In the Field: Mapping the Central Coast

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.

A hotspot within a hotspot

The Central Coast is a hotspot of biological diversity within a state that belongs to one of the world’s 36 biodiversity hotspots. The Central Coast Ranges rise suddenly and dramatically out of the sea, creating a wall of mountains—including the Santa Lucias—that block a significant portion of precipitation from reaching inland. This dynamic creates a host of microhabitats, which weave a unique floral tapestry of plants, both common and rare, unlike anywhere else in California. Paleoendemic (species that were once more widespread but are now restricted) and neo–endemic (more recent species that arose through reproductive isolation) plants grow here. Many plants reach the southern and northern edges of their ranges, and blend into a kaleidoscope of vegetation communities—especially shrublands and woodlands—that seem almost at odds with one another.  

Along the Big Sur coast, chaparral-cloaked hillsides plunge into deep valleys lined with coast redwood forests, and Monterey pine woodlands give way to coastal sage scrub. Further south, the serpentine barrens and diverse grasslands of the Irish Hills rise suddenly into dense coast live oak woodlands. The traditional homeland of the Rumsen, Salinan, Esselen, Ohlone, Amah Mutsun, and Northern Chumash Tribes, this is a massive area that has been home to humans for thousands of years who have influenced vegetation patterns through cultural burning and nurturing the biodiversity we see today. 

Recently, the CNPS Vegetation team wrapped up two years of vegetation community sampling associated with fine-scale mapping in the Central Coast of California. Members from the CNPS San Luis Obispo and Monterey Bay chapters and the Vegetation team—in collaboration with Althouse & Meade, Inc. and California Polytechnic University, San Luis Obispo—completed over 2,200 vegetation surveys across Monterey and San Luis Obispo counties from March 2023 to October 2024. Funding came from the California Department of Fish & Wildlife and State Coastal Conservancy along with the U.S. Geological Survey and California Natural Resources Agency. In addition, the University of California, Santa Cruz, collected over 400 samples across the rest of this region. The field-based assessments are crucial for understanding the landscape-scale patterns of vegetation to inform resource protection policies, conservation, fire management, and restoration.  

Rapid assessment and relevé

Last spring in interior San Luis Obispo County, the team surveyed Carrizo Plain and various ranch lands, taking advantage of the superblooms from the rainy 2022–23 winter. They went on to survey patterns from coastal lagoons in Morro Bay to cypress groves in Monterey using rapid assessment and relevé protocols. A rapid assessment survey is usually deployed to record key species and environmental conditions in patches of vegetation dominated by woody plants, while a relevé plot is used for herbaceous or diverse stands to capture every single plant species within a localized area, to inform what occurs on a landscape scale. In total, they surveyed at least 210 field alliances with 700 vegetation associations. The data will also provide information on new associations or alliances of vegetation, and this information will be included in fine-scale mapping over the next 1.5 years. Additionally, they collected baseline vegetation data at Big Sur Land Trust’s recently acquired Basin Ranch, a collection of 19 different parcels of land—at one time potentially slated for development—that the Land Trust will be co-managing with the Esselen Tribe. 

Beyond the fog

The Central Coast is known for mysterious and wild coastlines obscured by fog, but many of its most closely guarded secrets exist well above the fog line. Bristlecone fir (Abies bracteata), CRPR 1B.3, is endemic to a narrow strip of Big Sur. It’s the last remaining conifer of an order older than all other true fir (Abies) species in North America, and a relic of the last Ice Age. Bristlecone fir forests can be found on mainly on northern facing aspects, deep river valleys, and rocky mountain peaks, usually in the most remote and fire-protected parts of the region. The Vegetation team climbed mountains and wended through chaparral to survey nine stands. This will allow us to better learn understand the bristlecone fir’s biogeography and associated plants, which is crucial to preserving the species as more severe wildfires and a changing climate threaten populations.  

Threats to the biodiversity of the Central Coast makes it even more important to develop a working understanding of the area’s vegetation complexity. Several large–scale fires, like the 2020 Dolan and River fires, as well as the 2016 Soberanes Fire have modified the landscape, as have urban development, invasive weeds, and the forced removal of the land’s traditional caretakers. Mapping the surviving vegetation communities will provide land managers with accurate information on how to conserve and restore these ecosystems so they survive well into the future.

Mike Heine is a Lead Field Botanist with the CNPS Vegetation Program.