RedwoodIntro.pdf

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Youth Education Programof San Francisco Botanical Garden Society

Redwood Trail

Introduction to Redwoods

THE ENDURING GIANTS

The beauty, majestic size, and survival power of the redwoods have long inspired poets

and artists, and delighted people who love natural beauty. Redwoods are the world’s

largest living things, and live to be among the oldest as well. Trees can tower over

35-story buildings and weigh as much as 800 buses! Living for centuries, some trees

standing in California right now were tiny seedlings when the Egyptians ruled, and were

already grown trees when George Washington became president. As redwoods evolved

over the centuries to adapt to life in a changing world, they developed the ability to resist

fire, disease, and pests, and to alter their own environment. The story behind these

beautiful living treasures is as remarkable as the trees themselves.

LIVING FOSSILS

Redwoods are a living link to our past, for the history of this ancient race of trees began

over 160 million years ago. When dinosaurs roamed the land, most of the northern half

of the planet was covered with lush redwood forests. These primeval forests flourished for

millenia until gradual changes in the climate left the land covered with sheets of ice. Of

the dozens of species of redwoods that once grew, the three species we’ll explore in our

walks are those that survived the cold of the glacial age - the coast redwood, the giant

sequoia, and the dawn redwood. Today redwood forests cover less than 1% of their

original range, growing naturally only along a narrow strip of land on the coasts of

California and Oregon, on the western slopes of the Sierra Nevada, and in one remote

valley in China.

Even confined to this small territory the redwoods played an important role in the history

of California. For centuries only the Indians knew of the vast coastal redwood forests.

They respected and worshipped the trees and used the wood in many ways. Bark and

root were shredded and used for clothing and baskets. Tree trunks were split and used

for dwellings and sweathouses, and large logs were hollowed out and fashioned intocanoes.

When the first European explorers arrived the sailors used the enormous redwoods

growing around the San Francisco bay as landmarks to guide them. A group of Spanish

explorers led by Don Gaspar de Portola were the first to describe and document the

magnificent redwood forests in 1769. Awed by the size and beauty of the trees they



Redwood TrailIntroduction to Redwoods

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named them “palos colorados” – the red tree. In 1874, the redwoods were given their

official Latin name, Sequoia sempervirens – ‘Sequoia’ from the name of the Cherokee

Indian who created a written language for his people (Sequoya), and ‘sempervirens’

meaning ever-green.

As the Spanish moved into California they used the redwood trees to build their missions.But surprisingly, the first Europeans to extensively log and use the redwoods were Russian

trappers who came to the northern coast of California in the early 1800’s to hunt for

otter. They settled at the mouth of the Russian River and built a fort, now named Fort

Ross. At 160 years old, this fort is the oldest wooden building in the West and a

testament to the durability of the redwood.

Gradually other Europeans arrived in California. As settlers, traders, and gold miners

began to build their homes in California and the demand for lumber soared. With its

beauty, strength, and durability the wood of the redwood was in great demand. Mills to

log the redwood forests and railroads to transport the lumber sprang up all along the

coast and a new industry was born.

The awesome size and cathedral-like stillness of the vast forests gave rise to many myths,

legends, and folktales about the redwoods. The Indians drank the sap of the redwood

hoping to capture some of the redwood’s magical powers of strength and endurance.

Some believed that the redwoods were strong warriors turned into trees. European

settlers believed that gnomes made the redwoods their homes as they helped to care for

the creatures of the forest. Lumbermen told tales about Paul Bunyan’s visit to the

redwoods and his adventures clearing land for settlers.

THE FAMILY OF REDWOODS

Taxonomically speaking, redwoods form a distinct subfamily within the cypress family,

and the three species include two that are native to California and one which is native to

China.

Coast Redwood (Sequoia sempervirens – “evergreen sequoia”)

The world’s tallest tree, the coast redwood can grow to at least 380 feet – that is over 2

½ times the height of the Statue of Liberty! The oldest known tree has been alive for2,200 years. The coast redwood is found only in the coastal fog belt, a narrow strip of

land about 20 miles wide that extends for 500 miles along the coastal mountains of

central and northern California and southwest Oregon. The San Francisco Bay area is

lucky to have great stands of these living treasures.




