Water & Drought

Getting in touch with our California prairie

Valley oak: Often hundreds of years old, these huge evergreen trees provide habitat for many species of California prairie wildlife.
Valley oak: Often hundreds of years old, these huge evergreen trees provide habitat for many species of California prairie wildlife. Bee file

In the natural scheme of things, where does Sacramento belong? That ecological question has puzzled botanists since the 1800s. Some thought the Central Valley shared similarities with Nebraska. Others described our vegetation as all desert chaparral. In reality, we’re neither Midwest grassland nor Mexican desert, but something unique. Think of the Central Valley as California prairie.

In light of California’s prolonged drought, that description has become an important consideration for homeowners, landscapers and restoration experts as they try to find the right plants to grow here – with less water.

We live in a Mediterranean climate, but that describes weather, not landscape. Like similar regions, we’re (normally) wet in winter, dry in summer.

Central Valley soils – clay, loamy, rocky – push us into a temperate prairie profile, but with a few twists. “People are puzzled by these anomalies,” said botanist Glen Holstein of the California Native Plant Society. “Rain doesn’t fall when plants need it most, so they’re much more dependent on soil here than the rest of the country.”

That heavy clay soil that’s a bane to Sacramento gardeners and a necessity for rice farming also is key to our eco-region’s identity. Clay holds tight to any moisture it gets, helping native plants survive those dry summer months.

“It’s important to look at the soil,” Holstein said. “Prairie plants do best with clay soil. It holds water close to the surface. These plants have shallow roots. Trees and shrubs (with deeper roots) need more porous, rocky soil.”

California prairie originally stretched over much of the Central Valley, identified by the World Wildlife Fund as an endangered eco-region. Farming and development dramatically changed the terrain. “The Central Valley originally was a vast floodplain interspersed with raised areas of Valley oak woodland and bunchgrasses,” said Ellen Zagory, director of public horticulture for the UC Davis Arboretum. “The permanently wet areas were tules – giant impenetrable areas of mud and water – while the raised areas were the sites of villages. These floodplains were threaded with rivers with riparian vegetation.”

Bordering the floodplain is shrubland with rockier soils. It supports woody plants that need excellent drainage, something shrubs don’t get in clay soil.

“Prairie” – French for “meadow” – is preferable to “grassland,” Holstein said. “The myth is that the Valley was all native bunchgrasses, but actually wildflowers covered the floor of the Valley.”

Native plants evolved here over thousands of years, surviving dry summers without additional irrigation, he added. “These plants adapted to a place with long droughts in the past, and there will be more droughts in the future.”

Debbie Arrington: (916) 321-1075

Central Valley icons

Valley oak: Often hundreds of years old, these huge deciduous trees provide habitat for many species of California prairie wildlife.

Tule: This giant sedge covered Central Valley marshes. An important plant for California native tribes, it provided food, shelter, clothing, transportation and more.

Native plants reflect their soil

Prairie: Heavy clay soil is ideal for plants with shallow roots.

Examples:

Ithuriel’s Spear (Triteleia laxa)

Narrow-leaved mule’s ear (Wyethia angustifolia)

Purple needlegrass (Nassella pulchra)

Virgate tarplant (Holocarpha virgata)

Riverland: Rich loamy soil and available water make for abundant trees and fast-growing vines.

Examples:

California pipevine (Aristolochia californica)

California wild grape (Vitis californica)

Willow (Salix, several species)

Shrubland: Rocky soil with fast drainage is preferred by shrubs and trees as well as many perennials.

Examples:

Silver bush lupine (Lupinus albifrons)

Toyon (Heteromeles arbutifolia)

Western redbud (Cercis occidentalis)

For more on these plants, go to www.sacvalleycnps.org

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