Grasslands of the World.pdf - Disasters and Conflicts - UNEP

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Plate 8.3
Harvested wheat in the Yarlung Tsangpo river valley.
Grasslands of the world
includes all grassland in the Tibet Autonomous Region and Qinghai Province
(118.4 million hectares), on the northern flanks of the Kunlun Mountains in
southern Xinjiang (15 million hectares) and in western Sichuan (14 million
hectares), northwestern Yunnan (5 million hectares) and western Gansu
(12 million hectares). Less than one percent of the steppe is cultivated, although
crops have expanded in recent decades, especially in the Qaidam Basin. In the
east of the plateau, crop land is in the lower valleys; in western Tibet, along the
valley and tributaries of the Yarlung Tsangpo (Brahmaputra River). The upper
limit of cultivation , which is as low as 3 300 m in some eastern parts, can reach
4 400 m in the west. The major crops are barley, wheat (Plate 8.3), peas, rape
and potatoes.
The Tibetan Steppe has several distinct topographic regions determined
by drainage and the parallel mountain ranges that divide it (Schaller, 1998).
Only the east and south have outlets to the ocean; rivers originating in the
Kunlun Mountains flow north to the Taklimakan and Qaidam Deserts. Much
of the Steppe consists of large lake basins with no outlets, ringed by mountains.
Forests are limited to the eastern edge in western Sichuan, northwestern
Yunnan, southeastern Qinghai and eastern Tibet , and in some valleys on the
northern slopes of the Himalaya .
CLIMATE
The Tibetan Steppe has a severe continental climate and is affected by the
southeastern monsoon in summer and western air circulation patterns and high
Mongol-Siberian air pressures in winter (Huang, 1987). The Steppe slopes to
the southeast, so moisture from the southwest monsoon comes up gorges from
S.G. REYNOLDS