Island Oak
Encyclopedia
Quercus tomentella, the Island Oak, also the Island Live Oak or Channel Islands Oak, is an oak
in the section Protobalanus.
and the Baja California Peninsula
including:
usually less than 20 metres (65.6 ft) in height. Its bark is usually gray and becomes furrowed with age. The specific epithet tomentella, Latin
for "beset with tomentum
(fuzz)", references the dense hairs found on the undersides of its leaves. Leaves, which are evergreen
, are usually 5-8 cm in length, oblong to oblong-obvate in shape, with a toothed margin, deeply indented. Acorns take 2 years to mature and are saucer- to bowl-shaped with a rounded tip, and large in size (cup 20-30 mm wide, 6-8 mm deep, nut 20-35 mm).
Island Oak can hybridize with all other members of the section Protobalanus, although its natural range overlaps only with the Canyon Live Oak (Quercus chrysolepis)
.
s of Island Oak have been found in mainland California; the youngest known fossils are two to ten million years old and were found near St. Mary's College, somewhat near the Oakland hills. The oldest known fossils are 30 to 60 million years old and were found in the Mojave desert
. Island Oak is no longer native to mainland California, and is thought to be a relict of a climate that was warmer and wetter than today's. However, it will grow readily in mainland California if planted and regularly watered.
s. The National Park Service
has classified Island Oak as a species of special environmental concern
.
On Guadalupe Island, the local population is threatened as it has declined some 80-90% since the 1950s, and one or two dozen trees are all that remains. These do not seem to be reproducing any more. While the Island Oak was once an important part of the local ecosystem
, its decline was caused by tens of thousands of feral
goat
s swarming the island since the mid-19th century. Removal of the goats was finally all but complete in 2005 and fenced enclosures have been built since 2001, permitting recovery of local flora
. Even if the local oaks should disappear, the population could be reestablished from Channel Islands stock.
Oak
An oak is a tree or shrub in the genus Quercus , of which about 600 species exist. "Oak" may also appear in the names of species in related genera, notably Lithocarpus...
in the section Protobalanus.
Distribution
The Island Oak, Quercus tomentella, is endemic to six islands off the coast of CaliforniaCalifornia
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...
and the Baja California Peninsula
Baja California Peninsula
The Baja California peninsula , is a peninsula in northwestern Mexico. Its land mass separates the Pacific Ocean from the Gulf of California. The Peninsula extends from Mexicali, Baja California in the north to Cabo San Lucas, Baja California Sur in the south.The total area of the Baja California...
including:
- the Channel Islands of CaliforniaChannel Islands of CaliforniaThe Channel Islands of California are a chain of eight islands located in the Pacific Ocean off the coast of Southern California along the Santa Barbara Channel in the United States of America...
- Santa Rosa IslandSanta Rosa Island, CaliforniaSanta Rosa Island is the second largest of the Channel Islands of California at 53,195 acres . Defined by the United States Census Bureau as Block 3009, Block Group 3, Census Tract 29.10 of Santa Barbara County, California, the 2000 census showed an official population of 2 persons. It is part of...
, - Santa Cruz IslandSanta Cruz IslandSanta Cruz Island was the largest privately owned island off the continental United States, but is currently part-owned by the National Park service . The island, located off the coast of California, is long and from wide...
, - Anacapa IslandAnacapa IslandAnacapa Island is a small volcanic island located about off the coast of Port Hueneme, California, in Ventura County. The Island is composed of a series of narrow islets six miles long, running in a mostly east-west orientation, five miles east of Santa Cruz Island...
, - Catalina IslandSanta Catalina Island, CaliforniaSanta Catalina Island, often called Catalina Island, or just Catalina, is a rocky island off the coast of the U.S. state of California. The island is long and across at its greatest width. The island is located about south-southwest of Los Angeles, California. The highest point on the island is...
, - San Clemente IslandSan Clemente IslandSan Clemente Island is the southernmost of the Channel Islands of California. It is owned and operated by the United States Navy, and is a part of Los Angeles County. Defined by the United States Census Bureau as Block Group 2 of Census Tract 5991 of Los Angeles County, California, it is long and...
,
- Santa Rosa Island
- the island west of Baja CaliforniaBaja CaliforniaBaja 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...
, MexicoMexicoThe 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...
- Guadalupe IslandGuadalupe IslandGuadalupe Island, or Isla Guadalupe is a volcanic island located 241 kilometers off the west coast of Mexico's Baja California peninsula and some 400 kilometers southwest of the city of Ensenada in Baja California state, in the Pacific Ocean...
