Map Quest

They call it a hitch: a trip into the field to map California’s vegetation. It’s undertaken by a sampling crew of botanists assembled in small teams—usually a group of three or four people composed of CNPS botanists and/or project partners from other organizations. The crews ramble over dirt roads and occasionally ford rivers en route to walking forests, shrublands, deserts, grasslands, or sprawling (and often breathtaking) mashups of all of the above terrains.

A hitch could take a day, or several days, with breaks to camp. It can be hot or cold, wet or dry, high or low. It involves a lot of looking down and around, assessing vegetation patterns across the landscape while scouring for discoveries and surprises amid the wondrous flora of California. In a state as temperate as ours, with its bountiful biodiversity and geographic variety, a hitch can happen any time of year. Wherever and whenever they take their participants, they all revolve around a single, fundamental question: What is growing here? That question is invariably followed, whether moments or weeks or months later, by the next question: Why? Then, finally, the culmination: So what?

The spirit and mission of conservation and stewardship are the heart of how “veg” mappers answer that last question, informing every hitch in some way. Consider the hitch that CNPS botanists Bryce King, Kimberly Dispenza, and Laura Breidenthal took in May to the mountains south of Palm Springs. In a landscape predominated by drought-adapted shrubs and small herbs, you’ll also find small pockets of California fan palms (Washingtonia filifera) in steep canyons where groundwater manages to creep to the surface. The palms can look like Hollywood props, imported to a sunny, parched desert set. But Hollywood took its inspiration from somewhere, and indeed, this naturally occurring oasis tells a story of its own. For starters, King says, they offer an abundance of resources in a landscape that can be extremely harsh for even the most well-adapted organisms. Palm fruit feeds birds and ground mammals. The shade of the robust palm overstory offers relief from daytime temperatures. The uncommon habitat—there are fewer than 100 estimated unique occurrences of this vegetation community across the entire state, according to King—have an outsized influence on the biological richness of the region.

“Understanding the location and distribution of these communities is critical to protecting and preserving so much diversity within the desert,” King says. Hitches like these involve tracking down such isolated areas as the fan palm oases plus the more common plant communities that clothe the landscape, with the goal of creating an accurate, wall-to-wall map of the vegetation of California. “By identifying these communities and protecting them, we can cause a positive downstream effect for the hundreds of species that rely on them for their survival,” King says.

Throughout the spring and into the summer, veg sampling crews have fanned out elsewhere across the state to survey sites from the Klamath Mountains to the Cosumnes River Preserve (south of Sacramento) to the Los Padres and Angeles national forests. The crews zero in on native plant populations that aren’t readily identified or tracked from aerial imagery, assessing the habitats’ size, health and hardiness. They also survey the risks that non-native plants pose to those habitats, or the ways everything from development to climate change could impact the habitats’ future. They provide the scientific backup for partners like The Nature Conservancy (which has enlisted CNPS to map and catalog the plant populations at conservation sites like the 24,000-acre Dangermond Preserve in Santa Barbara County and the 13,500-acre Las Piletas Ranch in eastern San Luis Obispo County) or mapping firms like Aerial Information Systems and Tukman Geospatial. These specialists team up with CNPS to help clarify inscrutable vegetation “signatures” picked up on aerial imagery and highly sophisticated satellite readings to develop fine-scale vegetation maps.

The amazing thing about vegetation mapping is that you don’t just have a set of labels. You have layers upon layers of information.”

 

— Julie Evens, CNPS Vegetation Program Director

Open-space planning, wildfire resilience, and restoration projects throughout California require vegetation maps to show land managers and planners how to account for what is growing where. “Agencies have identified the need to produce vegetation maps across the state, in different areas in different spaces and times,” says Julie Evens, the Vegetation Program Director for CNPS. She cites the federal Bureau of Land Management (BLM) and the California Department of Fish and Wildlife (CDFW) among the parties in need of accurate, current vegetation information. When the California Energy Commission wants to know how and where to proceed with renewable energy projects, it consults CNPS and CDFW vegetation maps. When officials in Alameda, Contra Costa, Marin, and other Bay Area counties sought to know more about oak tree mortality in the region, mapping data provided a closer look.

Evens adds that such mapping at the local level—often in conjunction with CNPS chapters and volunteers—helps identify and protect sensitive natural communities that are undergoing disturbances and threats, from development to short-interval fires. Those volunteers include CNPS members like Cindy Roessler, a retired ecologist with the San Luis Obispo Chapter. Roessler’s early years in the field involved training on CNPS vegetation mapping protocols in the redwood forests around the Santa Cruz Mountains. Decades later, after retiring to San Luis Obispo, Roessler has participated in 12 vegetation surveys—and counting—alongside CNPS staff members.

