Tempo-spatial changes and sustainable use strategies of cropland in China over the past 2000 years

Clarifying the spatial and temporal changes of cropland and its sustainable use strategies in historical China can provide experience and lessons for the development and protection of current and future land resources. This study integrated reconstructed data on the spatial distribution of agricultural areas and cropland cover to analyze the temporal and spatial changes of cropland cover in China over the past 2000 years. Then, focusing on the problems encountered during the expansion of agricultural areas in different historical periods, this study discussed the sustainable strategies for the cropland utilization. The main conclusions are as follows:① The cropland in China showed an increasing trend with fluctuations in the past 2000 years, which was around 3.33×10⁷ ha from the 1st century to the 8th century, about 5.33×10⁷ ha in the late 11th century, more than 6.67×10⁷ ha in the early 17th century, over 9.33×10⁷ ha by the end of the Qing Dynasty (AD 1910), and over 13.33×10⁷ ha after 1980. ② The agricultural areas in China experienced three expansions over the past 2000 years. First, the cropland expanded to the north of the Yangtze River during the Western Han Dynasty. Second, the expansion of cropland south of the Yangtze River contributed to the formation of cropland distribution pattern in modern China. Third, the cropland expansion since the Qing Dynasty was mainly characterized by the intensification of cultivation in the plains and the reclamation of cropland in the mountainous and frontier areas. ③ The sustainable strategies of cropland use in historical China were based on flexible adaptations to local conditions, including various agricultural production techniques such as water conservancy infrastructure and farming implements, as well as field management techniques such as cropping methods and seed selection. These factors were indispensable for sustaining the long−term existence and development of an intensively cultivated peasant economy during historical periods in China.