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Valley Grassland

The Valley Grassland plant community is a result of a few soil/water issues.

1. Seasonal flooding.

An account from an early American explorer:

“We again looked toward the north, and between the low range to the northwest and the Sierra Nevada we saw an immense plain [Footnote 380] which on that side apparently ran in the same direction as the Sierra Nevada; but on the other side it opened about to the west, with such a sweep that it embraced almost the entire semicircle of the horizon. This is the plain through which the sea of fresh water extends, not continuously but in places leaving great areas uncovered or with little water, forming those great green tulares that begin near the mission of San Luis. According to their direction and to this account they must be more than a hundred leagues long to this place, not counting the distance which they may extend above, for we were unable to see their terminus, and in width they must be some twenty-five or thirty leagues. I surmised that these tulares must run to the vicinity of the port of Bodega, and that the green field which Captain Don Juan de la Quadra saw to the east of his port must have been tulares like these which we saw here, or that they might even have been the same ones, extending as far as that place. “ Font, 1776[a league is 3 miles]

2. In late spring the soil drains and becomes very dry and alkaline in a matter of weeks.

“All the ground was covered, not with grass and green leaves, but with radiant corollas, about ankle-deep next to the foothills, knee-deep or more five or six miles out. Here were bhia, maderia, burielia, chrysopsis, corethgyne, grindella, etc., growing in close social congregations of various shades of yellow, blending finely with the purples of clarkia, orthocarpus, and oenothera, whose delicate petals were drinking the vital sunbeams without giving back any sparkling glow.
Because so long a period of extreme drought succeeds the rainy season, most of the vegetation is composed of annuals, which spring up simultaneously, and bloom together at about the same height above the ground, the general surface being but slightly ruffled by the taller Phacelias, Penstemons, and groups of Salvia carduacea, the king of the annuals.” Muir

3. Some areas of the oak woodland plant communities can have pockets of grassland where the soil is too shallow to support trees.

These areas are probably not a true grassland either, more like a grass, bulb, forb and wildflower land. They are a part of the oak savanna and woodland.

4. Many areas (particularly within the San Joaquin Valley) have high boron or sodium soils.

High amounts of boron (5 ppm or more) or sodium(250 ppm or more) or other element imbalance severely limit evergreen bushes and trees. Short-lived perennials, grasses and wildflowers can get around the problem by flourishing in spring after the winter rains have diluted the salt content down to a more reasonable number. As the soil dries out, the salts come back to the surface and these plants shut down and go dormant. The areas right along the coast that have this soil problem are called coastal prairie.

5. Many areas of the Valley Grassland plant community may have been freshwater marshlands.

We know the Sierran snow melt filled up much of the Sacramento and San Joaquin valley floors; there is just not enough information as to how much it filled and how long the water stood. If the soil stood for a month under water, it was probably a grassland. If the soil stood for three months or more it was probably more a seasonal marsh. Anza's men measured an ebb and flow of 8 or 9 feet within the 'vast inland freshwater sea' and it was approximately “breadth some twenty-five or thirty leagues”[league=three miles] wide. Now the valley floor from his vantage point was only about 70 miles wide, so the water must have been present from the Sierran foothills to the coastal foothills. In a high snowfall year with a warm spring as Font saw it the water level in the San Joaquin Valley may have been to 60-70 feet above sea level (about the elevation of Los Banos).

6. The historic data of what and where the grasslands of California were is very poor, maybe non-existent.

Just a few words. It was discovered by Europeans in 1776 and almost completely destroyed ( drained and plowed ) by 1840 or 1850. It was one of the largest marshlands for waterfowl in North America; now ,it is but a minuscule patch of its former self.

To plant a Valley Grassland plant community in your garden, you will need shallow soil, and/or soil with high boron or high sodium, or low rainfall, (in other words , be a valley resident!) to make the best plant community. But you will still have to weed a lot! If you can suppress the weeds for three years, you may have a chance at a fairly stable plant community. If you live in the Sacramento or San Joaquin Valleys you are one of the luckiest people ever, because you can grow one of the rarest plant communities in the world! In other areas of California, without the distinct soil and climate conditions, you can grow this plant community but you will be constantly weeding out the large weeds, alien grasses, and weedy trees that find their way there.

Annual precipitation:

7-35 inches

Common Animals

Coyote, Western meadowlark, Burrowing owl, Cottontail rabbit

Common Plants:

annual wildflowers, some rushes (Juncus spp.) and sedges (Carex spp.), Needlegrass (Stipa (Nassella)spp.) and Bluegrass (Poa spp.)

Soil and climate notes:

An area of poor drainage, wet in winter(often under water) dry in summer. Rushes, sedges in winter, wildflowers in late spring, bunch grasses in summer, baked salt flats in fall.

Valley Grassland would have been better named Valley Wildflower Marshes, or Valley Seasonal Flood Plain because for the most part, grasses were not a major component of the plant community. This plant community is commonly misunderstood and misrepresented in its species composition and ecology. It was Not like the prairie of the midwest.

This is a map of the areas of California that are now probably Valley Grassland. Before 1830, the middle areas, maybe all but the edge dots were freshwater marshes.

Towns like Terra Bella or Davis come to mind.

(Again, you only find a grassland in patches in California, in areas of high sodium or high boron, shallow soils, or serpentine, or another element imbalance, or seasonally flooded for a short period of time)


A list of California native plants that grow in the Valley Grassland plant community.

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Edited on Jan 12, 2013. Authors:
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