Identifying a scenario for preindustrial cropland cover using cultivation data: A case study of France, Germany and Italy

Cropland expansion is effected by physiogeographic and sociocultural factors, which vary across region and over time, but have not been adequately represented in large-scale anthropogenic land cover change scenarios. Taking preindustrial cropland expansion in France, Germany, and Italy as a case study, this study first adopted a productivity-based estimation of cropland per capita, which converted crop yield to cropland demand per capita through negative correlations under different crop rotations, to improve the accuracy of national cropland areas. Then, a new allocation algorithm was proposed to allocate national cropland areas into 5′× 5′ grids. The algorithm combines land suitability, which characterizes regional differentiation of potential productivity indicated by physiogeographic factors (climate, topography, soil, etc.) that dominate cultivation, and cultivation preference, which quantifies sociocultural impacts by kernel density estimation based on city information (i.e., location, size, accessibility). The cropland cover scenario here shows similar phases but different modes of cropland expansion in these countries: (1) National cropland areas increased 1.73–2.46 times during the 11th–13th centuries, manifested by the expanding cultivated ranges in France and Germany and the increasing cultivation intensity in Italy. (2) National cropland fractions decreased by 9.16–19.98 percentage points in the 14th century, accompanied by widespread reductions in cultivation intensity. (3) Cropland gradually recovered toward its peak in 1300 AD during the 15th–18th centuries, achieved by general and remarkable increases in cultivation intensity. Compared to representative global datasets, this study is more consistent with cultivation-related descriptions in the literature, especially with respect to the cropland expansion in newly cultivated regions and on marginal lands.