Appreciating the magic of Sonoma County's vernal pools

These habitats in our region are home to plants with innovative strategies for survival, including our county's rare and showy plant, Sonoma Sunshine.|

A rare and showy plant is blooming right now. Its name is “Sonoma Sunshine” (Blennosperma bakeri), and it is aptly labeled, as it beams a brilliant shade of yellow. What makes this plant so special is that the world’s entire population is right here in Sonoma County, and it occupies a unique and often overlooked habitat in our region: vernal pools.

Vernal pools are places on the landscape that hold water in spring but dry up completely in summer. If you think about it, that’s a hard place to be a plant, so vernal pools are home to plants with innovative strategies for survival. Most of them are annuals, meaning they go through their entire life cycle in one season and survive the hot, dry summer season as seeds.

Sonoma Sunshine is one of these.

In the early spring the seeds germinate in the shallow saturated waters of the vernal pool and send roots down and leaves upward. The plant grows quickly in full knowledge that its time is limited. It reaches up toward the sky and develops its showy daisy-like flower. And then it waits.

If lucky, the plant is in a vernal pool with a large seed bank producing hundreds of other Sonoma Sunshine, because when they all bloom together they make a large enough display to attract bees and other pollinators.

For vernal pools, very specific bees called solitary bees are key. Solitary bees nest in the ground near vernal pools and are built to carry the pollen of species like Sonoma Sunshine. This fact means that vernal pools and the uplands around the pool are inextricably tied together.

Once a plant receives pollen from a neighbor, it can produce a seed, essentially giving birth to the next generation. Shortly after the seed is set, the water in the vernal pool succumbs to evaporation as summer days lengthen and warm, the pond dries up and the parent plant dies. The seeds can lay dormant for months, keeping the plant population intact until the rainy season returns and the cycle repeats.

Sonoma Sunshine and solitary bees are not the only beneficiaries of vernal pools. Burke’s goldfields, Sebastopol meadowfoam, tiger salamanders, fairy shrimp and several other rare and endangered plants and animals share this wetland habitat and have similarly mind-bending adaptations to the wet-then-dry environment.

Vernal pool habitat is severely threatened. More than 90 percent of this habitat type in California has been lost, mostly to development and agricultural conversion. In many cases, vernal pools are impacted by landowners who unknowingly build ditches to dry the land for hay pastures, excavate them to create ponds or fill them to create roads or parking areas.

In Sonoma County, most of the remaining vernal pools are in Sonoma Valley and on the Santa Rosa Plain in the Laguna de Santa Rosa watershed. The world’s population of Sonoma Sunshine occupies just 23 of these sites, including one at our very own Sonoma Valley Regional Park. Together with partner organizations like the Laguna Foundation and Bouverie Preserve, we are working to monitor, protect and steward this precious resource.

These seasonal wetlands are amazing jewels dotting our landscape and yet much of the year they are nearly invisible. Now is the time to look around and notice the vernal pools near you.

Melanie Parker is the Natural Resource Manager for Sonoma County Regional Parks.

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