Got Questions? Dr. Brinegar welcomes your questions about the biology and ecology of the indigenous redwood forest. He regrets that he cannot answer questions about redwoods grown as ornamentals or in non-native habitats, and he advises that questions about disease, pruning or structural damage from redwood roots should be directed to a professional arborist in your local area. E-mail your questions to Dr. Brinegar.

It occurred to me that since Redwoods live so long they are the ideal plant based carbon sink. Where most trees and plants might lock up carbon for 50-100 years redwoods could lock it up for hundreds even thousands of years. On average how much carbon is stored in one mature redwood tree?

Since I can't find a reference that estimates the amount of carbon sequestered in a mature redwood, I've done my own calculation based on the following set of facts:

             • The density of dry old growth redwood is about 28 pounds per cubic foot.
             • The trunk volumes of some of the largest redwoods range from about 26,500 to 35,500 cubic feet.
             • Dry wood is roughly 50% carbon by weight (cellulose and lignin are about 40% and 60% carbon, respectively).

If you do the math based on these figures, youíll find that the mass of carbon in the biggest redwoods averages about 434,000 pounds ñ and that doesnít even take into account the carbon in the branches, needles, and roots. That much carbon is equivalent to nearly 800 tons of carbon dioxide. From fossil fuel consumption, the average American produces about 1600 tons of carbon dioxide during their lifetime. Simply put, each one of you can offset your personal carbon footprint by helping the Sempervirens Fund protect just two redwoods. What a deal!

Summer 2007

Do you know when redwood trees stop growing? Do they ever completely stop growing after a certain number of years?

Redwood trees grow until they die. Even the older redwoods, which exceed 2,200 years, are still growing. However, once they get to be a few hundred years old, their growth slows down significantly and most of the growth is in radial expansion of the trunk. Also, the crowns of old trees are prone to wind and lightning damage, so sometimes the growing tip is knocked off, which further slows vertical growth.

Measuring the age of large standing redwoods is not an easy task, since standard increment borers—devices used to obtain trunk cores for counting annual rings—are not long enough to penetrate to the center of the trunk.

Due to different environmental and growing conditions, you cannot estimate age accurately by measuring height or diameter. Unfortunately, for the biggest trees we have to count the rings after they have fallen over or have been cut down.

Summer 2006

What is the evolutionary history of Sequoia?

The early history of conifers, including the ancestors of modern Sequoia, parallels the evolution of dinosaurs. Their origins and major diversification was during the Mesozoic Era (Triassic, Jurassic and Cretaceous Periods) about 250-65 million years ago. Fossils of extinct genera indicate that a recognizable ancestral form of Sequoia had been established by at least100 million years ago. Species of the genus Sequoia reached their widest global distribution around 50 million years ago (when the middle and higher latitudes of the Northern Hemisphere were warmer than today), with fossils of that age found in North America, Europe, Asia nd even as far north as the Arctic Circle! A cooling and drying trend in global climate led to the loss of Sequoia forests except on the U.S. Pacific coast, where the uplifting of the coastal mountain ranges (about 5 million years ago) created a moist, temperate climate for modern Sequoia sempervirens.

Spring 2006

How can I collect seeds from redwood cones?

Mature redwood cones slowly turn from green to brown as they begin to dry out in the Fall.  Once they are dry enough, the cone scales separate and release the seeds.  The timing of this dispersal can be quite variable, but most seeds are shed between November and February as the winter storms blow through.  To guarantee that you'll get the seeds before they drop out of the cone, pick one before it opens (around December or January) then allow it to desiccate for a few weeks or more in a dry environment until the scales separate enough for you to shake the seeds free.  But if you try to germinate and plant them, please use seeds from local stock in order to grow redwoods that are adapted to this region.

Fall 2005

I've just learned that there are several varieties of Sequoia sempervirens. How many are there and how are they used in reforestation efforts?

There is quite a bit of natural variation in needle color, branch angle, crown shape and growth rate in redwoods. When propagated for commercial use, these natural varieties are called cultivars. Well over 20 such cultivars are available in nurseries. One of the most popular ornamental types is "Aptos Blue", which has deep blue-green foliage and rapid growth. Others, such as Prostrata, are selected for their short mature height. Most reforestation, however, is done using seedlings grown from a seed pool obtained from healthy trees in the same region. This ensures that the new redwoods will be adapted to the local climate and elevation.

Spring 2005

In the Giant Sequoia grove near Wawona in Yosemite, our guide told the group that as redwoods age (in late maturity) they lose some of their height and become wider. Lots of giggles from the group of mostly seniors. Is this indeed true, or was he just putting us on?

Plants display indeterminate growth (which means they don't stop growing until they die), and giant sequoias and coast redwoods are no exceptions. However, once these trees get past a few hundred years of age, their upward growth slows down considerably and most of their increase in mass is due to an increase in trunk diameter via annual rings. Neither giant sequoias nor redwoods actually "shrink" like humans when they age, but the growing tips of very tall trees are sometimes broken by wind or lightning so they can lose some of their height. In a way, your Wawona guide was telling the truth, although he left out a few illuminating facts!

