California oak woodland
Encyclopedia
California chaparral and woodlands
The California chaparral and woodlands is a terrestrial ecoregion of lower northern, central, and southern California and northwestern Baja California , located on the west coast of North America...
ecoregion
Ecoregion
An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...
of California
California
California is a state located on the West Coast of the United States. It is by far the most populous U.S. state, and the third-largest by land area...
in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
and northwestern Baja California
Baja California
Baja California officially Estado Libre y Soberano de Baja California is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is both the northernmost and westernmost state of Mexico. Before becoming a state in 1953, the area was known as the North...
in Mexico
Mexico
The United Mexican States , commonly known as Mexico , is a federal constitutional republic in North America. It is bordered on the north by the United States; on the south and west by the Pacific Ocean; on the southeast by Guatemala, Belize, and the Caribbean Sea; and on the east by the Gulf of...
. Oak woodland is widespread at lower elevations in: coastal California; interior valleys of the Coast Ranges, Transverse Ranges
Transverse Ranges
The Transverse Ranges are a group of mountain ranges of southern California, in the Pacific Coast Ranges physiographic region that runs along the Pacific coast from Alaska to Mexico in North America. The Transverse Ranges begin at the southern end of the California Coast Ranges and lie between...
and Peninsular Ranges
Peninsular Ranges
The Peninsular Ranges are a group of mountain ranges, in the Pacific Coast Ranges, which stretch from southern California in the United States to the southern tip of Mexico's Baja California peninsula; they are part of the North American Coast Ranges that run along the Pacific coast from Alaska...
; and in a ring around the California Central Valley grasslands. The dominant trees are oaks, interspersed with other broadleaf and coniferous trees, with an understory of grasses, herbs, geophytes, and California native plants
California native plants
California native plants are plants that existed in California prior to the arrival of European explorers and colonists in the late 18th century...
.
Oak savannas occur where the oaks are more widely spaced due a combination of lack of available moisture, and low-intensity frequent fires.
The Oak woodlands of Southern California
Southern California
Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...
and coastal Northern California
Northern California
Northern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
are dominated by Coast Live Oak
Coast Live Oak
Quercus agrifolia, the Coast Live Oak, is an evergreen oak , native to the California Floristic Province. It grows west of the Sierra Nevada from Mendocino County, California, south to northern Baja California in Mexico. It is classified in the red oak section Quercus agrifolia, the Coast Live Oak,...
(Q. agrifolia), but also include Valley Oak
Valley Oak
Quercus lobata, commonly called the Valley oak, grows into the largest of North American oaks. It is endemic to California, growing in the interior valleys and foothills. Mature specimens may attain an age of up to 600 years. This deciduous oak requires year-round access to groundwater.Its thick,...
(Q. lobata), California Black Oak
California Black Oak
Quercus kelloggii, the California Black Oak, also known as simply Black Oak, or Kellogg Oak, is an oak in the red oak section , native to western North America...
(Q. kelloggii), Canyon live oak (Q. chrysolepis), and other California oaks. The foothill oak woodlands around the Central Valley are dominated by Blue Oak
Blue Oak
Quercus douglasii, the Blue Oak, is an oak in the white oak section of the genus, Quercus sect. Quercus. It is endemic to California and is found in foothills surrounding the Central Valley of California and certain locations in the California Coast Ranges, USA...
(Q. douglasii) and Gray Pine
Gray Pine
Pinus sabiniana , with the common names gray pine, California foothill pine, and the more historically and internationally used digger pine, is a pine endemic to California in the United States...
(Pinus sabiniana).
California oak woodland communities
- Oregon Oak woodland is found in Northern CaliforniaNorthern CaliforniaNorthern California is the northern portion of the U.S. state of California. The San Francisco Bay Area , and Sacramento as well as its metropolitan area are the main population centers...
's Klamath-Siskiyou, Northern Coast Ranges, and southern Cascade RangeCascade RangeThe Cascade Range is a major mountain range of western North America, extending from southern British Columbia through Washington and Oregon to Northern California. It includes both non-volcanic mountains, such as the North Cascades, and the notable volcanoes known as the High Cascades...
