Biodiversity Hotspots of the World (2 of 36): California Floristic Province

In every walk with nature one receives far more than he seeks

— John Muir

The Scottish-American naturalist and author John Muir was so inspired by the beauty of the forests of the western United States that he became a passionate advocate for the protection of these iconic landscapes. His advocacy work led to the formal protection of areas that we now know as the Yosemite Valley and Sequoia National Park. Today, over a hundred years after Muir’s death in 1914, this land is part of a biodiversity hotspot known as the California Floristic Province.

I grew up in the San Francisco Bay Area and have visited California on a regular basis even after moving to New Mexico in 2000. Over the years, I’ve been fortunate to visit many of the state parks and National Wildlife Refuges of California. I’ve long known that this landscape was special. Yet, I had never heard of the term “California Floristic Province” until a few years ago.

Map of the California Floristic Province Biodiversity Hotspot, from the Critical Ecosystem Partnership Fund (CEPF)

The California Floristic Province biodiversity hotspot runs along the California coast, extending into Oregon and Mexico. It also extends inland to Carson City, Nevada, encompassing the Sierra Nevada mountains, Transverse Ranges of southern California, the Coast Ranges, and the Klamath-Siskiyou Mountains of northwest California and southwest Oregon.

This biodiversity hotspot boasts a wide range of habitat types. These include sagebrush steppe, prickly pear shrubland, coastal sage scrub, chaparral, juniper-pine woodland, upper montane-subalpine forest, alpine forest, riparian forest, cypress forests, mixed evergreen forests, Douglas fir forests, sequoia forests, redwood forests, coastal dunes, and salt marshes. The region has a Mediterranean climate with summers that are hot and dry, and winters that are cool and wet.

What makes this area a biodiversity hotspot are its plants. The California Floristic Province features over 8,000 species of plants. Over 3,400 of these plant species are found nowhere else on Earth. This includes two famous, endangered tree species: the giant sequoia (Sequoiadendron giganteum) and the coast redwood (Sequoia sempervirens). Giant sequoias are the most massive tree species ever to live on Earth. In Sequoia National Park, you can find the world’s largest tree measured by volume. Known as the General Sherman tree, it is roughly 2,200 years old, stands 275 feet tall, has a circumference of 102 feet, and weighs 2.7 million lbs. Not to be outdone, the coast redwoods are slimmer but reach greater heights of up to 350 feet. These are awe-inspiring trees.

Giant sequoia trees in Sequoia National Park in California can reach up to 275 feet in height.

With such a large variety of habitat types, it’s no surprise to learn that many species of animals call the California Floristic Province home. But, compared to the plants, the animals have much lower rates of endemism, with the notable exception of amphibians. Scientists have recorded 340 bird species (10 endemic), 150 mammal species (20 endemic), 70 reptile species (4 endemic), 50 amphibian species (25 endemic) in the hotspot. Insects are also prolific in the California Floristic Province. There are an estimated 28,000 species of insects and 32% of these are endemic. This represents roughly one-third of all known insects in the United States and Canada.

Some of more well-known animal residents in the region include the Critically Endangered California condor (Gymnogyps californianus), Endangered giant kangaroo rat (Dipodomys ingens), desert slender salamander (Batrachoseps major aridus), kit fox (Vulpes macrotis), island fox (Urocyon littoralis), Roosevelt’s elk (Cervus elaphus roosevelti), and tule elk (Cervus elaphus nannodes).

In the 1980s, there were only 22 California condors. Today there are around 230 free-flying California condors in California, Arizona, and Baja California, with another 160 in captivity.

Conservation Status

If California was a country, it would rank as the 5th largest economy in the world. Despite it wealth, the State of California is one of the four most ecologically degraded states in the United States. This is due to habitat loss, expansion of large-scale agriculture, strip mining, oil extraction, invasive species, road construction, livestock grazing, logging, suppression of natural fires, urbanization, and other human population pressures in the nation’s most populous state.

