Long-term dynamic characterization of aeolian desertification in northwest Shanxi, China.

Northwest Shanxi is located on the farming-pastoral ecotone of northern China, where aeolian desertification is one of the most serious environmental and socioeconomic issues. The remote sensing image and geostatistical approach were implemented to estimate aeolian desertified land (ADL) dynamic variations from 1975 to 2015. Results showed that the ADL covered 11,685.21 km2 (82.29%) of the study area in 2015, the majority of which was classified as a light or moderate degree. The area of ADL gradually expanded at an increasing rate of 87.37 km2 a-1 during the 1975-2000 periods. More specifically, the area of ADL has increased by 1259.23 km2 from 1975 to 1990 and by 924.96 km2 from 1990 to 2000, respectively. In contrast, spatial transfer of ADL areas has dwindled by 2365.85 km2 with a net decrease of 157.72 km2 a-1, and the mitigated areas of aeolian desertification were 10,602.24 km2 between 2000 and 2015. During the past 40 years, the gravity center of ADL migrated to southeast until 2000 and moved northwest in 2000-2015. From 1975 to 2000, the migration distance of severe ADL was the largest, migrated toward the northwest by 19.03 km in 1975-1990 and by 20.16 km in 1990-2000, respectively. From 2000 to 2015, the migration distance of light ADL was the largest, 27.54 km migrated to the northwest. Aeolian desertification rapidly expanded from 1975 to 2000 under the combination of climate change and intensive human activities. Since the year of 2000, ecological engineering strategy initiated by the governments has been the dominant contributor to the aeolian desertification severity reversal. Aeolian desertification prevention is a complicated process. Both the central and local government should play a critical role in the rehabilitation of ADL in the long term.