The Sierra del Carmen, also called the Sierra Maderas del Carmen, is a northern finger of the

Sierra Madre Oriental The Sierra Madre Oriental () is a mountain range in northeastern Mexico. The Sierra Madre Oriental is part of the American Cordillera, a chain of mountain ranges (cordillera) that consists of an almost continuous sequence of mountain ranges that f ...

in the state of

Coahuila Coahuila (), formally Coahuila de Zaragoza (), officially the Free and Sovereign State of Coahuila de Zaragoza ( es, Estado Libre y Soberano de Coahuila de Zaragoza), is one of the 32 states of Mexico. Coahuila borders the Mexican states of N ...

Mexico Mexico (Spanish language, Spanish: México), officially the United Mexican States, is a List of sovereign states, country in the southern portion of North America. It is borders of Mexico, bordered to the north by the United States; to the so ...

. The Sierra begins at the

Rio Grande The Rio Grande ( and ), known in Mexico as the Río Bravo del Norte or simply the Río Bravo, is one of the principal rivers (along with the Colorado River) in the southwestern United States and in northern Mexico. The length of the Rio G ...

Big Bend National Park Big Bend National Park is an American national park located in West Texas, bordering Mexico. The park has national significance as the largest protected area of Chihuahuan Desert topography and ecology in the United States, and was named after ...

and extends southeast for about , reaching a maximum elevation of . Part of the Sierra del Carmen is protected in the

Maderas del Carmen Maderas del Carmen is a biosphere reserve in the northern Mexican state of Coahuila. Maderas del Carmen encompasses part of the Sierra del Carmen, a northern finger of the Sierra Madre Oriental range. The reserve includes both dry Chihuahuan D ...

Biosphere Reserve as part of a bi-national effort to conserve a large portion of the

Chihuahua Desert Chihuahua may refer to: Places *Chihuahua (state), a Mexican state **Chihuahua (dog), a breed of dog named after the state **Chihuahua cheese, a type of cheese originating in the state **Chihuahua City, the capital city of the state ** Chihuahua Mu ...

in Mexico and

Texas Texas (, ; Spanish: ''Texas'', ''Tejas'') is a state in the South Central region of the United States. At 268,596 square miles (695,662 km2), and with more than 29.1 million residents in 2020, it is the second-largest U.S. state by ...

Geography

Some authorities include the Chisos and other mountains of Big Bend National Park as part of the Sierra del Carmen. From the Mexican side of the

, the Sierra runs southeast for about to 28’ 40° North latitude and a maximum width of about . Elevations increase toward the south culminating in several peaks with heights of more than and a maximum altitude of .Google Earth The western side of the Sierra del Carmen features a high limestone escarpment that formed along a fault line. Sierra del Carmen1

The Sierra del Carmen is an isolated range, a

sky island Sky islands are isolated mountains surrounded by radically different lowland environments. The term originally referred to those found on the Mexican Plateau, and has extended to similarly isolated high-elevation forests. The isolation has s ...

, that rises above the

. Because of its elevation, higher than any other mountain ranges in the Bolson de Mapimi, the Sierra del Carmen is home to flora and fauna that are more characteristic of the mountains of the western United States and Mexico. At lower elevations, desert vegetation surrounds the higher elevations. Oak and oak-pine forests are found at elevations of . Above , the forest is dominated by pine. Conifer species such as

Douglas fir The Douglas fir (''Pseudotsuga menziesii'') is an evergreen conifer species in the pine family, Pinaceae. It is native to western North America and is also known as Douglas-fir, Douglas spruce, Oregon pine, and Columbian pine. There are three v ...

, and

Durango fir ''Abies durangensis'' is a species of conifer in the family Pinaceae. It was described botanically by Maximino Martínez in 1942 and is found only in Mexico (Durango, Chihuahua, Coahuila, Jalisco and Sinaloa Sinaloa (), officially the Est ...

are found at elevations of or more. The Sierra del Carmen is home to 446 species of birds, 3,600 species of insects, more than 1,500 plant species, and 75 mammals."U.S., Mexico Announce Binational Cooperative Conservation Action Plan" News Release. U.S. Department of the Interior, 24 October 2011 Among the mammals are

American black bear The American black bear (''Ursus americanus''), also called simply a black bear or sometimes a baribal, is a medium-sized bear endemic to North America. It is the continent's smallest and most widely distributed bear species. American black bear ...

beaver Beavers are large, semiaquatic rodents in the genus ''Castor'' native to the temperate Northern Hemisphere. There are two extant species: the North American beaver (''Castor canadensis'') and the Eurasian beaver (''C. fiber''). Beavers a ...