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Sequoia (Sequoiadendron giganteum – “giant sequoia”)

Imagine a tree so big that its trunk alone could provide the wood for 40 five-room

houses! While not as tall as the coast redwood, the giant sequoia is the most massive of

all living things. One tree named General Sherman weighs 12 million pounds – the same

as a small steamship. They can grow to be 300 feet tall, and they can live to be anastonishing 3,600 years old. These massive giants grow only in one very small area on

the western slopes of California’s Sierra Nevada mountains. Because their brittle wood

was not suitable for logging, over 90% of these magnificent trees are now protected in

state and federal parks.

Dawn Redwood (Metasequoia glyptostroboides – “akin to sequoia”)

Thought to have been extinct for over 20 million years, the survival of this redwood was a

wonderful surprise for botanists. It was found in 1944 growing only in one very remote

valley in the interior of China. At one time it had been a dominant tree in the northernhemisphere. This smaller cousin of the redwoods grows to at least 150 feet and may live

to be about 600 years old. Unlike the other redwoods this lovely tree is deciduous, losing

its needle-like leaves each fall. While it still grows naturally only in its secluded valley in

China, these trees have been successfully cultivated in gardens in many countries around

the world.

THE REALM OF THE COAST REDWOOD

Coast redwoods are strong and hardy trees, but they do need a special type of climate to

survive and grow. They need a lot of moisture all year-round and protection from strongwinds. California’s coastal range provides a perfect habitat with its mild temperatures,

heavy rains and cooling fog.

Coast redwood are very thirsty trees and need from 40” to 100” of rain a year. More

than half of the redwood’s massive weight is water. They can hold more water in their

trunks than any other tree – as much as 8,000 gallons of water! When the rainy season

stops, fog provides them with the moisture they need and slows the evaporation of water

from their leaves. These amazing trees comb moisture from the air as fog droplets

condense onto their needles and drip to the ground, adding literally feet of annual

precipitation in some cases.

Given good soil, sunlight, and the right amount of moisture redwoods can grow 200 feet

in less than a century.




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SURVIVAL OF THE FITTEST

Each part of a coast redwood tree reveals a special trait or characteristic that enables it to

survive. For example, the beautiful red bark of the redwood protects the tree in many

ways. The soft, fibrous bark grows up to a foot thick, providing insulation that shields the

tree from fire. In addition, the bark and wood contain very little of the resins that makeother trees so flammable. Even coast redwoods that have been partly burned have a

remarkable ability to survive and heal over their scars. Another important adaptation is a

strong, acidic chemical in the bark and wood of the tree called tannin. It is the tannin that

gives the redwood its beautiful reddish color and helps it resist disease, fungus, and

insects.

For such enormous trees you might imagine that the roots must grow down for miles. But

surprisingly, the coast redwood’s roots extend no deeper than the height of an average

man! Their shallow root system only grows from 6 to 8 feet deep to take advantage of

the water available near the soil’s surface, but the roots extend outward as much as 100

feet. Since redwoods don’t have a long, deep taproot like other trees, balance is critical.

Strong winds are a dangerous enemy and a winter storm can topple the tallest giants. If

a tree begins to lean, it can balance itself by growing heavy limbs to pull the weight back

and by forming more wood on the side that leans to brace itself.

The leaves of the coast redwood are also wonderfully adapted for survival. Like other

trees, the leaves of the redwood manufacture food for the tree through photosynthesis.

But they are also specially adapted to catch moisture from rain and fog, and to release

moisture from their undersides and drip it down onto the roots. At the top of the tree theneedles grow flat along the stem, but on the parts of the tree that grow in shade the

needles open in broad sprays so that they can catch more light. Each spray of needles is

divided into sections, with each section representing one year’s growth. Long segments

indicate a good growing season for the tree, while short segments indicate a dry year

with less growth.

Another important adaptation that helps the coast redwood to survive is its ability to

reproduce in two ways, by seed and by sprouting.

It is hard to believe but a redwood can grow from a tiny seed weighing 1/800th

of anounce – less than a small feather! The seeds are held in small cones that can hold from

50 to 150 seeds. Each tree grows both male and female cones. Pollen grains from the

male cones drift down to fertilize the seeds in the female cones, and the seeds begin to

grow. When they are mature, billions of seeds are released from the cones each autumn.

These tiny seeds must find exposed soil and a patch of sunlight, and must be able to




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survive insects, animals, fire, and flood if they are to grow. Fewer than one in a million

seeds survive to become a mature redwood.

