C. Phillip Weatherspoon
Since its discovery in the mid-nineteenth century, giant sequoia (Sequoiadendron giganteum), also called sequoia, bigtree, and Sierra redwood, has been noted for its enormous size and age, and its rugged, awe-inspiring beauty. Because the species has broad public appeal and a restricted natural range, most groves of giant sequoia have been accorded protected status. Outside its natural range, both in the United States and in many other countries, giant sequoia is highly regarded as an ornamental and shows promise as a major timber-producing species.
Regularity: Regularly occurring
Occurrence in North America
The natural distribution of giant sequoia is restricted to about 75
groves, comprising a total area of only 35,607 acres (14,416 ha) along a
limited area of the western Sierra Nevada, California. The northern
two-thirds of its range, from the American River in Placer County
southward to the Kings River has only eight disjunct groves. The
remaining groves are concentrated between the Kings River and the Deer
Creek Grove in southern Tulare County [10,28]. Groves range in size
from approximately 2,470 acres (1,000 ha) with 20,000 giant sequoias to
small groves with only six living trees .
Regional Distribution in the Western United States
This species can be found in the following regions of the western United States (according to the Bureau of Land Management classification of Physiographic Regions of the western United States):
4 Sierra Mountains
- The native range of giant sequoia.
Giant sequoias grow to an average height of 250 to 275 feet (76-84 m)
and 15 to 20 feet (5-7 m) d.b.h. Record trees have been reported to be
310 feet (95 m) in height and 35 feet (11 m) d.b.h. The leaves are
awl-shaped, sessile, and persistent. Seed cones are 2 to 3 inches (5-8
cm) long, serotinous, persistent, and may remain green up to 20 years.
Bark is fibrous, furrowed, and may be 2 feet (0.6 m) thick at the base
of the columnar trunk [6,10]. The oldest known giant sequoia based on
ring count is 3,200 years old .
becoming open with age; branches of young trees spreading, on older trees drooping; axis of branchlets green or dark green in 1st year, thereafter pale brown to reddish brown. Leaves blue-green, base decurrent, distal free portion 3-5 mm, apex sharply pointed. Seed cones ellipsoid, 5-8 × 3-5.5 cm; cone scales shieldlike, ca. 2.5 cm, apical scales 6-10 mm wide, with distal groove, ending in a long, terete spine at middle when young. Seeds pale brown, elongate-ellipsoid, 3-6 mm.
Habitat and Ecology
Low temperatures seem to be the limiting factor for giant sequoia at the
upper elevational limits of its range, as well as in areas with severe
winters where the species has been introduced. Distribution of giant
sequoia at lower elevations appears to be restricted to sites with
available soil moisture throughout the summer drought period [24,28].
Climate: Giant sequoia is found in a humid climate characterized by dry
summers. Mean annual precipitation varies from 35 to 55 inches (88-138
cm). Most precipitation comes in the form of snow between October and
April. Mean annual snowfall ranges from 144 to 197 inches (360-493 cm),
and snow depths of 6.6 feet (2 m) or greater are common. Mean daily
maximum temperatures for July are typically 75 to 84 degrees Fahrenheit
(24-29 deg C). Mean minimum temperatures for January vary from 34 to 21
degrees Fahrenheit (1 to -6 deg C) .
Soils and topography: Most giant sequoia groves are on granitic-based
residual and alluvial soils. Some groves are on glacial outwash from
granite. Other common parent materials include schistose, dioritic and
andesitic rocks. Giant sequoia grows best in deep, well-drained sandy
loams. It occurs with higher frequency on mesic sites, such as drainage
bottoms and meadow edges. Soil pH ranges from 5.5 to 7.5, with an
average of about 6.5. Long-term site occupancy develops soil of high
fertility, good base status, and low bulk density. Except for its
moisture content, soil typically plays only a minor role in influencing
the distribution of the species .
Elevation: Elevation of the giant sequoia groves generally range from
4,590 to 6,560 feet (1,400-2,000 m) in the north, and 5,580 to 7,050
(1,700-2,150 m) to the south. The lowest natural occurrence of the
species is 2,720 feet (830 m) and the highest is 8,860 feet (2,700 m).
Giant sequoia generally appears on southern slopes in its northern
distribution and on more northerly slopes in the south .
Key Plant Community Associations
Giant sequoia principally occurs in scattered groves. Nowhere does it
grow in pure stands, although in a few small areas stands do approach a
pure condition . Although the giant sequoia groves of the central
and southern Sierra Nevada represent only a specific mesic segregate of
typical white fir (Abies concolor) forest communities, these groves are
often given special community recognition. Only giant sequoia is
restricted to the groves .
Typically, giant sequoia is found in a mixed conifer type dominated by
California white fir (A. concolor var. lowiana). Characteristic
associates include sugar pine (Pinus lambertiana), Jeffrey pine (P.
jeffreyi), ponderosa pine (P. ponderosa), Douglas-fir (Pseudotsuga
menziesii), incense-cedar (Calocedrus decurrens), and California black
oak (Quercus kelloggii). Shrub types include bush chinkapin
(Castanopsis sempervirens) and mountain whitethorn (Ceanothus
Giant sequoia as a dominant species in the following typings:
Terrestrial natural communities of California 
Montane and subalpine vegetation of the Sierra Nevada and Cascade Ranges 
This species is known to occur in the following ecosystem types (as named by the U.S. Forest Service in their Forest and Range Ecosystem [FRES] Type classification):
FRES21 Ponderosa pine
FRES23 Fir - spruce
FRES28 Western hardwoods
Habitat: Cover Types
This species is known to occur in association with the following cover types (as classified by the Society of American Foresters):
243 Sierra Nevada mixed conifer
Habitat: Plant Associations
This species is known to occur in association with the following plant community types (as classified by Küchler 1964):
K005 Mixed conifer forest
Soils and Topography
Typical soil series are Dome, Shaver, Holland, and Chaix. Characteristic soil families are coarse-loamy, mixed, mesic Dystric Xerochrepts; coarse-loamy, mixed, mesic Entic (and Typic) Xerumbrepts of the order Inceptisols; and fine-loamy, mixed, mesic Ultic Haploxeralfs of the order Alfisols. The natural range of the species lies mostly within the mesic temperature regime, extending only a short distance into the frigid regime, and wholly within the xeric moisture regime (22).
Giant sequoia grows best in deep, well-drained sandy loams. Its density also is much greater in the more mesic sites, such as drainage bottoms and meadow edges, than in other habitats within a grove. Total acreage of these productive sites is small, however. Relatively shallow and rocky soils support vigorous individuals, some large, wherever the trees can become established and where underground water is available to maintain them (16,32).
Soil pH ranges mostly from 5.5 to 7.5, with an average of about 6.5 (22). Long-term site occupancy by giant sequoia appears to develop a soil of high fertility, good base status, and low bulk density (40).
Adequate soil moisture throughout the dry growing season is critical for successful establishment of giant sequoia regeneration, although seedlings do not survive in wet soils (36). One study has shown more available soil moisture within a grove, possibly associated with subterranean flow from higher elevations, than in adjacent forested areas (34). Except for its moisture content, soil apparently plays only a minor role in influencing the distribution of the species, as evidenced by the considerable variability in parent material among groves and the fact that giant sequoia grows vigorously when planted in diverse soils around the world (16).
Elevations of the groves generally range from 1400 to 2000 m (4,590 to 6,560 ft) in the north, and 1700 to 2150 m (5,580 to 7,050 ft) in the south. The lowest natural occurrence of the species is 830 m (2,720 ft) and the highest is 2700 m (8,860 ft). The eight northern groves are all on slopes of a generally southern aspect. Between the Kings River and the southern boundary of Sequoia National Park, groves appear on north and south slopes with about equal frequency. Farther south, aspects are predominantly northerly (32).
Mean daily maximum temperatures for July for typical groves are 24° to 29° C (75° to 84° F). Mean minimum temperatures for January vary from 1° to -6° C (34° to 21° F). Extremes are about -24° and 40° C (-12° and 104° F) (32,37).
Low temperatures seem to be a limiting factor for giant sequoia at the upper elevational limits of its range, as well as in areas with severe winters where the species has been introduced. Distribution of the species at low elevations is limited mainly by deficient soil moisture during the growing season (34).