, these woodlands are composed primarily of Oregon Oak (Quercus garryana), Interior Live OakInterior Live OakQuercus wislizeni, known by the common names Interior Live Oak, and Sierra Live Oak, is an evergeen oak, highly variable and often shrubby, found in areas of California in the United States. It also occurs south into northern Baja California in Mexico...
(Quercus wislizenii), and Coast Live Oak (Quercus agrifolia), together with California Black Oak, Canyon Oak (Quercus chrysolepis), Blue Oak (Quercus douglasii), Pacific MadronePacific MadroneArbutus menziesii, commonly known as the Pacific Madrone, is a species of Arbutus found on the west coast of North America, from British Columbia to California...
(Arbutus menziesii), California Bay (Umbellularia californica), Incense Cedar (Calocedrus decurrens), Coast Douglas Fir (Pseudtsuga menziesii), and Ponderosa PinePonderosa PinePinus ponderosa, commonly known as the Ponderosa Pine, Bull Pine, Blackjack Pine, or Western Yellow Pine, is a widespread and variable pine native to western North America. It was first described by David Douglas in 1826, from eastern Washington near present-day Spokane...
(Pinus ponderosa). - Blue Oak woodland is found in the inner coast ranges and the Sierra Nevada foothills, surrounding the Central Valley. Primary species are Blue OakBlue OakQuercus douglasii, the Blue Oak, is an oak in the white oak section of the genus, Quercus sect. Quercus. It is endemic to California and is found in foothills surrounding the Central Valley of California and certain locations in the California Coast Ranges, USA...
(Quercus douglasii) and Interior Live OakInterior Live OakQuercus wislizeni, known by the common names Interior Live Oak, and Sierra Live Oak, is an evergeen oak, highly variable and often shrubby, found in areas of California in the United States. It also occurs south into northern Baja California in Mexico...
(or on west facing slopes facing the exterior ranges, particularly in Contra Costa and Alameda counties, Coast Live OakCoast Live OakQuercus agrifolia, the Coast Live Oak, is an evergreen oak , native to the California Floristic Province. It grows west of the Sierra Nevada from Mendocino County, California, south to northern Baja California in Mexico. It is classified in the red oak section Quercus agrifolia, the Coast Live Oak,...
takes Interior Live Oak's place), together with Valley OakValley OakQuercus lobata, commonly called the Valley oak, grows into the largest of North American oaks. It is endemic to California, growing in the interior valleys and foothills. Mature specimens may attain an age of up to 600 years. This deciduous oak requires year-round access to groundwater.Its thick,...
, Canyon Oak, California Scrub OakCalifornia Scrub OakQuercus berberidifolia, the California Scrub Oak, is a small evergreen or semi-evergreen shrubby oak in the white oak section Quercus sect. Quercus...
(Q. berberidifolia), Gray PineGray PinePinus sabiniana , with the common names gray pine, California foothill pine, and the more historically and internationally used digger pine, is a pine endemic to California in the United States...
(Pinus sabineana), California Buckeye (Aesculus californica), and Western Redbud (Cercis occidentalis). - Coast Live Oak woodland is widespread in northern and southern California, and is dominated by Coast Live Oak (Quercus agrifolia), together with California BuckeyeAesculus californicaAesculus californica is a species of buckeye that is native [ |] to California and southwest Oregon [Jackson, County], and the only buckeye native to these states.-Description:...
, Pacific Madrone (Arbutus menziesii), California Bay (Umbellularia californica), and California WalnutJuglans californicaJuglans californica, the California black walnut, also called the California walnut, or the Southern California black walnut, is a large shrub or small tree of the Juglandaceae family endemic to California....
(Juglans californica). - Valley Oak woodland is found in the interior valleys of northern, central and southern California, and is dominated by Valley Oak (Quercus lobata) and Coast Live Oak (Quercus agrifolia), together with Gray PineGray PinePinus sabiniana , with the common names gray pine, California foothill pine, and the more historically and internationally used digger pine, is a pine endemic to California in the United States...
