The Coast Redwood or California Redwood (Sequoia sempervirens) is an evergreen, long-lived, monoecious tree in the family Cupressaceae. It is the tallest tree in the world, reaching up to 112 m in height, and 7 m diameter at the base. The crown is conical, with horizontal to slightly drooping branches. The bark is very thick, soft and a bright red-brown when freshly exposed (whence the name 'redwood'), weathering darker. The leaves are variable, being 15-25 mm long and flat on young trees and shaded shoots in the lower crown of old trees, and scale-like, 5-10 mm long on shoots in full sun in the upper crown of older trees; there is a full range of transition between the two extremes. They are dark green above, and with two blue-white stomatal bands below. Leaf arrangement is spiral, but the larger shade leaves are twisted at the base to lie in a flat plane for maximum light capture. The cones are ovoid, 15-32 mm long, with 15-25 spirally arranged scales; they mature about 8-9 months after pollination in late winter. Each cone scale bears 3-7 seeds, each seed 3-4 mm long and 0.5 mm broad, with two wings 1 mm wide. The seeds are released when the cone scales dry out and open at maturity.
The oldest known Coast Redwood is about 2200 years old; many others in the wild exceed 600 years of age. It is one of three species of trees known as redwoods.
Trees over 60 m (200 feet) are common, and many are over 90 m (300 feet).
- The tallest is the "Stratosphere Giant" in the Humboldt Redwoods State Park, at 112.56 metres (369 feet 4 inches), last measured in 2002 (was 112.34 m in Aug 2000).
- There are 15 known living trees more than 110 m (361 feet) tall.
- There are 47 trees that are more than 105 m (344.5 feet) tall.
- A tree thought to be 115.8 m (380 feet) was cut down in 1912.
- The tallest non-redwood tree is a 100.3 m (329 foot) tall Douglas-fir.
In 2004, an article in Nature reported that the theoretical maximum potential height of Coast Redwoods (or any other tree) is limited to between 122-130 m (400-425 feet), due to gravity and the friction between water and the vessels through which it flows.
Among current living trees only 15 Giant Sequoias are larger; these are less tall, but have thicker trunks. The largest living redwood has a volume of 1,037 cubic metres (36,620 cubic feet), compared to the largest Giant Sequoia with a volume of 1,487 cubic metres (52,510 cubic feet). A redwood cut down in 1926 had a claimed volume of 1,794 cubic metres (63,350 cubic feet), but this is not verified.
The Coast Redwood root system is composed of deep, widespreading lateral roots with no taproot. The bark is up to 30 cm (12 inches) thick and quite fibrous. This thick, tannin-rich bark, combined with foliage that starts high above the ground provides good protection from both fire and insect damage, contributing to the Coast Redwood's longevity.
Coast Redwood reproduces both sexually and asexually. Seed production begins at 10-15 years of age, and large seed crops occur frequently, but viability of the seed is low, typically around 20%. The low viability may be an adaptation to discourage seed predators, which do not want to waste time sorting chaff (empty seeds) from edible seeds. The winged seeds are small and light, weighing 3.3-5 mg (200-300 seeds/g; 5600-8500/ounce). The wings are not effective for wide dispersal, and seeds are dispersed by wind an average of only 60-120 m (200-400 feet) from the parent tree. Coast Redwoods can reproduce asexually by layering or sprouting from the root crown or stump. Sprouts orginate from dormant or adventitious buds at or under the surface of the bark. They develop all round the circumference of a cut stump, but tend to be most numerous on the downhill side of the stump. Within a short period after sprouting each sprout will develop its own root system, with the dominant sprouts forming a ring of trees around the parent root crown. Sprouts can achieve heights of 2.3 m (8 feet) in a single growing season.
Range and ecology
Coast Redwood, Redwood National Park
Coast Redwoods occupy a narrow strip of land approximately 750 km (470 miles) in length and 8-75 km (5-47 miles) in width along the Pacific coast. The northern boundary of its range is marked by two groves on the Chetco River on the western fringe of the Klamath Mountains, 25 km (15 miles) north of the California-Oregon border. The largest populations are in Jedediah Smith Redwoods State Park (Del Norte County), Redwood National Park and Humboldt Redwoods State Park (Humboldt County). The furthest inland are 75 km from the sea, in Napa County. The southern boundary of the range is marked by a grove in Salmon Creek Canyon in the Santa Lucia Mountains of southern Monterey County.
This native area provides a unique environment with heavy seasonal rains (2500 mm or 100 in annually), cool coastal air and fog keeping this forest constantly damp year round. As this heavy rain has left the soil with few nutrients, these trees depend on the entire biotic community of the forest, and complete recycling of the trees when dead. Logging interrupts this process. This forest community includes Douglas-fir, Western Hemlock, Tanoak, Madrone, and other trees along with a wide varieity of ferns, Redwood sorrel, mosses and mushrooms. Redwood forests provide habitat for a variety of mammals, birds, reptiles, and amphibians. Remnant old growth redwood stands provide habitat for the federally threatened Spotted Owl and the California-endangered Marbled Murrelet.
Coast Redwood is one of California's most valuable timber species. The wood is soft, weak, easily split, and very resistant to decay. The clear wood is used for dimension stock, siding, fencing, and shingles. Redwood burls are used in the production of table tops, veneers, and turned goods.
- Gymnosperm Database - Sequoia sempervirens (http://www.botanik.uni-bonn.de/conifers/cu/se/index.htm)
- US National Park Service (http://www.nps.gov/redw/trees.html)
- US Forest Service Fire Effects Database (http://www.fs.fed.us/database/feis/plants/tree/seqsem/index.html)
- Reed F. Noss (editor), The Redwood Forest: history, ecology and conservation of the Coast Redwood (ISBN 1-55963-726-9)