Bay Nature magazineSummer 2004


In the Shadow of Giants

July 1, 2004

People often describe old-growth redwood forests as “primordial,” and so they are. The trees themselves have changed little in the last hundred million years. The redwood forest is still a habitat for giants. In those times nature lived extra large. Dinosaurs dominated the land, giant pterodactyls plied the skies, and huge centipedes combed the redwood duff for prey. Of the era’s most salient giants, only the coast redwoods and their Sierran cousins the sequoia remain.

But on a geological time scale, redwoods have long been in radical decline. Ten million years ago they were one of North America’s dominant tree species. In those much warmer and wetter days, redwoods were found in China and Europe as well as North America. But with climate change and continental shift, that range began to evaporate.

The drying and cooling climates preceding the last Ice Age drove North America’s redwoods into a retreat to the Pacific Coast, where the maritime habitat afforded them sufficient moisture and relative seasonal stability. Their recent Pacific refuge was, until the 1800s, an impressive one, covering about 2 million acres of California stretching from the Oregon border south to Big Sur.

Western Trillium
Western trillium brighten the shady forest floor in Redwood Regional Park. Photo by Charles Kennard.

Although the redwood is one tough tree, nothing in its natural history could have prepared it for the appetites of men with saws and cities to build. Today only 5 percent of the historic old-growth forest remains.

Up until the mid-1800s, the Bay Area, too, had magnificent old-growth redwood forests. Though their East Bay range in the Oakland hills east to Moraga remains more or less intact, there are only two significant patches of old growth left near the Bay Area: the 300 acres in Muir Woods National Monument in Marin and, in Santa Cruz County, 4,670 acres in Big Basin State Park.

To survive, redwoods require a fairly stable temperate climate and sufficient water. They tend to congregate in bowls and basins or on north- and east-facing slopes that catch water and prolong their exposure to moist soil. Strictly speaking, the precipitation regime here, with typically less than 30 inches of winter rain and endless dry summers, is inadequate for redwoods. But by growing in places with high water tables and catching summer fog in their needles and dripping the water down to their roots, East Bay redwoods can extract another ten inches or so a year from the environment. To exploit the fog, though, they must have some exposure to its path, without being overexposed to the drying air and direct sun. While their roots seek valleys, their fog-catching needles seek heights, one possible explanation for their extraordinary stature. Bowls and basins also act as cool air sinks. The coolness of a redwood grove allows the trees time to soak up moisture before it evaporates. If you’ve ever walked into a redwood grove from neighboring chaparral or grassland, you know how steeply the temperature can drop.

The acoustics of redwood forests sometimes seem otherworldly: You can hear the whoosh of an owl’s feathers, the beat of your own heart, the clicking of ladybird beetles’ enamel-like wings as they swarm over ferns. But the quiet of the East Bay’s groves belies a roaring and tragic redwood history. There were once magnificent forests here and possibly some of the largest coast redwoods ever known. But in just 15 years, between 1845 and 1860, they were cut in an orgy of logging. Every last one.

In 1893, William P. Gibbons, a naturalist with the California Academy of Sciences, published an account from some 40 years earlier when he had surveyed the “sea of stumps” in the Oakland hills, where Roberts Recreation Area and the adjacent Redwood Regional Park’s Redwood Bowl now stand. One of those stumps was about 31 feet across at a height of four feet above the ground. That would be one of the widest trees on record. Naturalists suspect that it may have been one of two trees used by sailors beginning in the Spanish colonial period as landmarks to help them navigate through the Golden Gate without hitting Blossom Rock, a treacherous, barely submerged rock near Yerba Buena Island. After the “Blossom Rock” trees were cut in the early 1850s, Alcatraz lighthouse took over their navigational function.

Shortly before the turn of the 20th century, Gibbons brought conservationist John Muir and evolutionary biologist Alfred Russell Wallace to see the stumps of this and other felled East Bay groves. Both men were duly awed by the size of the stumps and saddened by the destruction of the forest a half-century before. One hundred years ago, Gibbons and his guests mourned the lost opportunity to create what would have been, he said, “one of the noblest natural parks conceivable.”

In 1939, the area did become a park, under the management of the newly formed East Bay Regional Park District (EBRPD). In 1988, EBRPD forester John Nichols set out to find the site of the Blossom Rock trees. Using ships’ logs, navigation charts, and triangulation techniques, he was led to an area now near the picnic sites in Roberts Recreation Area. Nichols and botanist Stephen Edwards, director of the Regional Parks Botanic Garden, found what they believe to be the original locations of these tremendous trees. This area between the Roberts parking lot and Skyline Boulevard is full of circles of trees often called “fairy rings,” redwoods that grow in rings around the edges of the stumps of their predecessors, creating little enclosures that kids, and allegedly fairies, too, love to play in. A state historical marker now stands near the site.

