Sierra Madre Occidental pine-oak forests
The Sierra Madre Occidental pine-oak forests are a subtropical coniferous forest
Tropical and subtropical coniferous forests
Tropical and subtropical coniferous forests are a forest biome. They are located in regions of semi-humid climate at tropical and subtropical latitudes. Most tropical and subtropical coniferous forest ecoregions are found in the Nearctic and Neotropic ecozones, from Mexico to Nicaragua and on the...

 ecoregion of the Sierra Madre Occidental
Sierra Madre Occidental
The Sierra Madre Occidental is a mountain range in western Mexico.-Setting:The range runs north to south, from just south of the Sonora–Arizona border southeast through eastern Sonora, western Chihuahua, Sinaloa, Durango, Zacatecas, Nayarit, Jalisco, Aguascalientes to Guanajuato, where it joins...

 range of western Mexico
The 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...

 and the southwestern United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. They are home to a large number of endemic plants and important habitat for wildlife.


The Sierra Madre Occidental run north to south in western Mexico from the centre of the country up towards the United States border, where the northern extent of the ecoregion consists of patches of forest on the Madrean Sky Islands
Madrean sky islands
The Madrean Sky Islands are enclaves of Madrean pine-oak woodlands, found at higher elevations in a complex of small mountain ranges in southern and southeastern Arizona, southwestern New Mexico, and northwestern Mexico. The sky islands are surrounded at lower elevations by the Sonoran and...

 sticking up out of the desert in the Mexican state of Sonora
Sonora officially Estado Libre y Soberano de Sonora is one of the 31 states which, with the Federal District, comprise the 32 Federal Entities of Mexico. It is divided into 72 municipalities; the capital city is Hermosillo....

 and in the US in Arizona
Arizona ; is a state located in the southwestern region of the United States. It is also part of the western United States and the mountain west. The capital and largest city is Phoenix...

 and New Mexico
New Mexico
New Mexico is a state located in the southwest and western regions of the United States. New Mexico is also usually considered one of the Mountain States. With a population density of 16 per square mile, New Mexico is the sixth-most sparsely inhabited U.S...

. This is a dramatic ladscape of steep mountains cut through with canyons including Copper Canyon
Copper Canyon
Copper Canyon is a group of canyons consisting of six distinct canyons in the Sierra Tarahumara in the southwestern part of the state of Chihuahua in Mexico...

, the deepest in North America.

The ecoregion consists of a complex of high elevation pine-oak forest enclaves surrounded at lower elevations by deserts and xeric shrublands
Deserts and xeric shrublands
Deserts and xeric shrublands is a biome characterized by, relating to, or requiring only a small amount of moisture.-Definition and occurrence:...

 and tropical dry forests
Tropical and subtropical dry broadleaf forests
The tropical and subtropical dry broadleaf forest biome, also known as tropical dry forest, is located at tropical and subtropical latitudes. Though these forests occur in climates that are warm year-round, and may receive several hundred centimeters of rain per year, they have long dry seasons...

 at lower elevations, including the Sonoran Desert
Sonoran Desert
The Sonoran Desert is a North American desert which straddles part of the United States-Mexico border and covers large parts of the U.S. states of Arizona and California and the northwest Mexican states of Sonora, Baja California, and Baja California Sur. It is one of the largest and hottest...

 to the northwest, the Chihuahuan Desert
Chihuahuan Desert
The Chihuahuan Desert is a desert, and an ecoregion designation, that straddles the U.S.-Mexico border in the central and northern portions of the Mexican Plateau, bordered on the west by the extensive Sierra Madre Occidental range, and overlaying northern portions of the east range, the Sierra...

 to the northeast and east in Arizona, the Meseta Central matorral and Central Mexican matorral
Central Mexican matorral
The Central Mexican matorral is an ecoregion of the Deserts and xeric shrublands Biome of central Mexico.-Setting:The Central Mexican matorral covers an area of on the southern portion of the Mexican Plateau....

 to the southeast, and the Sinaloan dry forests to the west and southwest. The Sierra Madre Occidental pine-oak forests are one of the Madrean pine-oak forests ecoregions, which are found throughout the Sierra Madre ranges of Mexico and the US Southwest.


The original habitats of the Sierra Madre Occidental included forest of pine
Pines are trees in the genus Pinus ,in the family Pinaceae. They make up the monotypic subfamily Pinoideae. There are about 115 species of pine, although different authorities accept between 105 and 125 species.-Etymology:...

s and Douglas-fir
Douglas-fir is one of the English common names for evergreen coniferous trees of the genus Pseudotsuga in the family Pinaceae. Other common names include Douglas tree, and Oregon pine. There are five species, two in western North America, one in Mexico, and two in eastern Asia...

s at the higher elevations with 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...

-wooded grassland on the lower slopes. The pines and oaks are especially important as there are so many different species of each including a number of endemics.
Predominant conifers among the 27 species found here include Apache Pine
Apache Pine
Pinus engelmannii, commonly known as the Apache Pine, is a tree of Northern Mexico, in the Sierra Madre Occidental with its range extending a short distance into the United States in southwestern New Mexico and southeastern Arizona...

