Characteristics and influencing factors of farmland abandonment in the karst rocky desertification area of Southwest China

Owing to rocky desertification, farmland abandonment in karst areas is different from that in normal landforms. Aiming at the phenomenon of large-scale farmland abandonment in the karst region of Southwest China, this study investigated the characteristics of farmland abandonment in different rocky desertification control areas of typical counties. We interpreted land use changes in the study area using high-resolution images (5 m) in 2010 and 2020 through human-computer interaction. After removing patches of converted farmland to forests, we extracted the spatial distribution of abandoned farmland. The study area was found to have a high abandonment rate (24.83 %), with dryland showing 2-3 times higher abandonment rate than paddy fields. The abandoned area in rocky desertification dryland accounts for 50.57 % (499.04 km2) of the abandoned area of karst dryland. It is worth noting that the abandonment rate of non-rocky desertification dryland in the karst dryland is the lowest (22.45 %), while the abandonment rate of dryland shows no significant difference among other rocky desertification grades, with an average of 28.00 %. In addition, with the change of rocky desertification level, the index of abandonment degree showed a trend of initial increase followed by a decrease. Slope, lithology and soil type have a joint effect on karst dryland abandonment. Slope is the core factor affecting karst dryland abandonment, and the interaction between slope and soil type is the dominant factor affecting its change. The results of this study show that farmland abandonment is serious in karst rocky desertification areas, primarily occurring in rocky desertification dryland. The government should take targeted management measures based on the current status of abandoned drylands at different levels of rocky desertification, especially in sloping farmland areas.