, and

cougar The cougar (''Puma concolor'') is a large cat native to the Americas. Its range spans from the Canadian Yukon to the southern Andes in South America and is the most widespread of any large wild terrestrial mammal in the Western Hemisphere. ...

. A small subspecies of white-tail deer, the Carmen Mountains white-tailed deer is found in the Sierra. Extirpated from the region and not at present found in the Sierra are

Grizzly bear The grizzly bear (''Ursus arctos horribilis''), also known as the North American brown bear or simply grizzly, is a population or subspecies of the brown bear inhabiting North America. In addition to the mainland grizzly (''Ursus arctos horri ...

and the

Mexican wolf The Mexican wolf (''Canis lupus baileyi''), also known as the lobo,; nah, Cuetlāchcoyōtl is a subspecies of gray wolf native to southeastern Arizona and southern New Mexico in the United States, and northern Mexico; it also previously rang ...

. There are no rivers, paved highways, or towns in the Sierra, which has been called one of the most remote places on earth."Sky island: El Sierra del Carmen" http://mexicolesstraveled.com/sierradelcarmen.htm, accessed 13 Mar 2013 Drainage of the mountains is by small, mostly ephemeral streams on the east side of the Sierra to the Rio Grande. Off the western side of the Sierra, small streams leaving the mountains disappear quickly in the desert of the Bolson de Mapimi.

Vegetation

According to the International Ecological Classification Standard the vegetation of Sierra del Carmen can be classified as follows Temperate or subpolar needle-leaved evergreen forest Madrean Lower Montane Conifer Forest: Dominant trees are Arizona pine often growing with

Chisos red oak ''Quercus gravesii'' (also called Chisos red oak or Grave's oak) is an uncommon North American species of oak in the red oak section ''Quercus'' section ''Lobatae''. It is found in Mexico and the United States. It is a deciduous tree up to tall ...

Silverleaf oak ''Quercus hypoleucoides'', the silverleaf oak or the whiteleaf oak is a North American species of oak tree or shrub. It grows in the southwestern United States and northern Mexico. Description ''Quercus hypoleucoides'', though usually seen as ...

and

Netleaf oak ''Quercus rugosa'', commonly known as the netleaf oak, is a broad-leaved tree in the beech and oak family Fagaceae. It is native to southern North America. Description ''Quercus rugosa'' is an evergreen shrub or tree. The bark is brown and scal ...

in association with

Poverty oatgrass ''Danthonia spicata'' is a species of grass known by the common name poverty oatgrass, or simply poverty grass. It is native to North America, where it is widespread and common in many areas.Piptochaetium pringlei ''Piptochaetium'', or speargrass, is a genus of plants in the grass family, native to North and South America. ''Piptochaetium'' is a bunchgrass genus in the tribe Stipeae.Clayton, W. D., et al. (2006 onwards)''Piptochaetium''.GrassBase - The Onl ...

Prairie Junegrass ''Koeleria macrantha'' is a species of grass known by the common name prairie Junegrass in North America and crested hair-grass in the UK. It is widespread across much of Eurasia and North America. It occurs in many habitat types, especially prai ...

Little bluestem ''Schizachyrium scoparium'', commonly known as little bluestem or beard grass, is a species of North American prairie grass native to most of the contiguous United States (except California, Nevada, and Oregon) as well as a small area north of t ...

and

Bromus lanatipes ''Bromus'' is a large genus of grasses, classified in its own tribe Bromeae. They are commonly known as bromes, brome grasses, cheat grasses or chess grasses. Estimates in the scientific literature of the number of species have ranged from 100 ...

. ''Madrean Upper Montane Conifer Forest:''

and

are the dominant trees growing along

Pinus arizonica ''Pinus arizonica'', commonly known as the Arizona pine, is a medium-sized pine in northern Mexico, southeast Arizona, southwest New Mexico, and western Texas in the United States. It is a tree growing to 25–35 m tall, with a trunk diameter of ...

