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Plant Communities in the Greater Sacramento Region

California’s plant life was, and still is, exceptionally diverse in two senses.  First, a very large number of plant species, many of them endemic (endemic is defined as , grow within the state’s borders.  Authorities list between 5,800 and 6,300 species.  Second, these species grow together in particular patters to form very many types of vegetation.  This diversity can be seen in the way the vegetation changes as one moves from valley to mountain, from north to south, and from moist coast to arid, rain-shadowed desert.

Vegetation can be divided into types, each having a characteristic physical structure.  Some of the major broad types are marsh, grassland, shrubland, woodland, and forest.  Vegetation types are in turn divided into plant communities.  A plant community is a distinctive grouping of plant species, defined as “an aggregation of living organisms having mutual relationships among themselves.”  Each plant community is distinguished by the presence of certain dominant or characteristic plant species.  For its size, California has one of the largest numbers of plant communities in the world, in part because of its varied climates, soils, and topographies.

(This is an exerpt from M. Kat Anderson's book: Tending the Wild, Native American Knowledge and the Management of California's Natural Resources.  About the book.)

Plant Communities described below are: California Prairie, Chaparral, Freshwater Marsh, Pine Hill Gabbro, Oak Woodland, Riparian Woodland, and Vernal Pool Prairie.

 

California Prairie

Description: Many open areas in our valleys and foothills are California prairie. Prairie, often called “grasslands”, is actually covered with a mixture of forbs (wildflowers) and grasses. Prairie is a much better name since most of its grasses are exotic weeds, while many of its forbs are native wildflowers.California Prairie

Interesting facts

  • Prairie soils do not support trees and shrubs because their hardpans and clay horizons keep most water too close the soil surface.
  • California prairie was once grazed by herds of tule elk and pronghorn antelope. Now much of it is grazed by cattle.
  • Some believe California prairie was once covered by bunchgrasses (which are now uncommon), but there is little documentation or evidence for this belief.

Why is this community important?

  • Numerous native plants, invertebrates, amphibians, reptiles, birds, and mammals are found only in California prairie.
  • It is important raptor hunting grounds. Some birds-of-prey use it year round, while others hunt there only in summer or in winter.
  • It is beautiful! If you’ve found a field of wildflowers, you’ve found California prairie.

Conservation Status and Threats: Many of our prairie areas have been lost to farming and urban development. Remaining California prairie is often denied attention and protection because of the myth that “it’s only weeds”, while its native forbs, wildflowers, and wildlife habitat are overlooked and undervalued.

 

Chaparral

Description: Chaparral is a community of mostly shrubs. Chaparral shrubs are evergreen, and have thick, leathery leaves with wManzanita in Chaparral photo by Chris Lewisaxy surfaces. Grasses and herbs are sparse or rare (except after a fire, when grasses and wildflowers briefly flourish).

Chaparral is fire-prone and typically burns every 10-40 years.

Interesting facts

  • Chaparral (composed of unrelated plant species) also grows in Mediterranean Europe, South Africa, Chile and Australia. These coastal areas all have mild, wet winters and dry summers.
  • Because chaparral has a low canopy and grows on steep slopes, chaparral fires are hot, hot, hot; temperatures may exceed 1,200° F!
  • Many chaparral plants have seeds will only grow after a fire, and some species rely entirely on those seeds for their persistence, because the adult plants do not survive fires.
  • Soils derived from serpentine rock are nutrient-poor (which makes it difficult for many plants to grow) and support distinctive plant communities, including plants that are found only these unusual soils.

 

Why is this community important?

  • Numerous native plants and animals are found only in chaparral.
  • Chaparral is the most extensive vegetation in many of our watersheds.
  • Chaparral fires affect the safety of many rural and suburban communities.

Conservation Status and Threats: For some types of chaparral, large areas have been conserved. For other types, little or no land has been conserved, especially at lower elevations. Thus, development is a major threat in the Sierra Nevada foothills, and fire management practices (including post-fire seeding for erosion control) can have a major effect on chaparral communities.

 

Freshwater Marsh

Description: Freshwater marshes include a diverse assortment of wetlands in California. One of the best examples of freshwater marsh in our area is the Sacramento – San Joaquin Delta.Freshwater Marsh

Interesting Facts

  • Freshwater marshes are dominated by emergent perennial plants, such as rushes, bulrushes (tules), sedges, cattails, willows and floating plants.
  • The water level in the delta marshes rise and fall, twice daily, with the tides, a difference of 2 to 5 feet.

Why is this community important?

  • The Delta freshwater marsh provided critical staging areas for some of the most threatened native resident and migratory fishes, such as salmon, smelt, steelhead, and green sturgeon, in California.
  • Freshwater marshes are valuable nesting, feeding and resting habitat for waterfowl, such as ducks, geese, swans, and, Sandhill cranes, and herons.
  • Wetlands are able to store water and reduce flooding.
  • Freshwater marsh plants protect levees from erosion (and flooding of Delta islands) in the Sacramento - San Joaquin Delta by calming wave forces.
  • Marsh plants improve water quality by trapping sediments in the water.

Conservation Status and Threats: Intensive agricultural development, levee construction, and water diversions have reduced freshwater marshes to less than 6 percent of their original extent in California. Although it has been heavily impacted by levee construction and urban water demands, the Delta wetland region remains a very important area for wildlife. Who would have thought? - waves from speedboats also threaten this habitat by eroding soils.

