Most recent installment in the VPP survey of climate change on public lands in California
Skyline Boulevard and Skyline Drive — Pacific and Atlantic bookends of outdoor America, they share much. Their latitudes are similar. Both occupy conifer-shrouded mountain crests. Hikers and mountain bikers fill their roadside parking lots — from San Francisco, 30 miles away; and Washington, D.C., 90.
Each has memorable dining. Neil Young made his Harvest Moon video among the redwoods at Mountain House Restaurant along Skyline Boulevard. Skyline Drive’s Skyland Dining Room features blackberry ice cream pie from a view 3,000 feet above the Shenandoah Valley.
Each retains spirits of wilderness. Mountain lions roam near Skyline Boulevard; essentially spirits, rarely sighted. The timber rattlesnakes of Skyline Drive appear materially at the tourist overlooks. The snakes thrive in the tangled abundance of the cleared forest adjacent to the stone overlook walls.
“Rattlesnakes like the food and cover that some overlooks provide,” says Shenandoah National Park biologist Rolf Gubler. “They like rock walls, boulder fields and rock/log access for cover. They also use these areas to bask in the sun. They like the openings of overlooks and scenic vistas because they provide food (small mammals like voles, mice, chipmunks, etc.).”
The two Skylines rise into a world of climate change. Along Skyline Drive, warming temperatures aid and abet the destructive hemlock wooly adelgid. This insect strips the eastern hemlock of its needles and has killed nearly all of them there. This ecosystem is ancient, however, and this just a turning over of its elements. It opens up the scenic views, with their transcendent freedom of sunsets and hair-waving wind.
Along Skyline Boulevard, at El Corte de Madera Open Space Preserve, the nearby Pacific acts as a great preservative. Its mist feeds the redwood stands with moisture, re-purifying air already cleansed by their dense greenery. The turning of the ecosystem is slower: The Methusaleh Redwood at roadside is 1,800 years old. The freedom here is an ancient freedom of sensuality, the red woods of redwood and Pacific Madrone, deep green filling the air like the backdrop of a painting.
Paintings, millennia are insignificant alongside the enabler of the redwoods: The Pacific Ocean. Any change in the redwoods points to a global, climatic change rather than one of mere weather. When that Pacific system of moisture sends less mist among the redwood trunks, a broader concept is implicated.
Residents of the San Francisco Bay area view with alarm their pet redwoods succumbing to a 5-year moisture deficit. In parks and along streets, the model redwood groves die. In the old groves, the established ecosystem sustains them; but elsewhere, nothing remains but to analyze the loss.
In a recent research initiative, Save The Redwoods League had volunteer citizen scientists monitor the ferns in the redwood understory. The meter-long fronds of sword fern, Polystichum munitum, featured in so many photographs send out new growth each year. During wet years, the frond length is correspondingly greater. Measurements over many years tell not so much the weather but the climate, the amount of moisture entering the ecosystem.
Emily Burns, Director of Science at Save the Redwoods, 415-362-2352, summarizes the results of a recent fern study focused on the 2012-2014 California drought, likely a 1,000-year event. Per her research abstract, “Results showed that P. munitum throughout the ecosystem range avoided the drought by reducing total crown leaf area by approximately one third.” This size reduction corresponds to a latitudinal size gradient from wetter to drier sections of redwood range. Put simply, the ferns retreat under stress and then resurge. The avoidance tactic succeeds, hinting at similar mechanisms elsewhere in the ecosystem. Yet, it signals stress throughout the forest, among the redwood trees themselves.
Climate change limits the social/natural bond. The supply of virgin redwood forest is fixed. Now climate change further constricts our scope of experience by challenging the token plantings. As for the return of the eastern hemlock forest, the redwoods will likely be waiting for them; yet, we don’t know that it will return.
The pattern of forest succession does not favor the return of the hemlocks. Incipient sweet birch forest tangles trailsides near Skyland. Logging industry history tells us that hardwoods replace hemlocks; global warming further inhibits their resurgence. The ever-green, earth’s elevated self, the coolness — whether in Virginia or California, we pay homage to its climatic conservatism.