Central Tibetan Plateau alpine steppe

Category: Grassland, Tundra, and Human Biomes.

Geographic Location: Asia.

Summary: This cold, inhospitable plateau has prevented significant human incursion from upsetting the balance of the local ecosystem.

The Tibetan Plateau is a vast elevated plateau that includes most of the Qinghai province of Tibet and China, as well as parts of Jammu and Kashmir in India. It is sometimes called the Roof of the World, because it is the highest and largest plateau, at almost 1 million square miles (2.6 million square kilometers), surrounded by enormous mountain ranges, including the Himalayas to the south.

An area of grasslands and shrublands about the size of Texas, the alpine steppes of central Tibet includes a large part of western Tibet, the southern part of the Changtang plateau, and high enclosed basins extending northeast to Qinghai Lake. Plant cover is about 20 percent. The vegetation is too sparse and the climate is too cold to support human-directed pastoralism, so the ecosystem of roaming herds of ungulates, the plants they graze on, and the predators that hunt them is less disturbed by human incursions than many places elsewhere in the world.

Like the rest of the plateau, the climate of the alpine steppe is affected by seasonal monsoons. Climate change may not only affect the plateau, but also in time completely change the character of the alpine steppe. Because the plateau includes the world’s third-largest store of ice, warming temperatures that accelerate melting will make the steppe more hospitable to agriculture and grazing, and the resulting introduction of new plant and animal species could destroy many of the indigenous species in the ecosystem through grazing, predation, and competition.

At the moment, though, the climate is predominantly cold. Even the summer months do not exceed 50 degrees F (10 degrees C), and the mean annual temperature is just below 32 degrees F (0 degrees C). Portions of the steppe more closely resemble semiarid desert.

Vegetation

The dominant vegetation of the steppe consists of purple feather grass (Stipa purpurea), a grass with feathery flowering spikes, and cushion plants and alpine forbs such as Arenaria bryophylla, Thylacospermum caespitosum, Saussurea, and Leontopodium. In the colder, drier regions, Kobresia pygmaea is more common; this dense, turf-forming sedge grows alongside thick mats of cushion forbs such as Ceratoides compacta.

The higher the elevation, the more likely Carex sedges are to replace Stipa feathergrasses. Less-arid elevated areas support dwarf shrubs such as Ajania and Potentilla fruticosa, as well as herbaceous legumes such including Thermopsis lupinodides and locoweed (species in the Oxytropis and Astragalus genera), so named because they are generally toxic to grazing animals. Where the steppes transition into the Himalayan alpine shrub and meadows ecosystem, more herbaceous plants can be found, primarily species of Aster, Anemone, Jurinea, Gentiana, Delphinium, and Pedicularis, as well as shrubs of rhododendrons.

Fauna

The Changtang plateau includes the Changtang Cold Desert Wildlife Sanctuary, in an area of deep gorges and broad plateaus, and including 11 lakes and 10 marshes. It is one of the few habitats of the kiang (Equus kiang), the largest of the wild asses, which is endemic (found nowhere else) to the Tibetan plateau. It has a shoulder height of nearly 5 feet (1.5 meters) and weighs up to 0.5 ton (0.45 metric ton).

There are three subspecies of the kiang, all found in the ecoregion and the northern frontier of Nepal: the western kiang (Equus kiang kiang), eastern kiang (E. kiang holdereri), and southern kiang (E. kiang polyodon). The kiang is an herbivore, feeding on feathergrass and digging for Oxytropis roots in the winter. Most of their water comes from the plants they eat and winter snows. They sometimes gather in herds on a temporary basis, but older males are nearly always solitary. They are preyed upon by wolves.

The steppes are also home to the bearded vulture (Gypaetus barbatus), one of the rarest raptors. Mated pairs of vultures hunt, breed in, and defend huge territories in which the presence of other vultures is not tolerated. It is the only known animal with a diet consisting primarily of bone; it drops bones from a large height to break them, feeding on the marrow first and then on small pieces of bone. This adaptation allows the bird to feed on carcasses already picked over by predators or other scavengers.

Other animals in the region include the formerly endangered Tibetan antelope (Pantholops hodgsonii), the fine underfur of which has made it a target for poachers. Its population had dropped to fewer than 20,000 in the 2000s and the antelope was placed on China’s endangered species list. However, protection efforts have helped the antelope population bounce back to more than 70,000 by 2016, leading to its status being changed to “threatened.” One of its predators, the snow leopard (Panthera uncia), which also hunts partridges, hares, and Tibetan snowcocks; the wild yak (Bros grunniens); the white-lipped deer (Cervus albirostris); the wolf (Canis lupus); the threatened Himalayan brown bear (Ursus arctos); and the argali (Ovis ammon), a wild sheep that grazes on the sparse grasses at elevations of 9,843–16,404 feet (3,000–5,000 meters).

Bibliography

Chang, D. H. S. “The Vegetation Zonation of the Tibetan Plateau.” Mountain Research and Development 1, no. 1 (1981).

Schaller, G. B. Wildlife of the Tibetan Steppe. Chicago, IL: University of Chicago Press, 1998.

Wanli, Yang, and Palden Nyima. “Protection Efforts See Tibetan Antelope Population Rebound.” The State Council, the People's Republic of China, 23 Aug. 2021, english.www.gov.cn/news/topnews/202108/23/content‗WS6122f504c6d0df57f98deff8.html. Accessed 30 Aug. 2022.

Zheng, Du, Qingsong Zhang, and Shaohong Wu. Mountain Geoecology and Sustainable Development of the Tibetan Plateau. New York: Springer, 2000.