| China is a large agricultural country with a population of 1.4 billion.Food production and consumption are at the forefront of the world.Ensuring food security is of great significance to the national economy and people's livelihood.Food production is closely related to climate change.Agricultural climate resources change with climate change,which directly affects crop climate suitability and distribution of maturation cropping,and has a profound impact on agricultural production.Therefore,the analysis of the climate suitability of grain crops and the distribution of maturation cropping has guiding significance for adjusting crop planting structure and optimizing crop distribution.This study is based on the existing crop planting division,combined with previous research results and empirical statistics,establish the index system of grain crops climate suitability and the maturation cropping distribution,analyzes the history and future of weather conditions,dynamic of crops climatic suitability and the distribution of maturation cropping system.Firstly,obtains the daily meteorological data of 635 meteorological stations in China from 1960 to 2016,the corresponding meteorological indicators were screened and calculated according to the conformity degree of light,temperature and water conditions required for crop growth and planting environment.Secondly,based on the year as a benchmark,and analyzed the existence probability 100%,90%and 80%of main grain crops respectively under rainfed or fully irrigated conditions.At the same time,the daily meteorological data of the future 20102050 were generated by using the MIROC5 climate model in CMIP5 to study and analyze the variation law of grain crops climate suitability and distribution of maturation cropping under future climate scenarios.Calculated the main climatic factors affecting the grain crops climate suitability on the spatial scale of China and the time scale of year as the benchmark.Analyzed the main grain crops spatiotemporal distribution dynamics of the suitable planting areas at every levels when satisfied the existence probability of 100%,90%and 80%and under rainfed or fully irrigation conditions on 1960s,1980s,2000s,2020s,2040s.The results showed that the area of plantable area of single rice maintained an increasing trend from 1960s to 2000 s when the probability of 100%was met.In 2020s,the area of plantable area of single rice decreased significantly in central Sichuan,and increased by 72.29 ×104 km2 in 2040s.The plantable area of double rice decreased in 1980s,increased by 20.09×104 km2 in 2000s,continued to decrease by 15.96×104 km2 in 2020s,and increased by 31.11×104 km2 in southern Jiangsu,Anhui and Mianyang,Sichuan procince to Jiulong area.After the decrease of winter wheat plantable area in 1980s,the concentration of 2000 s to 2040 s in Henan,Hubei and Shaanxi maintai1ed an increasing trend,and 2040s increased 97.87×104 km2 compared with 2020s.The plantable area of summer corn decreased in 1980s compared with 1960s,and increased steadily from 1980s to 2040s with the passage of time.The plantable area of summer corn in 2040s increased by about 135.68×104 km2 compared with that in 2020s.Spring corn plantable areas showed a steady growth trend from 1960s to 2020s.Compared with 2000s,2020s increased by about 56.57×104 km2 mainly in northern Xinjiang and northeastern Inner Mongolia.When fully irrigated,the plantable area of single rice and double rice decreased in 1980s and 2020s,and increased significantly in 2000 s and 2040 s.The plantable area of single rice and double rice increased respectively by 72.39×104 km2 and 93.58×104 km2 in 2040s.After the decrease of winter wheat plantable area in 1980s,the concentration of 2000s to 2040s in Henan,Hubei and Shaanxi maintained an increasing trend,and 2040s increased 97.87×104 km2 compared with 2020s.The plantable area of summer corn and spring corn has been increasing steadily from 1960s to 2040s.Compared with 2000s,the plantable area of summer corn and spring corn has the widest expansion in Xinjiang and Northeast China,with an increase of about 157.51×104 km2 and 79.59×104 km2,respectively.Under the conditions of 90%probability and 80%probability,the variation law of climate suitability distribution of five crops is basically the same as that of 100%probability.In summary,when the rainfed or fully irrigated conditions are met,climate change in the 2040s will result in the growth of plantable areas of single rice,double rice,winter wheat,summer corn and spring corn to varying degrees.On the basis of climate regionalization of China's cropping system,the accumulated temperature is taken as the dividing index,the national region as the spatial scale,and the different years as the time scale.Compared and analyzed quantitatively the effects of historical and future climate warming on the maturation cropping distribution of China's cropping system.The results showed that the proportion of one crop a year in China decreased from 1960s to 2040s.The planting proportion of double crops a year showed a steady growth trend from 1960s to 2000s.The planting proportion of double crops a year decreased in 2020s,while the planting proportion of 2040s increased to 43.11%of the total area of China,The area of three crops a year decreased in 1980s and 2040s,and increased in other decades,and reached the largest planting proportion of 22.89%in 2040s.2020s compared with 1980s,the planting boundary of three crops a year moved northward from Hangzhou-Anqing-Tianmen-Sangzhi-Kaili-Yuxi in 1980s to Changzhou-Bengbu-XinyangFangxian-Wanxian-Youyang-Dushan-Kunming in 2000s,and the area of three crops a year increased by 36.22×104km2.The planting boundary for double crops a year is also moving northward,mainly from Huailai-Taiyuan-Tongchuan-Tianshui Line in 1980s to ZhangjiakouYulin-Xifeng Town-Minxian line in 2000s.The area of double crops a year has increased by about 54.80×104 km2 in 2000s.The results of this study will help to clarify the impacts of climate change on the climate suitability of grain crops and the distribution of cropping system ripening in China,and provide opinions for coping with future climate change and developing agricultural climate resources rationally. |
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