A California Treasure: Conserved

Jepson Prairie Preserve is owned and managed by the Solano Land Trust, the Nature Conservancy and an active docents group. It is a living laboratory for University of California researchers and students as part of their Nature Reserve System and a treasure for the public who come to enjoy the flush of wildflowers, birds and open spaces. The Preserve supports a strong docent program to educate the public on the value of this undisturbed sample of the state’s natural prairie system, leading tours in the spring months. It is open for visitors year-round.

In a small corner of Northern California’s central valley, parched brown fields lie tucked between gently rolling farmlands. For 5 months of the year, the area is pleasant but unremarkable. Surrounded by small towns and agriculture, most people drive by without knowing about the treasures lying just over the fence line.

Then, coming over the rise in early spring after the winter rains, you’ll see a transformed panorama of lush-green Purple needlegrass meadows and riotous patches of bright yellow Goldfields and Yellow Carpet, Mariposa lilies, and sky-blue Downingia. It is a place that for the best views and most interesting photographs one has to tread carefully and lie on one’s belly in the soft grasses.

I am fortunate to live in an area rich with protected natural spaces, including this local and unassuming flat grassland in California’s Central Valley, the Jepson Prairie Preserve. This small reserve (634 hectares) protects the best remaining undisturbed sample of one of California’s most interesting and unique natural ecosystems of clay-pan vernal pools and native forb and bunchgrass prairie habitats, and is refuge to a surprising number of rare and endangered endemic plants and animals.

Vernal Pool Goldfields (Lasthenia fremontii). Jepson Prairie Preserve, April 2018.

Collecting water in the same location since the last ice age, Jepson Prairie comes alive from February through May. The playa lake Olcott fills with water and then birds, salamanders, shrimp, and insects, and the land is covered with tiny ground-growing flowers that bloom in successional waves around the vernal pools.

In early California history, vernal pools and native bunchgrass prairie habitats could be found across the Great Central Valley. Today, only a small fraction of those habitats survived the millions of people moving into the state. The extensive system of vernal pools supporting millions of migrating birds was plowed and planted into the rich agricultural lands we know now.

American avocets (Recurvirostra americana) feeding on invertebrates in Olcott lake, April 2018. This playa lake provide an important layover for migrating birds, especially critical now because they have lost their extensive feeding grounds along the Central Valley which have been converted to agriculture over the past century.

By protecting this unique ecosystem, Jepson Prairie Preserve provides wetland habitat for millions of migrating waterfowl and wading birds. It supports over 400 species of plants – of which 15 species are rare and endangered, including Bogg’s Lake hedge-hyssop, dwarf Downingia, Baker’s navarretia, Colusa grass, and Solano grass.

Included in the list of 5 rare, threatened and endangered animals protected by the reserve is the Delta green ground beetle which is known only from the 10 square-mile area surrounding Jepson Prairie. Also endemic and endangered are vernal pool fairy shrimp, Conservancy fairy shrimp, vernal pool tadpole shrimp, and the California tiger salamander, which emerges with the rains and quickly reproduces before the next dry season which could last for years.

The stunning waves of flowers attract spring visitors and docent tours, but perhaps just as importantly the flowers support solitary ground bees. University of California research has shown an incredible diversity of bee species endemic to vernal pool habitats. They synchronize their life-cycles and are vital cross-pollinators to the succession of vernal pool flowers including Yellow Carpet, Meadowfoam, Goldfields, and Downingia (UC Davis Natural Reserves link). Some of these bee species are single species pollinators and rely on a specific species of flower found only near vernal pools.

All of these plants and animals rely on a carefully evolved and dependable timeline of rain, blooming, feeding, breeding and migrating. The climate crisis has recently been changing that fine-tuned system. The Jepson Prairie area now has unpredictable periods of high heat in the spring, rains in summer, more frequent years-long droughts, and unusual cold spells in the late spring and summer, even snow in the nearby, low-elevation coastal range. Fortunately, through the work of dedicated volunteers and generous land purchases, the unique ecosystems of Jepson Prairie are being protected and managed to preserve the remarkable plants and animals that have adapted to these harsh cycles of plentiful or scarce water availability.

I am hopeful the Jepson Prairie Preserve will survive and thrive through the changing climate with its strong system of support from the Nature Conservancy’s visionary land purchase in 1980, Solano Land Trust’s management and stewardship, the committed docents, and the inclusion of the Preserve in the University of California’s system of natural reserves.

For more information visit the Jepson Prairie website, or see the excellent field guide produced by the Jepson Prairie docents “Jepson Prairie Preserve Handbook” to learn about the natural history, geography, plant and animal species, cultural significance, and conservation of this area.

A Western Meadowlark (Sturnella neglecta) singing from a Jepson Prairie Preserve fence post, March 2021. In the background lies the dry lakebed of Olcott lake. In a normal year during the month of March, this area would be brimming with water and migrating birds.

Photos by Kathy West, ©2018 and ©2021.

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