| Under the background of global climate changing,natural resource degrading and population expanding,the global food security has attracted worldwide attentions.Bangladesh,India,and Myanmar are the typical agricultural countries which are seriously affected by global climate change.They are also the key areas and nodes of “The Belt and Road”.The grain production of this area is of great significance for ensuring regional food security and supporting the construction of “The Belt and Road”.In order to understand the current situation and potential of grain production in Bangladesh,India,and Myanmar,and to analyze the key factors affecting grain yield,this study developed a method to estimate the potential yield and yield gap based on GLOPEM-CEVSA model,which integrated satellite remote sensing and Leaf Area Index(LAI)simulation module,realized the spatio-temporal continuous simulation of yield gap in Bangladesh,India,and Myanmar,and analyzed the spatio-temporal distribution characteristics of grain yield gap and increase production potentialities under two climatic(yield level)scenarios.Then,Based on the Multiple Regression Model,the influence mechanism of main climatic and socio-economic factors on grain yield was determined in order to provide scientific basis and decision support for narrowing the grain yield gap and achieving sustained and stable increase of grain yield in Bangladesh,India,and Myanmar.The main results and conclusions were summarized as follows:(1)From 1982 to 2015,the average annual yield of Bangladesh,India,and Myanmar were2.99,2.25 and 3.20 t/ha,respectively.The distribution of grain yield was higher in northern Bangladesh than in southern Bangladesh,increasing in India from west to east,and higher in southern Myanmar than in central Myanmar.Over the past 30 years,grain yield of Bangladesh and India increased at the rates of 0.014 t/(ha·a)and 0.017 t/(ha·a),respectively,and southwest India,northeast India and northwest Bangladesh have the fastest growth rates.While there is no significant inter-annual change in Myanmar.(2)The impacts of climate change on grain yield in 2000 to 2015 significantly extended and intensified when compared with that from 1982 to 2000 in Bangladesh,India and Myanmar,showing a trend of eastward and southward expansion.From 1982 to 2000,the yield of the three countries positively responded to the change of annual precipitation.After 2000,yield in Bangladesh changed to a negative response to precipitation change;Except for the areas with average annual temperature lower than 20 ?,such as the south foot of Himalayas,grain yield showed a positive response to temperature change,the other areas were mainly negativeresponse in 1982-2015.However,the proportion of negative response area to temperature in the whole region has increased,the average sensitivity has decreased,and the highly sensitive area of negative response in India has moved southward in 2000-2015;As far as the response of yield to solar shortwave radiation is concerned,the south foot of the Himalayas showed negative response,while most of the other areas showed positive response from 1982-2000,but after 2000,the yield of the whole study area was mainly positive response to solar radiation change and its sensitivity was increased.(3)Under the temperature and water stress scenario,Myanmar has the highest average potential yield and the largest yield gap.And the potential yield and yield gap in Bangladesh and Myanmar both showed an increasing trend over the past 30 years,while the annual variation in India was not significant.The average increase production potentiality index of Bangladesh,India,and Myanmar were 4.34%,40.05% and 68.45%,respectively;Under the temperature stress scenario,the average potential yield and yield gap of Bangladesh,India and Myanmar were all significantly higher than that under the temperature and water scenario.And the average increase production potentiality index of the whole study area was 70.07%.Under the current water(precipitation)conditions,India,especially the south foot of Himalayas and the central and Western Deccan Plateau,is most affected by water stress and this impact is relatively stable,which means that grain yield is expected to be greatly improved by adopting reasonable irrigation and measures of flood control and disaster reduction.(4)In addition to the biological characteristics of crops and local climatic resources,grain production also depends on the labor force,the level of economic development and material input and other social and economic conditions.The results of correlation analysis between grain yield and major social and economic factors show that population,GDP and pesticide use have an important impact on narrowing the production gap and increasing grain yield in Bangladesh.India's grain production is mainly affected by population and GDP,while Myanmar's grain production is only affected by pesticide use.Comprehensive analysis of the relationship between grain production and climatic and socio-economic factors shows that grain production in the three countries is significantly affected by climate change and socio-economic conditions.Specifically,Bangladesh's yield is most affected by annual average temperature.And annual precipitation in India has the most significant impact on its yield.while Myanmar's grain yield is affected by pesticide use and annual average temperature.Finally,based on the study results,several corresponding adaptive management measures were put forward in order to provide scientific basis and technical support for effectively responding to climate change,narrowing yield gap,steadily and constantly improving grain production and ensuring regional food security in Bangladesh,India and Myanmar. |
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