The Sahara desert, as defined by the World Wide Fund for Nature (WWF), includes the hyper-arid center of the Sahara, between latitudes 18° N and 30° N. It is one of several desert and xeric shrubland ecoregions that cover the northern portion of the African continent.
The ecology of California can be understood by dividing the state into a number of ecoregions, which contain distinct ecological communities of plants and animals in a contiguous region. The ecoregions of California can be grouped into four major groups: desert ecoregions, Mediterranean ecoregions, forested mountains, and coastal forests.
The Intermountain West, or Intermountain Region, is a geographic and geological region of the Western United States. It is located between the Rocky Mountain Front on the east and the Cascade Range and Sierra Nevada on the west.
The Eastern Anatolian montane steppe is a temperate grasslands, savannas, and shrublands ecoregion. It is located in the Armenian Highlands, covering parts of eastern Turkey, Armenia, Azerbaijan, southern Georgia, and northwestern Iran.
The Southeast Tibet shrub and meadows are a montane grassland ecoregion that cover the southeast and eastern parts of the Tibetan Plateau in China. The meadows in this region of Tibet are in the path of the monsoon rains and are wetter than the other upland areas of the Tibetan Plateau. The "high cold" alpine terrain is one of high species diversity, due to the relatively high levels of precipitation for the region. Precipitation is lower in the northwest, and hence the vegetation thins from shrub to meadow or even desert.
The Helanshan montane conifer forests ecoregion covers an isolated, forested mountain range surrounded by desert and semi-arid basins. As such, it has been called a "mountain island in the sky", and supports endemic species of plants and animals. The region supports the endangered Helan Shan pika.
The Tian Shan montane steppe and meadows ecoregion covers a 2,000 km long stretch of grasslands of the isolated Tian Shan mountains of Central Asia. It is characterized by high-altitude flat and rolling grasslands.
The Pamir alpine desert and tundra ecoregion covers the high plateau of the Pamir Mountains, at the central meeting of the great mountain ranges of Central Asia: Himalaya, Karakoram, Hindu Kush, Kunlun, and Tian Shan. It is a region of relatively high biodiversity due to its central location and high elevation differentials, but it also acts as a barrier between the climate and habitats of north and south Asia.
The Central Tibetan Plateau alpine steppe ecoregion covers the high alpine plateau that stretches over 1,600 kilometres (1,000 mi) across the Tibetan Plateau to Qinghai Lake in China. Because of the high altitude—much it over 5,000 metres (16,000 ft)—the region is a cold, arid desert that is only 20% covered with steppe and meadow vegetation. The area has been relatively free from human development due to the hostile climate and unsuitability for agriculture. The ecosystem is relatively intact, and supports herds of wild antelope, sheep, deer, and gazelles.
The Kopet Dag woodlands and forest steppe ecoregion coincides with the Kopet Dag mountains, straddling the southern border of Turkmenistan and the northeastern border of Iran. The region is one of high biodiversity, as it includes a full range of altitude zones, and variety of habitats included juniper-wooded slopes, montane grasslands, and tugay.
The Gissaro-Alai open woodlands ecoregion covers the western foothills winding around two western offshoots of the Tian Shan Mountains in western Tajikistan, and parts of eastern Uzbekistan and western Kyrgyzstan, in Central Asia. The woodlands are typically of Juniper trees and shrubs, fitting the altitude zone situated between the desert valley floor, and the tree line, above which the mountain ridges are glaciated and barren.
The Middle East steppe ecoregion stretches in an arc from southern Jordan across Syria and Iraq to the western border of Iran. The upper plains of the Tigris and Euphrates Rivers dominate most of the ecoregion. The terrain is mostly open shrub steppe. The climate is arid. Evidence is that this region was once more of a forest-steppe, but centuries of overgrazing and gathering firewood have reduced tree and grass cover to small areas and along the riverine corridors. Despite the degraded condition of the steppe environment, the ecoregion is important for water birds as the rivers and reservoirs provide habitat in the arid region.
The Ghorat-Hazarajat alpine meadow ecoregion covers the high mountainous elevations of central Afghanistan. The ecoregion fans out to the west from the capital city of Kabul at the eastern point. Vegetation is thornbush meadows and alpine grassland. The region is the home of the critically endangered Afghan brook salamander, which depends on the cold waters of the high streams of the ecoregion.
The Central Persian desert basins ecoregion covers the arid steppe and desert basins of central Iran, stretching into northwestern Afghanistan. The ecoregion extends over the Central Iranian Plateau, which is surrounded by mountain ranges and has no outlets to the sea. Much of the terrain is hot sand-and-gravel desert and large salt flats. The vegetation includes many specialized species of halophytes (salt-tolerant), xerophytes (drought-tolerant), and psammophile (sand-loving) plants.
The Central Afghan Mountains xeric woodlands ecoregion covers the xeric (dry) eastern and southern slopes of the central mountain range of Afghanistan, between the sandy desert to the south and the alpine meadows in the higher, wetter region to the north. Despite the 'woodlands' in the ecoregion name, very little of the territory is forested – less than 1% – but is instead sparse vegetation or herbaceous cover.
The South Iran Nubo–Sindian desert and semi-desert ecoregion covers the northern coastal plain of the Persian Gulf and the inland desert hills south of the Zagros Mountains of Iran. The region also has extensions reaching into southeastern Iraq, and eastward into southwestern Pakistan. The region is one of hot sand deserts, shrubland, and open thorn woodlands inland. Mangrove forests and swamps are found along the coast.
The Paropamisus xeric woodlands ecoregion covers the portion of northeastern Afghanistan north of the central mountain range and the Hindu Kush Mountains. The name is derived from the Old Persian name for the region, Parupraesanna. While there are low canopy woodlands in the northeast of the ecorgegion, most of the territory is desert or xeric (dry) scrubland.
The Baluchistan xeric woodlands ecoregion covers the middle elevations of a series of mountain ranges of western Pakistan and northeastern Afghanistan, reaching 1,200 kilometres (750 mi) from the Arabian Sea in the south to the Hindu Kush Mountains and the Himalayas in the north. The characteristic vegetation is xeric (dry) woodlands of shrubs and herbaceous cover. The region has rich biodiversity but relatively few endemic species.
The Sulaiman Range alpine meadows ecoregion covers a series of higher altitude mountain ranges along the crest of the Sulaiman Mountains, a southerly extension of the Hindu Kush Mountains along the Afghanistan-Pakistan border. The area is relatively undeveloped, with about a third of the terrain either forested or in 'alpine steppe' shrub or herbaceous cover.
