Average Amount and Stability of Available Agro-Climate Resources in the Main Maize Cropping Regions in China during 1981–2010

The available agro-climate resources that can be absorbed and converted into dry matter could directly affect crop growth and yield under climate change. Knowledge of the average amount and stability of available agro-climate resources for maize in the main cropping regions of China under climate change is essential for farmers and advisors to optimize cropping choices and develop adaptation strategies under limited resources. In this study, the three main maize cropping regions in China—the North China spring maize region（NCS）, the Huanghuaihai summer maize region（HS）, and the Southwest China mountain maize region（SCM）—were selected as study regions. Based on observed solar radiation, temperature, and precipitation data, we analyzed the spatial distributions and temporal trends in the available agro-climate resources for maize during 1981–2010. During this period, significantly prolonged climatological growing seasons for maize [3.3, 2.0, and 4.7 day（10 yr）–1 in NCS, HS, and SCM] were found in all three regions. However, the spatiotemporal patterns of the available agro-climate resources differed among the three regions. The available heating resources for maize increased significantly in the three regions, and the rates of increase were higher in NCS [95.5°C day（10 yr）–1] and SCM [93.5°C day（10 yr）–1] than that in HS [57.7°C day（10 yr）–1].Meanwhile, decreasing trends in the available water resources were found in NCS [–5.3 mm（10 yr）–1] and SCM[–5.8 mm（10 yr）–1], whereas an increasing trend was observed in HS [3.0 mm（10 yr）–1]. Increasing trends in the available radiation resources were found in NCS [20.9 MJ m–2（10 yr）–1] and SCM [25.2 MJ m–2（10 yr）–1], whereas a decreasing trend was found in HS [11.6 MJ m–2（10 yr）–1]. Compared with 1981–90, the stability of all three resource types decreased during 1991–2000 and 2001–10 in the three regions. More consideration should be placed on the extreme events caused by more intense climate fluctuations. The results can provide guidance in the development of suitable adaptations to climate change in the main maize cropping regions in China.