(Pinus sabineana), and Coulter PineCoulter PineThe Coulter Pine or Big-cone Pine is a native of the coastal mountains of southern California and northern Baja California . Isolated groves are found as far north as the San Francisco Bay Area in Mt. Diablo State Park and Black Diamond Mines Regional Preserve...
(Pinus coulteri). - Island Oak woodland is found on the California Channel Islands, and is made up primarily of Island OakIsland OakQuercus tomentella, the Island Oak, also the Island Live Oak or Channel Islands Oak, is an oak in the section Protobalanus.-Distribution:...
(Q. tomentella) and Coast Live Oak (Quercus agrifolia)', together with Canyon Oak (Quercus chrysolepis), MacDonald scrub Oak (Quercus berberidifolia) hybridized with Valley or other oaks), Catalina Ironwood (LyonothamnusLyonothamnusLyonothamnus is a monotypic genus of trees in the rose family containing the single species Lyonothamnus floribundus, which is known by the common name Catalina ironwood, and the subspecies ssp. aspleniifolius and ssp...
floribundus), and Bishop PineBishop PineThe Bishop Pine, Pinus muricata, is a pine with a very restricted range: mostly in the U.S. state of California, including several offshore Channel Islands, and a few locations in Baja California, Mexico...
(Pinus muricata). - Engelmann Oak woodland is found in a few locations in the northern Peninsular RangesPeninsular RangesThe Peninsular Ranges are a group of mountain ranges, in the Pacific Coast Ranges, which stretch from southern California in the United States to the southern tip of Mexico's Baja California peninsula; they are part of the North American Coast Ranges that run along the Pacific coast from Alaska...
of Southern CaliforniaSouthern CaliforniaSouthern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...
, including the Santa Rosa PlateauSanta Rosa PlateauThe Santa Rosa Plateau is an upland plateau and southeastern extension of the Santa Ana Mountains in Riverside County, southern California. It is bounded by the rapidly urbanizing Inland Empire cities of Murrieta to the northeast, and Temecula to the southeast.The Santa Rosa Plateau Ecological...
and San Gabriel MountainsSan Gabriel MountainsThe San Gabriel Mountains Range is located in northern Los Angeles County and western San Bernardino County, California, United States. The mountain range lies between the Los Angeles Basin and the Mojave Desert, with Interstate 5 to the west and Interstate 15 to the east...
foothills. It consists mostly of Engelmann OakEngelmann OakQuercus engelmannii, the Engelmann Oak or Pasadena Oak, is a species of oak in the white oak section Quercus sect. Quercus, native to Southern California and northwestern Baja California, Mexico.-Description:...
(Q. engelmanii), together with Coast Live Oak (Quercus agrifolia).
Status and future of California oak woodlands
Blue oak woodlands cover about 2939000 acres (11,893.7 km²) of the state, and of this area about 79%, or 2322000 acres (9,396.8 km²), shows no evidence of past cutting of trees. Recent research by the University of ArkansasUniversity of Arkansas
The University of Arkansas is a public, co-educational, land-grant, space-grant, research university. It is classified by the Carnegie Foundation as a research university with very high research activity. It is the flagship campus of the University of Arkansas System and is located in...
Tree-Ring Laboratory has studied several unlogged stands of Blue Oak
Blue Oak
Quercus douglasii, the Blue Oak, is an oak in the white oak section of the genus, Quercus sect. Quercus. It is endemic to California and is found in foothills surrounding the Central Valley of California and certain locations in the California Coast Ranges, USA...
woodlands, and suggests that the state may harbor over 500000 acres (2,023.4 km²) of such old growth forests
Old growth forest
An old-growth forest is a forest that has attained great age , and thereby exhibits unique ecological features. An old growth forest has also usually reached a climax community...
. This would make California's oak woodlands some of the most extensive old growth forests left in the state. However, most oaks of full tree size are more than one hundred years old, and few saplings are ever produced, because cattle often tear the plants to pieces.
