Desertification (AQA A Level Geography)

Figure 4

Surrounded by mountains and far from any sea or ocean, the region of Xinjiang Uygur in the north-west region of the People’s Republic of China represents the largest stretch of drylands in China. Xinjiang territory stretches over 1 650 000 km² of which 49.5% are mountainous zones and 22.5% is desert. It is estimated that 400 million people are suffering from the impact of desertification and the effects of sand dust that can attack skin and lungs. Desertification in China is mainly caused by human induced factors and by extreme climatic conditions.

An oasis is an area with a plentiful supply of water in an otherwise arid environment. Vegetation growth will be adapted to the conditions in the oasis and will contain different species to the surrounding environment.

What is shelterbelt system in the Xinjiang Oasis?

• Around the perimeter of the oasis, shelterbelts made up of shrubs and grasses have been planted.

• Within the inner zone of the oasis, a forest belt of mature trees reinforces the function of the shelterbelt.

• Deep inside the oasis, a forest network has been planted in the interior, between the agricultural lands. This is composed four to six narrow rows of trees planted closely together.

• In general, the width of the shelterbelt should not be less than 200 m.

Ground wind speed is reduced by the presence of shrubs and grasses standing 50 cm to 60 cm high. In areas where sand accumulates, vegetation can reduce the development of dunes once the vegetation covers 40% of the surface.

The shelterbelt also acts as a biological drainage system that plays an important role in the Xinjiang oases. In Anjiahi, in the northern part of Xinjiang, the groundwater level of farmland has been lowered by between 20 cm and 70 cm. The tree network creates a microclimate. In some instances, the rate of water consumption for one kilogram of wheat or corn has decreased by between 15% and 22.8%.