Estimating historical cropland distribution over the past 2220 years in China

Abstract:

Existing studies (Ramankutty and Foley, 1999; Goldewijk, 2001) have extended such reconstruction back in time for 300 years at 10-year intervals. Some available historical records of China evidenced that there is a good relationship between cropland coverage and population in preindustrial periods, which was one of the methods used by Goldewijk (2001). Goldewijk (2001) also noted that historical data is particularly important for validating integrated models of environmental change. Therefore, a simple approach was used to derive geographically explicit changes of historical croplands distribution over the past 2220 years in China based on refining the relationship between croplands and population in this study. By collecting historical croplands data and population from different historical population records, we derived a Chinese representation of croplands over the past 2220 years. We compiled a dataset of Chinese historical croplands data, at the province level, based on the historical population data of China. Moreover, we used ArcGIS application to digitize all of the past 2220 year’s historical maps and natural landscapes (e.g. rivers, mountains, and lakes etc.) of China for presenting historical croplands distribution in China. By overlaying the historical croplands distribution maps of China over the modern-day map of China based on latitude and longitude; we can identify those historical croplands’ locations on the modern-day map of China. Finally, for the each and every year we can develop a historical cropland distribution map and a historical cropland density map to present the land-cover change. We believe that the estimation and the resulting dataset will facilitate the development of regional and global climate and ecosystem models to simulate and understand the effects of land-cover change on climate and the cycling of carbon and water.