Coast Redwood

The coast redwood is known scientifically as Sequoia sempervirens and is the sole living species of the genus Sequoia within the cypress family Cupressaceae. Its native range is a narrow Pacific coastal band running from central California to south-western Oregon. The species has produced the tallest living trees on Earth.

Mature coast redwoods typically reach 60–100 m (200–330 ft) in height. The tallest tree confirmed in the record is Hyperion, measured in 2006 at 379.1 ft (115.5 m). Trunks can grow to a maximum diameter of up to 8.9 m (29 ft) at breast height. Models of the species' limits suggest a theoretical maximum height of 122–130 m barring mechanical damage.

The bark of a mature tree may be up to about 35 cm (1.15 ft) thick, and the National Park Service cites a figure of about 12 in (30 cm). This thick bark, together with foliage held high above the ground, shields mature redwoods from all but the hottest fires. The wood itself lacks flammable pitch or resin, adding to the tree's resistance. Its high tannin content suppresses decay and repels pests, so that diseases of the coast redwood are virtually unknown and insect damage is insignificant. Because of these defenses, windthrow rather than fire or disease is the main cause of natural death in mature trees.

The coast redwood anchors itself without a taproot. Its roots descend only a short distance before turning outward, spreading horizontally to interlace with the roots of neighbouring trees and forming a shared network that steadies the stand against wind and slope. Water reaches these trees by more than one route. Because lifting water through a column of great height is physiologically difficult, redwoods evolved the capacity to absorb moisture directly through their leaves and bark as well as through their roots. The forest floor itself is a demanding substrate: the subsoils are highly weathered and nutrient-poor, so the ecosystem depends on rapid nutrient cycling in the topsoil together with abundant rainfall and fog.

Fog is central to redwood ecology rather than incidental to it. Summer fog reduces evaporation from the trees and from the ground, and the drip it sheds raises soil moisture through the dry season. When fog condenses on redwood foliage part of the water is absorbed directly by the tree, while the remainder drips to the forest floor and is taken up by the roots. By stripping water directly from fog through stomata at every level of the canopy, redwoods obtain nearly 40 percent of their water uptake during the dry summer. Work by UC Berkeley ecologist Todd Dawson indicates that summer fog can supply 30 percent or more of the annual water intake of a coast redwood, the water that allows the species to grow past 300 feet.

The fog itself is a seasonal product of the coast. It forms from May through October when cold, upwelled ocean water meets warm moist air offshore, condensing vapour into droplets that inland valley heat then draws ashore. Dawson's data further show that continuous redwood forest makes its own weather: the trees cool and still the air and their drip raises humidity, so cleared land would be warmer and less foggy. The record of that fog is not stable. A 2010 study coauthored by Dawson found coastal fog fell 33 percent over the 1951 to 2008 period, and continuing work indicates a further 7 percent decline over the following 14 years. In warmer parts of the range with less fog, researchers have already observed redwood crowns thinning, unhealthy but not yet dying.

Height and water are bound together in the species' biology. The leading hypothesis for why trees stop growing taller is that water transport becomes constrained as height increases, which then cuts leaf photosynthesis. Height itself limits further height growth: gravity and the sheer path length of the water column raise leaf water stress enough to constrain leaf expansion and photosynthesis even where soil moisture is ample.

Water management in redwood country is also a matter of deliberate practice. The Yurok hold that burning brings more water, an empirical rule they have applied since time immemorial and now test with USGS soil-moisture sensors. By limiting excessive tree growth, prescribed burns reduce demand on the water table, which raises surface flow and keeps soil moisture longer into the dry season. Paired Yurok and USGS teams place soil moisture sensors that track how fast water evaporates, infiltrates or is taken up by plants in burned and unburned ground.

Age, Growth and Limits.

Maximum recorded age for coast redwood is about 2,000 years while mature trees average 500 to 700 years. Height growth is limited because gravity and water-column path length raise leaf water stress, constraining leaf expansion and photosynthesis. Regressions put the ceiling at 122–130 m absent mechanical damage.

The genome is hexaploid (2n = 66) at about 26.5 gigabases. Reproduction is largely asexual via basal burls that sprout new growth with its own root system. Windthrow, not fire or disease, is the main natural cause of death in mature trees.

Distribution and Remnant Forest.

The historic range of the coast redwood covered about 810,000 ha before the 1850s. What survives today forms a band roughly 750 km long and 8 to 75 km wide. The southernmost grove lies in Monterey County and the northernmost in extreme south-western Oregon.

Old-growth stands are now a small fraction of the whole. The National Park Service puts the remaining old growth at about 4 percent while Save the Redwoods League gives a figure of about 5 percent. Protection is unevenly distributed: about 75 percent of the remnant old growth is protected but only 29 percent of all redwood forest is protected. Second-growth stands grow so dense that thinning is used to restore the survivors.

The tallest living tree known to science is Hyperion, which stands at 116.22 metres and was found in Redwood National Park in mid-2006 by Chris Atkins and Michael Taylor. Formal measurement and verification came two years later from Stephen Sillett, whose climb of the tree was held back for two weeks by a restriction protecting nesting marbled murrelets. The delay points to a methodological problem at the heart of the field: laser range finders are accurate devices, but they cannot always sight a tree's highest leaf from the ground. Laser figures therefore remain provisional until confirmed by climbing. The accurate method is to climb the tree and lower a tape.

Atkins, Sillett and Taylor set out to document every living redwood over 350 ft. The survey found 136 such trees, against about 25 known when the work began in the 1990s. Hyperion's position on a steep slope surprised researchers, since most giants root in creek bottoms. The tree stands in the Redwood Creek basin, which was thoroughly logged during the 1970s until the 1978 boundary expansion of Redwood National Park stopped the cutting.

