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

S.G. REYNOLDS
The Tibetan Steppe 315
Plate 8.7
Turnips are becoming a popular crop for winter feed.
Along the drainage of the Yarlung Tsangpo, in the rain-shadow of the
Himalaya , between 3 500 to 4 000 m on valley floors and lower mountain
slopes, the dominant vegetation consists of xeric grasses such as Aristida
triseta , Stipa bungeana , Pennisetum flaccidum , Elymus nutans and Orinus
thoroldii . Shrubs such as Artemisia webbiana , Berberis spp. , Sophora
moorcroftiana , S. viciifolia , Lonicera spinosa , Leptodermis sauranja and
Ceratostigma griffithii are often mixed with grasses, or comprise distinct
communities . On the upper slopes, Juniperus shrub communities are found.
Since this central valley region is settled by farmers, most of the grasslands
have been subjected to heavy, continual grazing for centuries, if not thousands
of years, and are overgrazed and degraded (Meiners, 1991; Ryavec and
Vergin, 1998). Desertification , with moving sand dunes , is a serious problem
in many areas in the Yarlung Tsangpo valley.
Stock graze on stubble (Plate 8.6) and fodder crops like turnips (Plate 8.7)
are grown for winter feed.
Many plants in the alpine steppe have distinctive adaptations to the harsh
environment (Huang, 1987). Some have shiny hairs, possibly to retain humidity
and reflect heat into the interior. Some have large taproots for nutrient storage,
and cushion plants create their own micro-environment by accumulating
windblown soil and snow. In the alpine steppe, plant canopy cover ranges
from 10 to 30 percent and productivity is often low (