Habitat & Distribution
Plant / associate
fruitbody of Agaricus gennadii is associated with Sequoiadendron giganteum
Foodplant / pathogen
Armillaria mellea s.l. infects and damages Sequoiadendron giganteum
Plant / associate
fruitbody of Buchwaldoboletus lignicola is associated with rotting wood of Sequoiadendron giganteum
Other: major host/prey
Foodplant / saprobe
fruitbody of Hemimycena pseudolactea is saprobic on dead, fallen, decayed needle of litter of Sequoiadendron giganteum
Foodplant / saprobe
fruitbody of Lepiota ochraceofulva is saprobic on soil of tree of Sequoiadendron giganteum
Foodplant / pathogen
fruitbody of Phaeolus schweinitzii infects and damages live root of mature tree of Sequoiadendron giganteum
Other: minor host/prey
Foodplant / saprobe
fruitbody of Postia rennyi is saprobic on dead, decayed (very) wood of Sequoiadendron giganteum
Other: minor host/prey
Foodplant / saprobe
long-rooted fruitbody of Strobilurus stephanocystis is saprobic on buried, partially decayed cone of Sequoiadendron giganteum
Remarks: season: often in spring
Other: unusual host/prey
Associated Forest Cover
Based on density or canopy coverage, groves typically are dominated strongly by California white fir (Abies concolor var. lowiana), despite the presence of emergent individuals of giant sequoia that overtop the canopy. Sugar pine (Pinus lambertiana) is a characteristic associate. Incense-cedar (Libocedrus decurrens) at low elevations and California red fir (Abies magnifica) at high elevations may rival California white fir for dominance. Ponderosa pine (Pinus ponderosa) and California black oak (Quercus kelloggii) often occupy drier sites within the grove boundaries. Trees less commonly associated with giant sequoia include Jeffrey pine (Pinus jeffreyi), Douglas-fir (Pseudotsuga menziesii), Pacific yew (Taxus brevifolia), Pacific dogwood (Cornus nuttallii), California hazel (Corylus cornuta var. californica), white alder (Alnus rhombifolia), Scouler willow (Salix scoulerana), bigleaf maple (Acer macrophyllum), bitter cherry (Prunus emarginata), and canyon live oak (Quercus chrysolepis).
Shrub species most often found in giant sequoia groves are bush chinkapin (Castanopsis sempervirens), mountain misery (Chamaebatia foliolosa), mountain whitethorn (Ceanothus cordulatus), littleleaf ceanothus (C. parvifolius), deerbrush (C. integerrimus), snowbrush (C. velutinus), greenleaf manzanita (Arctostaphylos patula), western azalea (Rhododendron occidentale), Ribes spp., Rosa spp., and Rubus spp. (16,17,33,36).
Stand structure and species frequency vary substantially with elevation, latitude, exposure, soil moisture, and time since fire or other disturbance. In general, protection of groves from fire has resulted in increased prevalence of California white fir, reduced regeneration of giant sequoia and pines, and reduced density of shrubs. The age-class distribution of giant sequoia also varies widely among groves. Most groves today, however, appear to lack sufficient young giant sequoias to maintain the present density of mature trees in the future. In these groves, giant sequoia regeneration evidently has been declining over a period of 100 to 500 years or more (33).
Diseases and Parasites
Larger giant sequoias, because of their thick nonresinous bark and elevated crowns, are more resistant to fire damage than associated species. Nevertheless, repeated fires over the centuries sear through the bark of a tree's base, kill the cambium, and produce an ever-enlarging scar. Almost all of the larger trees have fire scars, many of which encompass a large percentage of the basal circumference (16). Few veterans have been killed by fire alone, but consequent reduction in supporting wood predisposes a tree to falling. Furthermore, fire scars provide entry for fungi responsible for root disease and heart rot (29). Decayed wood, in turn, is more easily consumed by subsequent fires. The net result is further structural weakening of the tree. In addition, fire scars have been cited as the main cause of dead tops, so common in older trees (35).
Lightning strikes, besides starting ground fires, sometimes knock out large portions of crowns or ignite dead tops. Mature trees seldom are killed by lightning, however (16).
Old giant sequoias most commonly die by toppling. Weakening of the roots and lower bole by fire and decay is primarily responsible (16,29). The extreme weight of the trees, coupled with their shallow roots, increases the effects of this weakening, especially in leaning trees. Other causative factors include wind, water-softened soils, undercutting by streams, and heavy snow loads (16).
Although diseases are less troublesome for giant sequoia in its natural range than for most other trees, the species is not as immune to disease as once assumed (1). Heartwood of downed sequoia logs is extremely durable, sometimes remaining largely intact for thousands of years. The heartwood of living trees, however, is less resistant to decay (2). At least nine fungi have been found associated with decayed giant sequoia wood. Of these, Heterobasidion annosum, Armillaria mellea, Poria incrassata, and P. albipellucida probably are most significant (29). The first two species also are serious root pathogens. Diseases generally do not kill trees past the seedling stage directly, but rather by contributing to root or stem failure. No other types of diseases, including seedling diseases, are known to be significant problems within the natural range of giant sequoia (2). In nurseries and when planted outside its natural range, however, giant sequoia is highly susceptible to, and sometimes rapidly killed by, a number of organisms that may attack it at any stage from seedlings to mature trees (1,25,39).
Insect depredations do not seriously harm giant sequoias older than about 2 years, although sometimes they may reduce vigor (17). Carpenter ant (Camponotus spp.) galleries in decayed wood of tree bases evidently are not a direct cause of tree failure. Carpenter ants and other insects may facilitate the entry and spread of decay fungi, although the importance of such a role is not well known (29). Like disease injury, damage by insects is more significant outside the tree's natural range.
Of various types of human impact on giant sequoia in the groves (16,17,29), the most significant has been fire exclusion. The damage caused by fire is outweighed by its benefits in perpetuating the species. Fire is necessary to create and maintain conditions favorable for regeneration (17). Furthermore, the elimination of frequent fires has permitted a large buildup of both dead and live fuels, and an associated increase in the potential for catastrophic crown fires. Agencies responsible for managing most of the groves currently have programs designed to reintroduce fire into giant sequoia ecosystems (15,27,31).
Fire Management Implications
This study investigated methods by which the impacts of prescribed fire
on certain biotic and abiotic elements of the sequoia-mixed conifer
forest ecosystem could be measured. Giant sequoia was present as a
co-dominant species with an estimated 11.4 trees per acre (28.2/ha). A
comparison of results was detailed from previous high-severity 1969 burn
to the lower-severity 1970 burn reported here. In summary, a high-severity
burn followed by another moderate-severity burn 7 to 10 years later is
an option for obtaining management objectives on a mixed sequoia stand;
or, alternatively, implement two low-severity burns in closer sequence
in order to gradually kill young seedlings and cleanup heavy fuels.
Both strategies would allow for more natural regeneration of seral species,
while reducing the potential threat of hazardous wildfires.
The elevation along the ridge ranges from 6,400 feet (1,950 m) at the
saddle to nearly 7,000 feet (2,134 m). Hygrothermograph records show a
yearly low of 17 degrees Fahrenheit (-8.4 deg C) and a high of 82
degrees Fahrenheit (28 deg C). Temperatures in November just before the
burn ranged from 32 to 58 degrees Fahrenheit (0-15 deg C). Relative
humidity fluctuated between 30 and 80 percent. Winds in and near the
study plots were moderate when present, varying from 0 to 5 mph (0.3
kmh). Average slope was 35 percent. Large portions of this study area
were found on soils derived from metamorphic schists.
Burn day conditions were as follows:
Temperature: 59 deg F (15 deg C)
Humidity: 20 percent
10-hour fuel sticks: 10 grams
Wind speed: 0 mph
Fire Management Considerations
Research on the importance of periodic fire in maintaining natural giant
sequoia forests has justified the need to restore a natural fire regime.
The principal goal of fire management in giant sequoia groves in
Sequoia, Kings Canyon, and Yosemite National Parks is to restore or
maintain the natural fire regime to the maximum extent possible.
Prescribed burns are now conducted by igniting fires in a spot pattern
and allowing nature to produce a mosaic of effects .
The long-standing fire suppression policy of federal and state land
agencies has created at least two major problems for the giant sequoia:
(1) the continuing reproduction of the species has been seriously
hampered and (2) the build-up of dead fuels and the growth of other
young trees in the understory pose threats of destructive forest fires
in the crowns of existing groves. In 1969, the National Park Service
began a program or prescribed burning in Kings Canyon National Park.
Prescribed burning has produced relatively few deleterious side effects
on giant sequoia groves .
