Characteristics and effects on crop production of heat resources changes in Heilongjiang Province

Under the global warming background, heat resources variation has significant impact on production environment, growth and development, cropping system and cultivation zone of corps in the clod region.To explore variations in cultivation zones, growing seasons and yields of major crops (rice, maize and soybean) under climate change of Heilongjiang Province, China, we analyzed the characteristics of tempo-spatial changes and abrupt changes by using accumulated anomaly method, Mann-Kendall trends test and Empirical Orthogonal Function (EOF) of heat resources indices, including accumulated temperature above 10℃ and 0℃ and frost-free periods in 67 meteorological stations from 1971 to 2014 in Heilongjiang Province.We also calculated regression coefficients between heat resources indices and development stages of crops to investigate the influence of heat resources change on crop development.The differences in crop cultivate zones and yields between before and after abrupt change year were also discussed according to accumulated temperature above 10℃ and actual and meteorological yields.The results showed that the accumulated temperatures above 10℃ and 0℃ increased significantly at rates of 86.7℃·d·((10a)^-1 and 80.5℃·d·((10a)^-1, respectively, from 1971 to 2014.The annual frost-free period increased at a rate of 3.8 d·(10a)^-1.There were abrupt changes in the accumulated temperatures above 10℃ and the annual average frost-free period in 1993.The accumulated temperature above 10℃ increased 226.1℃·d averagely, and the frost-free period prolonged 9.2 d averagely after the abrupt change year.The abrupt change promoted the initial dates and postponed the ending dates of the temperatures above 10℃, 0℃ and the frost-free period.From 1971 to 2014, the increasing rates of accumulated temperatures above 10℃ and 0℃ were greater in the west than in the east.The annual frost-free period was longer in mid-west than in northeast.The area with greater change of heat resource was also sensitive area of agricultural heat resources change.With the increase of heat resources, the suitable growth period of crops prolonged.The planting areas of rice, maize northward and westward expended.The center of soybean cultivation area northward moved.The planting areas with original especial-early-maturing and early-maturing crops varieties became the areas suitable for middle-maturing and middle-late-maturing varieties of crops.In general, the increased heat resources provided more yield increasing potential of rice, maize and soybean in Heilongjiang Province.