Spatio-temporal variation of agricultural thermal resources at different critical temperatures in China's temperate zone
2017, 39 (11):
Agricultural production is facing serious risks under global warming. The spatio-temporal variation of agricultural thermal resources is of great significance to examine agricultural ecological environment,crop pattern and cropping system. In this study,the data,including daily mean temperature,maximum temperature and minimum temperature,are obtained from 840 meteorological stations during 1960—2015 in China’s temperate zone within a range of 200km. We analyzed spatio-temporal variation of agricultural thermal resources and changes in planting boundaries of double cropping regions,as well as winter wheat and spring maize. In addition,we,with the aid of ANUSPLIN interpolation software,used a deviation method to calculate start date,end date,the number of duration days,and accumulated temperature passing stably different critical temperatures （0℃,5℃,10℃,15℃ and 20℃）. ANUSPLIN interpolation software was used in local statistical modeling of smooth thin plate spline function,considering longitude,latitude and altitude. Compared with the Inverse Distance Weight method and the Ordinary Kriging method,ANUSPLIN interpolation method was more suitable in the research on time series of meteorological data. Results show that it became the trend that start dates were advanced,end dates delayed,the number of duration days and accumulated temperature increased in China’s temperate zone,and the greatest change was observed in areas with ≥15℃ thermal resources;start dates at different critical temperatures delayed from south to north,end dates were advanced,and the number of duration days and accumulated temperature decreased. The number of duration days,as well as accumulated temperature anomalies had a shift from negative value to positive value,and there were significant differences between 1960s—1980s and 2000s—2015;a rising trend was found in high value areas of thermal resources in middle and warm temperate zones,while a decreasing trend was in low value areas in cold temperate zone. Compared with period I （1960—1989）,planting boundaries of double cropping regions,together with winter wheat and spring maize,tended to expand northward at period II （1990—2015） to a certain degree.
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