Social vulnerability assessment by mapping population density and pressure on cropland in Shandong Province in China during the 17th-20th century

Abstract

Cropland area per capita and pressure index on cropland are important parametersfor measuring the social vulnerability and sustainability from the perspective of food security ina certain region in China during the historical periods. This study reconstructed the change inspatial distribution of cropland area per labor/household and pressure index on cropland duringthe 17th-20th century by using historical documents, regression analysis, pressure index model, and GIS (geographic information system). Following this, we analyzed the impacting process ofclimate change and sustainability of cropland use during the different periods. The conclusions ofthis study are as follows: (i) there was an obvious spatial difference of labor/household density, as there was higher density in three agricultural areas, which had the same pattern as croplanddistribution during the same periods; (ii) Cropland area per capita was relatively higher during the17th-18th century, which were above 0.4 ha/person in the majority of counties and were distributedhomogenously. Until the 19th century and the beginning of 20th century, cropland area per capita ina considerable proportion of regions decreased below 0.2 ha/person, which embodies the increase insocial vulnerability and unsustainability at that time; (iii) The pressure index on cropland also showeda spatial pattern similar to cropland area per capita, which presented as having a lower thresholdthan nowadays. During the 17th-18th century, there was no pressure on cropland. In comparison, in the 19th century and at the beginning of 20th century, two high-value centers of pressure index oncropland appeared in the Middle Shandong and the Jiaodong region. As a result, pressure on croplanduse increased and a food crisis was likely to have been created; (iv) A higher extent of sustainablecropland use corresponded to the cold period, while a lower extent of sustainable cropland usecorresponded to the warm period in Shandong over the past 300 years. The turning point of the 1680sfrom dry to wet was not distinctively attributed to the decrease in the extent of sustainable croplanduse in Shandong. Since the beginning of the 20th century, the increasing pressure on the sustainabilityof cropland use finally intensified the social conflict and increased the probability of social revolts.