California Central Valley grasslands

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California Central Valley grasslands
Waterfowl-Central Valley 152 (19566364770).jpg
Waterfowl in the Central Valley wetlands
California Central Valley Grasslands map.svg
Location of the California Central Valley grasslands
Ecology
Realm Nearctic
Biome temperate grasslands, savannas, and shrublands
Borders California interior chaparral and woodlands
Bird species184 [1]
Mammal species79 [1]
Geography
Area46,275 km2 (17,867 sq mi)
CountryUnited States
State California
Coordinates 37°00′N120°18′W / 37°N 120.3°W / 37; -120.3 [2]
Climate type Mediterranean (Csa)
Conservation
Conservation status Critical/endangered [3]
Protected1,935 km2 (4%) [4]

The California Central Valley grasslands is a temperate grasslands, savannas, and shrublands ecoregion in California's Central Valley. It a diverse ecoregion containing areas of desert grassland (at the southern end), prairie, savanna, riparian forest, marsh, several types of seasonal vernal pools, and large lakes such as now-dry Tulare Lake (which was the largest freshwater lake in the United States west of the Mississippi), Buena Vista Lake, and Kern Lake.

Contents

The Central Valley has been greatly altered by human activity. Most of the land has been converted to farms, pastureland, or cities. Most of the valley's wetlands have been drained. The introduction of exotic plants, especially grasses, has altered the region's ecology.

Geography

Central Valley seen from space. Central Valley STS040-609-38.jpg
Central Valley seen from space.

The ecoregion covers an area of 46,275 km2. It extends north–south through California's Central Valley. The valley is ringed with mountains – the Sierra Nevada to the east, and the Coast Ranges to the west.[ citation needed ]

The grasslands ecoregion occupies the valley floor, which is mostly flat or gently rolling. The oak woodlands and chaparral that fringe the valley constitute the California interior chaparral and woodlands ecoregion. [3]

The northern portion of the valley, known as the Sacramento Valley, is drained by the Sacramento River and its tributaries. The San Joaquin River and its tributaries drain most of the southern portion of the valley, which is known as the San Joaquin Valley. The Sacramento and San Joaquin rivers flow into a large inland delta before they empty westwards into the Pacific Ocean via San Francisco Bay, which occupies a gap in the Coast Ranges.[ citation needed ]

The volume of water carried by the rivers varies seasonally, increasing with winter rains and spring snowmelt from the Sierra Nevada, and decreasing during the drier summer and fall months. The rivers used to form broad seasonal wetlands, which would flood in the winter and spring and dry out in the summer and fall. Smaller vernal pools form in poorly-drained areas during the wet season. The annual precipitation also recharged a large freshwater aquifer under the valley.[ citation needed ]

Upstream dams now regulate the annual water flows on many of the valley's rivers, impounding spring runoff to use for summer irrigation. Many of the seasonal wetlands, including most of the former delta wetlands, have been drained for agriculture, and the rivers contained in levees. The aquifer underlying the valley is also heavily tapped for irrigation and urban water, and in the past century the water table has dropped enormously across much of the valley.[ citation needed ]

The southernmost portion of the valley is a closed basin which emptied into Tulare Lake, Buena Vista Lake, and Kern Lake. These lakes and the surrounding seasonal wetlands have now mostly been drained and converted to cropland.[ citation needed ]

Climate

The ecoregion has a temperate Mediterranean climate, with most of the annual rainfall occurring during the winter months. Rainfall generally decreases from north to south. The western side of the valley, which is in the rain shadow of the Coast Ranges, is generally drier than the eastern side.[ citation needed ]

Flora

The dominant grasses in the moister areas of the valley were perennial bunch grasses, including Nassella pulchra mixed with other species. In the more extensive arid central regions this was probably not the case. [5] Native species were adapted to cool-season growth during the wet winter months. Introduced annual grasses, which germinate at the onset of the rainy season and set seed then die during the summer drought, now dominate most valley grasslands. Grassland wildflowers include California poppy (Eschscholzia californica), lupines, and purple owl's clover ( Castilleja exserta ), which can still be seen, especially in the Tehachapi Mountains and Antelope Valley south of the valley, and the Carrizo Plain southwest of the valley, where they create colorful springtime blooms. [3]

