In the Field: CNPS Vegetation Mapping in the North Coast and Coast Ranges

From top left to bottom right: Bluff lettuce (Dudleya farinosa); Round-leaved sundew (Drosera rotundifolia); Syctheleaf onion (Allium falicifolium); Images: Abra Schlotz; A Darlingtonia stand located within a fen ecosystem; Image: Kelsey Guest

Exploring towering redwoods and lost coasts

Welcome to In the Field, a blog series where CNPS continues to highlight the important mapping work the Vegetation Program is conducting throughout the state.

By Thomas Van Eyk, with additions from Kelsey Guest, Abra Scholtz, and Michael Heine

Spanning more than 3 million acres from Del Norte to Mendocino County, California’s North Coast and Coast Ranges feature rugged coastlines, fog-cloaked mountains, and seemingly endless forests of the tallest trees on Earth. The region boasts the longest stretch of undeveloped coastline in the United States, creating an ecological haven characterized by diverse landscapes and unique plant communities. The North Coast and Coast Ranges encompass the natural lands of many Tribes: Bear River​, Cahto​, Cayuse,​ Pomo​, Chilula​, Chit-dee-ni, Yuki​, Hupa​, Karuk, Kashaya, Lassik, Yurok​, Confederated Tribes of Siletz, Mattole​, Nongatl,​ Wintu, Sinkyone​, Tolowa Dee-ni’​, and Wiyot. Over the past two years, a dedicated team of more than 80 trained botanists and CNPS members from the North Coast, Dorothy King Young, and Sanhedrin chapters have conducted over 1,700 vegetation surveys across the Northern California Coast to catalogue the remarkable vegetation diversity in this region.  

In collaboration with the California Department of Fish and Wildlife (CDFW) and with the invaluable mapping expertise of Tukman Geospatial and Aerial Information Systems (AIS), our collective aim is to construct a comprehensive vegetation classification, key, and map of this isolated region. The map, designed at a fine-scale level, will help improve land management practices, identify invasive and rare plant species, and unravel the intricate relationships among various vegetation communities. The objective is to create a tool that deepens the understanding of Northern California’s unique ecology.  

Left: The project area, a blank slate for reference; Right: The same project area displaying survey points coverage; Images: Thomas Van Eyck
Putting the project together

CNPS began actively collecting field data along the North Coast in 2022, focusing primarily on identifying and surveying distinct related groups of vegetation known as alliances. Vegetation Program staff and expert volunteers have collected a wealth of environmental information, including soil composition; geological characteristics; landform attributes; and ecological impacts, alongside detailed documentation of plant species. To capture the diversity of the vegetation within a specific stand (a place where plant species compete for light, air, water, and other nutrients), they employ two related protocols: a Relevé and a Rapid Assessment. 

While following the Rapid Assessment/ Relevé protocol, the team collects environmental data like soil composition and underlying geology; Image: Kelsey Guest

The Relevé systematically records every plant species and their abundance within a designated area, while a Rapid Assessment swiftly documents the key species across entire forest stands. They use this dataset as the basis for creating a classification key that categorizes the various vegetation alliances and associations across the North Coast. The collected data is now undergoing rigorous quality control measures to ensure the highest quality information for guiding the subsequent stages of our project. 

CNPS Staff and North Coast Chapter volunteers conducting a Relevé survey at Flenner Creek on the Lost Coast; Image: Sara Bandali
Appreciating these diverse landscapes

A comprehensive exploration of the North Coast’s diverse landscapes not only unveils their intrinsic beauty but also sheds light on the ecological relationships that underpin them. The team’s meticulous cataloging effort has revealed more than 480 distinct vegetation associations within 160 unique alliances, each providing a glimpse into the rich diversity of regional flora. Over the course of the work, they ventured into stately oak woodlands carpeted with grasses and flowers, and mapped riparian forests of willow, alder, and maple trees that provide critical habitat and help protect our watercourses. Additionally, they‘ve encountered expansive coastal prairies, showcasing the remarkable adaptability of plant life to coastal conditions. Of special note is the coast redwood (Sequoia sempervirens) alliance, which was by far the most sampled vegetation community throughout the study. Sequoia sempervirens is the only surviving member of an ancient genus that once grew all over the northern hemisphere. A kaleidoscope of plants and animals rely on Sequoia sempervirens, from marbled murrelets nesting in old-growth branches to salamanders that can spend their whole lives in the canopy without ever touching the ground. 

The diverse landscapes in the Leonard Lake Preserve. How many distinct vegetation alliances can you spot in this photo? Image: Samantha Swatling-Holcomb
Revealing rare and sensitive species

Throughout the North Coast mapping, CNPS surveyed a range of unique, sensitive, and occasionally rare ecosystems across Northern California. These diverse environments provided habitat for equally unique plant species, each adapted to its own ecological niche, contributing to the region’s remarkable biodiversity. Among them, the team explored rare and sensitive fen ecosystems, home to remarkable species like California pitcher plant (Darlingtonia californica), and sundews (Drosera spp.), which use carnivory to thrive in nutrient-poor habitats. They also delved into challenging serpentine soil ecosystems, uncovering notable findings, including syctheleaf onion (Allium falicifolium), perfectly adapted to the lownutrient serpentine soil niche. The exploration extended to unforgiving seaside cliffs, where bluff lettuce (Dudleya farinosa) lives in harsh coastal conditions, illustrating this species adaptability and the intricate web of life within these coastal ecosystems. 

A silver lupine (Lupinus albifrons) stand; Image: Samantha Swatling-Holcomb
Next steps for the project

The North Coast Vegetation Mapping Project is dedicated to documenting the region’s plant life and establishing the groundwork for a range of practical applications. CDFW, with critical feedback and refinement from CNPS and AIS, is in the process of developing and refining the Vegetation Field Key for North Coast and North Coast Ranges to aid in the standardized identification of vegetation assemblages. (A newly CDFW funded project in 2024 will result in the entirety of the North Coast and Coast Ranges ecoregion being mapped by March 2026!) Simultaneously, Tukman Geospatial and Aerial Information Systems (AIS) are utilizing our data to create a high-resolution vegetation map, which will enhance our understanding of the landscape. This work will influence land management decisions, support conservation planning, facilitate habitat restoration, and contribute to climate change monitoring. These applications highlight the significant impact of the project on preserving the region’s ecology and its diverse ecosystems. As CNPS continues on this journey, we invite you to join us in appreciating the value of this ongoing exploration of Northern California’s hidden treasures. 

CNPS Chapter Members Conducting a Relevé Survey at Dry Lagoon. Image: Renee Pasquinelli


Thomas Van Eyk is an Associate Vegetation Ecologist with the CNPS Vegetation Program. 





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