基于遥感识别与DNDC模型的不同稻作模式评价--以潜江市为例. (Chinese)

[Objective] The purpose of this study was to estimate the greenhouse gas emission and carbon sequestration of different rice-based cropping systems in Qianjiang City, China, and to evaluate potential for their green development. [Method] First, classified remote-sensing images were with the random forest method to map the distribu・ tion of rice cropping systems in Qianjiang City. Combined with meteorological, soil, and crop management datasets, a revised and validated DeNitrification-DeComposition (DNDC) model was used to conduct regional simulations. Estimates for methane (CHJ and nitrous oxide (NQ) emissions and changes in soil organic carbon (dSOC) in Qianjiang City were obtained. Second, scenario simulations were conducted in the DNDC model under the assumption that the current rice-crayfish system was evolved from different rice cropping systems, and changes in the related indicators were used to evaluate the green development potential of the systems. [Results] All indicators showed that the validated DNDC model had good performance to simulate the effect on CH4 and N2O. In 2019, the CH4 and NZO emissions and the annual dSOC of the main rice cropping systems per km2 in Qianjiang City were 0.40-64,043.34 kg, 0.002-227.08 kg, and 0.18-5,835.27 kg C, respectively. The annual CH4 and NQ emissions per unit area in the rice-crayfish system were the lowest, at 394.50 kg-hm'2 and 1.43 kg-hm \ respectively. The dSOC per unit area was the highest in the rice-crayfish system, at 274.30 kg C-hin \ and that in the rice-fallow system was the lowest, at 204.95 kg C'hm'2. The annual total CH4 emission increased by 2.31%-11.25%, the total NQ emission increased by 11.49%-67.09%, and the dSOC decreased by 9.95%-22.8l% when the rice-crayfish system was converted to other rice cropping systems in Qianjiang City. [Conclusion] In this study, the rice-wheat system showed the largest CH4 emission, and the rice-rape system showed the largest N2O emission, both of which had moderate carbon sequestration capacity. The greenhouse gas emission of the rice-fallow system is lower than that of the rice-dryland rotation system, but its carbon sequestration ability is poor. The rice-crayfish system has stronger emission reduction and carbon sequestration ability compared with the other rice-based systems, and has higher green development potential, though there is still potential for emission mitigation. [ABSTRACT FROM AUTHOR]

【目的】本研究旨在获得潜江市不同稻作模式温室气体排放和固碳情况, 以评价不同稻作模式的绿色发展 潜力。【方法】首先, 利用随机森林对遥感影像进行分类, 获得了潜江市各稻作模式分布数据, 结合气象、 土壤、作物管理数据库, 利用校正和验证后的DNDC模型进行区域模拟, 获得潜江市甲烷(CH4)和氧化亚 氮(％0)两种温室气体排放量及土壤有机碳变化量(dSOC)。其次, 在DNDC模型中设置情景分析, 假设 目前稻虾模式由不同稻作模式变迁而来, 利用相关指标的变化评价稻虾模式在潜江地区的绿色发展潜力。 【结果】各项指标表明, 校正后DNDC模型对CH。和模拟效果良好。2019年潜江市每lkm?范围内主要稻 作模式CH。和瞩0排放量及全年dSOC总量变化区间分别为0.40kg- 64043.34 kg, 0.002kg - 227.08 kg和0.18 kgC ~ 35835.27 kgCo潜江市全年单位面积CH4和排放量均表现为稻虾模式最小, 分别为394.50kg-hm'2, I. 43kg'hm'2,单位面积dSOC表现为稻虾模式最大为274.30 kg C-hm'2,稻闲模式最小, 为204.95 kg C-hm'2o 当潜江市稻虾模式转变为其他主要模式后, 其周年CH。排放总量增加2.31%~11.25%,瞩0排放总量增加 II. 49%~67.09%, dSOC减少9.95%~22.81%。【结论】本研究中, 稻麦模式表现为CH。排放最大, 稻油模式的 瞩0排放最大, 两者固碳能力中等;稻闲模式由于只有一季种植, 温室气体排放小于稻旱轮作模式, 但其固 碳能力较差;稻虾模式的减排和固碳能力相较于稻闲与稻旱轮作模式强, 具有更高的绿色发展潜力, 但其 仍具有减排空间. [ABSTRACT FROM AUTHOR]

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