Abstract:

With the rapid development of urbanization and the continuous loss of the rural labor force, large areas of farmland have been abandoned in some regions of China. Remote sensing technology can indirectly help to detect the size and quantity of abandoned farmland, which is of great significance for the protection of farmland and food security. Using Qingyun and Wudi counties of Shandong Province as the study area, and based on the Landsat data and HJ-1A data, this paper uses the CART decision tree classification method to develop land use maps from 1990 to 2017, set down rules to identify abandoned farmland, and explore the spatial distribution, duration, and reclamation area of abandoned farmland. The results showed that the accuracy of the CART decision tree classification was higher than 85% from 1990 to 2017. The maximum abandoned farmland area was 5503.86 hm² from 1992 to 2017, and the maximum abandonment rate was 5.37%. The rate of farmland abandonment reached the peak from 1996 to 1998, and the overall trend of abandonment has decreased year by year after 2006. The maximum duration of abandonment was 15 years during the period of 1992 to 2017. Most of the durations were within four years and a few durations were more than ten years. From 1993 to 2017, the maximum reclamation area of abandoned farmland was 2022.3 hm², and the minimum reclamation area was about 20 hm². The maximum reclamation rate was 67.44% and the annual average reclamation rate was 31.83%. The results from this paper not only help analyze the driving forces of farmland abandonment in the study area, but also provide references for the identification of abandoned farmland in other areas.

Key words: CART, abandonment, reclamation, farmland, Shandong Province, Landsat data