北方春小麦种植区小麦种植结构变化的气候依据与冻害风险

Climate cause for the change in cropping structure from spring wheat to winter wheat and its freeze injury risk in north China

气候变暖引起我国冬小麦种植北界北扩西移,导致许多传统上种植春小麦的区域改为种植冬小麦。利用研究区1980-2012年28个气象站观测数据和全国格点数据,分析了北方春小麦种植区小麦种植结构变化的气候依据和种植冬小麦可能的冻害风险。结果表明,33a来,观测站点年平均气温和地面温度分别升高了1.3℃和1.98℃,年平均最低气温和地面温度分别升高了1.58℃和2.83℃;冬小麦生育期>0℃的有效积温增加了340℃·d;日最低气温和地面温度<0℃的日数和负积温分别减少了4.6,5.6 d/10a和57,233.8℃·d/10a;日最低地面温度<-18℃的日数和负积温分别减少了6.7 d/10a和143.5℃d/10a;1月平均最低地面温度显著升高了2.54℃。这些变化使冬小麦种植区域向西北扩展。气候资源的显著变化为北方春小麦种植区小麦种植结构变化提供了气候依据。然而,影响冬小麦安全越冬的1月平均气温、1月最低气温和1月平均地面温度并没有显著升高,最低地面温度<-18℃的冻害日数和积温从1997年前后的平均13d和1200℃·d又增加到2012年的20d和3500℃·d左右。适合种植冬小麦的区域范围有较大的不确定性。

The climate warming has expanded the winter wheat planting region toward north and west where the spring wheat was traditionally planted in north China. In this paper, meteorological data from 28 stations in spring wheat planting region during 1980 -2012 were used to analyze the cause for changes in cropping structure from spring wheat to winter wheat and its risk of freeze injury in north China. The results show that, in the past 33 years, the annual average air and surface temperature （Tave, Ts - ave） have significantly increased by 1.3, 1. 98℃ , respectively, and mean annual minimum air and surface temperature （Tmin, Ts -rain） have significantly increased by 1.58 and 2.83 ℃, respectively. The effective temperature accumulated during winter wheat growing season increased 340 ℃ d. The number of days and accumulation of cold in each year with minimum air tempera- ture and surface temperature below 0 ℃ were decreased significantly by 4.6, 5.6 d/10a and 57,233.8 ℃ d/10a,respectively. The number of days and accumulation of cold in each year with minimum surface temperature below - 18℃ were decreased significantly by 6.7 d/10a and 143.5 ℃ d/10a, respectively. The mean minimum surface temperature in January has significantly increased by 2.54 ℃. The changes in these parameters have supported the expansions of winter wheat planting region toward north and west. However, as the critical parameters of overwinte- ring for winter wheat, the average air temperature, the minimum air temperature and average surface temperature in January have not increased significantly. The number of days and the accumulated temperature in each year with minimum surface temperature below -18 ℃ were increased from approximately 13 days and 1200 ℃ d in 1997 to 20 days and 3500 ℃ d in 2012. There is much uncertainty as to the range of region suitable for winter wheat plant-ing.