The forests of Tibet are mainly made up of spruces,
fir trees, pines, larches, cypress, birches and of
oaks. They are generally old, certain trees
are more than two-hundred-years old.
The oldest forest zones are in
U-Tsang and reach a density of 2.300m ³ /ha, the
highest density of conifers of the world.
Those covered more or less 221.800 km ² until 1949,
when Tibet has been invaded by the Republic
Popular of China.
Forest of the mountain chain of Sichuan.
In 1985, those covered only 134.000 km ², that is to say a little more half, consequence of the construction of new roads
in the areas far away from Tibet.
These roads are built by teams of engineers of the Chinese army, and their cost are devoted to the “development of Tibet”.
Once the old forests reached, the most current method is systematic demolition.
This deforestation led to the denudation of vast hills in Kham and the east of U-Tsang.
In 1985, the total volume of demolitions reached 2.442 million cubic meters, that is to say 40% of the forest stock of 1949, a value of 54 billion dollars.
Deforestation would now reach 85%, according to a recent study of World Watch Institute.
This deforestation causes landslides as well as an increase of the vase in the rivers.
The regeneration and the reafforestation were negligible because of the difficult conditions: the inclined relief, the ground, the humidity as well as the great temperature variations. Under such conditions, the effects of systematic demolition are irreversible.
The meadows of Tibet
The meadows cover more or less 70% of Tibet.
They are the spinal-cord of the agricultural economics dominated by the breeding.
The pastures makes 70 million animals and a million human beings live.
Chinese reports note a vast degradation of the pastures.
They claim that animal overpopulation on the plates is the cause of this degradation.
The Tibetans know the needs for their fragile meadows.
They have habits inherited from thousands years of
experiment. Moreover they hold annual registers
about the use of the pastures, the systematic migrations
of the herds of yaks, sheep and goats, and an individual
and collective responsibility which avoids the excessive
exploitation of these grounds.
The cause of this degradation is elsewhere, particularly
in the use of vast expanses by the Chinese army, with the
overexploitation of the low grounds by the farmers and
Chinese immigrants, upon the increasing request of meat in China.
All these causes have constrained the Tibetan nomads to reduce the number of the traditional ways of migration, and that caused these grounds an irreversible damage.
The grounds of culture
The cultivable grounds of Tibet represent only 2% of its total surface area but they are extremely productive and constitute an important resource for the population.
Since 1950, the Chinese interventions on the arable lands of Tibet led to the extension of the farms in abrupt and marginal areas, to the increase of the corn culture ( the Chineses prefer it to the barley, which is Tibetan’s basic food) and to the introduction of hybrid seeds and artificial fertilisers.
The hybrid species are prone to disease and to death in the hard climate of Tibet.
The diseases regularly touched the new varieties of corn in 1979, they destroyed all the harvest.
The principal grounds of culture were arable niches located along the river valleys in Kham, in the valley of Tsangpo, U-Tsang and of Machu in Amdo.
The barley is the basic culture.
Traditional agriculture is based on a system of organic principles of periodic succession of crops and fallows which are appropriate to a mountain fragile environment.
The cereal yield is exceptional in Tibet, on average 2.000 kg/ha in U-Tsang and more important in the valleys of Amdo and Kham.
It exceeds other yields in comparable climates: in Russia (1 700 kg/ha) and in Canada (1 800 kg/ha).