Prescribed burning is currently an active management strategy in giant
sequoia groves. Fire prepares seedbeds, recycles nutrients, maintains
successional diversity, decreases the number of trees susceptible to
attack by insects and disease, reduces fire hazards, and favors wildlife
[5,10,27]. A prescribed burn in Kings Canyon National Park resulted in
an increase in flycatcher and robin numbers [4,13]. A number of changes
in bird and mammal populations are forecasted if fire is reintroduced on
a large scale. High-severity fire will increase the number of
trunk-feeding birds preying on the increased amount of insects .
Prior to protection under Park status in 1864, the Mariposa Grove and
Yosemite National Park sustained fires every 20 to 25 years . Other
research found that in presettlement times, any given site in the middle
elevations of the Sierra was burned over every 5 to 10 years [18,27].
Broad-scale Impacts of Plant Response to Fire
A fall prescribed fire in the Tharp Creek Watershed of Sequoia National Park
resulted in no giant sequoia mortality on a white fir-mixed conifer
site monitored for 5 years after fire. The fire burned from 23 to 26 October
1990. Relative humidity during the day was 21% to 30% and at night was 30%
to 40%. Fuel moisture levels in the litter and duff averaged 28%. For 100-hour
and 1,000-hour fuels, moisture levels were 14% and 64%, respectively. At the
time of ignition, air temperatures were 50 to 61 Â°F (10-16 Â°C), and winds were
calm. The fire was a combination of backing and strip head fires with flame lengths
of 0.16 to 7.9 feet (0.05-2.4 m). One-hour, 10-hour, and 100-hour fuels
were reduced by 96%, 77%, and 60%, respectively. Tree (≥4.6 feet (1.4 m))
mortality was evaluated before and after fire as well as from an unburned
reference site. Basal area changes were also monitored before and after
the fire. Compared to the unburned control, mean annual percent change in giant
sequoia basal area increased by an average of 1.27% on the burned site before
the fire. From 1989 to 1994 (includes 1 year of prefire data), giant sequoia basal
area increased by 0.90% on the burned site compared to the control . For
more information, see the entire Research Paper by Mutch and Parsons .
Plant Response to Fire
Immediately following the passage of fire, seeds will drop as a reaction
to hot convectional air movement through the canopy. Seeds will
germinate on the favorable mineral seedbeds created by the fire .
Postfire seedling establishment: When high-severity fires burn in dense
stands of mature giant sequoias, as many as 40,485 seedlings per acre
(100,000/ha) may develop following heat-induced seedfall . After a
prescribed burn in Sequoia and Kings Canyon National Parks, a
high-severity burn resulted in 40,000 seedlings per acre (98,800/ha) the
first year after burning. A lower-severity burn resulted in 13,000
seedlings per acre (32,110/ha). Not a single giant sequoia seedling was
found on the unburned control plot in this study .
Immediate Effect of Fire
In Sequoia and Kings Canyon National Parks, a moderate-severity
prescribed fire contributed little to the mortality of giant sequoia
that were larger than 1 foot (0.30 m) d.b.h. Additionally, there is no
evidence that previous fire scarring had any relationship to tree
mortality . Low- to moderate-severity fires scorch the bark of giant
sequoia and usually cause scarring. High-severity fires may reach the
crown and consume part or all of the canopy cover . A direct
relationship exists between the size of the basal fire scar in mature
giant sequoias and the the likelihood of damage to the top or foliage of
the trees . Reduction of supporting wood from scarring predisposes
the tree to falling, and provides an opening for fungi responsible for
root disease and heart rot .
Fire is the most serious damaging agent to young giant sequoia.
Seedlings and saplings are highly susceptible to mortality or serious
injury by fire. Giant sequoia exhibits the following adaptations to
fire: rapid growth, fire resistant bark, elevated canopies and
self-pruned lower branches, latent buds, and serotinous cones [10,12].
Mature giant sequoia are more resistant to fire damage and few are
killed by fire alone .
Giant sequoia groves represent a fire climax community whose stability
is maintained by frequent fires. In the absence of regular ground
fires, litter accumulates on the forest floor and limits germination and
establishment of seedlings . Giant sequoia in Whitaker's Forest,
California, produced 9,089 pounds per acre (10,181 kg per ha) of ground
litter . If these conditions are maintained in the future, the
groves will become a long-standing seral community trending toward a
mature white fir forest without giant sequoia .
More info for the term: density
Giant sequoia has adapted to keep its crown higher than that of its
associates. On disturbed sites, giant sequoia is a strong competitor,
although never totally dominating a stand . Current data does not
indicate that any enlargement of giant sequoia groves is taking place.
Mature giant sequoia mark the outer boundaries, which have remained
stable over a period of 500 to 1,000+ years. High levels of
reproduction are not necessary to maintain the present population
levels. Few groves, however, have sufficient young trees to maintain
the present density of mature giant sequoias for the future. The
majority of giant sequoias are currently undergoing a gradual decline in
density since the European settlement days .
Giant sequoia regenerates primarily by seed, although occasionally it
may reproduce naturally by vegetative methods. Giant sequoias up to
about 20 years of age may produce stump sprouts subsequent to injury.
Giant sequoia of all ages may sprout from the bole when old branches are
lost to fire or breakage. Cuttings from juvenile donors root quickly
and in high percentages (up to 94 percent) .
Flowering and fruiting: Giant sequoia is monoecious; male and female
cone buds form during late summer. Pollination takes place between the
middle of April and May. Fertilization usually occurs in August when
the cones are nearly full-sized. Embryos develop rapidly during the
next summer and reach maturity at the end of the second growing season.
Seed production and dissemination: Young trees start to bear cones at
the age of 20 years. Cones may remain attached to the tree for 8 to 12
years and much of the seed will be retained. During the late summer,
however, some seed is shed when the cone scales shrink. Most seeds are
liberated when the cone dries out and becomes detached. Each cone yields
an average of 230 seeds. The average number of cleaned seeds per pound
is approximately 81,000 (200,070/kg). Stored giant sequoia seed remains
moderately viable for many years [5,10,28]. At any given time, a large
tree may be expected to have approximately 11,000 cones. The upper part
of the crown of any mature giant sequoia invariably produces a greater
abundance of cones than its lower portions.
A mature giant sequoia has been estimated to disperse from 300,000 to
400,000 seeds per year. Seed dispersal results from seed falling from
the tree-top, insect and rodent activity, or by cones falling to the
ground. The winged seeds may be carried up to 600 feet (183 m) from the
Seedling development: Giant sequoia seeds germinate best when totally
buried in disturbed mineral soil. April, May, September, and October
temperatures are best for early development. Soil moisture conditions
and seedling survival are generally better in spring than during any
other season. Light conditions are generally best for growing at
one-half full sunlight. Upon germination, the seedling stands 3/4 to 1
inch (1.9-2.5 cm) high, usually with four cotyledons. By autumn,
seedlings have up to six branches and are 3 to 4 inches (8-10 cm) tall.
After the second year, the seedling attains a height of 8 to 12 inches
(20-30 cm) with a taproot penetrating to a depth of 10 to 15 inches
(25-38 cm) .
Growth and yield: Giant sequoia is the worlds largest tree in terms of
total volume. Beyond the seedling stage, giant sequoia unhindered by an
overstory continues to grow at the same rate as its competitors. Yields
of second growth stands dominated by giant sequoia were found to equal
or slightly exceed those of second-growth mixed-conifer stands on the
same site. Lower branches die fairly readily from shading, but trees
less than 100 years old retain most of their dead branches. Boles of
mature trees generally are free of branches to a height of 98 to 148
feet (30-40 m) .
Growth Form (according to Raunkiær Life-form classification)
Broad-scale Impacts of Fire
flammable, it burns hotly when splintered and dry .
off-site colonizer; seed carried by wind; postfire years 1 and 2
off-site colonizer; seed carried by animals or water; postfire yr 1&2
Reaction to Competition
Fires or other disturbances that bare mineral soil and open the canopy characteristically benefit intolerant species, including giant sequoia, and move plant communities to earlier successional stages. In contrast, successful regeneration of giant sequoia in shade and in the absence of disturbance is less likely than that of any associated conifer (17).
Once established, and with adequate light, young giant sequoias maintain dominance over competitors through rapid growth. In dense thickets, however, trees stagnate and recover slowly if released (36). At maturity, giant sequoias are the tallest trees in the forest.
Although conspicuous in late successional communities dominated by California white fir, giant sequoia is not a true climax-stage species, because it fails to reproduce itself successfully in an undisturbed forest. Instead, mature trees are successional relicts because they live for many centuries while continuing to meet their light requirements by virtue of their emergent crowns (16).
