Sierra del Carmen

The Sierra del Carmen is the northernmost section of the eastern Sierra Madre range in Coahuila, Mexico. Much of this rugged 65 - 72 km (40 - 45 mi) section of the range is a so-called "sky island" with ridges and peaks that rise from the base of the Chihuahuan Desert.

The Sierra has a maximum width of about 32 km (20 mi). Elevations increase toward the south culminating in several peaks with heights of more than 2,400 m (8,000 ft) and a maximum altitude of 2,720 m (8,920 ft).

There are no rivers, paved highways, or towns in the Sierra del Carmen. Drainage of the mountains is by small, primarily ephemeral streams on the eastern side emptying into the Rio Grande. Off the western side, small streams dry up quickly in the desert of the Bolson de Mapimi basin.

At lower elevations, desert vegetation surrounds the higher elevations. Oak and oak-pine forests are found at 1,300 - 1,800 m (4,400 - 5,900 ft). Above 1,800 m (5,900 ft), the forest is dominated by pine. Conifer species such as Douglas and Durango fir are found at 2,000 m (6,600 ft) or higher elevations.

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. Among the mammals are the American black bear, beaver and cougar. In addition, a small subspecies of white-tailed deer, the Carmen Mountains white-tailed deer, is found in the Sierra.

The climate in the Sierra is arid to semi-arid, with more humid conditions at higher elevations. Annual precipitation ranges between 250 and 510 mm (10 and 20 in), most of which is in the summer.

Part of the Sierra del Carmen is protected within the Maderas del Carmen Biosphere Reserve.

Maderas del Carmen Biosphere Reserve

The Maderas del Carmen Biosphere Reserve is located in the northern Mexican state of Coahuila. The reserve, dedicated in 2006, encompasses part of the Sierra del Carmen, a northern extension of the Sierra Madre Oriental range. It has a total surface area of 208,381 ha (514,920 acres).

The Biosphere Reserve is located at the convergence of three physiographic regions:

• The Chihuahuan Desert in the west

• Tamaulipas thorny scrubland in the southeast

• The Coahuila plains in the central region

The Maderas del Carmen Biosphere Reserve includes dry Chihuahuan Desert shrublands and forested "sky island," high-elevation enclaves of Sierra Madre Oriental pine-oak forest.

The Biosphere Reserve is a refuge for migratory species of Neotropical and Nearctic birds and birds of prey. It harbors the Golden Eagle, the peregrine falcon, the American black bear (Ursus americanus), the collared peccary (Pecari tajacu), the cougar (Puma concolor), the white-tailed deer, and the mule deer.

In addition, small endemic and relict mammals can be found that include the gray shrew, moles, opossums, armadillos, squirrels, castors, the North American porcupine, and the kit fox, etc.

Healthy populations of Candelilla (Eophorbia antisyphilitica) can be found on the chalkstone hills.