“I thought I knew my local ecosystems, but these surveys helped me notice subtle differences in geology,” says Roessler, citing the detailed vegetation survey forms that gauge factors from soil type to prior land use and plant density. She also commended the teamwork and collaboration encouraged on vegetation surveys, whether volunteers or professionals. “I feel like I walk away from these surveys with so much learning about plants and alliances, but also fun.”

The collective whole of vegetation maps—whether obtained by light detection and ranging (i.e. LIDAR), near-infrared reflection (NIR), aerial and satellite imagery, smartphone apps, or just pen and paper—make up a critical defense in California’s ongoing conservation fight.“The amazing thing about vegetation mapping is that you don’t just have a set of labels—‘Oh, here is this chaparral, or this rare serpentine vegetation,’” Evens says. “You have layers upon layers of information. A vegetation map shows the vegetation type. It shows it has a cover of shrubland layer or tree layer. It looks at our vegetation resources from the bottom up—identifying the plant community type and mapping it across an entire landscape.”   

Cutting-edge technology aside, vegetation mapping as a conservation tool has changed relatively little over the years. A hitch is a hitch. It’s mostly the stakes—and their corresponding funding—that increase. Efforts like California’s ambitious 30×30 initiative—which aims to conserve 30 percent of the state’s lands and coastal waters by 2030—depend on the availability of reliable, actionable data at local, regional, and statewide scales to gauge its progress and direction. “Originally, most mapping consisted of small projects pieced together, and recently it has included countywide projects,” says Jennifer Buck-Diaz, Vegetation Ecologist with CNPS. Buck-Diaz notes that today, with the influx of state and federal funding, mappers are undertaking “ecoregional” projects comprising multiple counties and often millions of acres statewide. The North Coast is one such ecoregion, spanning Del Norte County down to Mendocino County and inland, where CDFW and other state agencies have
called for mapping to inform its stewardship and conservation efforts.

And that’s just the start, Evens says. “In the North Coast, it’s over 3 million acres that is getting mapped right now,” she explains. “In the Central Coast, over 5 million acres is getting vegetation mapped right now. In the desert, over 4 million acres of mapping is happening now—within a three-to-four-year timeframe. It’s on another level.”

Vegetation mapping starts by the book—literally. CNPS, in collaboration with CDFW, supports a statewide classification of vegetation through its Manual of California Vegetation, commonly known by botanists and plant wonks statewide as the MCV. As biodiversity status goes, the MCV views common plant communities as no more or less worthy of conservation than sensitive or endangered plant communities. (Evens notes that oak woodlands, not generally threatened, are important to the viability of more than 300 vertebrate species and thousands of insect species.) Once an agency or office has determined its needs for vegetation data, CNPS works with them to arrange funding and planning for mapping projects. Next, CNPS loops in its data-gathering collaborators like Tukman Geospatial for sampling trips and hitches into the field.

At such a hitch this past May, CNPS botanist Paul Excoffier accompanied two analysts from Tukman to investigate inconclusive signatures at a rocky, hilly expanse in the Santa Lucia Mountains in southern Monterey County. The team scrambled over grass-fringed boulders onto a mossy plateau. Tukman analyst Tyler McCarthy held up an iPad to gauge their location in the existing vegetation map. Excoffier and Tukman botanist Brian Kreb strolled to the edge of the bluff and stared across the distance at a cluster of valley oaks (Quercus lobata) and gray pines (Pinus sabiniana), punctuated by spindly black husks of fire-stricken trees.

“We’re looking at things that burnt and that are coming back—either regenerating from the base of a tree, or a shrub regenerating,” Kreb said. “It’s hard to know when they’re all the same height. When we’re out here in person, we can actually try to get confirmation.”

Excoffier lifted binoculars to his eyes. “This burned in the 2020 Dolan fire,” he said.

“I’d like to be over there,” Kreb said. “The base of that hill looks like a regenerating tree.”

The trio retreated down the hill and to their vehicle, in which they drove further up Del Venturi Road to another mystery signature. After 15 additional minutes of hiking, climbing, and navigating through brush and fallen trees, the group arrived at their destination: A creek where they sought to determine the distribution of Western sycamore (Platanus racemosa), arroyo willow (Salix lasiolepis), or Fremont cottonwood (Populus fremontii) trees that clustered on their map. Excoffier returned to work with his binoculars as Kreb and McCarthy crunched mapping data. In the end, the maps will be fine-tuned to share with the commissioning agencies—CDFW, the California Department of Conservation and State Coastal Conservancy, the US Geological Survey, and the California Natural Resources Agency—on what they found and its significance to the overall habitat.

