Sky island

 Sky islands are mountains that are isolated from the surrounding lowlands of a totally different environment, a situation which, in combination with the altitudinal zonation of ecosystems, has significant implications for natural habitats. endemic populations, vertical migration, and relics are among the natural phenomena found on islands in the sky. The complex dynamics of species richness in the sky islands called the attention of the discipline of biogeography, and biodiversity is of interest to conservation biology. One of the key elements of an island in the sky is the separation by the huge physical distance from the mountains, resulting in an island habitat, such as a forest surrounded by desert. Some sky islands serve as refuges for boreal species stranded by climate warming since the last ice age. In other cases, localized populations of plants and animals tend to speciation, the same process that occurs on oceanic islands like the Galapagos Islands.

The term was popularized by the writer of the nature of Weldon Heald, a resident of southeastern Arizona. In his 1967 book, Sky Island, demonstrated the concept by describing a unit of the town of Rodeo, New Mexico, in the lowlands of the Sonoran Desert, with a peak in the Chiricahua Mountains, 35 miles (56 km) away and 5600 m (1707 m) higher in elevation. Rising from the hot, dry desert, the environment transitions to grassland, then oak-pine forest, pine and spruce-fir forest finally, aspen. The book mentions the concept of a biome, but prefers the terminology areas of life, and refers to the work of Clinton Hart Merriam. The book also describe the wildlife and the lives of the Chiricahua.
Around the same time, the idea of ​​mountains as islands of habitat is maintained with scientists and has been used by such popular writers as David Quammen] and John McPhee. This concept is included in the study of island biogeography. Not limited to the mountains in southwestern North America, but can be applied to the mountains, highlands, and massive worldwide.