Sequoia sempervirens

redwood

Cupressaceae

The Basics

Taxonomy: Kingdom - Plantae (plants). Subkingdom - Tracheobionta (vascular plants). Superdivision - Spermatophyta (seed plants). Division - Coniferophyta (conifers). Class - Pinopsida Order - Pinales Family - Cupressaceae (cypress family). Genus - Sequoia Endl. (redwood ). Species - Sequoia sempervirens (Lamb. ex D. Don) Endl. (redwood).

Ecology: Redwood is a native, evergreen, long-lived (greater than 2,200 years), monoecious tree. Redwoods are among the world's tallest trees; trees over 61 m are common, and many are ove 91 m. The largest tree thus far was measured at 110.3 m in height and 6.1 m in d.b.h. The root system is composed of deep, widespreading lateral roots with no taproot. The bark is up to 30 cm thick and quite fibrous. Redwood self-prunes well in dense stands; the base of the bole is strongly buttressed.

Redwood is endemic to the coastal area of northern California and southwestern Oregon. Redwood is one of California's most valuable timber species. The wood is soft, weak, easily split, and very resistant to decay. The redwoods occupy a narrow strip of land approximately 724 km in length and 8-56 km in width.Redwood occurs in a maritime Mediterranean climate, where the winters are cool and rainy, and the summers are dry. The dry summers are mitigated by a heavy fog belt. The fog reduces the drought stress of this hydrophilic plant by reducing evapotranspiration and adding soil moisture.

Redwood is classified as a shade-tolerant to very shade-tolerant species due to its high photosynthetic capacity at low light levels. There is some debate over the classification of redwood as a climax species. Some consider redwood a climax species, while others consider it a fire-dependent seral species. After disturbance redwood dominates in early seres due to its ability to sprout.

Redwood is long lived, grows taller than any other tree species in the world, and is exceeded in bulk only by the giant sequoia. Redwoods are sexually mature at 10 years or less but continue to increase in volume for centuries. Under some conditions, redwood can endure suppression almost indefinitely. A 25-cm suppressed tree might be more than 100 years old. Small trees may be suppressed for more than 400 years but still maintain a remarkable capacity to accelerate growth rates when released if they have not been crowded too closely and are not injured seriously during logging or slash burning. Large trees also can accelerate growth when released from competition.

Identification

This imposing conifer is densely branched and gracefully pyramidal in youth; with time losing the lower branches to 50-100 ft. from the ground. It retains a relatively narrow, pyramidal crown. Fibrous bark is exquisite, red-brown in color and the needles are dark-green through the seasons. Redwood grows to 300 ft. The world’s tallest tree, with reddish-brown trunk much enlarged and buttressed at base and often with rounded swellings or burls and slightly tapering; crown short, narrow, irregular and open with horizontal or drooping branches.

The world’s tallest tree is a Redwood 368 (112 m) high. The age of these trees at maturity is 400-500 years; the maximum age counted in annual rings is 2200. Circles of trees grow from sprouts around stumps and dead trunks.

Threats

Fire effects: Fire is the principal damaging agent in both young-growth and old-growth stands. The above-ground portions of young stands may be killed outright by a single ground fire, but the stands sprout and reoccupy the site. Fires are especially damaging to trees less than 20 years old because their thin bark does not protect them. The thick bark; great height; and ability to sprout from the root crown or from dormant buds located under the bark of the bole and branches are adaptations that allow redwood to survive cool to hot fires. After fires that destroy all aboveground portions, both mature and young redwoods will sprout from the root crown; even seedlings have the ability to sprout after top-kill.

Several insects are found on redwood but none cause significant damage. Most common heart rot in the southern part of the range of redwood is a brown cubical rot, caused by Poria sequoiae. Most significant farther north is a white ring rot caused by P. albipellucida... Bark stripping by the American black bear has caused serious damage in some parts of the redwood region.

Reproduction

Flowering and Fruiting - Redwood is monoecious; inconspicuous male and female flowers are borne separately on different branches of the same tree. The ovulate conelets grow into broadly oblong cones...Redwood cones are terminal and are 13 to 29 mm long. They mature in autumn of the first year after flowering and are open from early September until late December. Although cones persist for several months, they open and shed seeds soon after ripening.

Seed Production and Dissemination - Redwoods start to bear seeds when 5 to 15 years old...Redwood seeds are small and light, number about 265,000/kg, but lack efficient wings to slow them in falling. They fall at rates between 1.5 and 6.2 m/s, averaging 2.6 m/s. These rates are faster than for most other wind-disseminated forest seeds and limit seed dispersal considerably.

One study showed that seed viability increased with the age of parent trees. Maximum seed viability was reached when trees were more than 250 years old. Seeds produced by trees younger than 20 years generally were less than 1 percent viable, and seeds from trees more than 1,200 years old were not more than 3 percent viable...The germination rate of redwood seeds is usually low. Poor germination often results from a low percentage of sound seeds (less than 15 percent) rather than from dormancy.

Seedling Development - In its early stages, redwood grows rapidly in height. Seedlings often grow about 46 cm in the first season and trees 4 to 10 years old sometimes grow 0.6 to 2.0 m in a year...Juvenile growth of redwood is best in full sunlight. Although redwood seedlings can endure heavy shade, growth there is slow.

Vegetative Reproduction - Redwood can sprout from stumps and root crowns anytime of the year. Numerous and vigorous sprouts originate from both dormant and adventitious buds within 2 to 3 weeks after logging. Sprouting capacity is related to variables associated with tree size or age. Stumps of small young trees sprout more readily than those of large old trees. Stumps often are circled by more than 100 sprouts...Sprouting by redwood is principally from root crowns, but sprouts sometimes grow from the sides and tops of stumps...Redwood can also sprout along almost the entire length of its trunk. If the crown of a tree is destroyed by fire or mechanically damaged, or the stem is suddenly exposed to light, numerous dormant buds along the trunk are stimulated and produce new foliage.

Species Distribution

Citation

USDA Plant Database
USDA, NRCS. 2016. The PLANTS Database (http://plants.usda.gov, 4 February 2016). National Plant Data Team, Greensboro, NC 27401-4901 USA.

Flora of North America
Flora of North America Editorial Committee, eds.  1993+.  Flora of North America North of Mexico.  19+ vols.  New York and Oxford.

Silvics of North America
Burns, R.M., and B.H. Honkala. 1990. Silvics of North America (Volume 1: Conifers). USDA Forest Service Agricultural Handbook 654.

Intermountain Herbarium
Consortium of Intermountain Herbaria. 2016. http//:intermountainbiota.org/portal/index.php. Accessed on February 04.

Jepson Manual
The Jepson Manual: Vascular Plants of California. B.G. Baldwin, D.H. Goldman, D.J. Keil, R. Patterson, T.J. Rosatti, and D.H. Wilken [editors]. 2012. 2nd edition, thoroughly revised and expanded. University of California Press, Berkeley, CA. $131.95, hardcover; 1600 pages. ISBN-13: 978-0520253124.

USGS Plant Species Range Maps
Critchfield, W.B., and Little, E.L., Jr., 1966, Geographic distribution of the pines of the world: U.S. Department of Agriculture Miscellaneous Publication 991, p. 1-97.
Little, E.L., Jr., 1971-1978, Atlas of United States trees, volume 1,3,13,17, conifers and important hardwoods: U.S. Department of Agriculture Miscellaneous Publications.