Urban expansion or poor productivity: Explaining regional differences in cropland abandonment in China during the early 21st century

Cropland abandonment has long been recognized as a marginalization process in rural regions but recently also as a precursor to urbanization in peri-urban regions. This study aimed to evaluate the relative importance of urbanization and poor productivity in cropland abandonment. A thorough investigation was conducted on 345 cities/towns at the prefecture level or higher in China using 500-m annual maps for 2003-2016. Cropland abandonment was spatiotemporally coupled with the urbanization. At a national scale, approximately 0.55% of the total cropland area (approximately 862 km(2) per year) has been abandoned. Cropland abandonment increased significantly until 2009, declined in the early 2010s, and then leveled off in recent years. In particular, the new first-tier cities suffered the greatest abandonment per capita. However, cropland abandonment was increasingly shifted to lower-tier cities, particularly the high-quality cropland abandonment in the medium-tier cities. Low-quality cropland in rural regions of the medium- and lower-tier cities experienced incessant abandonment. Results showed that the extent of cropland abandonment increased with city sizes described either by population/GDP or by built-up area. High-quality cropland abandonment was more closely related to the built-up area than to population and GDP for total abandonment. Urbanization-induced abandonment in peri-urban areas was dominant for most cities, with exceptions only for a few small cities. Contrary to expectation, cropland abandonment for most cities/towns in rural regions was not more driven by poor productivity, compared to peri-urban regions. Our study highlights that urbanization mainly accounted for the regional differences in cropland abandonment in China during the past two decades.