Winter 2005

Is it true redwood trees lose about 1/3 of their foliage each year?

Each branchlet on a redwood tree persists for about 3 years and then is shed in the fall. so what you heard is correct—about 1/3 of all the foliage is shed each year. Especially hot summers can hasten the "browning" effect.

Fall 2004

I know that high levels of tannins help the coast redwoods resist both disease and decay.  Yet tan oak trees in the redwood forest – which also have high levels of tannins -- are often loaded with parasites, and they decompose readily.  What is it besides tannins that explains this difference?

High tannin content can impart disease resistance, but bark thickness also plays a role.  Tan oak bark can be relatively thick in places but it is deeply furrowed and has a tendency to split as the tree ages, leaving the wood exposed or only minimally covered.  The bark of a redwood, although furrowed, can be a foot thick  in older trees and completely covers the wood.  Therefore, tan oaks offer more infection sites for fungi and entry points for wood-boring insects that do not occur so readily in redwoods.  There are probably many other unknown genetic factors that account for their differences in disease and insect resistance.

Summer 2004

How many cones and seeds does a coast redwood tree produce each year?

Cone and seed production in coast redwoods can be extremely variable. Some trees can generate tremendous numbers of seeds while others may not even develop cones in a given year. My research group in the Conservation Genetics Laboratory at San Jose State University is currently conducting a reproductive study on a 70-year-old, 3-foot diameter, 140-foot tall coast redwood in the Soquel Demonstration State Forest which produced over 5,000 female cones this year. We estimate that it produced more than 400,000 seeds. (Mature redwoods have the potential to produce well over 1 million seeds!) Of course, not all redwood seeds are viable and very few, if any, from an individual tree will successfully germinate and grow into mature trees.

I recently found an albino (white) redwood tree in the forest. How common is it?

Albino redwoods are not very common. But in my own hikes through the Santa Cruz Mountains, I've run across a dozen or so of them. Most likely, the albinism is caused by a mutation in one of the genes involved in the production of chlorophyll. The failure to synthesize chlorophyll sometimes results in an off-white, slightly yellowish tissue. In other cases, the tissue is snow white. As far as I know, there are no other conifers that have this albino trait. With your discovery, you are now a trusted member of the "albino redwood club," which means you need to keep the location of the tree a secret. I'm always afraid that someone will want to chop one down for a Christmas tree!

I recently encountered a large redwood tree with a huge bark-covered bulge at the base of the tree. What causes this?

The growth you describe is almost certainly a "burl" or, technically, a "lignotuber." A burl forms at the base of the tree and provides a reservoir of dormant buds that can sprout in the event of major structural damage to the trunk. The burl tissue provides a source of carbohydrates to its growing sprouts and can also generate roots. In California, it's not uncommon to find redwood burl for sale. Unfortunately, most burl is harvested illegally from parks and conservation land causing damage and disfigurement to the trees. Burl is best left in its natural state where it can serve its important role in redwood regeneration. [Editor: Read Dr. Brinegar's essay: About Redwood Burl for more detail.]

I live in (pick any city, state or country). The redwood tree I planted in my yard appears to be dying. Can I do anything to save it?

I have lost count of the number of e-mails I have received on this topic! After seeing groves of majestic coast redwoods and giant sequoias in California's state and national parks, it comes as no surprise that people would want to plant their own. Unfortunately, many attempt to cultivate these trees in climates that are far too extreme. Several inquiries from Oregon and Washington bemoan the browning of the growing tips of their ornamental coast redwoods (too cold). One reader described the poor condition of a giant sequoia she found planted in Kansas (too dry). Californians try to grow coast redwoods too far inland, even in the Central Valley (too hot). Against all odds, one intrepid redwood-lover has managed to grow a relatively healthy tree in his backyard garden in Warsaw, Poland! However, he was only able to do this by warming the root system in the winter. There are a few regions of the world that are hospitable to redwoods, such as parts of New Zealand and Spain because they mimic the temperate, moist, foggy conditions of coastal northern California. But there is no other region in the United States where coast redwoods will grow nearly as well as on the California coast. [Editor: For more on this topic, see Dr. Brinegar's essay: Growing Redwoods in Non-Native Habitats.]

Is there an easy way to tell the difference between a Sequoia sempervirens and a Sequoia gigantea, except for location?

Yes, it is very easy to tell the difference between a coast redwood and a giant sequoia. The leaves on a coast redwood are flat needles (about 1 inch long) arranged in flat "sprays" on the branchlets, whereas the leaves of a giant sequoia are very tiny, overlapping and " awl-shaped" similar to a cypress or juniper. Also the cone of a giant sequoia is about the size of an egg while the coast redwood's cone is only one quarter as big. In mature trees, the giant sequoia's crown is more obviously rounded than the crown of a coast redwood.

I have seen a grove of redwoods that had all their foliage burned. Now it appears dormant buds have generated new growth. Is this normal?