Riverside trees include willows, western sycamore ( Platanus racemosa ), box elder ( Acer negundo ), Fremont cottonwood ( Populus fremontii ), and valley oak ( Quercus lobata ). [3]

Fauna

The Central Valley was once home to large populations of pronghorn antelope (Antilocapra americana), elk including the endemic tule elk subspecies (Cervus elaphus nannodes), mule deer (Odocoileus hemionus), California ground squirrels, gophers, mice, hare, rabbits and kangaroo rats. Several species or subspecies of rodents are endemic or near-endemic to the southern valley habitats, including the Fresno kangaroo rat (Dipodomys nitratoides exilis), Tipton kangaroo rat (Dipodomys nitratoides nitratoides), San Joaquin pocket mouse (Perognathus inornatus), and giant kangaroo rat (Dipodomys ingens). The San Joaquin kit fox (Vulpes macrotis mutica) is an endangered subspecies surviving on the hillsides of the San Joaquin Valley. [3]

The wetlands of the Valley were an important habitat for wintering waterbirds and migrating birds along the Pacific flyway. Three birds are nearly endemic to the ecoregion – the yellow-billed magpie (Pica nuttalli), tricolored blackbird (Agelaius tricolor), and Nuttall's woodpecker (Picoides nuttalii). [3]

Reptiles and amphibians of the valley include the endemic San Joaquin coachwhip snake ( Masticophis flagellum ruddocki), blunt-nosed leopard lizard (Gambelia sila), Gilbert's skink (Eumeces gilberti) and the western aquatic garter snake (Thamnophis couchii). There are also a number of endemic invertebrates. [3]

The Central Valley is also home to a wide variety of endemic fish species, including the Sacramento pikeminnow, Sacramento perch, Sacramento blackfish, and Sacramento splittail, among others. [3]

Protected areas

1,935 km2, or 4%, of the ecoregion is in protected areas. 3% of the area outside protected areas remains in grassland or other undeveloped habitat. [4] Most of the protected and undeveloped area is dominated by introduced species, with smaller areas of relatively intact habitat. [3]

The Great Valley Grasslands State Park preserves an example of the habitat in the valley, while oak savanna habitats remain near Visalia. There are areas of wetland and riverside woodland in the north especially on the Sacramento River system including the Nature Conservancy's Cosumnes River Preserve just south of Sacramento, Gray Lodge Wildlife Area, Butte Sink Wildlife Management Area, and other patches in the delta area. Remaining vernal pools include Pixley National Wildlife Refuge between Tulare, and Bakersfield and Jepson Prairie Preserve in the delta. There are large blocks of desert scrubland in the southern San Joaquin Valley and in the Carrizo Plain, a basin lying southwest of the Central Valley in the Coast Ranges which has a similar climate and landscape.[ citation needed ]

Related Research Articles

<span class="mw-page-title-main">Central Valley (California)</span> Flat valley that dominates central California

The Central Valley is a broad, elongated, flat valley that dominates the interior of California. It is 40–60 mi (60–100 km) wide and runs approximately 450 mi (720 km) from north-northwest to south-southeast, inland from and parallel to the Pacific coast of the state. It covers approximately 18,000 sq mi (47,000 km2), about 11% of California's land area. The valley is bounded by the Coast Ranges to the west and the Sierra Nevada to the east.

<span class="mw-page-title-main">San Joaquin River</span> Longest river of Central California, United States

The San Joaquin River is the longest river of Central California. The 366-mile (589 km) long river starts in the high Sierra Nevada, and flows through the rich agricultural region of the northern San Joaquin Valley before reaching Suisun Bay, San Francisco Bay, and the Pacific Ocean. An important source of irrigation water as well as a wildlife corridor, the San Joaquin is among the most heavily dammed and diverted of California's rivers.

