Stylized facts of past 1000-year of China’s cropland changes

Quantifying long-term and large-scale changes in cropland cover is critical for evaluating the intensity of past human activity, climate change, biodiversity loss, food security, and carbon and water cycles. This study used multiple data sources, i.e., historical reconstruction, remote sensing, statistics, and their derived products, and a combined approach for quantitative reconstruction and gridding allocation to create the Chinese Historical Cropland Dataset+ (CHCD+). Our findings showed a substantial gross change of 30.82 × 107 ha in cropland cover, equivalent to 32 % of China’s land area. This represents a 3.2-fold increase compared to the net change. Such a large-scale agricultural land cover change has not been identified previously. Traditional agricultural areas, predominantly in the Yellow River and Yangtze River basins, have established a fundamental pattern for the historical development of agriculture in China. The proportion of croplands in this region consistently exceeded 70 %, reaching 90 % before the mid-Qing dynasty. We identified a two-phase pattern of historical cropland cover changes in China. Before the Qing Dynasty, there was slow growth and a substantial change in the cropland area. This has been constrained by geographical conditions, tax systems, and population size, with the gross change being six times the net change. Since the Qing Dynasty, a rapid growth and expansion phase has been observed in cropland areas, which can be explained by tax system reforms, population expansion, and the introduction of cold- and drought-resistant crops.