By the time Gibbons wrote his account of the East Bay redwoods in 1893, some of the cut groves had been growing back for nearly half a century, and many of the trees may already have been more than a foot thick and over 100 feet tall. In 1906, however, after the great San Francisco earthquake and fire, the second-growth stands were cut for lumber to rebuild the city across the Bay. For a second time, their stumps were chopped apart for roof shingles and firewood.

Regional Park naturalist Gail Broesder tells me, as we walk through the second- and third-growth forests of Redwood Regional Park, how valuable these trees are as lumber. Redwoods are so thoroughly saturated with astringent tannin that fungi and insect pests pretty much steer clear of them and fire rarely penetrates their thick bark. Redwoods’resistance both boosts the trees’ natural longevity and makes the lumber especially valuable to builders: strong, straight, long-lasting, and easy to work with. A free-market reductionism views a redwood tree as a giant fortune on a stick. “One old-growth redwood tree can make enough lumber to build five eight-bedroom houses,” says Broesder.

It is remarkable that the East Bay’s urban redwood forests, primarily the neighboring Redwood Regional Park, Roberts Regional Recreation Area, and the City of Oakland’s Joaquin Miller Park, are now managed for their habitat and recreation value. After it was logged for the second time, the area was owned by a succession of water companies that sold Redwood Creek water to East Bay residents. By the late 1930s, the water companies had become public agencies, and soaring demand led the newly formed East Bay Municipal Utility District (EBMUD) to abandon Redwood Creek in favor of the greater volume of the Mokelumne River. EBMUD sold its 1,500 acres of surplus juvenile redwood forest to the brand new East Bay Regional Park District.

Observed from a supine position on a picnic bench in Roberts Regional Recreation Area, near the likely site of the Blossom Rock Trees, the young redwoods look like adolescents surprised by their own height: a little awkward, but much more graceful than they know. They stay just far enough from each other that their upper branches remain close but do not touch until a gust of wind makes them sway and their extremities brush with the casual familiarity of high school athletes. It is striking how distinctive the individual trees are, how differently they lean and grow and sway. It will take more than a thousand years before they resemble the eccentric old ancestor trees of Muir Woods, say, but already each of them has its own scars, its own distinct grace.

A redwood tree can live in excess of two thousand years by employing a three-pronged longevity strategy: First, because of their tannin they rarely get sick or infested. Second, with their great size and closed canopies, redwood forests create their own microhabitats, insulating themselves from heat, drought, and other climatic caprices. Third, they pretty much dominate whatever neighborhood they occupy. Sometimes Douglas-fir or oaks or bay laurel trees coexist with redwoods, but in the moist habitats redwoods prefer, they excel at drawing light from the sky and water from the air and soil.

Redwoods reproduce in one of two ways: first, the old-fashioned way—by seeds released from mature cones—or, more commonly, by simply sprouting suckers from their trunks or their stumps. These new suckers are genetically identical to their parents, and they rely at first on the network of roots already in the ground. “Redwoods don’t die,” says Edwards. “The second- and third-growth trees we see today are genetically the same as the old growth cut down 150 years ago.” What’s missing from the forest, though, are the structural complexity and the intricate relationships and associations of plants and animals that evolve in a forest over millennia. And of course the sheer size.

Some native plants and animals have survived the traumas and tribulations of the East Bay redwood forests, but none remain unaffected. The world-famous steelhead trout was first named in 1855 based on specimens taken from the San Leandro Creek drainage, of which Redwood Creek is a part. The rainbows that still swim in Redwood Creek are direct descendants of that ancestral stock. In 1869, when Chabot Reservoir was built, Redwood Creek was amputated from the Bay, and what had been anadromous, ocean-going steelhead became rainbows. (Steelhead and rainbow trout are the same species, but steelhead, having access to the sea, undertake an anadromous stage during which they metabolically morph to tolerate salt water. Populations of these fish also can become naturally “landlocked” for long periods of time and suffer no ill effects, says Pete Alexander, EBRPD’s fisheries program manager.)

From the fish’s point of view, and that of the local ecosystem, the amputation was an ecological loss. But it had an environmental upside as well. The genetic integrity of these trout has been preserved. When scientists go looking for pure stocks of the original East Bay rainbow trout, now threatened, they come here. In 1983, 600 of the trout were moved into Wildcat Creek in Tilden Park as part of the restoration effort there. They are now thriving and successfully make their way to the sea each year.

Ocean-going steelhead played an important ecological role by bringing nutrients gleaned from the sea into the upper reaches of the creek. Rainbows in the San Leandro watershed have lost that key function. Today, however, they still do eat a lot of fly larvae and other aquatic insects and in turn provide food for ospreys, herons, and raccoons. Moreover, the redwood forest still plays a key role in the life cycle of the rainbow trout, providing the necessary well-protected, shaded, and cool stream bottoms required for spawning.

