Morgan Hill, California
April 28, 2023
We hiked the Frog Lake Loop from 10:00 am to 3:00 pm.
It was a scorching hot day with clear skies and a high of 85° F.
The higher elevation hills of Henry Coe State Park were incredibly dry and hot. There was an abundance of deciduous oak trees with adaptations well suited to hot, dry summers. Much of their activity is in the late winter through early summer, when water is available for vegetative growth and acorn development. They lose their leaves in the late summer or autumn, depending on water conditions. Gray pines were interspersed with the oaks. Gray pines are characterized by the round shape of their canopy, unlike the conical shape of many other conifers. During our April 28th trip, the water present drained down the hills through the watershed into a series of creeks at the bottom of the canyons. This creates distinctive areas of vegetation depending on elevation, and therefore access to water. When we were near the creek, more herbaceous understory plants appeared. There were several transitions between oak woodland and oak savannah.
The three main deciduous oaks that we encountered were the black oak (Quercus velutina), the blue oak (Quercus douglasii), and the valley oak (Quercus lobata). My major goal for that day was to practice my deciduous oak identification. A special challenge for identification was that the leaves were just emerging. While they were daintily beautiful, they were not fully developed. The black oaks became clear to me first, with their large leaves that had starkly pointed lobes. I enjoyed seeing the newly emerged leaves: small, feathery, red. Though the blue oaks had a lighter green leaf with a bluish tint, their characteristic blue color will become more apparent as their leaves develop to maturity. Valley oaks were heavily lobed with rounded edges. All three trees displayed amazingly twisty, curved, reaching branches. The form that the trunk and branches of the oak take are dreamy.
A blossom from a native tree that I do not regularly get to admire is that of the madrone. One can usually spot a madrone on a hike in the Bay Area as the yellow-orange bark always radiates out among the darker tones of the forest. There are some that confuse manzanitas and madrones. Though they both have the characteristic of thin, peeling bark, a major difference is the size of the leaves. Manzanitas tend to have many small leaves while madrones have much larger leaves. These beautiful little white flower bells had a smell of honey and sweetness.
A plant that really caught my fancy was the coffee fern. Every time we walked by one, I admired the light purple stem, the dainty leaves, and the soft velvety feel. Really, the soft but firm stems have such a unique feel and I encourage folks to explore with their sense of touch when they have the opportunity. As the plant matures, the stems turn into a dark purple-brown. The coffee ferns were in the Oak Woodland ecosystem, with them demonstrating that their leaves could stay firm despite a hot day without a lot of moisture in their immediate surroundings. They need water for reproduction and growth but were doing well despite dry conditions.
We stopped for lunch at Frog Lake. In the past, our professor mentioned that her class regularly saw four species of frog and lots of tadpoles. The only amphibian we saw in Frog Lake that day was the bullfrog. One of the starkest ecological interactions I learned about this spring was the role of the bullfrog in diminishing the frog population in the pond ecosystem. It is already alarming to know that Chytridiomycosis, caused by the fungal pathogen Batrachochytrium dendrobatidis (Bd), has been causing a significant decline in frog populations. Bullfrogs have significant competitive advantages as an invasive species in that they are high tolerance hosts of Bd and do not have any natural predators. Seeing very, very few frog tadpoles and zero adult frogs means that the pressures on frogs have shifted the pond community to be predominantly bullfrogs.
Scientific Name Glossary:
Black Oaks: Quercus velutina
Blue Oaks: Quercus douglasii
Valley Oaks: Quercus lobata
Gray Pine: Pinus sabiniana
Madrone: Arbutus menziesii
Coffee Fern: Pellaea andromedifolia