Madrean sky islands
Encyclopedia
Sky island
Sky islands are mountains that are isolated by surrounding lowlands of a dramatically different environment, a situation which, in combination with the altitudinal zonation of ecosystems, has significant implications for natural habitats. Endemism, vertical migration, and relict populations are...
s are enclaves of 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...
, found at higher elevations in a complex of small mountain ranges in southern and southeastern Arizona
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...
, southwestern 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...
, and northwestern Mexico
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...
. The sky islands are surrounded at lower elevations by the Sonoran
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...
and 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...
s. The northern west-east perimeter of the sky island region merges into the higher elevation eastern Mogollon Rim
Mogollon Rim
The Mogollon Rim is a topographical and geological feature running across the U.S. state of Arizona. It extends approximately from northern Yavapai County eastward to near the border with New Mexico.-Description:...
and the White Mountains
White Mountains (Arizona)
The White Mountains of Arizona are a mountain range and mountainous region in the eastern part of the state, near the border with New Mexico; it is a continuation from the west of the Arizona transition zone–Mogollon Rim, with the Rim ending in western New Mexico...
of eastern Arizona (southern Anasazi region).
The sky islands are the northernmost of the Madrean pine-oak woodlands, and are classified as part of the Sierra Madre Occidental pine-oak forests
Sierra Madre Occidental pine-oak forests
The Sierra Madre Occidental pine-oak forests are a subtropical coniferous forest ecoregion of the Sierra Madre Occidental range of western Mexico and the southwestern United States...
ecoregion
Ecoregion
An ecoregion , sometimes called a bioregion, is an ecologically and geographically defined area that is smaller than an ecozone and larger than an ecosystem. Ecoregions cover relatively large areas of land or water, and contain characteristic, geographically distinct assemblages of natural...
, of the tropical and subtropical coniferous forests
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...
biome
Biome
Biomes are climatically and geographically defined as similar climatic conditions on the Earth, such as communities of plants, animals, and soil organisms, and are often referred to as ecosystems. Some parts of the earth have more or less the same kind of abiotic and biotic factors spread over a...
. The sky islands were isolated from one another and from the pine-oak woodlands 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...
to the south by the warming and drying of the climate since the ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...
s.
There are approximately 27 Madrean sky islands in the United States, and 15 in northern Mexico. The major Madrean sky island ranges in the United States are the Baboquivari Mountains, Chiricahua Mountains
Chiricahua Mountains
The Chiricahua Mountains are a mountain range in southeastern Arizona which are part of the Basin and Range province of the southwest, and part of the Coronado National Forest...
, 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...
, Pinaleño Mountains
Pinaleno Mountains
The Pinaleño Mountains, or the Pinal Mountains, are a remote mountain range in southeastern Arizona. They have over of vertical relief, more than any other range in the state. The mountains are surrounded by the Sonoran-Chihuahuan Desert. Subalpine forests cover the higher elevations...
, Santa Catalina Mountains
Santa Catalina Mountains
The Santa Catalina Mountains, commonly referred to as the Catalina Mountains, are located north, and northeast of Tucson, Arizona, United States, on Tucson's north perimeter. The mountain range is the most prominent in the Tucson area, with the highest average elevation...
, and Santa Rita Mountains
Santa Rita Mountains
The Santa Rita Mountains, located about 65 km southeast of Tucson, Arizona, extend 42 km from north to south, then trending southeast. They merge again southeastwards into the Patagonia Mountains, trending northwest by southeast...
.