Important Plant Areas (IPAs)

Blue Oak at dawn

We’re in a race against time to protect California’s biodiversity

The state of California is a globally recognized biodiversity hotspot with over 6,500 native taxa, a third of which are found nowhere else. Its rapidly growing population, severe housing shortage, increased demand for resources, and changing climate have led to regional planning assessments to streamline the ability to meet such pressing and complex demands. 

To ensure that plants and their habitats are adequately represented and protected in such assessments, tools are needed to identify the most important areas to target conservation activities. CNPS is working region by region to build the state’s first comprehensive map of the plant places we most need to save and why. Collaborating with a network of science and land-use experts, CNPS has developed an Important Plant Area Model that can guide regional planners as they balance necessary development with plant conservation. Well-informed decisions allow us to address societal needs like energy production and affordable housing with the need to conserve biodiversity.

What constitutes an Important Plant Area

California’s Important Plant Areas (IPAs) are crucial to the conservation of the state’s botanical heritage. CNPS is not stating that areas that do not fit our criteria are not important, but through a rigorous data collection and modeling effort, we have determined IPAs to be particularly important for biodiversity conservation. Some of the general criteria that may define an IPA are: The presence of rare plant species, rare vegetation types, ethnobotanically/culturally important plant areas, areas with high levels of native plant species richness, large intact natural areas, areas of high biomass/carbon sinks, and/or areas of high habitat suitability for rare plant species. Each region varies drastically in physical and biological diversity, and our composite statewide map takes into account regional variance.

Important Plant Areas: California Central Valley Pilot Model Presentation

This presentation documents preliminary results from the CNPS Important Plant Areas Model for the California Central Valley. Modeling was conducted following a 2017 expert workshop in Bakersfield, CA. Iterations are based on feedback from internal CNPS review and feedback from the Technical Advisory Committee.These are preliminary results and will be reviewed by data contributors later this year during a demonstrative webinar (to be scheduled). The model will be reiterated and results updated based on feedback received. If you would like to learn more about the IPA model or are interested in reviewing IPA model results please contact Sam Young, Important Plant Areas Program Manager, at syoung@cnps.org.

Timeline of IPA Development

California Biodiversity Highlights

Channel Islands

Channel Islands

The Channel Islands represent a seaward extension of the transverse ranges. The Islands’ isolation from the mainland has resulted in a unique flora and fauna including 14 federally endangered plant species. Photo: Todd Keeler-Wolf

High Sierra

High Sierra

The rocky wall of the eastern Sierran slope forms a geographic barrier and creates climatic conditions which help to make California a global biodiversity hotspot. Photo: Jeff Bisbee

Monterey Peninsula

Monterey Peninsula

The Monterey Peninsula is home to numerous endemic species. The close proximity of rocky shores, sand dunes, rugged mountains, oak woodlands, and coast redwood canyons make the Monterey Peninsula truly unique. Photo: Carol Highsmith/PICRYL

Modoc Plateau

Modoc Plateau

Modoc Plateau is a unique landscape formed by extensive lava flows. The uplifted terrain forms a broad transition between the east slope of the Cascades and the northern Great Basin and Range province. Photo: Petr Brož/WikimediaCommons

Fern Canyon

Fern Canyon

With towering redwoods and stunning fern-covered walls, this canyon attracts thousands of visitors every year. Sharply transitioning from coastal dunes to prairie to redwood forest, California’s North Coast  is one of the centers for botanical endemism in California.  Photo from Public Domain

Torrey Pines State Reserve

Torrey Pines State Reserve

The Torrey pine (Pinus torreyana) is one of the rarest trees in the world, found only on Santa Rosa Island and the eponymous Torrey Pines State Reserve. The reserve is home to a variety of coastal habitats that are diminishing elsewhere in San Diego County. Photo: FeldBum/Wikimedia Commons

Mendocino Pygmy Forests

Mendocino Pygmy Forests

The rare Mendocino pygmy cypress woodlands are the product of nutrient poor acidic soils formed on marine terraces rising from the ocean like a giant sandstone staircase. Photo: Sam Young

Northern Baja California

Northern Baja California

Northern Baja California represents the southern boundary of the California Floristic Province as the climate shifts from Mediterranean to Desert. San Quintin is located near this transition, and hosts volcanic cones with endemic succulents and wetlands on the Ramsar List of Wetlands of International Importance. Photo: Sam Young

Joshua Tree

Joshua Tree

Joshua Tree National Park straddles the divide between the higher elevation Mojave Desert and lower, hotter Sonoran Desert. It boasts nearly 750 native species of vascular plants, so many that it was almost named Desert Plants National park. Photo: Sam Young

Carrizo Plain

Carrizo Plain

There are few places left in California where visitors can experience vast hillsides cloaked in a kaleidoscope of colors from a myriad of showy wildflowers. The Carrrizo Plain is also home to a herd of pronghorn and a newly re-introduced herd of tule elk. Carrizo is unique place where Californians can gain a glimpse of how the state used to be. Photo: Dan Gluesenkamp

Mather Field Vernal Pools

Mather Field Vernal Pools

Vernal pools fill with water in the rainy season and transform to concentric blooms of wildflowers in the spring. Special pools like those found at Mather Field feature a variety of plants and animals found nowhere else on Earth. Photo: Greg Suba

Klamath Mountains

Klamath Mountains

Proposed as a UNESCO biosphere reserve, the Klamath mountain ranges’ serpentine-rich, rugged terrain is home to globally significant biodiversity. Photo: Bob Wick

Sierra Foothills

Sierra Foothills

The western slope of the Sierra Nevada ranges spills into Cismontane California as the Sierran Block continues to tilt westward. The product of this are the rolling foothills which are home to a large variety of vegetation types which span both the elevational gradient between the Great Valley floor and California’s Sierran roof. Photo: Bob Wick

Coast Redwood Forest

Coast Redwood Forest

Coast Redwoods (Sequoia sempervirens) are the world’s tallest trees, relict from a cooler, wetter past. Now they are restricted to the foggy coasts from southern Oregon to Mendocino County with disjunct distributions in southern Marin County, the Santa Cruz Mountains, and the Big Sur coast on the rugged west slope of the Santa Lucias. Photo: National Park Service

Colorado Desert

Colorado Desert

Remnants of a more tropical past, California Fan Palm (Washingtonia filifera) oases have provided nourishment and refuge to wildlife and humans alike for thousands of years.

Bodie Hills

Bodie Hills

The Bodie Hills are an intact transition zone between the vegetation of the Sierra Nevada and Great Basin Desert, creating one of the highest levels of biodiversity present in the Great Basin region. Photo: Bob Wick

Tejon Ranch

Tejon Ranch

Tejon Ranch is one of the last great expanses of natural habitats on private land in Southern California. Located at the junction of five major ecoregions, it hosts more than 14 of the native California flora on just 0.25% of the state’s acreage. It is also one of the best places in California to see splendid displays of wildflowers. Photo: Nancy Buck

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