SPATIOTEMPORAL DEVIATION IN GROWING DEGREE DAYS AND SEASON UNDER INCREASING TEMPERATURE IN HEILONGJIANG PROVINCE

Thermal accumulation and base temperature (Tb) immensely effect phenology and vegetation growth. Therefore, growing degree days (GDD) and length of growing season (LGS), calculated based on three base temperatures (Tb) 0, 5 and 10 degrees C for better vegetation growth. The results obtained from 26 meteorological stations showed that SGS has advanced by 6.58 to 8.45 days and the EGS was delayed by 5.07 to 5.81 days. LGS and GDD showed positive sensitivity to mean annual temperature, LGS expansion was recorded 13.96 days and GDD has increased by 255.45 to 380.50 degrees C days in Heilongjiang province during the historical period of 56 years, based on selected Tb. The mean values of GDD and growing season parameters showed increase in Tb-0 and decrease in Tb-10. Trend being significant (Mann-Kendall test, p < .05) in GDD and increased over the province nevertheless, far northern part showed non-significance in GDD(10), trend was recorded higher in the central part comparative to far northern and southern part. The LGS was prolonged in lower Tb (Tb-0) and shortened with higher Tb (Tb-10), lengthening speed was higher in GDD(10) (2.5 Days/10 year). Additionally, in all parameters the turning points occurred mostly in 1986-1988 and 1993, while, minimum or slow trend was found in the early decade. This concluded that with increasing temperature variation in growing season length and accumulative thermal growing degree days have wide-ranging effect on agricultural production, environment, carbon cycle, forestry and plant growth in prospect.