 

Pine Hill - Gabbro

Description: The Pine Hill gabbro soil “island” is a type of chaparral scrub in an area of unique geology with a suite of rare native plants. The 30,000 acre gabbro area is centered on Green Valley Road in El Dorado County, and stretches north from Cameron Park to Folsom Lake.

Interesting factsEl Dordado Mule-Ears

  • This volcanically-derived soil is an ecological island sandwiched between valley soils to the west, and mountain soils to the east.
  • Gabbro soils are uncommon because they are made from rocks formed deep under the earth’s crust and then lifted up to the surface (as the Sierra Nevada mountains were being formed). The resulting soil is generally red (from iron), mildly acidic, and often contains other heavy metals, such as chromium, and nutrient-poor.
  • Growing on these gabbro soils are a suite of eight rare plants, commonly referred to as the Pine Hill endemics because they grow nowhere else in the world. Almost all of these rare plants can be found on the short trail to the top of Pine Hill.
  • See http://www.pinehillpreserve.org/about/index.htm

Why is this community important?

  • 740 plant species – almost 10% of all California plant species! – have been recorded on the gabbro area and adjacent soils. Eight of these species are extremely rare and found nowhere else in the world. Thus this tiny portion of the state contains nationally significant species diversity.

Conservation Status and Threats: Housing and commercial development have threatened the continued existence of the Pine Hill endemics. The Pine Hill Preserve currently encompasses over 3,900 acres; the goal is to protect 5,000 acres when the Preserve is completed.

 

Oak Woodland

Description: Oak woodlands are defined as oak (Quercus spp.) stands with more than 10 percent canopy cover. The predominant oak species in the Central Valley include valley oak, blue oak, and interior live oak.Oak Beauty

Interesting Facts

  • Acorn crops can vary greatly from year to year. During “heavy” years, acorns can rain down from the trees, almost covering the ground beneath them. In “sparse” years, one can travel from tree to tree and have difficulty locating more than a handful.
  • A single acre of oak woodland may be home to 10 to 100 million types of insects and other invertebrates.
  • Oak gall wasps actually put the oaks to work for them by manipulating oak biochemistry to form galls, the curiously shaped, often brightly colored swellings that occur on oak leaves and twigs. The galls provide nutrients and protection for the wasp’s larvae.

Why is this community important?

  • Oaks and other hardwoods are found on over 21 million acres in California, occurring in 48 of the state’s 58 counties.
  • Oaks preserve water quality and increase water availability in California by filtering runoff.
  • Healthy perennial oak grasslands provide excellent protection from erosion, and produce a much lower fire fuel load potential.

Conservation Status and Threats:

  • Approximately 80% of hardwood rangelands are in private ownership; therefore wildlife conservation will depend in large part on the activities of private landowners.
  • The principle threat to oak woodlands in the Central Valley comes from residential development and intensive agriculture conversion.

 

Riparian Woodland

Description: Riparian areas are the green, vegetated areas on each side of streams and rivers. In the central valley, riparian areas are usually dominated with trees and shrubs of varying heights, creating a “layered” diversity of habitats.Riparian Woodland

Interesting Facts

  • Riparian plants are highly adapted to flooding. Their stems are flexible to bend with high flows, and broken twigs and branches are often able to grow roots and plant themselves in the mud. Their seeds often float and/or require being buried by the dynamic movement of sand, silt and gravel.
  • Riparian areas support a diversity of plant and wildlife species and are second only to rain forests in their biodiversity.

Why is this community important?

  • Roots of native riparian plants, trap sediments, improving water quality, while stabilizing banks and reducing erosion.
  • Roots, stems, and in-stream wood maintain a habitat for aquatic invertebrates and healthy fish populations.
  • Riparian areas provide water, forage, and shade for fish and wildlife, as well as creating opportunities for fishing, camping, bird-watching and other recreational activities.

Conservation Status and Threats: Riparian woodlands are a dwindling treasure here in the Central Valley of California and all over the world where rivers meet humanity. Some studies have estimated that between 89 and 96 percent of riparian areas have been lost due to agriculture, urban development, gravel mining, dams, and levees.

 

Vernal Pool Prairie

Mather Vernal PoolsDescription: A vernal pool is a temporary wetland (generally in grassland or prairie) that fills with water during the rainy season and dries down in the spring. It remains dry for six to eight months awaiting the next winter rains. It is home to an assemblage of specially adapted flora and fauna.

Interesting Facts

  • The plants and animals are adapted to survive annual extremes of winter floods and summer drought.
  • From November through March, aquatic life races against the clock (and their predators) to grow up, mate and lay eggs before the pools dry up.
  • In April, vernal pool flowers create colorful concentric rings, patches, and ribbons of yellow, white, pink, and purple.
  • During the hot, dry summer months vernal pools appear brown and barren among the grasslands, however their sun-baked bottoms hold the eggs, cysts and seeds to restart the cycle during the next winter rains.

Why is this community important?

  • Over 200 plant species grow in vernal pool, and half of these are rarely found outside this unique habitat. 
  • A given pool typically supports only 15 to 20 species, in an unpredictable array of combinations. In that way vernal pools are a lot like snowflakes – botanically speaking, no two are alike.

CONSERVATION STATUS AND THREATS: Approximately 90 percent of California’s vernal pools have been destroyed. In the Sacramento Valley, the small amount of remaining habitat is being further damaged or lost due to impacts of urban growth and vineyard expansion.