If various natural agents of disturbance-especially fire-operated freely, giant sequoia groves would consist of a roughly steady-state mosaic of even-aged groups of trees and shrubs in various stages of succession. The patchy nature of vegetational units would correspond to the pattern of disturbances. In the absence of disturbance, however, successional pathways converge toward a multilayered climax forest of pure California white fir (4). In fact, since the advent of fire suppression, density of California white fir has increased markedly, while densities of early successional stage species have decreased (26).
Roots of a mature tree commonly extend 30 m (100 ft) or more from the bole in well-drained soils, and occupy an area of 0.3 ha (0.7 acre) or more. Along drainage bottoms or edges of meadows, the radial extent of the root system may be no more than 12 to 15 m (40 to 50 ft). The largest lateral roots are usually no more than 0.3 m (1 ft) in diameter. Few roots extend deeper than 1 m (3 ft), and even less in areas with a high water table. Most of the abundant feeder roots are within the upper 0.6 m (2 ft) of soil. Concentrations of feeder roots often are high at the mineral soil surface (16).
Immature trees, both in the groves and in older plantings, are notably windfirm (20). Considering the shallowness of the root system and the great aboveground mass of large giant sequoias, it is remarkable that so many of these giants, especially leaners, remain standing for so long (16).
Root grafting is common in giant sequoia (16,36).
Life History and Behavior
Giant sequoia flowers from April to May; cone ripening and seed
dispersal occurs in the spring and summer months. Seeds dropped just
before the first snow or just as the snow melts may have the best chance
of germinating and becoming successfully established. Growth of giant
sequoia generally begins in the early spring to late fall .
Cuttings from juvenile donors root quickly and in high percentages (up to 94 percent) (3,10,12). Limited success has been achieved in rooting cuttings from older (30- or 40-year-old) trees (3,10). Differences in vegetative regeneration capacities between juvenile and older donors may be reduced if cuttings are taken at the time of budbreak, instead of during the dormant period (24).
In contrast with most coniferous seeds, a large majority of seeds of giant sequoia die from desiccation and solar radiation soon after reaching the forest floor, especially during the summer. In one study, viability of seeds removed from fresh cones and placed on the ground dropped from 45 percent to 0 in 20 days. Seeds collected from the forest floor showed an average viability of 1 percent (17).
Seed dormancy is not evident in giant sequoia, so surviving seeds germinate as soon as conditions are favorable (17). Germination is epigeal. The most significant requirement for germination is an adequate supply of moisture and protection of the seed from desiccation. This is best provided by moist, friable mineral soil that covers the seed to a depth of 1 cm (0.4 in), and that is partially shaded to reduce surface drying. A wide range of temperatures is acceptable for germination. The generally sandy soils of the groves normally provide the additional requirement of adequate aeration and the optimum pH range of 6 to 7 (38). Because of rapid percolation, however, adequate moisture retention for germination and initial root development is often marginal.
Seeds dropped just before the first snow or just as the snow melts may have the best chance of germinating and becoming successfully established. Seedlings that produce roots early in the season during favorable soil moisture conditions are more likely to survive the dry summer. The first stage of germination-extension of the radicle-sometimes takes place beneath the snow (16).
Thick litter usually dries too quickly for seeds to germinate, and virtually all seedlings that do get started die before their roots can penetrate to mineral soil (17,36). Only in exceptionally wet years do significant numbers of seedlings become established on undisturbed forest floor. The role of damping-off fungi in the mortality of natural giant sequoia seedlings is not well known, but they are almost certainly a greater problem on thick litter than on mineral soil (2,25). After seedlings are established on more favorable seedbeds, a light covering of litter can moderate soil surface temperatures and retard drying (37).
Seedlings rarely become established in dense grass cover, probably because moisture is depleted in the surface soil early in the season (36).
Soil disturbance and increased availability of light and moisture resulting from past logging in some of the groves have led to establishment of several fine young-growth stands dominated by giant sequoia. Mechanical seedbed preparation is currently a legitimate regeneration option in some groves, although such treatment is inconsistent with management direction in most of the natural range of the species.
Of the various types of natural disturbances that may remove litter and bare mineral soil, fire is undoubtedly the most significant. Locally intense or highly consumptive fires are more effective than light surface fires or physical disturbance in promoting germination and subsequent seedling survival and early growth (17). The resulting short-lived friable soil condition facilitates seed penetration beneath the surface and root penetration following germination. Increased wettability in the surface soil layers resulting from high temperatures appears to improve water penetration and retention in the zones important for seeds and young seedlings. Fire also may kill some understory trees, thereby providing more light to speed the development (especially root penetration) of the shade-intolerant giant sequoia seedlings. Additional benefits include providing a surge of available nutrients, reducing populations of fungi potentially pathogenic to seedlings, and killing seeds and rootstocks of competing vegetation (17).
On the other hand, the dark surface and possibly increased insolation resulting from fire may cause more desiccation and heat killing of giant sequoia seeds and seedlings at the surface. Also, populations of endomycorrhizal fungi may be severely reduced temporarily (17). And low-consumption fires, rather than reducing competing vegetation, may instead greatly stimulate germination and sprouting of shrubs. Partially burned litter, in terms of its suitability for successful seedling establishment, ranks between undisturbed forest floor and areas subjected to hot fires (38).
First-year giant sequoia seedlings established on treated-bulldozed or burned or both-areas were 30 to 150 times more numerous than those on undisturbed forest floor (17). Mortality of first-year seedlings during the 3 summer months on one treated area averaged 39 percent, with an additional 25 percent dying during the next 9 months. Desiccation was the primary cause of mortality in the summer. During a year of increased seasonal precipitation, mortality attributable to desiccation decreased, whereas that caused by insects increased to 25 percent of total mortality. Heat canker, damage by birds and mammals, and fungal attacks were of minor importance.
In the same study, direct mortality of first-year seedlings from insect predation ranged from 3 to 18 percent of all seedlings present. Some of the significant additional insect damage probably caused delayed mortality. Largest seedling losses were in areas recently disturbed, especially by fire, probably because alternative food sources were reduced temporarily. Insects responsible for the damage were early instars of Pristocauthophilus pacificus, a camel cricket, and larvae of the geometrids Sabulodes caberata and Pero behrensaria.
Survival of sequoia seedlings for a 7- to 9-year period was 27 percent on areas subjected to a hot burn as opposed to 3.5 percent on other treated substrates. No seedlings survived in undisturbed areas. In another instance, only 1.4 percent of seedlings established following light surface burning were alive after two summers. Mortality slows substantially after the first 2 or 3 years. At the end of 3 years, surviving seedlings usually have root systems that penetrate the soil to depths that supply adequate moisture through the summer, or to about 36 cm (14 in).
Height growth of giant sequoia seedlings in the groves is relatively slow during the first few years, presumably because of competition for light and moisture from the larger trees. Seedlings 7 to 10 years old had grown at an average rate of about 4 cm (1.6 in) per year. Periodic annual height increment from 10 to 20 years was only 5 em (2 in). Seedlings grew significantly faster on areas subjected to hot burns than they did elsewhere (17).
In contrast, giant sequoia seedlings in the open grow rapidly and, given an even start, can outgrow any associated tree species. Height growth up to 60 cm (24 in) per year is not uncommon (9).
Up to 2 or 3 years of age, seedlings growing in dense shade (less than 25 percent of full sunlight) survive about as well as others, but grow poorly and develop abnormally (37). At higher light levels, one study found moderate reduction in height growth compared with seedlings in full sunlight (37), whereas another study found no significant effect of reduced light on height growth (17). The adverse effects of shade on older giant sequoias are more conspicuous with respect to both mortality and growth reduction.
Seed Production and Dissemination
Giant sequoias have serotinous cones which, at maturity, may remain attached to the stems without opening to release seeds. For 20 years or more, cones may retain viable seeds and continue to photosynthesize and grow, their peduncles producing annual rings that can be used to determine cone age (16,36).
A typical mature giant sequoia produces an average of 1,500 new cones each year, although variability among trees and from year to year is great. Cones produced during years with ample soil moisture are more numerous (more than 20,000 cones on one large tree in an exceptional year) and yield seeds of greater viability than those produced in dry years. The upper third of the crown generally bears at least two-thirds of the cone crop. Because of extended cone retention, a mature tree may have 10,000 to 30,000 cones at any given time, two-thirds of which may be green and closed, and the remainder opened, brown, and largely seedless (16,17).
