Comparison of the HYDE cropland data over the past millennium with regional historical evidence from Germany

Historical land cover data are the basis of quantifying the environmental effects of land use and land cover change (LUCC), and a lower deviation is expected when they are used to study the carbon cycle and create climate simulations. Generally, a global scenario of past LUCC that can be supported by relevant historical evidence is more likely to describe the actual LUCC pattern of a given region. Starting from this point, we selected qualitative and quantitative evidence of cropland cover changes in Germany over the last millennium to explore the feasibility of using historical information to discuss the deviation of global LUCC scenarios in regions lacking independent reconstructions. A comparison between the cropland data of HYDE 3.2.1, a representative and widely used global historical land use scenario, and German historical evidence was conducted. The total areas of croplands in HYDE showed high consistency with previous studies based on region-specific sources, although HYDE’s interpolation method after 1700 AD may need some improvement. Several deviations arise from cropland allocations in HYDE 3.2.1, especially for the early cropland expansion in areas along major rivers and wetlands. HYDE’s insufficient consideration of the spatial variation in population over time might account for the noticeable discrepancies between the spatial patterns of HYDE croplands and medieval settlements, as well as research on the agricultural landscape from 1000 AD to 1400 AD. The findings of this study suggest that the introduction of human indicators such as settlement data could help to improve the estimation and allocation algorithms of global-scale LUCC reconstructions.