existing in a cell. It’s possible that by better understanding the redwood genome, we may uncover the precise genetic mechanism that explains how these trees have gotten so big and tall.

Yet another factor may be the trees remarkable longevity. They are survivors. The Sierra Nevadas have long experienced dramatic swings in climate, and this may be yet another of those swings that the trees will simply endure. Or maybe not. For most of the time that redwoods and sequoias have existed, they have done a remarkable job fighting off fires, swings in climate, as well as disease and bug infestations. Because their bark and heartwood are rich in compounds called polyphenols, bugs and decay-causing fungi don’t like them.

Giant sequoias in California. Erik Olsen

The thirst for fog and proximity to water sources could be the trees undoing, however. Although they have managed to survive for hundreds if not thousands of years, climate change could well be the one new variable that changes everything for the trees.

As the air heats up due to global warming, there is a rising threat to the trees’ survival. Warm air pulls moisture from leaves, and the trees often close their pores, or stomata, to maintain their water supply. When the pores close, that prevents carbon dioxide from nourishing the tree, halting photosynthesis. The climate in areas where the trees grow hasn’t yet experienced the kind of temperatures that might kill them, but we are really just at the beginning of this current era of global warming, and some scientists warn hotter temperatures could doom many trees.

That said, other studies that show the increased carbon that causes warming could actually be good for the trees. According to an ongoing study from Redwoods Climate Change Initiative, California’s coast redwood trees are now growing faster than ever. As most people know, trees consume carbon dioxide from the air, so, the scientists argue, more carbon means more growth.

We will see. The good news is that to date, no drought-induced mortality has been observed in mature coastal redwoods or giant sequoias. 

It all comes down to some kind of balance. Trees may benefit from more carbon, but if it gets too hot, trees could start to perish. That’s a bit of a conundrum, to say the least.

Photo by Nikolay Maslov on Unsplash

The prospect of losing these magnificent trees to climate change is a double whammy. Not only would a mass die-off of trees be terrible for tourism and those who simply love and study them, but trees are some of the best bulwarks we have on the planet to fight climate change. Redwoods are among the fastest-growing trees on earth; they can grow three to ten feet per year. In fact, a redwood achieves most of its vertical growth within the first 100 years of its life. Among trees that do the best job taking carbon out of the atmosphere, you could hardly do better than redwoods and sequoias.

Numerous groups are actively trying to plant more redwoods around the world in the hope that they might become a sink for carbon dioxide in the atmosphere. Indeed, there is some evidence that planting vast tracks of trees globally could have a major impact on climate change.

The Archangel Ancient Tree Archive, an organization out of Copemish, Michigan, has been “cloning” California’s big trees for nearly a decade. They take snippets of the trees from the top canopy and replant them, essentially creating genetically identical copies of the original tree. It’s more like propagating than cloning, but that’s what they call it. The group’s founder, David Milarch, believes fervently that planting large trees is our best bet in stopping climate change. This is the video story I produced about Milarch back in 2013. It’s worth a watch. He’s an interesting character with a lot of passion.

Preserving and protecting what’s left of these amazing organisms should be a priority in California. These trees are not only part of the state’s rich natural legacy, but they offer ample opportunities for tourism and strengthening the economies of the regions where they grow. It’s hard to visit Redwood National and State Parks or Sequoia & Kings Canyon National Parks and to come away with anything but awe at these magnificent organisms. California is special, and we are blessed to have these trees and the places where they grow in our state.

Other resources:

Save the Redwoods League has got a lot of interesting information about California’s redwoods, including some great YouTube videos.

Redwood National and State Parks

A lovely short film part of Nat Geo’s Short Film Showcase on redwoods.

Video by California Through My Lens: 36 Hours in Redwood National Park

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