, Texas madrone in association with Umbellate wintergreen and

Piptochaetium pringlei ''Piptochaetium'', or speargrass, is a genus of plants in the grass family, native to North and South America. ''Piptochaetium'' is a bunchgrass genus in the tribe Stipeae.Clayton, W. D., et al. (2006 onwards)''Piptochaetium''.GrassBase - The Onl ...

. Sierra Madre Oriental endemic Pinus stylesii grows on the higher elevations, Chinquapin oak is also common although not dominant component throughout mixed conifer forest to oak-pine forest, Quaking aspen stands exist on moist slopes and canyons, thickets of Red raspberry and hawthorns such as Crataegus tracyi and

Crataegus greggiana ''Crataegus'' (), commonly called hawthorn, quickthorn, thornapple, Voss, E. G. 1985. ''Michigan Flora: A guide to the identification and occurrence of the native and naturalized seed-plants of the state. Part II: Dicots (Saururaceae–Cornacea ...

provide forage for wildlife. Montane or boreal cold-deciduous forest ''Madrean Upper Montane Oak Forest:'' The dominant tree species is

growing among other oaks such as Lacey oak, Arizona white oak,

in association with Piptochaetium fimbriatum,

, Muhlenbergia emersleyi, Nolina texana and

Temperate broad-leaved evergreen woodland ''Madrean Lower Montane Oak Woodland:''

, Arizona white oak, Quercus grisea and Emory oak are dominant trees, associates are

, Muhlenbergia glauca, Senecio carlomasonii, Pointleaf manzanita,

Sideoats grama ''Bouteloua curtipendula'', commonly known as sideoats grama, is a perennial, short prairie grass that is native throughout the temperate and tropical Western Hemisphere, from Canada south to Argentina. The species epithet comes from Latin " ...

, Blue grama, Alder-leaf mountain-mahogany, Muhlenbergia emersleyi, Mexican feathergrass and

Yucca faxoniana ''Yucca faxoniana'' is a bladed evergreen shrub of the genus ''Yucca''. It is known by the common names Faxon yucca, Spanish dagger, and giant dagger. Description The plant generally is a multitrunked shrub in height. They can be single trunked ...

. At least 20 species of oak grow in Sierra del Carmen, making it one of the most oak diverse sky islands, the following have been reported within its boundaries: Arizona oak, Quercus coahuilensis, Quercus carmenensis, Emory oak, Escarpment live oak,

Gambel oak ''Quercus gambelii'', with the common name Gambel oak, is a deciduous small tree or large shrub that is widespread in the foothills and lower mountains of western North America. It is also regionally called scrub oak, oak brush, and white oak. ...

, Quercus grisea,

, Lacey oak, Mohr oak, Chinquapin oak, Quercus sinuata, Sonoran blue oak, Quercus sideroxyla, Sandpaper oak, Coahuila scrub oak, Lateleaf oak, Quercus vaseyana and

. Temperate or subpolar needle-leaved evergreen woodland ''Madrean Pinyon-Juniper Woodland:'' Mexican pinyon, Papershell pinyon and Alligator juniper are the most common tree species, along them grow Alder-leaf mountain-mahogany,

, Muhlenbergia emersleyi, Nolina texana, Sandpaper oak, Mexican feathergrass and

. Sclerophyllous temperate broad-leaved evergreen shrubland ''Chihuahuan Interior Chaparral:'' Shrubs such as Fraxinus greggii, Mohr oak and Quercus vaseyana grow along

Achnatherum eminens ''Achnatherum'' is a genus of plants which includes several species of needlegrass. Several needlegrass species have been switched between ''Achnatherum'' and genus ''Stipa''; taxonomy between the two closely related genera is still uncertain. ...

, Agave lechuguilla,

Vauquelinia corymbosa ''Vauquelinia'', commonly known as the rosewoods, is a genus of the rose family, Rosaceae. It consists of two species of shrubs found in the southwestern United States and northwestern Mexico. The genus was named for French chemist Louis Nicolas ...