The tallest living coast redwood on record is Hyperion, measured at 116.22 metres^{1Sequoia sempervirens · Wikipedia ↗}. The tree was found in Redwood National Park in mid-2006 by Chris Atkins and Michael Taylor^{1Sequoia sempervirens · Wikipedia ↗}. A separate confirmation of the tree in 2006 placed its height at 379.1 ft (115.5 m)^{1Sequoia sempervirens · Wikipedia ↗}. The Nature study recorded Hyperion in 2006 at 112.7 m^{3The limits to tree height · Nature (Koch et al., vol. 428) ↗}.

The physical ceiling for redwood height has been estimated through regressions on how leaf traits change with height^{3The limits to tree height · Nature (Koch et al., vol. 428) ↗}. Absent mechanical damage, those regressions put the maximum at 122 to 130 m^{3The limits to tree height · Nature (Koch et al., vol. 428) ↗}. That figure sits close to the tallest trees recorded historically^{3The limits to tree height · Nature (Koch et al., vol. 428) ↗}.

By trunk volume the largest known living coast redwood is Grogan's Fault, found in Redwood National Park in 2014 by Chris Atkins and Mario Vaden^{1Sequoia sempervirens · Wikipedia ↗}. Its trunk volume is at least 1,084.5 m³^{1Sequoia sempervirens · Wikipedia ↗}.

Height records also extend to the animals that inhabit the canopy: the wandering salamander has been documented more than 150 ft above ground^{9Skydiving salamanders live in world's tallest trees · UC Berkeley News ↗}.

The crown of an old-growth coast redwood is not empty air but a habitat in its own right. More than 70 plant species have been documented growing in the canopy, sharing the upper forest with wandering salamanders and flying squirrels. Stephen Sillett's first climbs brought back reports of soil accumulations hundreds of feet above the ground, with salamanders living inside them, and of ferns, shrubs and trees rooted on giant limbs like hanging gardens.

The wandering salamander (Aneides vagrans) is about 4 in (10 cm) long and spends its entire life in crowns more than 150 ft above ground. High-speed video shows the animal parachuting and gliding during falls, and wind-tunnel trials show arboreal salamanders manoeuvring in the air where ground-dwelling species merely flail. To study such animals biologists climb with ropes and ascenders, capturing, marking and tracking them among the limbs.

The canopy also draws birds from the sea. Marbled murrelets are primarily seabirds, yet they will fly up to 50 miles inland to lay a single egg on a large limb of an old-growth redwood.

The fertility of these forests rests on a narrow layer. Redwood forests depend on rapid nutrient cycling in the topsoil together with abundant rainfall and fog, because the subsoils beneath are highly weathered and nutrient-poor.

The coast redwood survives fire through structure as much as through luck. Thick bark and foliage held high on the trunk shield mature trees from all but the hottest fires, and basal burls resprout after fire, cutting or toppling. The regenerative capacity of the species was measured directly after the CZU fire: radiocarbon dating of post-fire sprouts showed Big Basin redwoods built new leaves on carbon reserves more than 50 years old, drawn from buds dormant under the bark for centuries. Species that cannot resprout fared far worse in the same event, with Douglas-fir suffering nearly 100 percent mortality.

The CZU Lightning Complex Fire began on 16 August 2020 and burned 35,009 ha (86,509 acres), destroying 1,450 structures before it was contained on 22 September 2020. It burned more than 97 percent of Big Basin's 7,366-hectare forest, a park founded in 1902, at an intensity not documented in most groves for at least a century. The unusual intensity of the fire, followed by two successive years of extreme drought and summer heat, severely damaged most of the old-growth trees in Big Basin Redwoods State Park.

Fire also returns as a deliberate practice. Tolowa Dee-ni' cultural burning came back to Peacock Bar on the Smith River inside Jedediah Smith Redwoods State Park on 21 October 2025, covering about 10 acres of oak woodland and mixed conifer. It was the first such burning since the removals of the 1850s and the park's creation in 1929, run by Tolowa staff and citizens with state and federal support. Seasonal burning promotes basket, medicine and food plants, keeps foraging space open and cuts catastrophic fire and pest risk.

The ecological effects of such burning are under formal study. USGS and Yurok Tribe scientists are jointly investigating how culturally prescribed fires change vegetation and soil moisture on Yurok ancestral lands in north-western California. The work tests the Yurok rule that burning brings more water, using soil-moisture sensors in burned and unburned ground. Limiting excessive tree growth reduces demand on the water table and keeps soil moisture longer into the dry season.

Redwood National and State Parks combines one national park and three California state parks across about 139,000 acres in Del Norte and Humboldt counties. The North Coast region around the parks is the most seismically active region of the United States, where three tectonic plates meet at the Mendocino triple junction.

Despite a destructive fire season elsewhere in northern California, Redwood National Park completed six prescribed fires covering 840 acres early in the 2019 fiscal year.

Reading the rings of coast redwood requires reaching wood high in the canopy rather than sampling only the base of the trunk. Researchers climbed standing trees and cored trunks at several heights across 14 old-growth sites, taking 1,466 series and 483,712 annual rings from 120 trees.

The resulting crossdated redwood chronologies now extend up to 1,685 years for coast redwood, compared with 1,538 years for giant sequoia at the sites studied. The comparison places the two species side by side in the same body of work, with the redwood record reaching further back in time than the sequoia record at these locations.

The difficulty of the species lies in its ring structure. Although the decay-resistant wood of giant sequoia helped establish dendrochronology, the rings of coast redwood have proved much harder to decipher, which limits long climate reconstructions from the species. The obstacle is not a shortage of material but the labor required to align ring sequences reliably from tree to tree.