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Spatial and temporal variations of NDVI and its influencing factors in Qaidam Basin in the last 14 years.

WANG Lin-lin, LIU Pu-xing**, WANG Yun   

  1. (College of Geography and Environmental Science, Northwest Normal University, Lanzhou 730070, China)
  • Online:2015-06-10 Published:2015-06-10

Abstract: In this paper, the spatiotemporal variation of vegetation NDVI in Qaidam Basin and its influencing factors were analyzed by using MODIS/NDVI data during 2000-2013. The results showed that in the last 14 years, annual average and seasonal NDVI all showed an increasing trend, and the area of increased trend in spring was the largest, followed by summer, annual average and autumn. Differences in NDVI and NDVI change trend (θslope) were obvious among different elevations, with the maximum values found at elevations of 3750 and 3550 m, respectively. NDVI and θslope increased with the elevation when it was lower than 3750 and 3550 m respectively, and vice versa. Correlation analysis indicated that the relationships of the NDVI in spring, summer and autumn with temperature, precipitation and potential evapotranspiration were positive, and the corresponding area with positive correlation accounted for 81.96%, 96.94% and 76.54% of the total vegetation area, respectively. The annual average NDVI was most sensitive to precipitation, and 91.03% of the total vegetation area was positively related with precipitation. In addition, the lag effect of spring and summer NDVI in response to temperature and precipitation was obvious; the precipitation and extremely low temperature in winter affected most the vegetation growth in the coming spring, while the precipitation in spring had a great contribution to vegetation growth in summer. In addition to the natural factors, human activities such as crop planting area and the marketing rate of fattened stock also were important factors affecting NDVI in Qaidam Basin.

Key words: land use intensification, sustainable intensification, agricultural land, spatial-temporal pattern, material flow analysis.