The quick answer is yes -- it is quite common to see a redwood tree "refoliate" after burning. If the fire burns the foliage but leaves the trunk intact (that is, only scorches the bark), then the vascular cambium (inner bark) survives and is able to provide nutrients to regenerate new branches and needles. In the beginning stages of regrowth, the trees look a bit funny because the new foliage tends to make the trunk look "furry" for awhile. In cases of major fire damage where the parent tree's bark is girdled or the tree is burned down to the stump, new shoots will arise from dormant buds in the tree's burl (or lignotuber) at the base of the trunk. This results in a "fairy ring" of new trees circling the original stump.

While hiking in Big Basin I saw numerous fire scarred redwood trees and stumps. What is the recent fire history of the park?

The most recent wildfires in Big Basin occurred in 1980 and 1984 in the southern and southeastern sections of the park. In addition to these, there have been a series of intentional "prescribed burns" in the northern and northeastern parts of the park since 1978. Such low intensity fires are designed to lessen the fuel load on the forest floor to prevent future fires from spreading into the upper canopy. The ultimate goal, according to State Parks ecologist George Gray, is to mimic a natural 40-year fire return interval.

Earlier this year there were reports that redwoods might be susceptible to Sudden Oak Death. How much of a threat does this disease pose to redwoods?

According to the California Oak Mortality Task Force (COMTF), redwood is not a confirmed host of Sudden Oak Death (SOD). The earlier media reports were based on circumstantial evidence which is currently being investigated by researchers at UC-Davis and UC-Berkeley. They hope to have a definitive answer soon.

UPDATE (September 2003): According to the California Oak Mortality Task Force (COMTF), there are more than three dozen species of plants in California known to host P. ramorum. This now includes Sequoia sempervirens. However, according to Dave Rizzo (plant pathologist at UC-Davis), there is still no evidence that mature redwoods are harmed by the pathogen. For a complete list of host plants and future updates, please refer to the COMTF web site (see below).

Phytophthora ramorum, the pathogen that causes SOD, is a parasitic water mold with a broad host range among native California plants. Symptoms range from bleeding trunk cankers (coast live oak, California black oak, and tan oak), leaf spotting (rhododendron and buckeye), and leaf tip die back (bay and madrone). SOD can be fatal to some species, especially the oaks, but not necessarily to others such as rhododendron, buckeye, and bay. P. ramorum has never been proven to be the cause of disease in any conifer. Even if redwood seedlings and sprouts are affected, it is very possible that mature redwoods could show resistance to infection.

If further research indicates that redwoods are not significantly affected by SOD, the disease still poses a major threat to the redwood forest ecosystem. Tan oak, the most susceptible species, is one of the most common understory trees in the southern range of redwood forests. Many animals rely on tan oak acorns for food; birds and arboreal mammals use tan oaks for nesting. Dead tan oaks will not only jeopardize forest wildlife through loss of food and habitat, but could also lead to an increase in the fuel load resulting in more intense fires that could kill the larger redwoods and Douglas firs.

Although the eradication of SOD will not come soon, there is hope for the future. More funding has become available for SOD research, monitoring, management and education from private, state, and federal sources. The Gordon and Betty Moore Foundation has recently contributed $1 million to UC research efforts. The USDA is considering an allocation of $3.5 million in emergency funds. Senator Barbara Boxer has sponsored a rider to the current farm bill that would make $70 million available to study and fight this disease. Sempervirens Fund will continue to support these efforts through member-education and careful monitoring of its forest property.

Internet sources: www.suddenoakdeath.org; www.parks.ca.gov; www.ucmp.berkeley.edu/chromista/oomycota.html

What is the major ecological benefit of adding more land to local redwood parks?

If the addition of land is done strategically, then the major ecological benefit to a park is an increase in its "connectivity"-- the degree to which individual parcels of land contribute to a continuous forest uninterrupted by roads, urbanization or timber harvesting. The larger blocks of forest are more buffered from physical damage by wind or erosion and suffer less habitat disturbance caused by changes in canopy structure or invasion by non-native species. [Editor: For more on this theme, see our essay Protecting the Regional Ecosystem.]

How long does it take for a coast redwood to mature into a tree that produces seeds?

Redwoods that grow from seed can be anywhere from 5-15 years old before they start producing seeds themselves. No one knows exactly why there's such a wide range, but environmental and genetic factors probably control the production of seed-bearing cones.

What are the primary uses of redwood lumber? Are alternatives available?

The vast majority of redwood lumber is used for fences and decks. Cedar, with decay resistance similar to redwood, is a good natural alternative. Pine and fir can also be used if treated with weather-proofing coatings or stains. New "synthetic" lumber made from recycled wood and plastics (Trex^tm and Timbertec^tm) is an attractive and forest-friendly alternative. [Editor: For sources of alternatives, see our Synthetic Decking Materials page.]

Which is the bigger threat to redwood forests, logging or development?

In the sparsely populated counties of the northern redwood region (Mendocino, Humboldt and Del Norte) clear-cut logging is by far the bigger threat to redwood forest ecosystems. But in the Santa Cruz Mountains where more selective logging methods are used, the recent boom in housing and commercial development poses an equally great threat to redwood lands.