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MUIR WOODS:
WHAT HAPPENS WHEN
REDWOODS ARE SAVED

We departed Hilton Pond Center last week for our first-ever trip to San Francisco and a worldwide meeting of the American Geophysical Union (AGU)--attended largely by geologists, space scientists, vulcanologists, meteorologists, and similar scientists who study non-living phenomena. As one of the few biologists on the schedule, we were there to talk about "Operation RubyThroat: The Hummingbird Project" and The GLOBE Program, through which the Center encourages students and other folks in ten countries to investigate how environmental factors affect day-to-day behavior, migratory patterns, and survival of Ruby-throated Hummingbirds. We're grateful that the title of our presentation--"What's a Nice Hummingbird Like You Doing at an AGU Meeting Like This?"--was well-received and attracted lots of attention to the project.

All text & photos © Hilton Pond Center

All week we were warmly housed, amply fed, and expertly chauffeured by Doug Dietz, beloved roommate and fellow Frisbeee enthusisast from Newberry College undergrad days. Despite his pleasant company, after three days of San Francisco fog, meetings, traffic, and bustle we longed for something more idyllic, so Doug offered to drive to Mt. Tamalpais, a 2,500-foot peak overlooking all the Bay area. On a relatively clear morning, we hiked the trails and marveled at views from a forest service lookout tower (in the photo above, San Francisco's tall buildings--15 miles distant--are at upper right), and then set out by car for nearby Muir Woods, fabled home to some very special Coast Redwood trees.

Muir Woods is truly a national treasure. Donated to the federal government by California congressman William Kent, it was proclaimed a national monument in 1908 by President Theodore Roosevelt. Kent, in another magnanimous gesture, insisted the monument be named after writer and conservationist John Muir, founding father of the Sierra Club. In the century since, Muir Woods has expanded to 560 acres and has inspired thousands of visitors to think twice or thrice about the importance of protecting wild places for future generations.

Although we can use words to describe the natural components of Muir Woods, it's essentially impossible to convey the "feel" of the place. Our advice is: Go visit. Coast Redwood trees, Sequoia sempervirens, are enormous, towering above people on the walking trails (above) by more than 250 feet--nearly the length of a football field. At 370 feet, the largest known specimens are slightly taller than Giant Sequoias, Sequoiadendron giganteum, but the latter species--found in Yosemite and other isolated spots in eastern California--may be 40 feet in diameter at breast height, or twice the WIDTH of the redwoods. Coast Redwoods demand cool temperatures and high humidity--the exact conditions provided along the Pacific shoreline of northern California and southern Oregon. Bathed by frequent fog and nurtured by rich soil, Coast Redwoods may live as long as 2,000 years or more--that's 20 centuries!

Muir Woods is a virgin old-growth stand--never logged and illustrative of how majestic nature can be when left undisturbed. The canopy of tall evergreens brings a sense of twilight even at high noon, and the redwoods' foot-thick bark absorbs sound like a sponge. The most magnificent stand of redwoods at Muir is in Cathedral Grove (above)--an appropriate name both for the towering trees and the church-like quiet that surrounds them.

The forest floor beneath is populated primarily by shamrock-like Redwood Sorrel (Oxalis oregana, above right), Sword Ferns (Polystichum munitum), and a thick carpet of mosses--all plants that are shade-tolerant--while diverse fungi do their best to decompose fallen redwoods that may have been on the ground 50 years or more. There are relatively few understory shrubs or trees, save some Big-leaf Maples (Acer macrophyllum), Bay Laurel (Umbellularia californica), and Tanbark Oaks (Lithocarpus densiflora). Many of the latter may not be around much longer because they are susceptible to S.O.D.--a "Sudden Oak Disease" caused by a fatal fungus. First discovered at Muir Woods in 1995, the pathogen typically kills its host, disrupting the balance of nature by eliminating acorns that feed small mammals that in turn are preyed upon by Northern Spotted Owls--a federally endangered species. No one is sure how the disease arose, but plant scientists are hard at work looking for potential treatments.

We saw few animals on our three-hour visit to Muir Woods, mostly birds such as migrant Ruby-crowned Kinglets and resident Stellar's Jays, Common Ravens, and Winter Wrens (left). Faunal diversity is limited by shaded conditions that provide little forage, fruits, or berries, but the woods still are able to support healthy populations of Sonoma Chipmunks (Eutamias sonomae) and Black-tailed Deer (Odocoileus hemionus columbianus).

Along with cool weather and abundant moisture, the most critical environmental factor that insures health of a redwood forest is fire. Historically, wildfires blew through Coast Redwood stands every quarter century or so, occasionally killing a few mature trees and opening holes in the canopy toward which their younger successors could grow. Nearly every big redwood at Muir has a "fire scar," a place where long ago flames burned through the bark and cambium layer (photo below). Resilient in the face of such phenomena, redwoods slowly cover the scar with new wood; eventually there will be no external sign the burn ever occurred.

Fires also scour the forest floor of "duff"--redwood needles and other organic matter--burning right down to mineral soil and eliminating fungi and bacteria that might kill redwood seeds before they sprout. For almost a hundred years, mis-guided fire suppression philosophy taught the public that all forest fires were bad, so for a century there was little new seedling growth at Muir Woods. In recent years, controlled burning has been re-instituted as an important part of the redwood ecosystem, making Muir a much healthier habitat with plenty of new redwoods sprouting and waiting to take their places among taller trees.

Although the awesome size and beauty of Coast Redwoods makes them valuable in their own right, their economic virtues have made them a sought-after commodity--especially because redwood is light, easy to work, and very slow to rot. Throughout the past century, vast redwood stands were clear-cut but not re-planted, and mature trees on private lands are still being logged. We realize some redwood today comes from managed timber farms, but long ago we decided not to use ANY redwood products at Hilton Pond Center, preferring instead to employ our plentiful, fast-growing, and local Eastern Red Cedar (Juniperus virginiana) in applications requiring rot-resistance.

Yes, that recent trip to Muir Woods made us feel good about our decision to avoid redwood products, especially when we stopped to look at a so-called "bicentennial" Coast Redwood tree (right)--one that likely sprouted in 1776 when our nation was born. It was a nice-looking specimen, but with only a two-foot diameter it was a shrimp by comparison to its big brothers and sisters. It seems to us this 227-year-old "sapling" and others like it deserve to be left standing rather than being turned into redwood planters, fences, and picnic tables. Now that we're back home at Hilton Pond we're thankful places like Muir Woods have been set aside in perpetuity to show visitors what the world was like before chain saws, bulldozers, and paving machines took their seemingly unquenchable toll.