The San Ysidro Mountains are a mountain range in southern
San Diego County, California
San Diego County (), officially the County of San Diego, is a county (United States), county in the southwest corner of the U.S. state of California, north to its Mexico-United States border, border with Mexico. As of the 2020 United States Cen ...
,
and
Baja California, Mexico. The mountains are a rugged coastal foothill range of the
Peninsular Ranges
The Peninsular Ranges (also called the Lower California province) are a group of mountain ranges that stretch from Southern California to the southern tip of the Baja California peninsula; they are part of the North American Pacific Coast Range ...
system. Major peaks include the highest summit of the range,
Otay Mountain, and the Cerro San Isidro which forms the southern extrusion of the range on the Mexican side of the border. The majority of the range is within the
Otay Mountain Wilderness area, in the United States.
Geography
Lying only inland from the
Pacific Ocean
The Pacific Ocean is the largest and deepest of Earth's five Borders of the oceans, oceanic divisions. It extends from the Arctic Ocean in the north to the Southern Ocean, or, depending on the definition, to Antarctica in the south, and is ...
, this mountain range rises out of the coastal plain of San Diego and Tijuana until it reaches a maximum height of on the summit of Otay Mountain. On the western side of the mountain lies
Lower Otay Lake and
Otay Mesa, with
Richard J. Donovan Correctional Facility and other detention centers and law enforcement properties lying on the southwest slope of the mountain. On the eastern flank, Mine Canyon and Marron Valley separate the San Ysidro Mountains from
Tecate Peak (Kuuchamaa).
Cerro San Isidro
The Cerro San Isidro, located in Tijuana, is separated from the rest of the range by the border fence and the Rio Alamar, and forms the southern portion of the mountains. The summit of the Cerro San Isidro reaches approximately , and supports many of the same endemic and rare plants found on Otay Mountain.
A ''
colonia'' of Tijuana, Valle Imperial, stretches across the western slope of the mountain.
On December 31, 2014, a rare snowfall event blanketed the Cerro San Isidro after low temperatures of .
Ecology
The native vegetation of the San Ysidro Mountains represents the
coastal sage scrub
Coastal sage scrub, also known as coastal scrub, CSS, or soft chaparral, is a low scrubland plant community of the California coastal sage and chaparral subecoregion, found in coastal California and northwestern coastal Baja California. It is ...
of the
California coastal sage and chaparral ecoregion
The California coastal sage and chaparral () is a Mediterranean forests, woodlands, and scrub ecoregion, defined by the World Wildlife Fund, located in southwestern California (United States) and northwestern Baja California (Mexico). It is part o ...
(western faces); and plants of the
California montane chaparral and woodlands ecoregion (inland). The San Ysidro Mountains are one of the few locations the rare
Tecate Cypress (''Cupressus forbesii'') is found. This tree was once abundant in the higher elevations of the range as well as in its canyons. The San Ysidro Mountains were deforested of living foliage by
wildfire
A wildfire, forest fire, or a bushfire is an unplanned and uncontrolled fire in an area of Combustibility and flammability, combustible vegetation. Depending on the type of vegetation present, a wildfire may be more specifically identified as a ...
s in 2003 and 2007. ''Cupressus forbesii'' is a
fire ecology
Fire ecology is a scientific discipline concerned with the effects of fire on natural ecosystems. Many ecosystems, particularly prairie, savanna, chaparral and coniferous forests, have evolved with fire as an essential contributor to habitat vit ...
dependent species, and there has been some evidence of regrowth starting.
See also
*
California chaparral and woodlands
The California chaparral and woodlands is a terrestrial ecoregion of southwestern Oregon, northern, central, and southern California (United States) and northwestern Baja California (Mexico), located on the west coast of North America. It is a ...
— ''Terrestrial
Biome
A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the ...
''
*
Chaparral
Chaparral ( ) is a shrubland plant plant community, community found primarily in California, southern Oregon, and northern Baja California. It is shaped by a Mediterranean climate (mild wet winters and hot dry summers) and infrequent, high-intens ...
References
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Peninsular Ranges
Mountain ranges of San Diego County, California
Mountain ranges of Baja California
Mountain Empire (San Diego County)
Mountain ranges of Southern California