Climatic suitability of the distribution of the winter wheat cultivation zone in China

Winter wheat is one of major grain crops in China. To scientifically map cropping patterns, it is very important to understand the area of its viable cultivation zone in China. Based on published data, geographical information, national climate data, and the MaxEnt model, the relationship between the distribution of the winter wheat cultivation zone and climate was established. The main indices controlling the distribution of the winter wheat cultivation zone were analyzed to reveal climatic suitability. The main controls on winter wheat distribution in China were: the negative accumulation of daily mean temperatures below 0°C during winter (i.e., negative accumulated temperature), annual mean extreme minimum temperatures, potential evapotranspiration, and annual precipitation. For winter wheat to safely survive the winter, the negative accumulated temperature should be higher than −700°C, and the annual mean extreme minimum temperature should be higher than −30°C. Climate suitability classification of the winter wheat cultivation zone was mapped, based on the MaxEnt probability distribution of winter wheat. Former studies indicated that the northeast boundary of the winter wheat cultivation zone is the south of Liaoning Province, and our study indicated that the northeast boundary of the winter wheat cultivation zone is the north of Heilongjiang Province; former studies indicated that the northwest boundary of the winter wheat cultivation zone is the south of Xinjiang Uygur Autonomous Region, and our study indicated that the northwest boundary of the winter wheat cultivation zone is the north of Xinjiang Uygur Autonomous Region. Our study describes a suitable winter wheat cultivation zone in China and the northern boundary of winter wheat cultivation, and it will be helpful for guiding the cultivation of Chinese winter wheat. Based on our climatic indices and their threshold determining the distribution of winter wheat, it will be helpful for gaining a scientific understanding of the effects of climate change.