, Desert ceanothus, Alder-leaf mountain-mahogany, Smooth-leaf sotol, Muhlenbergia emersleyi,

Muhlenbergia setifolia ''Muhlenbergia'' is a genus of plants in the grass family. The genus is named in honor of the German-American amateur botanist Gotthilf Heinrich Ernst Muhlenberg (1753-1815). Many of the species are known by the common name muhly. The greatest ...

and

. Extremely xeromorphic evergreen shrubland ''Chihuahuan Creosotebush Desert Scrub:'' Dominated by

Creosote bush ''Larrea tridentata'', called creosote bush and greasewood as a plant, chaparral as a medicinal herb, and ''gobernadora'' (Spanish for "governess") in Mexico, due to its ability to secure more water by inhibiting the growth of nearby plants. In S ...

associated with Whitethorn acacia, Agave lechuguilla, Bouteloua ramosa, Candelilla, New Mexico rubber plant and

Tiquilia hispidissima ''Tiquilia'' is a genus of flowering plants in the borage family, Boraginaceae. The 27 species in this genus are known by the common name crinklemat. They are native to the Western Hemisphere and are mostly found in desert regions. Selected spec ...

. Extremely xeromorphic deciduous subdesert shrubland Fflou ''Chihuahuan Mixed Desert Scrub:'' Whitethorn acacia, Vachellia neovernicosa, American tarwort,

Ocotillo ''Fouquieria splendens'' (commonly known as ocotillo (), but also referred to as buggywhip, coachwhip, candlewood, slimwood, desert coral, Jacob's staff, Jacob cactus, and vine cactus) is a plant indigenous to the Sonoran Desert and Chihuahuan ...

, Leucophyllum minus and Catclaw mimosa along with Agave havardiana, Agave lechuguilla, Black grama,

Engelmann's prickly pear ''Opuntia engelmannii'' is a prickly pear common across the south-central and Southwestern United States and northern Mexico. It goes by a variety of common names, including desert prickly pear, discus prickly pear, Engelmann's prickly pear i ...

, New Mexico rubber plant, Candelilla,

Aristida purpurea ''Aristida purpurea'' is a species of grass native to North America which is known by the common name purple three-awn. Distribution This grass is fairly widespread and can be found across the western two thirds of the United States, much of ...

, Smooth-leaf sotol, Aloysia gratissima,

, Blue grama and Bouteloua ramosa. ''Chihuahuan Mesquite Desert Scrub:'' Dominated by Honey mesquite along with Aloysia gratissima and American tarwort associated with

, Black grama, Blue grama, New Mexico rubber plant and Tobosa grass. Extremely xeromorphic evergreen subdesert dwarf-shrubland ''Chihuahuan Dwarf Desert Scrub:'' Dominants are Agave lechuguilla, Candelilla, Smooth-leaf sotol and New Mexico rubber plant associated with Texas false agave and Guayule. Temperate cold-deciduous shrubland ''Madrean Montane Scrub:'' Mainly consists of Alder-leaf mountain-mahogany and Pointleaf manzanita growing with Muhlenbergia emersleyi and

. Temperate or subpolar grassland ''Madrean Mesa-Foothill Grassland:'' This grassland is composed mainly by Black grama, Blue grama, Bouteloua ramosa,

Bouteloua hirsuta ''Bouteloua hirsuta'', commonly known as hairy grama, is a perennial short prairie grass that is native throughout much of North America, including the Great Plains and Canadian Prairies region, as well as Mexico and Guatemala Guatemala ( ...

, Purple three-awn, Bouteloua barbata,

Black speargrass ''Heteropogon contortus'' is a tropical, perennial tussock grass with a native distribution encompassing Southern Africa, southern Asia, Northern Australia, Oceania, and southwestern North America. The species has also become a naturalised wee ...

, Feather fingergrass and Tobosa grass among other species such as

, Mexican feathergrass,

. Temperate or subpolar grassland with a sparse shrub layer ''Chihuahuan Foothill-Piedmont Desert Grassland:''

, Muhlenbergia emersleyi,

grow along with plants such as Viguiera dentata and rosetophyllus Yucca thompsoniana, Smooth-leaf sotol and Agave lechuguilla. Gallery forest Riparian communities occur at all elevations and they are usually composed by deciduous species. At higher elevations Bigtooth maple, American basswood, Narrowleaf cottonwood, Chisos hop-hornbeam, Scouler's willow, Texas ash and

Arizona cypress ''Cupressus arizonica'', the Arizona cypress, is a North American species of tree in the cypress family Cupressaceae, native to the southwestern United States and Mexico. Populations may be scattered rather than in large, dense stands. Descripti ...

