North Expansion of Winter Wheat Planting Area in China under Different Emissions Scenarios

Suitable planting areas for winter wheat in north China are expected to shift northwardly due to climate change, however, increasing extreme events and the deficient water supply are threatening the security of planting systems. Thus, based on predicted climate data for 2021-2050 under the Shared Socioeconomic Pathways (SSP1-2.6, SSP3-7.0, and SSP5-8.5) emission scenarios, as well as historical data from 1961-1990, we use four critical parameters of percentages of extreme minimum temperature years (POEMTY), first day of the overwintering period (FD), sowing date (SD), and precipitation before winter (PBW), in order to determine the planting boundary of winter wheat. The results show that the frequency of extreme minimum temperature occurrences is expected to decrease in the North winter wheat area, which will result in a northward movement of the western part of northern boundary by 73, 94, and 114 km on average, in addition to FD delays ranging from 6.0 to 10.5 days. Moreover, agrometeorological conditions in the Huang-Huai winter wheat area are expected to exhibit more pronounced changes than the rest of the studied areas, especially near the southern boundary, which is expected to retreat by approximately 213, 215, and 233 km, northwardly. The north boundary is expected to move 90-140 km northward. Therefore, the change in southern and northern boundaries will lead the potential planting areas of the entire North winter wheat area to increase by 10,700 and 28,000 km(2) on average in the SSP3-7.0 and SSP5-8.5 scenarios, respectively, but to decrease by 38,100 km(2) in the SSP1-2.6 scenario; however, the lack of precipitation remains a limitation for extending planting areas in the future.