Estimates of percent germination of seeds removed from green cones range from about 20 to 40 percent (11,17,38). A number of variables, however, account for departures from these average values. Trees growing on rocky sites yield seeds with substantially higher germinability than those on bottom lands with deeper soils. Larger seeds germinate in higher percentages than small ones. In tests of cone age, germination increased from 20 percent for seeds from 2-year-old cones to 52 percent for 5-year-old cones, then dropped to 27 percent for cones 8 years of age. Germinability also varies with cone location in the crown, seed position within the cones, and among groves (16). Artificial stratification of seeds for 60 days or more resulted in faster germination, but not in higher germination percent (11).
Browning or drying of cones, with subsequent shrinkage of scales and dispersal of seeds, is brought about largely by three agents, two of which are animals. The more effective of the two is Phymatodes nitidus, a long-horned wood-boring beetle. The larvae of the beetle mine the fleshy cone scales and cone shafts, damaging occasional seeds only incidentally. As vascular connections are severed, scales successively dry and shrink, allowing the seeds to fall. Cones damaged during the summer open several scales at a time, beginning during late summer and fall, and continuing for 6 months to 1 year (17).
The second animal having a significant role in giant sequoia regeneration is the chickaree, or Douglas squirrel (Tamiasciurus douglasi). The fleshy green scales of younger sequoia cones are a major food source for the squirrel. The seeds, too small to have much food value, are dislodged as the scales are eaten. During years of high squirrel densities, the animals tend to cut large numbers of cones and store and eat them at caches. When squirrels are few, most of the cone consumption is in tree crowns-a habit more conducive to effective seed dispersal. The squirrels are active all year (17).
The chickaree prefers cones 2 to 5 years old, whereas Phymatodes is more prevalent in cones at least 4 years old. The combined activities of these animals help to ensure that seeds of all age classes are shed, and that rate of seedfall is roughly constant throughout the year and from year to year, despite variability in new cone production. An average rate is about 1 million seeds per hectare (400,000/acre) per year (17).
The third and perhaps most important agent of seed release is fire. Hot air produced by locally intense fire and convected high into the canopy can dry cones, resulting in release of enormous quantities of seed over small areas-for example, 20 million/ha (8 million/acre) (17). This increased seedfall coincides both spatially and temporally with fire-related seedbed conditions favorable for seed germination and seedling survival (fig. 2).
Giant sequoia seeds are well adapted for wind dispersal. They are light (average 200,000/kg [91,000/lb]), winged, and fall in still air at a rate of 1.2 to 1.8 m (4 to 6 ft) per second. Winds common in late summer and winter storms in the Sierra Nevada can disperse seeds more than 0.4 km (0.25 mi) from the tall crowns of mature trees (16,36).
Cone and seed insects other than Phymatodes have only a minor impact on seed production (17).
Birds and mammals exert a negligible effect on giant sequoia seeds on the ground. Sequoia seeds consistently rank at or near the bottom in food preference tests that include seeds of associated species, primarily because they are small and contain little energy (17,38).
Flowering and Fruiting
Growth and Yield
A notable characteristic of mature giant sequoias that contributes substantially to their great volume is the slight taper of the bole-a feature more prominent in this species than in any other Sierra Nevada conifer (16). In contrast, young open-grown giant sequoias taper markedly.
The greatest known age of a giant sequoia is 3,200 years, determined from a stump count of rings (16). Calculations based on increment borings yield age estimates of 2,000 to 3,000 years for many living trees.
Beyond the seedling stage, giant sequoia unhindered by an overstory continues to grow at least as well as associated species of the same age. In both clearcuts and group selection cuts on a high site in the central Sierra Nevada, it has outgrown other conifers in plantations up to 18 years of age. Furthermore, giant sequoia appears less susceptible than associated conifers to growth reductions caused by shrub competition (18). In a survey of California plantations up to 50 years of age in which giant sequoia had been planted, it outgrew other conifers (mostly ponderosa pine) in most instances in which species differed significantly in height or diameter growth. In the best plantations, giant sequoia averaged 0.5 to 0.7 m (1.6 to 2.3 ft) per year in height growth, and 1.3 to 2.0 cm (0.5 to 0.8 in) in diameter growth per year (9).
Yields of second-growth stands dominated by giant sequoia were found to equal or slightly exceed those of second-growth mixed-conifer stands on the same high sites (site index 53 m [175 ft] at base age 300 years) (6). Volumes at selected stand ages were as follows:
Stand Age Total volume yr m³/ha fbm/acre (Scribner) 18 2.6 188 31 83.1 5,938 63 339.3 24,237 86 757.1 54,077 In cubic measure, mean annual increment at age 86 was approximately 9 m³/ha (126 ft³/acre).
In contrast to the brittleness and low tensile strength of the wood of old-growth giant sequoia, young-growth trees have wood properties comparable to those of young-growth redwood (5,28). Because most groves have protected status, the potential of the species for fiber production within its natural range is limited. It has been planted widely and often successfully in many parts of the world, however. As in California plantations, on the proper sites it outperforms most other species (7). An 80-year-old giant sequoia plantation in Belgium, for example, grew at an average annual rate of 36 to 49 m³/ha (514 to 700 ft³/acre) (20). Many foresters see considerable potential for giant sequoia as a major timber-producing species of the world.
In old-growth groves, rapid height growth continues on the better sites for at least 100 years, producing dense conical crowns. At 400 years, trees range in height from about 34 to 73 m (110 to 240 ft). The rate of height growth declines beyond 400 years, and the typical tree levels off near 76 m (250 ft) at an age of 800 to 1,500 years (17).
Analysis of a large old-growth population showed an average d.b.h. of 48 cm (18.9 in) at 100 years, 132 cm (52.0 in) at 400 years, 219 cm (86.1 in) at 800 years, and 427 cm (168.0 in) at 2,000 years (17).
Although radial growth gradually decreases with age, volume increment generally is sustained into old age. The General Sherman tree, at an approximate age of 2,500 years, has a current radial growth rate at breast height of about 1 mm (0.04 in) per year (16). Average volume increment for this tree since 1931 has been estimated by different methods at 1.13 m³ (40 ft³) per year (16) and 1.44 m³ (51 ft³) per year (13). Therefore, the world's largest tree also may be, in terms of volume increment, the world's fastest-growing tree. A related conclusion can be applied to the species: the enormous size attained by giant sequoia results not only from its longevity, but also- despite the apparent decadence of most veterans- from its continued rapid growth into old age (16).
Lower branches of giant sequoia die fairly readily from shading, but trees less than 100 years old retain most of their dead branches. Boles of mature trees generally are free of branches to a height of 30 to 45 m (98 to 148 ft) (36).
Molecular Biology and Genetics
Races and Hybrids No races of giant sequoia exist (36). Fourteen horticultural forms are known, only two of which are common (16).
Hybridization of giant sequoia with redwood has been reported in the Soviet Union but is unconfirmed in the western literature (19).
Barcode data: Sequoiadendron giganteum
Statistics of barcoding coverage: Sequoiadendron giganteum
Public Records: 3
Specimens with Barcodes: 4
Species With Barcodes: 1
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1998Vulnerable (VU)
- 1998Vulnerable (V)
National NatureServe Conservation Status
Rounded National Status Rank: N3 - Vulnerable
NatureServe Conservation Status
Rounded Global Status Rank: G3 - Vulnerable
2 years. Carpenter ants (Campanotus laevigatus) do not directly harm
the trees, although they do create pathways for fungi . A
wood-boring beetle (Trachykele opulenta) may kill trees damaged by road
cuts or the undercutting of stream banks. The larvae of this beetle may
girdle a giant sequoia by feeding on the inner bark. The cerambycid
beetle (Phymatodes nitidus) lays its larvae in green giant sequoia
cones. Other cone larvae predators are the gelechiid moth (Gelechia
spp.) and lygaeid bug (Ischnorrhynchus resedae). In all, 151 species of
insects and 37 arachnids are known to be associated with the giant
sequoia in that they use it to complete some part of their life cycle
Disease: At least nine fungi have been found associated with decayed
giant sequoia wood. The most prevalent fungi are Heterobasidion
annosum, Armillaria mellea, Poria incrassata, and P. albipellucida.
Diseases generally do not kill trees past the seedling stage directly,
but rather by contributing to root or stem failure. No other types of
disease, including seedling disease, are known to be problems to giant
Air-pollution creating acidic mists significantly reduce root growth of
giant sequoia . The development of facilities for human use, such
as paved roads and buildings, can damage giant sequoia roots and hence
slow growth .
