气候变化对长江中下游稻区水稻产量的影响

选择长江中下游平原作为研究区域,按照政府间气候变化专业委员会(IPCC)排放情景特别报告(SRES)中的A2和B2方案,将基于区域气候模式PRECIS构建的气候变化情景文件与水稻生长模型ORYZA2000结合,模拟基准时段(1961—1990)气候(Baseline)和2021—2050时段A2、B2情景下的水稻产量,分析未来气候变化对长江中下游水稻产量的影响。构建两种影响评估方法,重点分析增温和大气CO2肥效作用对水稻产量的影响。结果表明,不考虑CO2肥效作用时,随着温度升高,水稻生育期缩短,产量下降。A2情景下水稻生育期平均缩短4.5d,产量减少15.2%;B2情景下平均缩短3.4d,产量减少15%。其中,减产达到20%以上的区域集中在安徽中南部、湖北东南部和湖南东部地区。当考虑CO2肥效作用后,A2情景下水稻平均产量减少5.1%,B2情景平均减少5.8%。减产区域缩小且幅度降低,江西和浙江部分地区则呈现一定程度增产,但增幅10%。大气CO2肥效作用一定程度上可提高水稻产量,使晚稻在增温的不利影响下仍呈现不同程度的增产态势,但对单季稻和早稻的增产贡献仍不足以抵消升温的负面影响。另外,大气CO2肥效作用可有利于提高未来气候变化下水稻的稳产性。

Impacts of Climate Changes on Rice Production in the Middle and Lower Reaches of the Yangtze River

Increasing atmospheric greenhouse gas concentration is expected to induce significant climate change over the next century, but the impacts on society remain highly uncertain. This paper aimed to assess the potential impacts of climate change on rice crop (Oryza sativa L.) production in the middle and lower reaches of the Yangtze River, where is one of the most important food production regions in China. Data taken from the PRECIS regional climate model were used as the baseline (1961–1990) and future (2021–2050) periods under IPCC SRES A2 and B2 scenario conditions, and were used as input of the rice model ORYZA2000. Simulations were performed with and without considering the enhanced CO₂-fertilization effects to evaluate the response of rice crop to raised temperature and CO₂ concentration, respectively. The results indicated that the rice growth duration would be shortened and yield would be declined significantly with raising temperature future when CO₂-fertilization effects was not considered. The rice growth duration would be shortened by 4.5 d and yield would be reduced by 15.2% under A2 scenario in 2021–2050 periods compared with the baseline weather while they would be 3.4 d shortened and 15% reduced respectively under B2 scenario in the same period. The areas where rice yield reduced more than 20% concentrated on most regions of Anhui, Hubei and Hunan provinces. The significance of the enhanced CO₂-fertilization effect to rice crop was found under the simulated future elevated CO₂ concentrations (2021-2050) for both A2 and B2 scenarios. But it was still not enough to offset the negative effects of warming for single crop rice and early rice, except for the late rice that the contribution of CO₂-fertilization effect on rice yield was greater. With considering CO₂-fertilization effect, the rice yields declined by 5.1% and 5.8% under A2 and B2 scenarios, respectively. The areas with a serious yield reduction decreased and the average yield reduction were lessened remarkably. Meanwhile, the areas with an increase in rice yields were founded in some parts of Jiangxi and Zhejiang provinces, although the yield increase might be less than 10%. In addition, the yield stability, defined as the ratio of standard deviation to average yield at each grid across each province, would be increased in 2021–2050 periods when CO₂-fertilization effect was considered, indicating that the CO₂-fertilization effect may reduce the future yield variability. However, there were still many uncertainties in this study. The possible impact of water stress under future climate was not considered, due to the automatic irrigation pattern selected. The soil parameters used as input to the ORYZA2000 might increase the uncertainties for assessing the impacts of climate change on rice yield. Finally, the overall results were compared with those in other studies, in which CERES-Rice was employed and a good agreement was obtained, indicating that the rice model ORYZA2000 can be well applied in assessing the impact of climate change on rice crop in China.