Impacts of climate change on climatic division for double cropping rice in Guangdong Pro-vince, China.

Based on the dataset of air temperature from 86 stations during 1961 to 2016, and DEM data derived from 1:250000 topographic maps, we analyzed the spatial-temporal changes of key climatic factors (safe period for double cropping rice, ≥10 ℃ active accumulated temperature) using the methods of linear regression, accumulative anomaly, and inverse distance weighted interpolation. The impacts of climate change on climatic division for double cropping rice was studied by combining with the changes of key climate factors for the periods of 1961-1990, 1971-2000, 1981-2010, before (1961-1997) and after (1998-2016) climatic mutation. The results showed that spatial distributions of safe period for double cropping rice and ≥10 ℃ active accumulated temperature were different from place to place in Guangdong. Generally, they were more or higher in south than in north part, in plain than in mountain regions. Under the background of global warming, the safe period for double cropping rice and ≥10 ℃ active accumulated tempera-ture showed a significantly increasing trend with the rate of 1.7 d and 43 ℃·d per decade, respectively. All climatic factor had mutation in the year of 1997. According to the climatic conditions of various maturing rice growth and development, climatic zoning for double cropping rice in Guangdong could be divided into three regions: early maturity with early maturity, early maturity with late maturity, late maturity with late maturity. Those regions were distributed in middle-subtropics of northern Guangdong, south-subtropics of middle Guangdong, and north-tropics of southern Guangdong, respectively. Due to the climate change, the area of late maturity with late maturity significantly increased, the area of early maturity with late maturity significantly decreased, and the area of early maturity with early maturity showed no significant change. Relative to that in 1961-1990, the areas of late maturity with late maturity in 1971-2000 and 1981-2010 increased 1.22×106 hm2 and 2.56×106 hm2, respectively, but the area of early maturity with late maturity decreased 1.13×106 hm2 and 2.56×106 hm2, respectively. The area of late maturity with late maturity was more than doubled, but that of early maturity with late maturity decreased about a half after 1997 than that before in Guangdong.基于广东省86个气象站1961—2016年的气温资料和1∶25万数字高程模型(DEM)数据,采用线性趋势分析、累积距平和反距离权重插值等方法,分析影响双季稻种植的关键气候因子(双季稻安全生育期日数、≥10 ℃积温)时空变化特征,结合气候因子在1961—1990年、1971—2000年、1981—2010年、气候因子突变前(1961—1997年)、突变后(1998—2016年)等5个时间段的变化,研究了气候变化对广东双季稻熟性搭配分布区域及其面积的影响.结果表明: 广东省双季稻安全生育期日数、≥10 ℃积温的空间分布表现为南高北低、平原高山区低.近56年,广东双季稻安全生育期日数以1.7 d ·10 a-1的速率显著增加,≥10 ℃积温以43 ℃·d·10 a-1的速率显著上升,各气候因子均在1997年发生了突变.广东双季稻熟性搭配可分为早熟+早熟、早熟+晚熟和晚熟+晚熟3个气候区.早熟+早熟区主要分布在北部中亚热带地区,早熟+晚熟区主要分布在中部南亚热带地区,晚熟+晚熟区主要分布在南部北热带地区.受气候变化的影响,广东晚熟+晚熟区面积明显扩大,早熟+晚熟区面积明显减小,而早熟+早熟区的面积变化不明显.与1961—1990年相比,1971—2000年和1981—2010年广东省晚熟+晚熟区面积分别增加了1.22×106和2.56×106 hm2,早熟+晚熟区的面积分别减小了1.13×106和2.56×106 hm2.与突变前(1961—1997年)相比,突变后(1998—2016年)晚熟+晚熟区的面积增大一倍多,早熟+晚熟区面积缩小近一倍.