| Global climate change,which is mainly characterized by warming,has a significant impact on the occurrence and catastrophe law of agro-meteorological disasters in China,and the losses caused by it continue to increase. Drought disasters induced by climate change frequently occur,posing a serious threat to China's food security and sustainable agricultural development. Under the background of climate change,the harmfulness and uncertainty of agricultural drought have caused huge potential risks to China's food security. Corn is the grain crop with the largest sown area in Northeast China. The middle and high latitudes where the main corn producing areas in Songliao Plain are located are the areas with the most sensitive response to climate change,which are facing severe challenges brought by climate change,especially affecting national food security and restricting the sustainable development of our society and economy. In recent decades,the frequency and risk of corn meteorological disasters have increased in this region,among which drought disasters have accounted for 60% of agricultural meteorological disasters,and at the same time,55% of grain production has been reduced. Drought disaster is the main cause of maize yield reduction. Although there are many studies on the impact of climate change on agriculture at home and abroad,most studies on drought risk are based on single drought index,while there are few studies on drought risk assessment based on comprehensive drought index,and there is a lack of studies on the impact of drought disaster on corn yield under different global warming scenarios. Therefore,carrying out drought risk assessment research in the main corn producing areas of Songliao Plain under the background of climate change,and studying the possibility of future drought occurrence and possible corn losses,will make up for the deficiency of the research foundation of drought hazard mechanism,risk early warning and prediction under the background of climate change,and solve the key problems of drought disaster risk management in corn agriculture to cope with the impact of climate change. The research results have broad application prospects and important scientific significance and application value.In this study,the main maize producing areas in Songliao Plain were selected as the main disaster-bearing body of drought disaster,and the impact of drought disaster was measured by the change of maize yield. Firstly,the meteorological,remote sensing,agricultural and soil data of the main maize producing areas in Songliao Plain were collected,and the historical drought characteristics of the study area were analyzed by SPEI index. At the same time,the maize yield was correlated with SPEI,PDSI,SPI and NDVI index,and the better drought index was determined. Then,based on the soilwater-atmosphere system,CDI comprehensive drought index is established,and the drought risk in the study area is evaluated based on Maxent model. The model of "drought risk-maize yield reduction rate" was constructed according to maize yield reduction rate. Finally,based on the global climate model data,the risk of drought disaster and the possible loss of maize yield under the scenarios of global warming of 1.5? and 2.0? are predicted. The main research results are as follows:(1)The temperature in the main maize producing areas in Songliao Plain has an upward trend from May to September in the recent 54 years,while the precipitation has a downward trend. In spatial distribution,the temperature generally increases from north to south,and the spatial distribution of precipitation shows an approximate meridional distribution,showing a gradual increase from west to east. According to the SPEI drought index,the drought in the study area became more and more serious under the background of warming and drying from 1965 to 2018,and the frequency and intensity fluctuated sharply between years. Maize yield in the main maize producing areas of Songliao Plain experienced three stages: "rising-stabilizing-declining" from 1981 to 2018. The relationship between climate yield and different drought indexes in the study area is as follows: PDSI and climate yield > SPEI-3 and climate yield > NDVI and climate yield > SPI-3 and climate yield > SPEI-1 and climate yield > SPI-1 and climate yield. At the same time,a comprehensive drought index(CDI)was established by PDSI,SPEI-3 and SPI-3.(2)According to the comprehensive drought index,most of the main corn producing areas in Songliao Plain belong to high and high drought risk areas in May,July and September,and there is no big difference in risk among all the areas in June,while the risk of the main corn producing areas in Songliao Plain increases from east to west in May to September. This is consistent with the local natural climate characteristics and crop yield reduction,which proves that it is feasible to quantify and evaluate the risk of drought disasters by using this comprehensive drought index.(3)Compared with the historical period,when the global temperature rises by .1.5?and 2.0? under the carbon emission path of RCP4.5 and RCP8.5,the temperature and precipitation increase in the growing season of maize,and the excessive warming amplitude offsets the positive influence of precipitation,so the future drought risk is more severe,among which the drought risk is the highest when RCP1.5?GW2.0,and the high-value areas of drought risk are distributed in Baicheng,Songyuan and Changchun in the northern maize producing areas of Songliao Plain. Under the same emission path,the risk of drought in 2.0? global warming scenario is obviously higher than that in 1.5? global warming scenario.(4)The relationship model of "drought risk-maize yield reduction rate" was used to predict the average yield reduction rate of maize in four periods. The results showed that there was an increase in yield in a small area,but the overall yield reduction rate increased,and the yield reduction rate was relatively high in areas with high risk. In RCP4.5?GW2.0 scenario,the yield reduction rate in northern maize producing areas of Songliao Plain increased by 0.02-0.03 compared with the historical period. Therefore,the risk can be reduced by adjusting the agricultural industrial structure,scientific irrigation and popularizing drought-tolerant crop varieties.The results of this study can provide theoretical basis and technical support for our country to implement major national strategies in response to climate change,food security,disaster prevention and mitigation,etc.,and have great practical significance for the country's future agricultural structure adjustment,especially the formulation of agricultural sustainable development,agricultural disaster prevention and mitigation countermeasures and measures. |
PDF Full Text Request