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The characteristics and driving forces of LUCC in the middle and lower reaches of Shule River Basin.

QI Jing-hui1, NIU Shu-wen1**, MA Li-bang2, WANG Wen-die1   

  1. (1College of Earth and Environmental Science, Lanzhou University, Lanzhou 730000, China; 2College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730000, China)
  • Online:2014-08-10 Published:2014-08-10

Abstract: With the support of ArcGIS and ENVI, five sets of TM remote sensing images of the middle and lower reaches of Shule River Basin in 1987, 1996, 2000, 2006, and 2010 were interpreted. Nine types of land use and land cover were obtained, and the characteristics and causes of the land use and land cover were analyzed. In the past 23 years, the area of artificial vegetation with an expanding trend (an increase of 900 km2 in total), while the natural vegetation showed a shrinking tendency (a decrease of 842.9 km2). Cropland, shrub land and urban construction land had a net increase in area; the area of non-vegetation land increased firstly and then decreased; and the others presented a net decrease. There were frequent conversions among the nine land use and land cover types, the main directions were that the high-coverage grassland was successively transformed into the grassland with medium coverage, low coverage and non-vegetation land; the increased shrub land was largely transformed from the grassland with medium and low coverage; the reduced wetland mainly changed into non-vegetation land or low-coverage grassland; the expansion of cropland primarily benefited from the decrease of non-vegetation land and low-coverage grassland; the non-vegetation land had a net decrease in the mutual conversion with the crop land, whereas had a net increase with lowcoverage grass land; the increase of urban construction land was largely brought by the reduced cropland and non-vegetation land; the snowice land was mainly transformed into non-vegetation land after they melt. The rate of the landuse and landcover change was relatively slow from 1987 to 1996, but it was quite rapid during 1996-2010. The vegetation coverage around irrigational areas presented an expanding trend, while it was in a degraded state in other areas. The driving force analysis showed that the main causes of land use and land cover change were the rapid growth of agricultural population, large-scale agricultural development, and the immigration policy, while natural factors, such as temperature, precipitation and annual runoff, had little influence.

Key words: Vaganov-Shashkin model, climate factors, tree-ring, Larix chinensis