<span class="mw-page-title-main">Giant kangaroo rat</span> Species of rodent

The giant kangaroo rat is an endangered species of heteromyid rodent endemic to California.

<span class="mw-page-title-main">Llanos</span> Tropical grassland ecoregion in Colombia and Venezuela

The Llanos is a vast tropical grassland plain situated to the east of the Andes in Colombia and Venezuela, in northwestern South America. It is an ecoregion of the tropical and subtropical grasslands, savannas, and shrublands biome.

<span class="mw-page-title-main">Vernal pool</span> Seasonal pools of water that provide habitat

Vernal pools, also called vernal ponds or ephemeral pools, are seasonal pools of water that provide habitat for distinctive plants and animals. They are considered to be a distinctive type of wetland usually devoid of fish, and thus allow the safe development of natal amphibian and insect species unable to withstand competition or predation by fish. Certain tropical fish lineages have however adapted to this habitat specifically.

<span class="mw-page-title-main">Yolo Bypass</span> Flood bypass in the Sacramento Valley

The Yolo Bypass is one of the two flood bypasses in California's Sacramento Valley located in Yolo and Solano Counties. Through a system of weirs, the bypass diverts floodwaters from the Sacramento River away from the state's capital city of Sacramento and other nearby riverside communities.

<span class="mw-page-title-main">Fresno kangaroo rat</span> Species of rodent

The Fresno kangaroo rat or San Joaquin kangaroo rat is a species of rodent in the family Heteromyidae. It is endemic to areas within and near the San Joaquin Valley of California in the United States. Habitat destruction due to agricultural development and urbanization has put this species at risk, and the International Union for Conservation of Nature has assessed its conservation status as "vulnerable".

<span class="mw-page-title-main">Zambezian flooded grasslands</span> Flooded grassland ecoregion in Africa

The Zambezian flooded grasslands is an ecoregion of southern and eastern Africa that is rich in wildlife.

<span class="mw-page-title-main">Yolo Bypass Wildlife Area</span> Protected area in California

The Yolo Bypass Wildlife Area, located within the Yolo Bypass in Yolo County, California, is managed by the California Department of Fish and Wildlife with the intent of restoring and managing a variety of wildlife habitats in the Yolo Basin, a natural basin in the north part of the Sacramento-San Joaquin River Delta. The creation of the wildlife area was spearheaded by the Yolo Basin Foundation. The California Department of Fish and Wildlife and Yolo Basin Foundation are the core partners in the operation of this resource located at 38.550515°N 121.626291°W

Great Valley Grasslands State Park is a state park of California, United States, preserving a parcel of remnant native grassland in the San Joaquin Valley. Such a temperate grasslands, savannas, and shrublands biome was once widespread throughout the whole Central Valley. The 2,826-acre (1,144 ha) park was established in 1982. Largely undeveloped, it was formed by combining two former state park units: San Luis Island and Fremont Ford State Recreation Area. Its chief attractions for visitors are spring wildflowers, fishing, and wildlife watching.

<span class="mw-page-title-main">Willamette Valley (ecoregion)</span> Temperate broadleaf and mixed forests ecoregion of the United States

The Willamette Valley ecoregion is a Level III ecoregion designated by the United States Environmental Protection Agency in the U.S. states of Oregon and Washington. Slightly larger than the Willamette Valley for which it is named, the ecoregion contains fluvial terraces and floodplains of the Willamette River system, scattered hills, buttes, and adjacent foothills. It is distinguished from the neighboring Coast Range, Cascades, and Klamath Mountains ecoregions by lower precipitation, lower elevation, less relief, and a different mosaic of vegetation. Mean annual rainfall is 37 to 60 inches, and summers are generally dry. Historically, the region was covered by rolling prairies, oak savanna, coniferous forests, extensive wetlands, and deciduous riparian forests. Today, it contains the bulk of Oregon's population, industry, commerce, and agriculture. Productive soils and a temperate climate make it one of the most important agricultural areas in Oregon.

The San Luis National Wildlife Refuge Complex is located in the northern San Joaquin Valley, within Merced County and Stanislaus County of California. The complex, with four federal National Wildlife Refuges, is managed by the U.S Fish & Wildlife Service.

