| Based on the daily meteorological data from 14 meteorological stations in the Hilly Area of Central Sichuan over the past 50 years(1970-2019)and rice production data,the characteristics of climate change in the region and the characteristics of climate change during the rice reproductive period are analyzed by means of climate propensity rate and M-K mutation test,and the climate mutation is tested.Then,the step-by-step correction model of climate production potential is used to calculate the rice climate production potential and its temporal and spatial dynamic characteristics,and predict its change trend.Finally,the impact of climate change on climate production potential is discussed,the current situation of rice planting and the utilization rate of Agroclimatic Resources after climate change are analyzed,and the optimization suggestions of rice spatial planting pattern are put forward.The main conclusions are as follows:1.Characteristics of climate and climate change during the reproductive period of rice in the Hilly Area of Central Sichuan in the past 50 years.(1)Climate change characteristics:the average annual temperature of the region in the past 50 years is 17.27?,showing a fluctuating upward trend(0.148?/10a),with a total increase of about 0.74?;the average value of the accumulated temperature is 5775?,showing a significant upward trend(187.1?/10a),with a total increase of about 936?;the average value of annual precipitation is 1048.1mm,with large interannual fluctuations(coefficient of variation 14.1%)but the change trend is not significant(5.52mm/10a);the mean value of annual sunshine hours is 1144h,which is in the low value area in the country,with an overall trend of decreasing and then increasing,and the overall tendency rate is-8.75h/10a;the regional differences of light,heat and water in this area are obvious and the changes are complex.(2)Characteristics of climate change during the rice reproductive period:The rice reproductive period in this area is concentrated in April-September,and the cumulative temperature starts around March 1 and ends at the end of November and the beginning of December,which lasts about 277 days.The average temperature during the rice reproductive period is 23.38?,and the accumulation temperature is 4088?on average for many years,and the accumulation temperature accounts for 75%of the whole year.The spatial distribution of temperature and accumulation temperature during the reproductive period is consistent with the spatial distribution of the whole year.The average value of precipitation during the reproductive period is 836mm,accounting for 80%of the year,with a north-south vertical belt distribution,gradually increasing from the center to the east and west poles;the number of sunshine hours is 806h,accounting for 79%of the year,showing the spatial distribution characteristics of less in the southwest(700h-750h)and more in the northeast(900h-950h).(3)Characteristics of abrupt climate change:According to the Mann Kendall mutation test results,combined with the mutation of temperature,precipitation and sunshine,the climate mutation time in this area is 2001.The mean annual temperature increased from17.25?before the mutation to 17.52?after the mutation(an increase of 0.26?);the difference between the mean precipitation value after the mutation and the mean value before the mutation was small(only 7.3mm);the mean sunshine hours after the mutation was smaller than the mean value before the mutation at most sites,from 1225h before the mutation to1160h(a decrease of 65mm).The mean value of temperature during rice fertility increased from 23.21?before the mutation to 23.39?after the mutation(0.18?increase).The mean value of precipitation during the rice reproductive period did not change much before and after the mutation(only 5.3mm difference);the mean value of sunshine hours during the rice reproductive period decreased from 850h before the mutation to 801h(49mm decrease).2.Characteristics of changes in the climatic production potential of rice in the Hilly Area of Central Sichuan in the last 50 years.(1)The multi-year average values of photosynthetic,light temperature and climatic production potential of rice in the last 50 years were 30141.1kg·hm-2,21114.2kg·hm-2and15165.9kg·hm-2,respectively,all showing decreasing trends with decreasing rates of-421.8kg·hm-2·10a-1,-91.42kg·hm-2·10a-1and The climatic production potential of the region decreased from 15230kg·hm-2before the mutation to 15038kg·hm-2,a change of-192kg·hm-2.Dazu(-880kg·hm-2)and Wanyuan(+768kg·hm-2),and the increase is obvious.(2)Spatial distribution of rice climatic production potential:The climatic production potential of rice is distributed in a northeast-southwest direction,with high and second-highest values in the east(15400kg·hm-2to 16608kg·hm-2),medium values in the middle(14800kg·hm-2to 15400kg·hm-2),and low and second-low values in the southwest and north of Wanyuan and Guangyuan(13631kg·hm-2).(13631kg·hm-2?14800kg·hm-2).(3)Prediction of future climate production potential trend:The multiple linear regression prediction model equation based on temperature,precipitation,and sunshine hours is:Y=-301.7T+0.359P-0.181S+18356.4,and the future climate production potential of rice in the central Sichuan hills will decrease at a rate of 41.1kg·hm-2·10a-1.3.Impact of climate change on the climatic production potential of rice,utilization of rice agro-climatic resources and optimization of production pattern.(1)Impact of climate change on climatic production potential:Sunshine resources and heat resources limit the increase of climatic production potential of rice to a certain extent,and moisture resources promote the increase of climatic production potential of rice to a certain extent.When the temperature remains unchanged,for every 10%increase in precipitation,the climatic production potential increases by about 9.5%;when the precipitation remains unchanged,for every 1°C increase in temperature,the climatic production potential decreases by about 4.3%,and precipitation has a greater degree of influence than temperature.(2)The regional differences in the utilization rate of rice climatic resources were obvious,from large to small:Suining(57.04%)>Guangyuan(56.58%)>Yibin(53.27%)>Nanchong(53.09%)>Leshan(51.68%)>Luzhou(50.86%)>Neijiang(50.68%)>Ziyang(49.86%)>Dazhou(46.78%)>Bazhong City(38.56%).(3)Optimization of spatial pattern of rice cultivation:among 91 counties in the region,36counties should appropriately increase the scale of cultivation(eastern districts and counties),35 counties should maintain a stable scale of cultivation(Guangyuan in northwest and Leshan in southwest),and 20 counties should appropriately reduce the scale of cultivation(Wangyuan in northeast,Langzhong in central,Yibin in south,etc.). |
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