Aeolian desertification in northern China

Background/Question/Methods

In China, the land degradation from wind erosion is called aeolian desertification, and defined as “a process of environment degradation under fragile ecological conditions and intensive human activities which leads to the occurrence of a desert-like landscape and a reduction in land productivity”. Researches show that aeolian desertified land area in Northern China was 0.137 ×10⁶ km², 0.176×10⁶ km², 0.334×10⁶ km² and 0.386×10⁶ km² in 1955, 1975, 1987, and 2000 respectively. Aeolian desertified land of Northern China mainly distributes in semi arid and sub humid agro-pastoral ecotones, arid and semi-arid desert steppes, and arid inland oasis.

Results/Conclusions

In these regions, over cultivation, over grazing and deforestation destroys the vegetation and results in the soil organism and fine material eroded by frequent strong wind. In some regions, the physical particle be eroded is about 25.9 t.hm^-2.y^-1, the organic matter be eroded is 2.6 t.hm^-2.y^-1 and nitrogen matter be eroded is 0.17 t.hm^-2.y^-1 from the earth surface. The fine dust blown upward moves into airflow and becomes the dust storm appearing in down wind regions. The sand materials moved downwind along land surface and form the sand sheets or dunes when encountering the barriers. After long periods of wind erosion, only coarse gravel without productivity or some aeolian landforms such as Yadangs are remained in earth surface. In addition to, fixed sand dunes with good vegetation coverage also can transfer into semi-fixed or activity sand dunes owing to the vegetation above sand dunes are destroyed or under water table descend from over exploitation.