Today, only about 25% of the original vegetation remains in pristine condition. Two of the hardest hit ecosystems include native grasslands and vernal pools, which have been reduced to 1% of their original area. Logging operations have reduced the distribution of redwood forests by 85%. Only 10% of the original wetlands, riparian woodlands, and southern maritime sage scrub remain. And while the grizzly bear is the state symbol featured on the California state flag, the last grizzly bear in California was shot in 1920. Similarly, the grey wolf, jaguar, and bison are no longer found in California. These massive declines, combined with the high levels of endemic species, are the reasons why the California Floristic Province is one of the 36 biodiversity hotspots of the world.

California state flag featuring the California grizzly bear. The last grizzly bear in California was shot by a hunter in 1920.

Unfortunately, these declines aren’t limited to the state of California. Guadalupe Island, a volcanic island in the Mexico portion of the California Floristic Province, has also experienced significant conservation challenges. Nearly 16% of the plant species on the island are endemic. Unfortunately, the release of feral goats in the early 19th century decimated many plant species. At least 26 native plant species have eradicated from the island. To make matters worse, over 60 exotic plant species, such as aggressive weeds, are now on the island.

Travel and Tourism

With nine national parks (Channel Islands, Death Valley, Joshua Tree, Kings Canyon, Lassen Volcanic, Pinnacles, Redwood, Sequoia, and Yosemite), 280 state parks39 National Wildlife Refuges, four National Marine Sanctuaries, and the Point Reyes National Seashore, it will take you awhile to run out of places to view wildlife in California. You can also explore the Lake Tahoe area and cross into the Nevada portion of the California Floristic Province around Reno and Carson City.

In southwestern Oregon a northwestern California, a great place to visit is the Klamath-Siskiyou region, the wildest place left on the west coast of the United States. It has a larger concentration of roadless wildlands and intact watersheds than anywhere else on the west coast. The Klamath-Siskiyou region has been proposed as both a World Heritage Site and UNESCO Biosphere Reserve.

The Baja California, Mexico portion of the California Floristic Province extends south from the California border to an area north of El Rosario. This includes the pine-oak forests of Sierra Juarez and the Sierra San Pedro Martir. Much of this habitat is intact as the mountains are difficult to access. These conifer forests are the only multi-species Mediterranean-climate forests in Mexico.

Guadalupe Island, Mexico is one of the best places in the world to view a great white shark (Carcharodon carcharias).

Guadalupe Island, Mexico is home to about 150 permanent residents. They are mostly lobster and abalone fisherman, goat farmers, and military personnel. The island is one of the best places in the world to view the great white shark. But it’s not the easiest place to get to. Guadalupe island is considered a biosphere reserve so you’ll need to get a permit from the Mexican government if you would like to visit. But, if you’re not concerned with staying on the island and only want to experience a cage dive in one of the world’s top shark diving destinations, then you have some options. Catch a boat from San Diego, CA or Ensenada, Mexico as your launching point for an adrenaline-filled experience. The boat journey takes about 18 – 22 hours and you’ll be living on the boat for a total of 3-5 days. The boats only run from August to October, when the water temperatures hit the sweet spot to attract great white sharks. About 170-180 individual great White sharks visit the water around Guadalupe Island each year.

Coming Attractions

I hope you enjoyed this introduction to the California Floristic Province biodiversity hotspot! Next stop, the Cape Floristic Region of South Africa.

Thanks for reading!


Author: Mark Aspelin

Mark Aspelin is a freelance nature, health, and travel writer who helps people become more engaged in biodiversity conservation and live a lifestyle that optimizes physical and mental health. Mark has worked as a conservation biologist, healthcare project manager, certified personal trainer, and he's the author of over 50 blog posts and articles and two highly rated books: “Profitable Conservation: Business Strategies That Boost Your Bottom Line, Protect Wildlife, and Conserve Biodiversity” and “How to Fail at Life: Lessons for the Next Generation”. He has a B.S. in Biology from the University of Notre Dame, M.S. in Biology from Creighton University, and MBA from the University of Texas at Austin. Mark has worked with a wide variety of organizations such as The Nature Conservancy, The Coca-Cola Company, Intel Corporation, Molina Healthcare, United HealthGroup, and The International Crane Foundation, and his articles and interviews have been featured by GreenBiz, Inside EPA, Perceptive Travel, and the E.O. Wilson Biodiversity Foundation’s Half-Earth Project. Mark is also an avid traveler who has visited over 100 countries and all 50 U.S. States and he lives in the mountains outside of Albuquerque, New Mexico.

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