A year ago, I led a field trip to see conifers in the Oakland Hills, starting next to the Chabot Space and Science Center. If the trip had gone as planned, we would have taken West Ridge Trail south through Reinhardt Redwood and Roberts regional parks. However, a rainless “wind event” closed both parks over concerns about falling branches. We instead stayed in the vicinity of the Chabot Space and Science Center, which provided several conifer species for comparison. This year, February had some rain and a windy rainstorm at the end of January that closed Roberts Regional Park a second time. I went back to find out what the winds had left.
In the Oakland Hills, confers grow tall in an endurance race for sunlight that coast redwoods (Sequoia sempervirens) win in the end. The 12 months from rainless February 2020 until the windy rainstorm on February 1 of this year presented conifers with several increased stresses. As I drove on Skyline Boulevard to the Chabot Space and Science Center, I noticed piles of sawn-up Monterey pines (PInus radiata, native to the Monterey area but not the East Bay) and eucalypts (Eucalyptus species) along the roadside. Still standing were some Monterey pines with the top-down needle browning seen in Monterey pines with pitch canker, an often-deadly fungal disease of pines that arrived in the Bay Area in the 1980s.
On the day of my trip, there was ample parking at the space center’s parking garage, so I saved a long hunt for roadside parking and went straight to the top level, with a sheltered view of wild and planted conifers from all over California.
First, I located the giant sequoia (Sequoiadendron giganteum) that had leaned over the garage wall against February 2020’s wind. Now, that Sierra Nevada native stands erect and festooned with tiny foliose lichens.
Across the other side of the parking garage, an aging Monterey pine bore wind damage not suffered by a much younger pine of the same species. Unlike the centuries of an undisturbed giant sequoia’s lifespan, Monterey pines usually do not survive past one century. My California horticulture text remarked in its Monterey pine entry, “may drop branches without warning.” I remembered that entry when I spotted the older pine again, with several pruning marks and a long, broken-off limb from last year’s wear and tear. The younger pine now stands straight, where it had almost bent into the coast redwood’s branches in last year’s wind. Whatever the wind-pruning had removed from the younger pine, its new growth had more than compensated.
I walked on West Ridge Trail into Roberts Regional Park, where I saw recent and older Monterey pine windfalls near the path. While the small twigs with fresh needles on the trail came from a mix of Monterey cypress (Hesperocyparis macrocarpa), Monterey pine, and coast redwood, almost all of the large trees that had fallen or broken off were Monterey pines. Some of these windfalls probably came down last year, as California blackberries (Rubus ursinus) and bee plants (Scrophularia californica) had already sprouted in or over the now-aboveground pine root balls.
Without large-scale cutting of Monterey pines, remnant chaparral and coastal prairies will continue to struggle near the second-growth redwood forest. However, where Friends of Sausal Creek volunteers have cut down pines to allow sunlight to reach the ground, the endangered pallid manzanitas (Arctostaphylos pallida) in this area have grown back with vigor. Over a decade ago, Reinhardt Redwood Regional Park observers found manzanitas sprouting where park staff had recently cut Monterey pines. Botanist and rare plant specialist Heath Bartosh confirmed that the new sprouts were pallid manzanitas, federally listed as a threatened species. Similarly, at least a baker’s dozen pallid manzanitas have sprung up in a newly sunny area downhill from the Chabot observatory, alongside Monterey pine stumps.
While it can be painful to see a downed tree that had grown for a century before falling, there’s a bright side in this part of the Oakland Hills. Fallen trees that are not native to the East Bay (like eucalyptus and Monterey pine) create habitat for our local native plants to recolonize.
— Janet Gawthrop, Field Trips Committee Chair, CNPS East Bay Chapter