Assessment of continuity and efficiency of complemented cropland use in China for the past 20 years: A perspective of cropland abandonment

The process of urbanization and infrastructure construction has resulted in the occupation and loss of high-quality cropland. Complemented cropland with higher altitudes and slopes from either development or reclamation has become an important component of cropland resources and plays a vital role in ensuring food security. However, existing research mainly focuses on the dynamic balance of quantity, quality, productivity, and impact on the environment, and not enough attention is paid to whether the newly added cropland is efficiently used in the long term. Based on a cropping intensity dataset from 2001–2019, this study applied the sliding window and change detection methods to assess the use continuity and efficiency of complemented cropland from the perspective of cropland abandonment and explored the impact of the abandonment on food production. The results showed the following: (1) The total area of complemented cropland in 2002–2019 reached 279,416.4 km2, accounting for 13.1% of total cropland in the base year (2001). (2) 45.1% of the complemented cropland was abandoned at least once during the past 20 years, making only 65.6% of that land efficiently used, and this percentage was higher in the middle plains and downstream of the Yangtze River. (3) Abandonment had significant impact on the food production of complemented cropland—with a trend of increasing and then decreasing—leading to a food production reduction of 24.3% per year on average, which was more severe in the middle plains and downstream of the Yangtze River. Higher slope and a migrated population promoted the abandonment of complemented cropland. Therefore, the government should strengthen the monitoring of long-term utilization of complemented cropland and strategic reserves to maintain stable utilization.