Monitoring the trends of aeolian desertified lands based on time-series remote sensing data in the Horqin Sandy Land, China

摘要

Aeolian desertification is one of the most significant environmental and socio-economic problems, represents a major component of land degradation, and seriously harms the ecological environment, leading to adverse impacts on human society. Monitoring aeolian desertification and identifying the driving factors behind it are crucial for developing prevention and management strategies to combat this issue. The objectives of this study were to monitor the trends of aeolian desertification in Horqin Sandy Land by using time-series MODIS-NDVI remote sensing data for the period of 2000-2013. A dimidiate pixel model was chosen to calculate the Vegetation Coverage Index (VCI), while a unary linear regression analysis was used for a temporal trend analysis of the Aeolian Desertification Index (ADI) and selected climate factors. The Sen's slope estimator and the Mann Kendall statistical test were used to analyze the spatial trends of the ADI. (1) The temporal trend of ADI showed three stages: reversion during the period of 2000-2005 and 2009-2013, and development during the period of 2005-2009. For the five classes of ADI, the areas of non-aeolian desertified lands (N) showed an increasing trend and the slight (SL), moderate (M), serious (S), and very serious aeolian desertified lands (VS) showed decreasing trends, with the decline in areas of SL and M contributing to the reversion of aeolian desertification. (2) The spatial distribution showed that the VS was mainly distributed in the southwestern portion, and the S was mainly distributed around the VS portion. The SL and M formed a straight line from the southwest to the northeast, bisecting the two areas of S. The N was mainly distributed in the northwestern portion and the eastern edges of the study area. (3) The spatial trends showed that areas of decreasing and significantly decreasing ADI trends occupied 78.44%, while areas with increasing and significantly increasing ADI trends only occupied 21.56% of the study area over the period of 2000-2013, indicating that aeolian desertification in Horqin Sandy Land is decreasing overall and advancing in certain portions. (4) The driving factors of aeolian desertification were analyzed from the perspectives of two groups: climate and anthropogenic factors. We found that the desertification control measures and favorable climate condition have played key roles in the process of desertification reversion; and climate fluctuations, reclamation and livestock pressure have led to the desertification development. The results can provide meaningful information for the prevention and control of aeolian desertification in Horqin Sandy Land.