. Coming down from the mountains several streams feed the Rio Grande, lining them grow Fremont's cottonwood,

Velvet ash ''Fraxinus velutina'', the velvet ash, Arizona ash or Modesto ash, is a species of '' Fraxinus'' native to southwestern North America, in the United States from southern California east to Texas, and in Mexico from northern Baja California e ...

Desert willow ''Chilopsis'' is a monotypic genus of flowering plants containing the single species ''Chilopsis linearis''. It is known commonly as desert willow

and Screwbean mesquite.

Climate

The climate of the Sierra del Carmen is arid to semi-arid with more humid conditions at higher elevations. Annual precipitation is between . Most precipitation is in the summer; snow often falls in the winter. The nearest weather station representative of the Sierra del Carmen is in Big Bend National Park which shares a similar climate. The climatic classification of this station is Bsk (Koppen) or Bsal (Trewartha).

Conservation efforts

The isolation of the Sierra del Carmen and its relatively undisturbed environment has led to conservation efforts in Mexico and jointly with the United States. Much of the Sierra del Carmen has been declared by the government of Mexico the Maderas del Carmen Flora and Fauna Protected Area, a designation which allows many economic activities and private land holdings to continue to exist within the boundaries. The protected area comprises . The Maderas del Carmen is part of a bi-lateral conservation project called the El Carmen—Big Bend Conservation Corridor Initiative which includes contiguous land designated for conservation on both sides of the border totaling more than , an area almost as large as the U.S. state of

Connecticut Connecticut () is the southernmost state in the New England region of the Northeastern United States. It is bordered by Rhode Island to the east, Massachusetts to the north, New York (state), New York to the west, and Long Island Sound to the ...

. In 2005, Maderas del Carmen became the first designated

Wilderness area Wilderness or wildlands (usually in the plural), are natural environments on Earth that have not been significantly modified by human activity or any nonurbanized land not under extensive agricultural cultivation. The term has traditionally re ...

Latin America Latin America or * french: Amérique Latine, link=no * ht, Amerik Latin, link=no * pt, América Latina, link=no, name=a, sometimes referred to as LatAm is a large cultural region in the Americas where Romance languages — languages derived ...

. The Maderas del Carmen Protected Area was created in 1994, although conservation efforts were initially slowed because the land was privately owned, either in large ranches or in the collective farms called

ejido An ''ejido'' (, from Latin ''exitum'') is an area of communal land used for agriculture in which community members have usufruct rights rather than ownership rights to land, which in Mexico is held by the Mexican state. People awarded ejidos in ...

s in Mexico. In 2000 a Mexican corporation, Cementos de Mexico (CEMEX) began to purchase lands for conservation in the region. On CEMEX land livestock and fences were removed and native vegetation encouraged. By 2006, CEMEX owned in or near the Maderas del Carmen and managed another . One of the important characteristics of the Sierra del Carmen is that it functions as a "corridor" enabling wildlife to migrate north and south. In the late 1980s the corridor between the Sierra and the mountains of west Texas enabled the black bear to disperse northward and reestablish itself in Big Bend National Park. The black bear had been extirpated from west Texas in the 1950s. In other initiatives, in 2000, CEMEX in cooperation with conservation organizations in Mexico and Texas began breeding and releasing to the wild

bighorn sheep The bighorn sheep (''Ovis canadensis'') is a species of sheep native to North America. It is named for its large horns. A pair of horns might weigh up to ; the sheep typically weigh up to . Recent genetic testing indicates three distinct subsp ...

which had been absent from the Sierra del Carmen for more than 50 years. On October 24, 2011, Mexico and the United States signed an agreement for "Cooperative Action for Conservation in the Big Bend-Rio Bravo Natural Area of Binational Interest." In 2019, 19 American Bison were reintroduced in the protected area with future plans of releasing more. Bison reintroduction https://www.youtube.com/watch?v=JyN_ozD8WGs

References

{{Mountains of Texas Sierra Madre Oriental Landforms of Coahuila Mountain ranges of Texas Protected areas of Coahuila Nature reserves in Mexico Landforms of Brewster County, Texas