A spatially explicit reconstruction of cropland cover in China from 1661 to 1996

Reconstruction of cropland cover is crucial for assessing human impact on the environment. In this study, based on existing studies concerning historical cropland, population data and government inventories, we obtained a provincial cropland area dataset of China for 1661-1996 via collection, revision and reconstruction. Then, the provincial cropland area was allocated into grid cells of 10 x 10 km depending on the land suitability for cultivation. Our reconstruction indicates that cropland increased from similar to 55.5 x 10(4) km(2) in 1661 to similar to 130.0 x 10(4) km(2) in 1996. From 1661 to 1873, cropland expanded tremendously in the Sichuan Basin, and land reclamation was greatly enhanced in North China Plain. For 1873-1980, agricultural development occurred primarily in northeastern China. After 1980, most provinces in the traditionally cultivated region of China experienced decreases in cropland area. In comparison with satellite-based data for 2000, we found that our reconstruction generally captures the spatial distribution of cropland. Also, differences are mostly < 20 % (-20 to 20 %). Compared with HYDE 3.1 dataset, which is designed for the global scale, our model is more suitable for reconstructing the historical crop cover of China at 10 x 10 km grid scale. Our reconstruction can be used in climate models to study the impact of crop cover change on the climate and carbon cycle.