 (Pinus engelmannii), Chihuahua Pine
Chihuahua Pine
The Chihuahua Pine is a tree, in Mexico is also called Tlacocote and ocote chino with a range primarily in Mexico with a small extension into the United States in southeast Arizona and southwest New Mexico. The Mexican range extends along the Sierra Madre Occidental and Sierra Madre del Sur from...

 (Pinus leiophylla), Mexican Pinyon
Mexican Pinyon
The Mexican Pinyon ' is a pine in the pinyon pine group, native to western North America.-Distribution:The range extends from westernmost Texas, United States , south through much of Mexico, occurring widely along the Sierra Madre Oriental and Sierra Madre Occidental ranges, and more rarely in the...

 (Pinus cembroides), Lumholtz's Pine (Pinus lumholtzii), Yécora Pine (Pinus yecorensis), Rocky Mountain Douglas-fir
Rocky Mountain Douglas-fir
The Rocky Mountain Douglas-fir, Pseudotsuga menziesii subsp. glauca, is an evergreen conifer native to the interior mountainous regions of western North America, from central British Columbia and southwest Alberta in Canada southward through the United States to the far north of Mexico...

 (Pseudotsuga menziesii subsp. glauca), and Mexican Douglas-fir (Pseudotsuga lindleyana).

Oaks (Quercus) are the dominant broadleaf trees, with 21 different species found including Quercus albocincta, Arizona oak (Q. arizonica) Q. carmenensis, Q. chihuahuensis, Q. cordifolia, Q. durifolia, Emory Oak (Q. emoryi), Q. grisea
Quercus grisea
Quercus grisea, commonly known as the gray oak, shin oak or scrub oak, is a deciduous or evergreen shrub or medium sized tree in the white oak group and is endemic to the south central montane regions of North America. It hybridizes with four other oak species where the ranges of each overlap, the...

, Mexican blue oak (Q. oblongifolia
Quercus oblongifolia
Quercus oblongifolia, commonly known as the Mexican blue oak or Sonoran blue oak, is an evergreen small tree or large shrub in the white oak group...

), Q. santaclarensis, and Q. tarahumara. Madroño (Arbutus xalapensis
Arbutus xalapensis
Arbutus xalapensis, commonly known as the Texas Madrone or Texas Madroño, is a species of flowering plant in the heather family that is native to the southwestern United States , south through most of Mexico and Central America to Nicaragua...

and A. arizonica
Arbutus arizonica
Arbutus arizonica is a tree species of southwestern North America, mostly in Mexico but also the United States, from the Sierra Madre Occidental cordillera, in the Ericaceae family...

) is found in association with oaks. Q. carmenensis and Q. deliquescens
Quercus deliquescens
Quercus deliquescens is a species of plant in the Fagaceae family. It is endemic to Mexico. It is threatened by habitat loss.-Source:* Nixon, K. et al. 1998. . Downloaded on 23 August 2007....

are two oaks endemic to the sky islands portion of the ecoregion.


The forests are home to more than 300 species of birds including Golden Eagle
Golden Eagle
The Golden Eagle is one of the best known birds of prey in the Northern Hemisphere. Like all eagles, it belongs to the family Accipitridae. Once widespread across the Holarctic, it has disappeared from many of the more heavily populated areas...

, Thick-billed Parrot
Thick-billed Parrot
The Thick-billed Parrot, Rhynchopsitta pachyrhyncha is an endangered, medium-sized, up to 38 cm long, bright green parrot with a large black bill and a red forecrown, shoulder and thighs...

 (which is now endangered having been trapped for collections), Military Macaw
Military Macaw
The Military Macaw is a large parrot and a medium-sized member of the macaw genus. Though considered vulnerable as a wild species, it is still commonly found in the pet trade industry. A predominantly green bird, it is found in the forests of Mexico and South America.-Taxonomy:There are three...

 and Tufted Jay
Tufted Jay
The Tufted Jay is a species of bird in the Corvidae family. It is endemic to a small area of the Sierra Madre Occidental of Sinaloa and Durango in Mexico....

, and were once home to the Imperial Woodpecker
Imperial Woodpecker
The Imperial Woodpecker is – or was – a member of the woodpecker family Picidae. If it is not extinct, it is the world's largest woodpecker species at 56-60 cm long...

 which is now thought to be extinct.

Mammals include the American Black Bear
American black bear
The American black bear is a medium-sized bear native to North America. It is the continent's smallest and most common bear species. Black bears are omnivores, with their diets varying greatly depending on season and location. They typically live in largely forested areas, but do leave forests in...

 and jaguar
The jaguar is a big cat, a feline in the Panthera genus, and is the only Panthera species found in the Americas. The jaguar is the third-largest feline after the tiger and the lion, and the largest in the Western Hemisphere. The jaguar's present range extends from Southern United States and Mexico...

. The rare Mexican Wolf
Mexican Wolf
The Mexican Wolf is a subspecies of the Gray Wolf. It is native to North America, where it is the rarest and most genetically distinct subspecies.- Physical features :...

 was once common in the mountains but is now not found in the wild while Mexican grizzly bear is now thought to be extinct.