<span class="mw-page-title-main">Cosumnes River Preserve</span> Jointly managed protected area in the Central Valley of California

The Cosumnes River Preserve is a nature preserve of over 51,000 acres (210 km2) located 20 miles (30 km) south of Sacramento, in the US state of California. The preserve protects a Central Valley remnant that once contained one of the largest expanses of oak tree savanna, riparian oak forest and wetland habitat in North America. Agricultural development has changed the landscape from groves of oaks and tule marshes to productive farmlands.

<span class="mw-page-title-main">Stone Lakes National Wildlife Refuge</span> Wildlife refuge near Sacramento, California

The Stone Lakes National Wildlife Refuge, located south of Sacramento, California, lies within the Sacramento-San Joaquin delta, the destination of thousands of migrating waterfowl, shorebirds, and other water birds. The refuge was established in 1994.

<span class="mw-page-title-main">Pixley National Wildlife Refuge</span> Wildlife Refuge in the San Joaquin Valley

Pixley National Wildlife Refuge is located 35 miles (56 km) south of Tulare, California and 45 miles (72 km) north of Bakersfield in the San Joaquin Valley. The 6,939-acre (2,808 ha) nature refuge represents one of the few remaining examples of the grasslands, vernal pools, and playas that once bordered historic Tulare Lake, the largest lake west of the Great Lakes until the late 19th century.

<span class="mw-page-title-main">Lake Chad flooded savanna</span> Flooded grassland ecoregion in Africa

The Lake Chad flooded savanna is a flooded grasslands and savannas ecoregion in Africa. It includes the seasonally- and permanently-flooded grasslands and savannas in the basin of Lake Chad in Central Africa, and covers portions of Cameroon, Chad, Niger, and Nigeria.

<span class="mw-page-title-main">Zambezian coastal flooded savanna</span>

The Zambezian coastal flooded savanna is a flooded grasslands and savannas ecoregion in Mozambique. It includes the coastal flooded savannas and grasslands in the deltas of the Zambezi, Pungwe, Buzi, and Save rivers.

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<span class="mw-page-title-main">California interior chaparral and woodlands</span> Mediterranean forests, woodlands, and scrub ecoregion in California, United States

The California interior chaparral and woodlands ecoregion covers 24,900 square miles (64,000 km2) in an elliptical ring around the California Central Valley. It occurs on hills and mountains ranging from 300 feet (91 m) to 3,000 feet (910 m). It is part of the Mediterranean forests, woodlands, and scrub biome, with cool, wet winters and hot, dry summers. Temperatures within the coast can range from 53° to 65 °F and 32° to 60 °F within the mountains. Many plant and animal species in this ecoregion are adapted to periodic fire.

Sacramento–San Joaquin is a freshwater ecoregion in California. It includes the Sacramento and San Joaquin river systems of California's Central Valley, which converge in the inland Sacramento–San Joaquin Delta. It also includes the mostly-closed Tulare Lake basin in the southern Central Valley, the rivers and streams that empty into San Francisco Bay, and the Pajaro and Salinas river systems of Central California which empty into Monterey Bay.

References

  1. 1 2 "The Atlas of Global Conservation". maps.tnc.org. Archived from the original on March 5, 2012. Retrieved November 16, 2020.
  2. "Central Valley". Geographic Names Information System . United States Geological Survey, United States Department of the Interior.
  3. 1 2 3 4 5 6 7 8 9 "California Central Valley grasslands". Terrestrial Ecoregions. World Wildlife Fund.
  4. 1 2 Eric Dinerstein, David Olson, et al. (2017). An Ecoregion-Based Approach to Protecting Half the Terrestrial Realm, BioScience, Volume 67, Issue 6, June 2017, pp. 534–545; Supplemental material 2 table S1b.
  5. Wester, Lyndon. "COMPOSITION OF NATIVE GRASSLANDS IN THE SAN JOAQUIN VALLEY, CALIFORNIA". California Botanical Society. Retrieved July 17, 2022.