By Mike Heine
Welcome to In the Field, a blog series where we follow the work of CNPS Vegetation and Rare Plant program teams across the state.
The gems of the Central Coast
While old growth redwoods and hills of dense chaparral tend to dominate the pop culture consciousness of California’s Central Coast, one of the true gems I’ve been fortunate enough to explore in this region are its coastal oak woodlands. Growing up in Massachusetts I never imagined these massive, sprawling evergreen trees could be oaks, nor that I would eventually survey them for the California Native Plant Society as a part of their Central Coast Vegetation Mapping Project.
Over the last two summers, my colleagues and I have been mapping vegetation communities across the public lands and private reserves to form a better understanding of landscape-scale vegetation patterns in Monterey and San Luis Obispo counties. I’ve experienced places ranging from serpentine grasslands to windy mountain peaks, but some of the areas I look forward to surveying most are the oak woodlands
While California has many variations on the oak woodland theme, along the Central Coast these woodlands consist mainly of coast live oak (Quercus agrifolia). Depending on geography, soils, and elevation, associated oak species can include interior live oak (Quercus wislizeni), canyon live oak (Quercus chrysolepis), blue oak (Quercus douglasii), black oak (Quercus kelloggii) and Shreve’s oak (Quercus parvula var. shrevei).
Entering an oak woodland
Like something out of Lord of the Rings, you always know when you’ve entered an oak woodland. Recognizing a distinct plant community from the surrounding landscape can be tricky, but the realms of oaks always have distinct characteristics that set them apart from other similar vegetation communities. Once I’ve determined that oaks are the dominant species, I look at the spatial arrangement of the trees. The canopy cover (the portion of the ground covered by branches and leaves when viewed from above) must be at least 10%, or else you’ve found yourself in an oak savanna.
Shrubs are not usually in high abundance, as the shading from the trees above doesn’t allow for dense underbrush. This leads to another characteristic, a semi-open “lawn” of grasses and wildflowers. Soils are deep and loamy—the result of years of organic matter accumulating. The understories tend to stay greener much later into the dry year, the result of massive, swooping branches intercepting the summertime fog and forming their own mini rainstorms, with the shady forest floor being fed fog drip well after the rainy season has ended. This creates a lush environment where some of the earliest spring wildflowers begin their blooms. Thanks to woodland’s unique moisture regimes, these blooms are prolonged until well after their more open environment counterparts have died back for the year. I’ve hiked dry, grassy ridges in the spring that dip down into a cool, moist oak woodland, where suddenly I’m surrounded by white fairy lanterns (Calochortus albus) and checker lily (Fritillaria affinis) long after the meadows have begun to senesce (grow old and decay). Even some rare species are found at home in the dappled sunlight, like white fairypoppy (Meconella oregana, CRPR 1B.1)—found in California in only a handful of distinct populations.
Checker lilies (Fritillaria affinis) show up en masse come March; Images: Mike Heine
Shaping the landscape
Indigenous burning practices helped shape what oak woodlands are today. Coast live oak can live for hundreds of years (up to 1,000 years in rare cases), and many of the intact stands began growing well before European colonization. The central coast is the unceded homeland of the Salinan, Ohlone, Esselen, and Chumash. These Peoples would periodically burn the vegetation to keep down shrubs, open the understory for edible forbs and bulbs, create better forage for game animals, and stimulate new woody growth for a myriad of weaving and building materials. The shrubs that do tend to show up in coastal oak woodlands are fairly shade tolerant, like toyon (Heteromeles arbutifolia), coffeeberry (Frangula californica), and fuschia flower gooseberry (Ribes speciosum). If allowed to go unburned for too long, these woodlands could eventually suffer a catastrophic fire, the result of an excessive buildup of fuels.
Perhaps one of the most well-known examples of a coastal oak woodland is the Elfin Forest in Morro Bay. Named for the seemingly miniaturized oak woodland, these trees are fully grown even at a maximum height as low as 4 feet. The combination of salty spray and desiccating winds from the ocean, as well as poor, sandy soils have stunted the trees here to a fraction of their size.
I can’t wait to spend many more seasons in these ecosystems, and I’m already dreaming of next spring.
Mike Heine is a Lead Field Botanist with the CNPS Vegetation Program.
