Painting by Gary Stutler (garystutler.com); image distributed by SMA with permission of artist.
Each year, members of the Society of Municipal Arborists (SMA) nominate and vote for the SMA Urban Tree of the Year. The 2021 choice is the majestic giant sequoia (Sequoiadendron giganteum). What follows is derived from a press release offered by the Association.
Although giant sequoia is native to a small swath of western slopes of the Sierra Nevada Mountains in California, its hardiness (given most generously as USDA Zone 6a to 9b, with some sources constraining that range) makes it suitable for use beyond its indigenous terrain and indeed, it’s been planted in many western spaces, urban or otherwise. Like most trees it prefers a loamy soil, even moisture, mid-range pH, adequate soil volume, freedom from soil compaction, and full sun. However, it can grow in less than these ideal conditions, and the more well-established the tree, the better it will be able to ride out periods of drought. Full sun appears to be the least negotiable condition for giant sequoia.
Addressing the elephant in the room: how can a giant sequoia, in all its massive glory, be considered for urban spaces?
Gordon Matassa is an Administrative Analyst in the Tree Services Division of the Oakland, California Department of Public Works. “If planted correctly in urban areas, this species can bridge the natural world to the cities that many of us call home,” he says. “Giant sequoia is well suited for climate-appropriate urban areas when given enough room to grow, such as when planted in city parks. We have several giant sequoias in our parks in Oakland, California, where they stand out as sentinels in the urban landscape.”
Giant sequoias are numerous in Portland, Oregon; many of them were planted circa 1900. There are seven Portland Heritage Tree program giant sequoias in the City—some growing in parks, others in the City right-of-way or in residential front and side yards. The tallest of them is growing in Portland’s Mt Tabor Park; it’s 200 feet (60 m) tall, with a 50-foot (15-meter) canopy spread and a 25.3-foot (7.7-meter) trunk circumference. (The genetic potential of giant sequoia’s height, given ideal conditions, can exceed 250 feet/75 m).
According to the Portland Parks and Recreation website, “Nearly 500 sequoias and California redwoods (Sequoia sempervirens) have been inventoried in the City, and 93% were rated as being in good or fair condition. These trees thrive in our urban forest, and as large-form evergreens, they provide us with enormous public health and environmental benefits. A mature giant sequoia in Portland can store over 6 tons of carbon and scrub pounds of pollutants from the air annually.
The City of Eugene, Oregon is celebrating the early fulfillment of their goal of planting 2021 giant sequoias by 2021. According to their website, “Giant sequoia grow quickly and are low maintenance because they are resistant to drought, wind, flooding, fire, and storm damage. While working hard to clean the air and sequester carbon, the giant sequoia also make our community more attractive, livable, and prosperous.” Through the “2021 by 2021” initiative, the City planted giant sequoia in shared public areas such as parks and street medians, as well as on the grounds of schools, local businesses, and homes. Eugene originally conceived the effort in honor of the City’s hosting of the 2021 World Athletics Championships, which have been rescheduled for 2022.”
A Bit More About the Giant Sequoia
By Larry Hodgson
So much for the press release from the Society of Municipal Arborists, but I thought I’d add further bits of information about this most striking tree.
The giant sequoia (Sequoiadendron giganteum), also called the giant redwood and Sierra redwood, also Wellingtonia in Great Britain, is the world’s most massive individual tree. In habitat, it grows to an average height of 164–279 ft (50–85 m) with trunk diameters ranging from 20–26 ft (6–8 m). It is therefore not at tall as the coast or coastal redwood (Sequoia sempervirens), a related Californian species that is the world’s tallest tree and reaches up to 379 ft (115.5 m) in height.
Both trees, plus the dawn redwood (Metasequoia glyptostroboides) are the last living members of the Sequoioideae, a subfamily of coniferous trees within the family Cupressaceae, once found all over the world. In fact, the giant sequoia itself was found throughout North America and Eurasia until the last ice age greatly reduced its range. Older fossils that are possibly giant sequoias have been found in Cretaceous era sediments as far afield as Australia and New Zealand.
The giant sequoia is also considered the world’s second-oldest individual tree, with several over 3,000 years old. Only the Great Basin bristlecone pine (Pinus longaeva) has older specimens, with one, called Methusalem, estimated to be 4,852 years old.
The species is highly adapted to fire, with tremendously thick, fire-resistant bark and cones that open after a blaze. It only seems to be able to regenerate naturally after fire has burned off the duff that has accumulated on the forest floor, exposing sprouting seedlings to the sun necessary for their development.
Giant sequoia is a popular park and urban tree in appropriate moderate temperate climates throughout the world, from southwest British Columbia and the Western US (as described above) to Chile, New Zealand and Australia. I’ve seen them all over Europe, from England to France, Germany, Spain and beyond. In most of those climates, it grows quite quickly and specimens can reach nearly 200 feet (60 meters) tall in about 150 years or so.
In Eastern North America, apparently hampered by hot, dry summers, it is slower growing, but prime specimens of about the same age (150 years), but half that height (about 100 feet/30 meters) can be seen there in many parks, gardens and arboretums, including one huge specimen I’ve seen in Blithewold Gardens, Bristol, Rhode Island.
And no, I couldn’t grow a giant sequoia myself, living as I do in much too cold a climate (Quebec City, USDA zone 3b, AgCanada zone 4b), but that doesn’t stop me from admiring it!
The giant sequoia: truly a majestic tree and one well worth naming as the SMA Urban Tree of the Year 2021!