Quercus tomentella

Quercus tomentella
Island Oak grove, Santa Rosa Island
Conservation status
Vulnerable (IUCN 2.3)
Scientific classification
Kingdom:	Plantae
(unranked):	Angiosperms
(unranked):	Eudicots
(unranked):	Rosids
Order:	Fagales
Family:	Fagaceae
Genus:	Quercus
Section:	Protobalanus
Species:	Q. tomentella
Binomial name
Quercus tomentella Engelm.

Quercus tomentella — foliage.

Quercus tomentella, the Island Oak, also the Island Live Oak or Channel Islands Oak, is an oak in the section Protobalanus.

Distribution

The Island Oak, Quercus tomentella, is endemic to six islands off the coast of California and the Baja California Peninsula including:

• the Channel Islands of California
  • Santa Rosa Island,
  • Santa Cruz Island,
  • Anacapa Island,
  • Catalina Island,
  • San Clemente Island,
• the island west of Baja California, Mexico
  • Guadalupe Island

Description

Island Oak is a tree usually less than 20 metres (66 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).

Fossils

Fossils 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.

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 herbivores. 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 goats 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 .

See also

• California chaparral and woodlands
• California coastal sage and chaparral ecoregion

References

• Junak, S.; Keitt, B.; Tershy, B.; Croll, D. & Sánchez, J.A. (2003): Recent conservation efforts and current status of the flora of Guadalupe Island, Baja California, Mexico. Presentation at Taller sobre la Restauración y Conservación de Isla Guadalupe ["Workshop on restoration and conservation of Guadalupe Island"]. Instituto Nacional de Ecología, November 13-14, 2003. HTML abstract
• León de la Luz, José Luis; Rebman, Jon P. & Oberbauer, Thomas (2003): On the urgency of conservation on Guadalupe Island, Mexico: is it a lost paradise? Biodiversity and Conservation 12(5): 1073–1082. doi:10.1023/A:1022854211166 (HTML abstract)
• Nixon, Kevin C. (1997): 39. Quercus tomentella. In: Flora of North America Editorial Committee (eds.): Flora of North America North of Mexico vol. 3.
• Nixon, K. et al. (1998). Quercus tomentella. 2006. IUCN Red List of Threatened Species. IUCN 2006. www.iucnredlist.org. Retrieved on 11 May 2006.

External links

• Jepson Manual Treatment - Quercus tomentella
• USDA Plants Profile: Quercus tomentella
• Quercus tomentella - Photo gallery