Relevance to Humans and Ecosystems
Other uses and values
native range. It is also used for Christmas trees .
Wildlife primarily use giant sequoia for cover. Early in giant sequoia
development, large mammals use dense stands as hiding and thermal cover.
Mature trees are used to a limited extent by arboreal species such as
birds, squirrels, and other small mammals .
Wood Products Value
Young giant sequoia has favorable wood properties. It is
decay-resistant and used as dimensional lumber, veneer, and plywood
. Old growth has low tensile strength and brittleness, making it
unsuitable for most structural purposes. The most historically popular
items milled from giant sequoia were fenceposts, grape stakes, shingles,
novelties, patio furniture, and pencils .
Importance to Livestock and Wildlife
Birds: Over 30 bird species have been identified in giant sequoia
groves. A variety of foliage- and air-feeding birds occupy the upper
canopy, while sapsuckers feed through the thin bark. Cavity-nesters
that use giant sequoia for nesting include white-headed woodpeckers and
flickers, and an occasional perching bird such as a nuthutch.
Mammals: Common mammal associates include the deer mouse, chipmunk,
shrew, gray squirrel, golden-mantled ground squirrel, mule deer, coyote,
black bear, and various reptiles. Reports of chipmunks using giant
sequoia sawdust for cleansing baths have been noted. The chickaree is
especially noted for its relationship to giant sequoia. Chickarees make
the soft flesh of green giant sequoia cone scales a major food item. An
individual chickaree may cut and eat as many as 3,000 to 3,500 cones per
dry weight. The outer portions of the cones provide 4,690 calories per
gram dry weight .
considered low in palatability .
Sequoiadendron giganteum (giant sequoia, giant redwood, Sierra redwood, Sierran redwood, or Wellingtonia) is the sole living species in the genus Sequoiadendron, and one of three species of coniferous trees known as redwoods, classified in the family Cupressaceae in the subfamily Sequoioideae, together with Sequoia sempervirens (coast redwood) and Metasequoia glyptostroboides (dawn redwood). The common use of the name "sequoia" generally refers to Sequoiadendron giganteum, which occurs naturally only in groves on the western slopes of the Sierra Nevada Mountains of California. It is named after Sequoyah (1767–1843), the inventor of the Cherokee syllabary.
- 1 Description
- 2 Biology
- 3 Distribution
- 4 Ecology
- 5 Discovery and naming
- 6 Uses
- 7 Cultivation
- 8 Superlatives
- 9 See also
- 10 Notes
- 11 References
- 12 Further references
- 13 Further reading
- 14 External links
Giant sequoias are the world's largest single trees and largest living thing by volume. Giant sequoias grow to an average height of 50–85 m (164–279 ft) and 6–8 m (20–26 ft) in diameter. Record trees have been measured to be 94.8 m (311 ft) in height and over 17 m (56 ft) in diameter. The oldest known giant sequoia based on ring count is 3,500 years old. Giant Sequoias are among the oldest living things on Earth. Sequoia bark is fibrous, furrowed, and may be 90 cm (3.0 ft) thick at the base of the columnar trunk. It provides significant fire protection for the trees. The leaves are evergreen, awl-shaped, 3–6 millimetres (0.12–0.24 in) long, and arranged spirally on the shoots. The seed cones are 4–7 centimetres (1.6–2.8 in) long and mature in 18–20 months, though they typically remain green and closed for up to 20 years; each cone has 30–50 spirally arranged scales, with several seeds on each scale, giving an average of 230 seeds per cone. The seed is dark brown, 4–5 millimetres (0.16–0.20 in) long and 1 millimetre (0.039 in) broad, with a 1-millimetre (0.039 in) wide, yellow-brown wing along each side. Some seeds are shed when the cone scales shrink during hot weather in late summer, but most are liberated when the cone dries from fire heat or is damaged by insects.
The giant sequoia regenerates by seed. Young trees start to bear cones at the age of 12 years. Trees up to about 20 years old may produce stump sprouts subsequent to injury, but unlike coast redwood, shoots do not form on the stumps of mature trees. Giant sequoias of all ages may sprout from their boles when branches are lost to fire or breakage.
At any given time, a large tree may be expected to have about 11,000 cones. Cone production is greatest in the upper portion of the canopy. A mature giant sequoia has been estimated to disperse 300,000–400,000 seeds per year. The winged seeds may be carried up to 180 metres (590 ft) from the parent tree.
Lower branches die fairly readily from shading, but trees less than 100 years old retain most of their dead branches. Trunks of mature trees in groves are generally free of branches to a height of 20–50 metres (66–164 ft), but solitary trees will retain low branches.
Because of its size, the tree has been studied for its water pull. Water from the roots can be pushed up only a few meters by osmotic pressure but can reach extreme heights by using a system of branching capillarity (capillary action) in the tree's xylem (the water tubules) and sub-pressure from evaporating water at the leaves. Sequoias supplement water from the soil with fog, taken up through air roots, at heights where the root water cannot be pulled to.
The natural distribution of giant sequoias is restricted to a limited area of the western Sierra Nevada, California. They occur in scattered groves, with a total of 68 groves (see list of sequoia groves for a full inventory), comprising a total area of only 144.16 km2 (35,620 acres). Nowhere does it grow in pure stands, although in a few small areas, stands do approach a pure condition. The northern two-thirds of its range, from the American River in Placer County southward to the Kings River, has only eight disjunct groves. The remaining southern groves are concentrated between the Kings River and the Deer Creek Grove in southern Tulare County. Groves range in size from 12.4 km2 (3,100 acres) with 20,000 mature trees, to small groves with only six living trees. Many are protected in Sequoia and Kings Canyon National Parks and Giant Sequoia National Monument.
The giant sequoia is usually found in a humid climate characterized by dry summers and snowy winters. Most giant sequoia groves are on granitic-based residual and alluvial soils. The elevation of the giant sequoia groves generally ranges from 1,400–2,000 m (4,600–6,600 ft) in the north, to 1,700–2,150 metres (5,580–7,050 ft) to the south. Giant sequoias generally occur on the south-facing sides of northern mountains, and on the northern faces of more southerly slopes.
High levels of reproduction are not necessary to maintain the present population levels. Few groves, however, have sufficient young trees to maintain the present density of mature giant sequoias for the future. The majority of giant sequoias are currently undergoing a gradual decline in density since European settlement.
Giant sequoias are in many ways adapted to forest fires. Their bark is unusually fire resistant, and their cones will normally open immediately after a fire. The giant sequoias are having difficulty reproducing in their original habitat (and very rarely reproduce in cultivation) due to the seeds only being able to grow successfully in full sun and in mineral-rich soils, free from competing vegetation. Although the seeds can germinate in moist needle humus in the spring, these seedlings will die as the duff dries in the summer. They therefore require periodic wildfire to clear competing vegetation and soil humus before successful regeneration can occur. Without fire, shade-loving species will crowd out young sequoia seedlings, and sequoia seeds will not germinate. When fully grown, these trees typically require large amounts of water and are therefore often concentrated near streams.
Fires also bring hot air high into the canopy via convection, which in turn dries and opens the cones. The subsequent release of large quantities of seeds coincides with the optimal postfire seedbed conditions. Loose ground ash may also act as a cover to protect the fallen seeds from ultraviolet radiation damage.
Due to fire suppression efforts and livestock grazing during the early and mid 20th century, low-intensity fires no longer occurred naturally in many groves, and still do not occur in some groves today. The suppression of fires also led to ground fuel build-up and the dense growth of fire-sensitive white fir. This increased the risk of more intense fires that can use the firs as ladders to threaten mature giant sequoia crowns. Natural fires may also be important in keeping carpenter ants in check.
In 1970, the National Park Service began controlled burns of its groves to correct these problems. Current policies also allow natural fires to burn. One of these untamed burns severely damaged the second-largest tree in the world, the Washington tree, in September 2003, 45 days after the fire started. This damage made it unable to withstand the snowstorm of January 2005, leading to the collapse of over half the trunk.
In addition to fire, two animal agents also assist giant sequoia seed release. The more significant of the two is a longhorn beetle (Phymatodes nitidus) that lays eggs on the cones, into which the larvae then bore holes. This cuts the vascular water supply to the cone scales, allowing the cones to dry and open for the seeds to fall. Cones damaged by the beetles during the summer will slowly open over the next several months. Some research indicates many cones, particularly higher in the crowns, may need to be partially dried by beetle damage before fire can fully open them. The other agent is the Douglas squirrel (Tamiasciurus douglasi) that gnaws on the fleshy green scales of younger cones. The squirrels are active year round, and some seeds are dislodged and dropped as the cone is eaten.