Compared to the old-growth forests of Humboldt, Marin, or the Santa Cruz Mountains, the East Bay’s redwoods are what Edwards calls “floristically depauperate”—that is, a number of plants that would seem naturally at home here are missing. For example, redwood sorrel, a lush clover-like plant that is common in Muir Woods and Big Basin, is conspicuously absent here.

Edwards isn’t sure why there are only one or two meager patches of redwood sorrel in the East Bay redwoods. But he speculates two causes for the relative poverty of plant diversity in the forest. First, the brutality of the logging techniques in the 1800s: The giant trees were felled by ax, saw, and fire and then dragged through the forest by oxen. The result was a forest floor scraped clean of delicate plants accustomed to the cover and security of the redwood canopy. Second, compared to other redwood areas along the coast, the East Bay redwoods are isolated from other forests that might usher a recolonization of redwood-associated plants.

Nevertheless, a walk through Redwood Regional Park, Roberts Recreation Area, or their Oakland Parks Department-managed neighbor, Joaquin Miller Park, shows that the area still hosts many lovely and interesting plants. Western trillium (Trillium ovatum), for example, is a common and beautiful little lily whose distinctive leaves and flowers punctuate the forest floor in spring. Pacific Northwest native wild-ginger (Asarum caudatum) is also common throughout the East Bay’s redwoods, and in the early spring its strands of red wine-colored flowers open near the ground, beckoning its specialized fungus gnat pollinators. The pretty little yellow stream violet (Viola glabella) and its cousin the wood violet (V. sempervirens) are both abundant as well.

Many of these understory plants are in constant competition for rare forest sunshine. “Wherever you go in the redwood forest,” says East Bay Park naturalist Margaret Kelley, “the sun is really a prize. Where the sun shines through, there’s always a lot of action.” When a tree falls, for instance, opening a window to the forest floor, all kinds of plants compete to take the photons and run: huckleberry, poison oak, and other shrubs. But it is typically redwoods that eventually prevail and grow tall enough to patch the hole.

Of East Bay redwood fauna, a favorite of mine is the native ladybug known as the convergent ladybird beetle. These little insects spend much of the year feeding on aphids and other soft-bodied insects in the grasslands and along Bay wetlands. When the rains stop and their prey begin to disappear, the ladybird beetles fly east to the first set of hills, where they find a cool, moist, and safe spot to cluster together, often on shrubs in redwood forest valleys. Here they enter an energy-saving kind of semi-hibernative state. The clusters in Redwood Park, which can often be observed near the Old Mill site in March, may contain hundreds of thousands of insects, says Alan Kaplan, an EBRPD naturalist.

Quite a lot of life can be found in a redwood forest’s upper canopy as well. Steve Sillett, a professor at Humboldt State University, has found extraordinary things living in the upper canopies of mature redwood forests in Humboldt County. “It’s just crazy up there,” he says. “Soils build up over a meter deep in the crotches of multiple branches; you get water stored in the canopy. Wandering salamanders and earthworms spend their entire life cycles 300 feet up. There are arthropods, ferns, shrubs. It’s a world unto itself.”

The redwood forests here in the Bay Area are too young and our rainfall too humble to create such biodiverse upper canopy, says Sillett. But ferns and huckleberry bushes can already be found at the tops of some of our more mature trees.

If each redwood tree is unique, so, I am reminded by Edwards, is each redwood forest one of a kind. A decades-old study of the redwood forests up and down the Pacific Coast, by revered UC Berkeley botanist Herbert Mason, found very little in the way of plant associations that held constant across their range. The sword fern is the one plant that apparently follows redwoods everywhere. We will never know for sure just what kind of forest we lost during the logging frenzy of the 1850s. And we could never re-create it. But our adolescent second- and third-growth forests present us with extraordinary opportunities for both restoration and learning, not to mention pleasure.

Who knows what our cities will look like in the year 3000, but as these already lovely forests continue to grow and age over centuries to come, their duff will slowly accumulate and grow deep and complex again. Myriad plants and animals will reoccupy their floors and canopies. If we let them, fires will scar and cleanse and alter them. These urban forests will grow old, rich, and even more beautiful and elaborate in ways that still lie beyond our powers of prediction. We can say for sure, though, that that unfolding process, and those aging and eventually ancient forests themselves, will be among the Bay Area’s most fascinating, beautiful, and salutary assets. And to get all that, pretty much all we need to do is avoid loving these urban forests to death, and let the trees mature in peace. Now that’s a great investment.

About the Author

Gordy Slack is a freelance writer living in Oakland. He writes an environmental column for California Wild, the quarterly magazine of the California Academy of Sciences, and he is the co-editor of Faith in Science (Routledge, 2001), a collection of interviews with religious scientists.

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