The Oaks 2040 survey estimates that 750000 acres (3,035.1 km²) of California oak woodlands are seriously threatened by 2040 as a burgeoning state population
Overpopulation
Overpopulation is a condition where an organism's numbers exceed the carrying capacity of its habitat. The term often refers to the relationship between the human population and its environment, the Earth...
makes ever more use of the wildland. This comprehensive survey includes oak woodland maps and inventory data for the ten oak types found in California. By evaluating this new information against current State of California economic growth projections, the location and extent of oak woodlands most at risk of development are identified.
Examples of occurrence
The headwaters area of Yulupa CreekYulupa Creek
Yulupa Creek is a southeast-flowing perennial stream that rises on the southeastern flanks of the northern Sonoma Mountains in Sonoma County, California, United States...
in Annadel State Park
Annadel State Park
Annadel State Park is a state park of California, USA, situated at the northern edge of Sonoma Valley and offering many recreational activities within its property...
is cited as one of the best examples of California oak woodlands. Much of this woodland is a relatively pristine ecosystem
Ecosystem
An ecosystem is a biological environment consisting of all the organisms living in a particular area, as well as all the nonliving , physical components of the environment with which the organisms interact, such as air, soil, water and sunlight....
with considerable biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...
. An unusual characteristic of this Annadel forest is the high content of undisturbed prehistoric bunch grass understory
Understory
Understory is the term for the area of a forest which grows at the lowest height level below the forest canopy. Plants in the understory consist of a mixture of seedlings and saplings of canopy trees together with understory shrubs and herbs...
, testifying to the absence of historic grazing
Grazing
Grazing generally describes a type of feeding, in which a herbivore feeds on plants , and also on other multicellular autotrophs...
or other agriculture
Agriculture
Agriculture is the cultivation of animals, plants, fungi and other life forms for food, fiber, and other products used to sustain life. Agriculture was the key implement in the rise of sedentary human civilization, whereby farming of domesticated species created food surpluses that nurtured the...
.
See also
- California chaparral and woodlandsCalifornia chaparral and woodlandsThe California chaparral and woodlands is a terrestrial ecoregion of lower northern, central, and southern California and northwestern Baja California , located on the west coast of North America...
- Oak savannaOak savannaAn oak savanna is a type of savanna, or lightly forested grassland, where oaks are the dominant tree species. These savannas were maintained historically through wildfires set by lightning, grazing, low precipitation, poor soil, and/or fires set by Native Americans...
- Cedar hemlock douglas-fir forestCedar hemlock douglas-fir forestCedar hemlock douglas-fir forest is a vegetation association in California, USA. This is one of the Kuchler system forest types used to classify California plant communities. As the name implies, dominant tree types are Incense-cedar, Western Hemlock and Douglas-fir. The forest type is classified...
- California native plantsCalifornia native plantsCalifornia native plants are plants that existed in California prior to the arrival of European explorers and colonists in the late 18th century...
- Blue Oak Ranch ReserveBlue Oak Ranch ReserveThe Blue Oak Ranch Reserve a unit of the University of California Natural Reserve System, is an ecological reserve and biological field station located in the Diablo Range, northwest of Mount Hamilton, in Santa Clara County, California, United States, located on at 1,500' asl .The land, part of...
General bibliography
- Dallman, Peter R. (1998). Plant Life in the World's Mediterranean Climates. California Native Plant Society–University of California Press; Berkeley.
- Gaman, Tom and Firman, Jeffrey (2006). Oaks 2040: The Status and Future of Oaks in California. Published by the California Oak Foundation, Oakland.
- Pavlik, Bruce M., Pamela C. Muick, Sharon G. Johnson,and Marjorie Popper (1991). Oaks of California. Cachuma Press and the California Oak Foundation; Los Olivos, CaliforniaLos Olivos, CaliforniaLos Olivos is a census-designated place in Santa Barbara County, California. The ZIP Code is 93441, and the community is inside area code 805...
. - Schoenherr, Allan A. (1992). A Natural History of California. University of California Press; Berkeley.