Response Of Potential Suitable Planting Areas Of Major Grain Crops To Climate Change In China

Climate change is affecting the distribution of crop cultivation,and reasonable crop planting planning is a prerequisite for ensuring food security.Previous studies often adopted crop potential distribution to assess planting suitability,however,the information about yield within the potential distribution range of the crop is unclear,it is difficult to make detailed and reliable plans for crop cultivation.To optimize crop planning in the context of climate change,taking China as a case,this study used data such as climate and CO₂ concentration to drive process based agroecosystem model（Lund-Potsdam-Jena General Ecosystem simulator,LPJ-GUESS）to simulate the potential crop yi elds of major grain crops（maize,wheat and rice）in China under three Shared Socioeconomic Pathways（SSP119,SSP245 and SSP585）during2001–2100.The temporal and spatial changes of potential crop yields in the current period（2001–2022）and the future period（2081–2100）were analyzed.Partial correlation analysis was used to determine the partial correlation coefficients between temperature,precipitation,radiation and CO₂ concentration and the potential yield of main grain crops and then to determine the dominate factors affecting the potential yield of main grain crops.The high and stable yield evaluation system was constructed according to the potential yield of crops,and the potential planting suitability areas of crops was divided according to the actual distribution sites of crops and the cumulative frequency method.Then the spatio-temporal pattern changes of crop planting suitable areas in different periods were analyzed.Based on the actual crop distribution data,the adjustment strategies of planting pattern of main grain crops under the future climate change were discussed.The main conclusions are as follows:（1）From 2021 to 2100,the average annual potential yield of maize,wheat and rice in China show a trend of fluctuation and increase under SSP245 and SSP585 scenarios.In the2001–2020,the average potential yields of maize,wheat and rice across China were 3.99±0.01t/ha,5.37±0.01 t/ha and 2.07±0 t/ha,respectively.Specifically,maize showed a high potential yield in the middle-lower Yangtze Plain and southern North China Plain,but a low potential yield in the Xinjiang,western Inner Mongolia and northern Great Khingan Mountains;wheat showed a high potential yield in the middle-lower Yangtze Plain,Wushan Mountain,Yunnan-Guizhou Plateau,Hengduan Mountains,southeast Tibet and Taiwan,and a low potential yield in the Qinghai-Tibet Plateau,Xinjiang,Qilian Mountains,Western Inner Mongolia Plateau and southern coastal provinces;rice showed a high potential yield in the south of China and a low potential yield in the north of China.Compared with averaged potential yields of maize,wheat and rice in the 2001–2020 period,those in the 2081–2100 period will increase under all climate scenarios.In the future,the areas of potential maize potential yield will increase and decrease account for 57.63～90.93%and 4.08～21.64%of China,respectively.The areas of wheat potential yield will increase and decrease account for 2.74～40.53%and 58.46～40.53%of China,respectively.The areas of rice potential yield will increase and decrease account for41.61～92.64%and 0.01～34.47%of China,respectively.（2）Under the three SSP scenarios,the areas where maize potential yield is dominated by annual precipitation,mean annual temperature,annual solar radiation,and CO₂ concentration would account for 29.39～39.73%,20.3～30.28%,5.26～6.96%and 3.95～32.72%of China,respectively,the areas where wheat potential yield is dominated by those would account for28.09～43.58%,11.42～22.05%,2.82～12.33%and 23.88～45.71%of China,respectively,and the areas where rice potential yield is dominated by those would account for 17.40～21.88%,2.51～13.3%,1.56～4.4%and 19.97～61.49%of China,respectively.Annual precipitation would show positive correlation with the potential yield of three crops in the north and center of China.Mean annual temperature would mainly show positive correlation with the potential yield in the south and northeast of China and areas with high altitude.Annual solar radiation would show positive correlation with the potential yield in the southern coastal areas of China while negative correlation in the northeast of China and areas with high altitude.The CO₂concentration would show positive correlation with the potential yield in most parts of China.（3）The stability of yield for each crop showed large spatial differences in the 2001–2020period.Compared with the stability of yield in the 2001–2020 period,future stable yield areas of maize will expand under the SSP119 scenario,but shrink under the SSP245 and SSP585scenarios,and wheat and rice will shrink under all climatic scenarios.In the 2001–2020 period,the proportions of optimal suitability,high suitability,moderate suitability,low suitability and unsuitable areas for maize were 11.29%,20.79%,17.67%,20.56%and 29.69%,respectively,those for wheat were 14.66%,18.71%,26.38%,25.71%and 14.54%,respectively,those for rice were 1.85%,19.29%,17.33%,20.82%and 40.71%,respectively.The optimal suitability area for maize was mainly distributed in the middle-lower Yangtze Plain and Sichuan basin.the optimal suitability area for wheat was mainly located in the middle-lower Yangtze Plain,Qinling Mountains,Yunnan-Guizhou Plateau and Eastern Wuyi Mountains.The optimal suitability areas for rice were mainly distributed in southeastern coastal provinces,Yunnan and Taiwan.Compared with suitability in the 2001–2020 period,the optimal suitability areas in the future for maize,wheat,and rice will expand under all climatic scenarios,with an increase in area of 7.72～11.04%,5.42～17.0%and 5.34～32.61%over China.Spatially,except for rice under the SSP119 scenario,their expanding areas will lie in the North China Plain,the middle-lower Yangtze Plain,Yunnan-Guizhou Plateau and the southern coastal provinces and parts of northeast of China.（4）From 2001 to 2020,the proportion of space matching area between the actual distribution of maize and the optimum suitability area and high suitability area accounted for12.71%,41.71%respectively.Corresponding to wheat,13.95%,53.75%,to rice 3.55%,70.49%,and the optimal suitability area for each crop has not been occupied by actual crop planting.Compared with the planting suitability of actual crops in the current period,those in the 2081–2100 period will be enhanced under all climatic scenarios,the proportion of actual distribution area matched with the optimal suitability area of maize,wheat and rice increased by 14.36～31.57%,26.98～65.62%and 17.79～80.46%,respectively.These results indicate that although the future natural environment conditions are more suitable for the actual distribution of the current crop,the actual distribution area of the crop will not fully occupy the optimal suitable natural environment resources.Spatially,maize planting can be extended to the middle and lower reaches of the Yangtze River plain and Hebei Province in the future.Wheat cultivation could be expanded to the north and south of existing areas,even to Jilin and Liaoning provinces.Rice cultivation can be transferred from the moderate suitable northeast area to the optimal and high suitable in southern area,such as Sichuan Basin and Guangdong and Fujian regions.