Ground-surface conditions of sand-dust event occurrences in the southern Junggar Basin of Xinjiang, China

The southern Junggar Basin of Xinjiang is one of the important source regions of sand-dust events in China. During the springtime periods from 2001 to 2004 when frequent sand-dust events can occur, the landform, soil, vegetation and impact of human activities were investigated, and soil and vegetation data collected. The physical and chemical properties of the soil samples were analyzed, and the characteristic indices of the vegetations were calculated. The vegetation cover, community biodiversity, degree of ecological dominance, topsoil water-content, soil organic matter, soil texture, soil salts and pH were chosen as the ground-surface variables most likely to affect the process of sand-dust event occurrence. With canonical discriminant analysis (CDA) using the SPSS10.0 software package, the study effectively discriminated the ground-surface characteristics of the study regions, which were (1) the AN Lake region with high-frequency sand-dust events and (2) the Gurbantunggut Desert with medium-frequency sand-dust events. The results show that in the AN Lake region, where the gray-brown desert soil and gray desert soil are widely distributed and where agricultural development is intensive, the main factors that negatively affect ground surface stability are the high soil surface pH, low soil organic matter contents and the high degree of ecological dominance (low biodiversity) of the vegetation. In the Gurbantunggut Desert, where stable and semi-stable aeolian sandy soils are distributed and are less disturbed by human exploitation, the erosion resistance of its topsoil benefits from the high vegetation cover, plant community diversity and coarser soil texture. The discriminant results also show that the agricultural development region in Kelamayi, with a large area of cleared land that previously belonged to a region of low-frequency sand-dust event, now has the ground surface characteristics of the regions with high-frequency sand-dust event occurrences. The study demonstrates the likelihood of increasing soil erosion and sand and dust storms in the Kelamayi area. The analysis indicates that the increased risk of wind erosion in the Kelamayi area could be reduced by strategic planting of forest shelter belts to reduce the size of sections of cleared land that are unprotected. (c) 2006 Elsevier Ltd. All rights reserved.