Elizabeth and I have gone on a morning hike every Thanksgiving for the last three years. This year was no different.
We’d gone to Las Trampas in previous years, but today I wanted to try somewhere new, yet still nearby. I chose to hike the northeast part of Briones Regional Park. It’s just 20 minutes away and would leave enough time to prepare for Thanksgiving dinner afterward. The last time I’d been to that part of the park was a clear October day in 2006, when there were nice fall colors on the leaves of the blue and valley oaks.
I sometimes complain about the monotonously perfect weather we get in the Bay Area, but on days like today, when it’s 60 degrees with only a slight haze from overnight fog, I have to admit that it is nice to hike in a t-shirt and shorts in late November. I brought my fleece jacket in case I got cold.
We hiked south on the Alhambra Creek Trail. It’s a dirt road on the west side of Alhambra Creek with grassy hills on one side and the creek itself on the other. The hills bore a few blue oaks and the creek was lined with leafy oaks and California bay. The creek also had a few California buckeyes, but their leaves were long gone and only their mottled gray branches remained.
In the canyon ahead of us was a dark evergreen forest. It closed in as we climbed. The air grew cooler, the grass was replaced by ferns, and the trees cast a deep shade. I put on my jacket.
We stopped at the Maricich Lagoons. Their water was muddy and their shores had been stomped into mud by cows. Despite being an unappealing scene to humans, the murky lagoons are perfect habitat for California newts and California tiger salamanders, which come there to breed. We walked around one of the lagoons, stepping carefully to avoid any cryptic amphibians, but could find none.
The haze layer was some 1,000 feet thick, which covered Mount Diablo’s lower elevations but left much of the 3,864-foot mountain exposed. Hiking above the haze at 1,400 feet on the Table Top and Spengler trails gave us excellent views of the peak.
The views ended on the Blue Oak Shortcut. We left the grassy highlands and were again plunged into a dark ravine where a stream trickled next to the trail and the tree trunks were covered with moss.
Why are the changes in vegetation so dramatic here? In the Appalachian Mountains, the difference in vegetation between a ridge and a ravine is unnoticeable if you’re not really paying attention. This isn’t because the plant species are the same, but because their growth forms are the same. Everywhere you go, the plants are mostly broadleaf deciduous trees with some conifers mixed in and shrubs in the understory. Here the differences are obvious. The climate, I guess, is on the borderline between what will support a forest and what will support a grassland. A slight change in aspect, soil, grazing history, or fire history is enough to tip the balance toward one or the other. But if we ignored the growth forms, would Appalachian hills exhibit the same variety of plants as Bay Area hills?
After passing by the park boundary and seeing a few roofs poking out from behind the trees, we climbed uphill, walking through a lovely woodland of blue oaks. We stopped for a little lunch at the top of the hill. At 1:30, we finished our hike with plenty of time to get ready for a big Thanksgiving dinner with family.