Meanwhile, roughly 100 miles southeast in eastern San Luis Obispo County, another mapping hitch had CNPS botanists spread out in the breezy grasslands and hills of Las Piletas Ranch. At a glance, the terrain looks like little more than the pasture that it is: Hundreds of cows tread the pale yellow grassland, grazing peacefully in the sun. Non-native red brome (Bromus rubens) crowds the landscape, interrupted by flashy specks of California poppy (Eschscholzia californica) and purple owl’s clover (Castilleja exserta) dancing low to the ground. Creeks burble and weave through riparian habitat in the hills. But look closer, and you’d see CNPS botanists Tom Reyes and Mike Heine trundling over the dirt road in their pickup truck, double-checking the identification on mapped grasses. Across the field and back toward the hitch campsite, their colleague Jordan Collins noted rare Douglas’ spineflowers (Chorizanthe douglasii) numbering in the hundreds. A few miles up the hill, their fellow botanists Kristen Nelson and Sharon Estrada examined a sizable new population of rare Camatta Canyon amole (Hooveria purpurea var. reducta) first spotted here in 2024.

The prominence of rare plants at Las Piletas Ranch is of particular note to The Nature Conservancy (TNC). The nonprofit acquired the land in 2022 as part of an ongoing effort to protect and link roughly 600,000 acres of wildlife crossing in California’s Inner Coast Range. But critters like the San Joaquin kit fox aren’t the only endangered species inhabiting that crossing. There’s also the poppy, the owl’s clover, the spineflowers, the amole, and countless other native plants—rare and common alike—calling it home as well.

According to Scott Butterfield, a lead scientist with the Land Program at TNC, vegetation mapping at Las Piletas Ranch will influence stewardship and protection strategies across the property. Virtual fencing guided by electronic collars could keep its 350 resident cattle from munching key native vegetation. Scientists can work to manage land not just for pronghorn, tule elk, grassland birds, and riparian species, but also for the rare native plants that further boost biodiversity at Las Piletas Ranch.

“There’s probably nobody short of ranchers themselves spending as much time on the ground in grassland and oak woodland as CNPS,” Butterfield says. “We’ve leveraged the CNPS expertise and knowledge base to help us think through recommendations for the land management itself. It used to be more static in my head—these things are really hard to see and track over time. Now I feel like it’s this more collaborative effort around how we take this amazing work that you’re doing, how we’re informing our management, and then looking at what those impacts are.”

Evens says the data from vegetation mapping is used daily at CNPS in one way or another, whether to update the MCV, evaluate conservation status ranks, to denote plant communities throughout the state, or for myriad other purposes. It’s all part of unprecedented conservation and restoration efforts underway statewide, with CNPS either leading or supporting the mapping across vast swaths
of California.

“Twenty years ago, we wouldn’t be able to do the scale that we’re doing right now,” Evens says. “And the reason we’re able to do that scale right now is because of this amazing, integrated approach that we figured out with the partners that we work with so collaboratively. We could be working on 10 projects all at one time, through the different methodologies and advanced technologies that we have.”

And this summer, you don’t need to be a botanist to join a hitch: CNPS will host “Veg-a-thons” across the state, welcoming members, volunteers and other native plant enthusiasts to join experts in the field for vegetation mapping collaborations. Two Veg-a-thons—in Lake Arrowhead from July 11-14, and in the San Gabriel Mountains near Big Pines and Paradise Springs from August 7-11—will support the Southern California mountains and valleys vegetation surveying project, a collaboration between CNPS, Althouse & Meade, Inc., and Tukman Geospatial, funded by and in partnership with the California Department of Fish and Wildlife. Another Veg-a-thon will take place in far Northern California at Whipple Ranch, in Siskiyou County, from August 6-13.

Along with its Veg-a-thons, the Vegetation team expects to provide more opportunities to join its mapping crews in the field during other hitches this year—an inclusive, adventurous, science-driven, and yes, even fun way to help save what matters most. Who knows? You may even happen upon a palm oasis.

“The landscape comes alive when you can see patterns,” Buck-Diaz says. “It fulfills that curiosity inside me about witnessing nature. I learn something every time I’m working outside.” ◆

Additional reporting by Melati Kaye