Fjölrit RALA - 05.12.1999, Page 111

Zambyn Batjargal
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many hundreds of years to re-develop. Thus, in those areas the soil ecosystem will be
disturbed for many years.
Figure 1. Moistening deficit of crops vegeta-
tion period.
Figure 3. Mean total precipitation amount
(mm).
Figure 2. Mean number of day with relative
air humidity lower than 30%.
SOIL
The principal soil type is dry-steppe chestnut soil that covers some 40% of Mongolia.
Other major soil types are brown desert-steppe and grey brown desert soils. Arable
soils are generally dark chestnut and chestnut soils, which are typically light, fine-
silty, around 20-30 cm deep with an organic matter content of 3-4% and pH of 6-7.
Due to above mentioned climatic factors the natural ecosystems, including soil, are
relatively fragile, highly susceptible to degradation by human activities, and slow to
recover. The rates of humus production and vegetative regeneration and growth are
very low throughout the country and agricultural productivity is low in comparison to
other countries of the same latitude.
Vegetation
Six vegetation zones can be defined in Mongolia based on different altitude, rainfall
distribution and soil type; alpine tundra (3.0% of totai area), mountain taiga (4.1%),
mountain steppe (25.1%), steppe (26.1%), desert steppe (27.2%) and desert (14.5%).
Roughly 124.3 million ha or 79% of land area are covered by grassland and 15
million ha are covered by forest and shrub. Sandy areas are estimated at about 4.4
million ha (3% of land) and roughly 4.3 million ha are occupied by settlements,