Discovery and naming
The giant sequoia was well known to Native American tribes living in its area. Native American names for the species include wawona, toos-pung-ish and hea-mi-withic, the latter two in the language of the Tule River Tribe.
The first reference to the giant sequoia by Europeans is in 1833, in the diary of the explorer J. K. Leonard; the reference does not mention any locality, but his route would have taken him through the Calaveras Grove. This discovery was not publicized. The next European to see the species was John M. Wooster, who carved his initials in the bark of the 'Hercules' tree in the Calaveras Grove in 1850; again, this received no publicity. Much more publicity was given to the "discovery" by Augustus T. Dowd of the Calaveras Grove in 1852, and this is commonly cited as the species' discovery. The tree found by Dowd, christened the 'Discovery Tree', was felled in 1853.
The first scientific naming of the species was by John Lindley in December 1853, who named it Wellingtonia gigantea, without realizing this was an invalid name under the botanical code as the name Wellingtonia had already been used earlier for another unrelated plant (Wellingtonia arnottiana in the family Sabiaceae). The name "Wellingtonia" has persisted in England as a common name. The following year, Joseph Decaisne transferred it to the same genus as the coast redwood, naming it Sequoia gigantea, but again this name was invalid, having been applied earlier (in 1847, by Endlicher) to the coast redwood. The name Washingtonia californica was also applied to it by Winslow in 1854, though this too is invalid, belonging to the palm genus Washingtonia.
In 1907, it was placed by Carl Ernst Otto Kuntze in the otherwise fossil genus Steinhauera, but doubt as to whether the giant sequoia is related to the fossil originally so named makes this name invalid.
The nomenclatural oversights were finally corrected in 1939 by J. Buchholz, who also pointed out the giant sequoia is distinct from the coast redwood at the genus level and coined the name Sequoiadendron giganteum for it.
John Muir wrote of the species in about 1870:
"Do behold the King in his glory, King Sequoia! Behold! Behold! seems all I can say. Some time ago I left all for Sequoia and have been and am at his feet, fasting and praying for light, for is he not the greatest light in the woods, in the world? Where are such columns of sunshine, tangible, accessible, terrestrialized?' 
Wood from mature giant sequoias is highly resistant to decay, but due to being fibrous and brittle, it is generally unsuitable for construction. From the 1880s through the 1920s, logging took place in many groves in spite of marginal commercial returns. Due to their weight and brittleness, trees would often shatter when they hit the ground, wasting much of the wood. Loggers attempted to cushion the impact by digging trenches and filling them with branches. Still, as little as 50% of the timber is estimated to have made it from groves to the mill. The wood was used mainly for shingles and fence posts, or even for matchsticks.
Pictures of the once majestic trees broken and abandoned in formerly pristine groves, and the thought of the giants put to such modest use, spurred the public outcry that caused most of the groves to be preserved as protected land. The public can visit an example of 1880s clear-cutting at Big Stump Grove near General Grant Grove. As late as the 1980s, some immature trees were logged in Sequoia National Forest, publicity of which helped lead to the creation of Giant Sequoia National Monument.
The wood from immature trees is less brittle, with recent tests on young plantation-grown trees showing it similar to coast redwood wood in quality. This is resulting in some interest in cultivating giant sequoia as a very high-yielding timber crop tree, both in California and also in parts of western Europe, where it may grow more efficiently than coast redwoods. In the northwest United States, some entrepreneurs have also begun growing giant sequoias for Christmas trees. Besides these attempts at tree farming, the principal economic uses for giant sequoia today are tourism and horticulture.
Giant sequoia is a very popular ornamental tree in many areas. It is successfully grown in most of western and southern Europe, the Pacific Northwest of North America north to southwest British Columbia, the southern United States, southeast Australia, New Zealand and central-southern Chile. It is also grown, though less successfully, in parts of eastern North America.
Trees can withstand temperatures of −31 °C (−25 °F) or colder for short periods of time, provided the ground around the roots is insulated with either heavy snow or mulch. Outside its natural range, the foliage can suffer from damaging windburn.
The giant sequoia was brought into cultivation in 1853 by Scotsman John D. Matthew, who collected a small quantity of seed in the Calaveras Grove,and took it home to his noted Horticulturist father Patrick Matthew of Gourdiehill near Errol in Perth Shire arriving with it in Scotland in August 1853. A much larger shipment of seed collected (also in the Calaveras Grove) by William Lobb, acting for the Veitch Nursery at Budlake near Exeter, arrived in England in December 1853; seed from this batch was widely distributed throughout Europe.
Growth in Britain is very fast, with the tallest tree, at Benmore in southwest Scotland, reaching 56.4 m (185 ft)in 2014 at age 150 years, and several others from 50–53 m (164–174 ft) tall; the stoutest is around 12 m (39 ft) in girth and 4 m (13 ft) in diameter, in Perthshire. The Royal Botanic Gardens at Kew in London also contains a large specimen. The General Sherman of California has a volume of 1,489 m3 (52,600 cu ft); by way of comparison, the largest giant sequoias in Great Britain have volumes no greater than 90–100 m3 (3,200–3,500 cu ft), one example being the 90 m3 (3,200 cu ft) specimen in the New Forest.
Numerous giant sequoia were planted in Italy from 1860 through 1905. Several regions contain specimens that range from 40 to 48 metres (131 to 157 ft) in height. The largest tree is in Roccavione, in the Piedmont, with a basal circumference of 16 metres (52 ft). One notable tree survived a 200-metre (660 ft) tall flood wave in 1963 that was caused by a landslide at Vajont Dam. There are numerous giant sequoia in parks and reserves.
Growth rates in some areas of Europe are remarkable. One young tree in Italy reached 22 m (72 ft) tall and 88 cm (2.89 ft) trunk diameter in 17 years (Mitchell, 1972). The tallest specimen measured in France is a tree near Ribeauvillé in France, at a height of 56.3 m (185 ft).
Growth further northeast in Europe is limited by winter cold. In Denmark, where extreme winters can reach −32 °C (−26 °F), the largest tree was 35 m (115 ft) tall and 1.7 m (5.6 ft) diameter in 1976 and is bigger today. One in Poland has purportedly survived temperatures down to −37 °C (−35 °F) with heavy snow cover.
United States and Canada
Giant sequoias are grown successfully in the Pacific Northwest and southern US, and less successfully in eastern North America. Giant sequoia cultivation is very successful in the Pacific Northwest from western Oregon north to southwest British Columbia, with fast growth rates. In Washington and Oregon, it is common to find giant sequoias that have been successfully planted in both urban and rural areas. In the Seattle area, large specimens (over 90 feet) are fairly common and exist in several city parks and many private yards (especially east Seattle including Capitol Hill, Washington Park, & Leschi/Madrona).
In the northeastern US there has been some limited success in growing the species, but growth is much slower there, and it is prone to Cercospora and Kabatina fungal diseases due to the hot, humid summer climate there. A tree at Blithewold Gardens, in Bristol, Rhode Island is reported to be 27 metres (89 ft) tall, reportedly the tallest in the New England states. The tree at the Tyler Arboretum in Delaware County, Pennsylvania at 29.1 metres (95 ft) may be the tallest in the northeast. Specimens also grow in the Arnold Arboretum in Boston, Massachusetts (planted 1972, 18 m tall in 1998), at Longwood Gardens near Wilmington, Delaware, in the New Jersey State Botanical Garden at Skylands in Ringwood State Park, Ringwood, New Jersey, and in the Finger Lakes region of New York. Private plantings of giant sequoias around the Middle Atlantic States are not uncommon. Since 2000, a small amateur experimental planting has been underway in the Lake Champlain valley of Vermont at the Vermont Experimental Cold-Hardy Cactus Garden where winter temperatures can reach −37 °C with variable snowcover. A few trees have been established in Colorado as well. Additionally, numerous sequoias have been planted with success in the state of Michigan.
A cold-tolerant cultivar 'Hazel Smith' selected in about 1960 is proving more successful in the northeastern US. This clone was the sole survivor of several hundred seedlings grown at a nursery in New Jersey.