Since so few seeds survive, the coast redwood’s ability to sprout is its primary means of

reproduction. New redwood trees sprout from fallen trees, from stumps, and from the

bases of living trees. Even when a tree falls or is destroyed by fire its life doesn’t end.Sprouts emerge from the stump, from the old root system, and from gnarled masses of

dormant buds called burls. In redwood forests you will often see “fairy circles” – a circle

of trees which began as young sprouts rising from the base of a tree that no longer

stands. New forest plants often take root in the stumps of fallen redwood trees where the

old wood provides moisture and nutrients. While redwood sprouts must still compete for

sunlight and moisture, they are usually more successful than seeds because they are

growing from an already developed root system.

RECIPE FOR A REDWOOD FOREST

Every coast redwood forest supports a great variety of life. Coast redwoods are only one

part of a community of plants and animals that rely on each other for survival. If you look

closely, you can see that a redwood forest is really made up of several layers of plants

from the low growing groundcovers to the high canopy formed by the crowns of the

trees. Each layer is home to plants and animals that have adapted to living in the

redwood forest ecosystem – many of them unique to the redwood forest.

Duff – This soft carpet of woody debris and leaf litter covers the forest floor, holds

moisture, and provides homes for animals and insects that break down dead plant and

animal materials, converting it into nutrient rich soil.

Ground cover - Here in the deep soft shade of the forest floor, redwood sorrel and wild

ginger creep along forming lush green carpets. Mushrooms, molds, and fungi grow from

rotting logs. Beautiful wildflowers like columbine, bleeding heart, and trillium grow

amidst clumps of ferns and primitive looking horsetails. Growing near water are skunk

cabbage and colonies of stream orchids. Many of the plants that grow in the shade

beneath the redwoods have developed broad, flat leaves that help them catch as much

sunlight as possible. Snakes, banana slugs, chipmunks and many other tiny creatures

make their homes here.

Shrubs – Many woody plants grow amidst the redwoods, especially where openings in

the forest give them additional light. They offer protection and food for birds and animals

like deer and Steller’s jays. Many of the shrubs produce berries, such as evergreen

huckleberry, thimbleberry, and red elderberry. Others grace the forests with their showy

flowers like the rhododendron and azalea.




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Understory – Here many other trees grow to share the redwood forest. Young redwoods

share the woods with Douglas fir, bigleaf maple, tanbark oak, California bay and coast

hemlock. Many of the trees grow only on the edges of the forest or in large gaps where

redwoods have fallen, where they can find enough sunlight.

Canopy – The top branches and leaves of the redwoods form a canopy high above theforest, shading the forest floor and keeping the redwood roots moist and cool. But this

high zone is home to more than just birds, and in fact, an entire ecosystem has

developed high up in the redwoods, including plants and animals that live and grow on

and among the branches.

THE ENDURING GIANTS

In the 200 years that our ‘modern civilization’ has known about coast redwoods, over

85% of the trees have been logged. After surviving for thousands of years California’s

redwoods were suddenly in danger of disappearing. It wasn’t until 1901 that the firstarea for protected redwoods was set aside. Because of the hard work and efforts of

individuals like John Muir and conservation groups like the Save the Redwoods League,

California now has 31 state redwood parks.

Most of our nation’s redwoods are here in California. Only a tiny percentage of ‘old

growth’ redwood forests remain – forests which have never been logged and so have the

greatest variety of plants and animals and the oldest trees. These old growth forests hold

the secrets of a complex community with the ability to change and survive over long

periods of time. Today the timber industry, environmentalists, and lawmakers are trying

to find a balance between the need for jobs that logging provides and the importance of

preserving these amazing trees.

An Iroquois Indian law says: “In our every deliberation we must consider the impact of

our decision on the next seven generations.” It is up to us to make sure that these

magnificent national treasures are here to inspire future generations, and that there are

places where the cycles and rhythms of the forest remain undisturbed. As we struggle to

deal with this complex issue, perhaps the redwoods can help us learn how to live in

balance with each other and our world.




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Range of Redwoods in California

Coast Redwoods

Giant Sequoias

Crescent City

Fort Bragg

San Francisco

Monterey




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Comparing the Redwoods

100 ft.

200 ft.

300 ft.

400 ft.

Coast Redwood Giant Sequoia Dawn Redwood

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