Mapping cropping patterns in the North China Plain over the past 300 years and an analysis of the drivers of change

It is essential to map the cropping patterns when investigating the mechanisms and impacts of climate change.However,the long-term evolution of cropping patterns remains poorly understood.This study collected hundreds of records of cropping intensity and crop combinations from local gazetteers and other relevant articles for the North China Plain(NCP)over the past 300 years.Then,we analyzed the evolutionary characteristics and drivers in terms of climate change and advances in agricultural technology.From the Qing Dynasty to the 1950s,one harvest per year(1H1Y)was the dominant pattern in the northern NCP,and three harvests in two years(3H2Y)was the dominant pattern in Henan and Shandong provinces.The 1H1Y crops were cereals and sorghum.The 3H2Y crop combinations were spring maize,winter wheat,and beans.In the 1960s and 1970s,the cropping intensity in much of the NCP was two harvests per year(2H1Y)or a mix of the 2H1Y and 3H2Y patterns.In the 1980s,the cropping intensity in the NCP was dominated by 2H1Y.Since the 1960s,the 2H1Y crop compositions have been winter wheat-summer maize in Shandong,Henan,and Hebei provinces,while winter wheat-rice dominated north of the Huaihe River.The 3H2Y summer crop changed from beans to maize/cereals over time.Climate warming was not the dominant factor driving the evolution of cropping intensity in the NCP.Advances in agricultural production conditions and reforms in production relations have promoted the rapid development of multiple cropping since the 1950s.