The many reptiles include the rock rattlesnake (Crotalus lepidus
Crotalus lepidus
Crotalus lepidus is a venomous pitviper species found in the southwestern United States and northern central Mexico. Four subspecies are currently recognized, including the nominate subspecies described here.-Description:...

), twin-spotted rattlesnake (Crotalus pricei
Crotalus pricei
Crotalus pricei is a venomous pitviper species found in the United States and Mexico. Currently, two subspecies are recognized, including the nominate subspecies described here.-Description:Adults usually do not exceed 50–60 cm in length...

), ridgenose rattlesnake (Crotalus willardi
Crotalus willardi
Crotalus willardi is a venomous pitviper species found in the southwestern United States and Mexico. It is the most recent rattlesnake species to be discovered in the United States. Its specific name is in honor of its discoverer, Professor Frank C. Willard. Five subspecies are currently...

) and some Spiny lizard
Spiny lizard
The spiny lizards are the genus Sceloporus in the family Phrynosomatidae. This genus includes some of the most commonly seen lizards in the United States.- Taxonomy :...

s (Sceloporus clarki, S. jarrovi, S. scalaris and S. virgatus).

Finally the mountains are important stage in the migration route of monarch butterflies.

Conservation and threats

The pine forests have been cleared by the logging and paper industries since the 1800s and only a very small percentage of original foest remains. This removal of habitat has resulted in the presumed extinction of the Imperial Woodpecker, once the largest woodpecker on earth. Areas prioritised for conservation include Bavispe
Bavispe is a small town and a municipality in the northeast part of the Mexican state of Sonora.-Location:The municipality is located in the northeast of the state at . The elevation of the administrative seat is 902 meters above sea level...

/Sierra del Tigre
Sierra del Tigre
Sierra del Tigre is a mountain range in northeastern Sonora, Mexico at the northern region of the Sierra Madre Occidental. The region contains sky island mountain ranges, called the Madrean Sky Islands, some separated from the Sierra Madre Occidental proper, and occurring in the northeastern...

 and Copper Canyon, while the only protected area is La Michilía. There are a number of protected areas of Madrean sky islands in Arizona which are part of the ecoregion although not the Sierra Madre Occidental themselves, including Chiricahua National Monument
Chiricahua National Monument
Chiricahua National Monument is a unit of the National Park Service located in the Chiricahua Mountains. It is famous for its extensive vertical rock formations. The monument is located approximately southeast of Willcox, Arizona. It preserves the remains of an immense volcanic eruption that...

, Galiuro Wilderness
Galiuro Wilderness
Galiuro Wilderness is a wilderness area encompassing the mid to upper slopes of the Galiuro Mountains. It is located within the Safford Ranger District of the Coronado National Forest in the U.S. state of Arizona. It is bordered on the south by the Redfield Canyon...

, the Rincon Mountain district of Saguaro National Park
Saguaro National Park
Saguaro National Park, located in southern Arizona, is part of the United States National Park System.-Overview:The park is divided into two sections, called districts, lying approximately east and west of the center of the city of Tucson, Arizona. The total area in 2010 was of which is...

, the Huachuca Mountains
Huachuca Mountains
The Huachuca Mountain range is part of the Sierra Vista Ranger District of the Coronado National Forest. The Huachuca Mountains are located in Cochise County, Arizona approximately south-southeast of Tucson and southwest of the city of Sierra Vista, Arizona...

, Pusch Ridge Wilderness Area
Pusch Ridge Wilderness Area
Pusch Ridge Wilderness Area is a 56,430 acre wilderness area. It is located within the Coronado National Forest in the Santa Catalina Mountains north of Tucson, Arizona, United States...

, the Santa Teresa Mountains
Santa Teresa Mountains
The Santa Teresa Mountains are located in western Graham County, Arizona, within the Coronado National Forest and within the Santa Teresa Wilderness.-External links:*...

 and the Pajarito Mountains
Pajarito Mountains
The Pajarito Mountains are a small mountain range of western Santa Cruz County, Arizona. The range is adjacent the Atascosa Mountains at its north, with both ranges in the center of a north-south sequence of ranges called the Tumacacori Highlands...


See also

  • List of ecoregions in the United States (WWF)
  • Madrean pine-oak woodlands
    Madrean pine-oak woodlands
    The Madrean pine-oak woodlands are subtropical woodlands found in the mountains of Mexico and the southwestern United States.The Madrean pine-oak woodlands are found at higher elevations in Mexico's major mountain ranges, the Sierra Madre Occidental, the Sierra Madre Oriental, the Trans-Mexican...

  • Conifers of Mexico
    Conifers of Mexico
    Mexican conifers extend mainly in the main mountain ranges: Sierra Madre Oriental, Sierra Madre Occidental and the neo-volcanic axis, enclosed between these mountains there are disperse groups of conifers in mid and high elevations valleys when rainfalls conditions allow its growth. Mexican...

External links

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