- Guadalupe Island
Description
Island Oak is a treeTree
A tree is a perennial woody plant. It is most often defined as a woody plant that has many secondary branches supported clear of the ground on a single main stem or trunk with clear apical dominance. A minimum height specification at maturity is cited by some authors, varying from 3 m to...
usually less than 20 metres (65.6 ft) in height. Its bark is usually gray and becomes furrowed with age. The specific epithet tomentella, Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
for "beset with tomentum
Tomentum
Tomentum may refer to the following:*In botany, a covering of closely matted or fine hairs on plant leaves. *A network of minute blood vessels in the brain.* Tomentum in zoology are a short, soft pubescence...
(fuzz)", references the dense hairs found on the undersides of its leaves. Leaves, which are evergreen
Evergreen
In botany, an evergreen plant is a plant that has leaves in all seasons. This contrasts with deciduous plants, which completely lose their foliage during the winter or dry season.There are many different kinds of evergreen plants, both trees and shrubs...
, are usually 5-8 cm in length, oblong to oblong-obvate in shape, with a toothed margin, deeply indented. Acorns take 2 years to mature and are saucer- to bowl-shaped with a rounded tip, and large in size (cup 20-30 mm wide, 6-8 mm deep, nut 20-35 mm).
Island Oak can hybridize with all other members of the section Protobalanus, although its natural range overlaps only with the Canyon Live Oak (Quercus chrysolepis)
Quercus chrysolepis
Quercus chrysolepis, commonly termed Canyon Live Oak, or Golden Cup Oak, is a species of evergreen oak that is found in the southwestern part of North America, notably in the California Coast Ranges. This tree is often found near creeks and drainage swales growing in moist cool microhabitats...
.
Fossils
FossilFossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...
s of Island Oak have been found in mainland California; the youngest known fossils are two to ten million years old and were found near St. Mary's College, somewhat near the Oakland hills. The oldest known fossils are 30 to 60 million years old and were found in the Mojave desert
Mojave Desert
The Mojave Desert occupies a significant portion of southeastern California and smaller parts of central California, southern Nevada, southwestern Utah and northwestern Arizona, in the United States...
. Island Oak is no longer native to mainland California, and is thought to be a relict of a climate that was warmer and wetter than today's. However, it will grow readily in mainland California if planted and regularly watered.
Threatened
The Island Oak is listed as Vulnerable (VU B1+2ce) by the IUCN. Many populations are in need of immediate restoration due to severe impacts of grazing by non-native herbivoreHerbivore
Herbivores are organisms that are anatomically and physiologically adapted to eat plant-based foods. Herbivory is a form of consumption in which an organism principally eats autotrophs such as plants, algae and photosynthesizing bacteria. More generally, organisms that feed on autotrophs in...
s. The National Park Service
National Park Service
The National Park Service is the U.S. federal agency that manages all national parks, many national monuments, and other conservation and historical properties with various title designations...
has classified Island Oak as a species of special environmental concern
Endangered species
An endangered species is a population of organisms which is at risk of becoming extinct because it is either few in numbers, or threatened by changing environmental or predation parameters...
.
On Guadalupe Island, the local population is threatened as it has declined some 80-90% since the 1950s, and one or two dozen trees are all that remains. These do not seem to be reproducing any more. While the Island Oak was once an important part of the local 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....
, its decline was caused by tens of thousands of feral
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
goat
Goat
The domestic goat is a subspecies of goat domesticated from the wild goat of southwest Asia and Eastern Europe. The goat is a member of the Bovidae family and is closely related to the sheep as both are in the goat-antelope subfamily Caprinae. There are over three hundred distinct breeds of...
s swarming the island since the mid-19th century. Removal of the goats was finally all but complete in 2005 and fenced enclosures have been built since 2001, permitting recovery of local flora
Flora
Flora is the plant life occurring in a particular region or time, generally the naturally occurring or indigenous—native plant life. The corresponding term for animals is fauna.-Etymology:...
. Even if the local oaks should disappear, the population could be reestablished from Channel Islands stock.
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...
- California coastal sage and chaparral ecoregionCalifornia coastal sage and chaparral ecoregionThe California coastal sage and chaparral, a sub-ecoregion of the California chaparral and woodlands ecoregion, is found in southwestern California and northwestern Baja California in Mexico.-Location:...