The Ballarat Botanical Gardens contain a significant collection, many of them about 150 years old. Jubilee Park and the Hepburn Mineral Springs Reserve in Daylesford, Cook Park in Orange, New South Wales and Carisbrook's Deep Creek park in Victoria both have specimens. Jamieson Township in the Victorian high country has 2 specimens which were planted in the early 1860s. In Tasmania specimens are to be seen in private and public gardens, as they were popular in the mid Victorian era. The Westbury Village Green has mature specimens with more in Deloraine. The Tasmanian Arboretum contains young wild collected material. The National Arboretum Canberra has begun a grove. They also grow in the abandoned arboretum at Mount Banda Banda in New South Wales.
Several impressive specimens of Sequoiadendron giganteum can be found in the South Island of New Zealand. Notable examples include a set of trees in a public park of Picton, as well as robust specimens in the public and botanical parks of Queenstown. There is also a tree at Rangiora High School, which was planted for Queen Victoria's Golden Jubilee and is thus over 125 years old.
Largest by trunk volume
Some sequoias, such as the Mother of the Forest, were undoubtedly far larger than any living tree today. However, as of 2009, the top ten largest giant sequoias sorted by volume of their trunks are:[note 1]
|Rank||Tree Name||Grove||Height||Girth at ground||Volume|
|1||General Sherman||Giant Forest||274.9||83.8||102.6||31.3||52,508||1,486.9|
|2[note 2]||General Grant||General Grant Grove||268.1||81.7||107.5||32.8||46,608||1,319.8[note 2]|
|3[note 2]||President||Giant Forest||240.9||73.4||93.0||28.3||45,148||1,278.4[note 2]|
|5||Stagg||Alder Creek Grove||243.0||74.1||109.0||33.2||42,557||1,205.1|
|7||Genesis||Mountain Home Grove||253.0||77.1||85.3||26.0||41,897||1,186.4|
|9||King Arthur||Garfield Grove||270.3||82.4||104.2||31.8||40,656||1,151.2|
- The General Sherman tree is estimated to weigh about 2100 tonnes.
- The Washington Tree was previously arguably the second largest tree with a volume of 47,850 cubic feet (1,355 m3) (although the upper half of its trunk was hollow, making the calculated volume debatable), but after losing the hollow upper half of its trunk in January 2005 following a fire, it is no longer of great size.
- Waterfall Tree - Alder Creek Grove - 47 metres (155 ft) - tree with enormous basal buttress on very steep ground.
Greatest base diameter
- Waterfall Tree - Alder Creek Grove - 21 metres (69 ft) - tree with enormous basal buttress on very steep ground.
- Tunnel Tree - Atwell Mill Grove - 17 metres (57 ft) - tree with a huge flared base that has burned all the way through.
Greatest mean diameter at breast height
- 0.9 metres (3 ft) or more
- List of giant sequoia groves
- Metasequoia glyptostroboides - Dawn Redwood
- Mother of the Forest
- Old growth forest
- Sequoia sempervirens - Coast Redwood or California Redwood
- The House (trees)
- List of superlative trees
- The volume figures have a low degree of accuracy (at best about ±14 cubic metres or 490 cubic feet), due to difficulties in measurement; stem diameter measurements are taken at a few set heights up the trunk, and assume that the trunk is circular in cross-section, and that taper between measurement points is even. The volume measurements also do not take cavities into account. The measurements are trunk-only, and do not include the volume of wood in the branches or roots.
- This table presents giant sequoias sorted by the volume of their trunks. In December 2012, Stephen Sillett announced a measurement of the President tree with a total of 54,000 cubic feet (1,500 m3) of wood and 9,000 cubic feet (250 m3) of wood in the branches. Ranked according to the total amount of wood in the tree, the General Sherman tree is first, the President tree is second, and the General Grant tree is third. General Sherman has 2,000 cubic feet (57 m3) more wood than the President tree.
- Schmid, R. & Farjon, A. 2013. Sequoiadendron giganteum. In: IUCN 2013. IUCN Red List of Threatened Species. Version 2013.1. <www.iucnredlist.org>. Downloaded on 13 July 2013.
- Sierra Nevada - The Naturalist's Companion. University of California Press. 1 June 2000. p. 55. ISBN 978-0-520-92549-6.
- Flint 2002
- water pull at Cropsview (an agriculture science magazine) website
- Studies on tree height limits, and the Sequoia in particular
- National Geographic Magazine December 2012
- Hartesveldt, RJ; Harvey, HT (1967). "The Fire Ecology of Sequoia Regeneration". Tall Timbers Fire Ecology Conference 7: 7.
- Farquhar, Francis P. (1925). "Discovery of the Sierra Nevada". California Historical Society Quarterly 4 (1): 3–58. doi:10.2307/25177743., Yosemite.ca.us
- Ornduff, R. (1994). "A Botanist's View of the Big Tree". In Aune, P. S. Proceedings of the Symposium on Giant Sequoias. US Dept. of Agriculture Forest Service (Pacific Southwest Research Station). General Technical Report PSW-GTR-151.
- Buchholz, J. T. (1939). "The Generic Segregation of the Sequoias". American Journal of Botany 26 (7): 535–538. doi:10.2307/2436578. JSTOR 2436578.
- Muir, John (November 1996). Gifford, Terry, ed. John Muir: His Life and Letters and Other Writings. Mountaineers Books. pp. 139–140. ISBN 0898864631.
- "Species Level Browse Results". NurseryGuide.com. Archived from the original on 2012-07-07.
- "The History of Cluny – The Plant Collectors". clunyhousegardens.com. Retrieved 23 December 2008.
- Christopher J. Earle. "Sequoiadendron giganteum (Lindley) Buchholz 1939". University of Hamburg. Retrieved 23 December 2008.
- Tree Register of the British Isles, tree-register.org
- "Top Trunks". Redwood World. Retrieved September 19, 2013.
- "Sequoie d'Italia". Retrieved January 22, 2014.
- "Giant sequoia in the forêt domaniale de Ribeauvillé". monumentaltrees.com. Retrieved September 18, 2013.
- Die Wiedereinführung des Mammutbaumes (Sequoiadendron giganteum) in die deutsche Forstwirtschaft. In: Mitteilungen der Deutschen Dendrologischen Gesellschaft. Vol. 75. pp. 57–75. Ulmer. Stuttgart 1984, ISBN 3-8001-8308-0
- Puzović, B. (August 15, 2011). "Lazarevac: Visoke sekvoje niču iz uglja" (in Serbian). Novosti.rs. Retrieved September 17, 2013.
- "Mansion and History". Blithewold Mansion, Gardens, and Arboretum.
- "Gardens". Blithewold Mansion, Gardens, and Arboretum.
- Big Trees Of Pennsylvania: Sequoiadendron - Giant Sequoia, pabigtrees.com
- "Colorado giant sequoia". giant-sequoia.com.
- Michigan giant sequoia - Giant Sequoia
- Jamieson & District Historical Society
- Rangiora High School | History
- Cone, Tracie (2012-12-01). "Upon further review, giant sequoia tops a neighbor". Associated Press.
- Quammen, David. "Giant Sequioas". National Geographic.
- Fry & White 1938
- Conifer Specialist Group (1998). Sequoiadendron giganteum. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006. Listed as Vulnerable (VU A1cd v2.3)
- Aune, P. S., ed. (1994). Proceedings of the Symposium on Giant Sequoias. US Dept. of Agriculture Forest Service (Pacific Southwest Research Station). General Technical Report PSW-GTR-151.
- Flint, W.D. (2002). To Find The Biggest Tree. Sequoia Natural History Association, Inc. ISBN 1-878441-09-4.
- Mitchell, Alan (1972). Conifers in the British Isles. HMSO. Forestry Commission Booklet 33.
- Mitchell, Alan (1996). Alan Mitchell's Trees of Britain. HarperCollins. ISBN 0-00-219972-6.
- Harvey, H. T.; Shellhammer, H. S.; Stecker, R. E. (1980). Giant sequoia ecology. Scientific Monograph Series 12. Washington, DC: U.S. National Park Service.
- Kilgore, B. (1970). "Restoring Fire to the Sequoias". National Parks and Conservation Magazine 44 (277): 16–22.
- Zsolt Debreczy, Istvan Racz (2012). Kathy Musial, ed. Conifers Around the World (1st ed.). DendroPress. p. 1089. ISBN 9632190610.
Redwood, including Sequoiadendron giganteum and Sequoia sempervirens , is the state tree of California.
Names and Taxonomy
Sequoiadendron giganteum (Lindl.) Buchholz [26,28]. There are no
recognized subspecies, varieties, or forms.
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