基于机器学习的广东省县域农业碳排放时空演变及驱动因素研究

Spatiotemporal evolution and driving factors of agricultural carbon emissions at county level in Guangdong Province based on machine learning

  • 摘要: 县域是深入剖析农业碳排放和城镇化关系的基本地域单元, 研究县域尺度农业碳排放的时空演变趋势和驱动机制对农村绿色低碳发展和乡村振兴具有重要指导意义。为明确广东省县域尺度农业碳排放的时空演变规律及其驱动机制, 本文基于最新排放清单系统测算了2000—2022年广东省124个县域(市、区)农业碳排放量, 并结合GIS局部空间自相关和随机森林(RF)机器学习算法协同识别了县域农业碳排放的时空演变格局及其核心驱动因素。结果表明: 1) 2000—2022年广东省县域尺度农业碳排放量整体呈波动下降趋势, 其中2000年、2010年、2016年和2022年全省碳排放总量分别为4533.27万t、3895.21万t、4034.23万t和3553.97万t, 区域内部碳排放量不均匀且具有较强的空间异质性; 2) GIS局部空间自相关揭示了广东省县域农业碳排放的空间集聚特征, 高高集聚区主要出现在粤西地区, 低低集聚区集中于珠三角核心区域, 各区域内部集聚程度呈持续上升趋势; 3)人均农业碳排放和总量具有明显区别, 高高集聚区主要出现在粤北和粤西, 低低集聚区主要集中在珠三角和粤东地区, 具有“空间溢出”效应; 4)基于Pearson相关性分析筛选后的农业指标所构建的RF模型的变量重要性排名表明, 翻耕面积、化肥和农药使用量以及农业机械总动力是广东省农业碳排放的主要来源, 其中化肥和农药使用量的增加不利于农业碳减排, 而农业机械化程度的提高则是广东省农业碳减排的正向驱动因素。本研究结果可为区域农业碳减排和绿色低碳发展提供政策依据和定量研究工具。

     

    Abstract: The county level serves as a fundamental regional unit for an in-depth analysis of the relationship between agricultural carbon emissions and urbanization. Understanding the spatiotemporal evolution and driving mechanisms of agricultural carbon emissions at the county level is crucial for guiding green and low-carbon development in rural areas and advancing rural revitalization efforts. The aim of this study was to elucidate the spatiotemporal evolution patterns and driving factors of county-level agricultural carbon emissions in Guangdong Province from 2000 to 2022. This study systematically calculated agricultural carbon emissions for 124 counties (cities, districts) in Guangdong Province using the latest emissions inventory system. We collaboratively identified the key driving factors and spatiotemporal evolution patterns of agricultural carbon emissions at the county level by integrating GIS and machine learning techniques, including local spatial autocorrelation analysis and the random forest (RF) algorithm. The results were as follows: 1) Overall, agricultural carbon emissions at county level in Guangdong Province exhibited a downward trend from 2000 to 2020, with total emission being 4533.27×104, 3895.21×104, 4034.23×104 and 3553.97×104 t in 2000, 2010, 2016 and 2022, respectively, while carbon emissions within the province were uneven and had strong spatial heterogeneity. 2) Geographic Information System (GIS)-based local spatial autocorrelation analysis revealed distinct spatial clustering characteristics of agricultural carbon emissions. High-high values were predominantly located in Western Guangdong, whereas low-low values were concentrated in the core area of the Pearl River Delta. Notably, the degree of internal clustering within each region showed a continuous upward trend over time. 3) A notable distinction between agricultural carbon emissions per capita and total emissions was observed, with high-high values of emissions per capita appearing mainly in Northern Guangdong and Western Guangdong, while low-low values were concentrated in the Pearl River Delta and Eastern Guangdong, indicating a “spatial spillover” effect where emissions in densely populated urban areas impact surrounding regions. 4) The RF model, constructed using agricultural indicators selected through Pearson correlation analysis, identified the primary factors influencing agricultural carbon emissions. These included plowing area, fertilizer and pesticide usage, and total power of agricultural machinery. Among these indicators, the increase of fertilizer and pesticide usage was adverse to the reduction of agricultural carbon emissions, whereas the advancement of agricultural mechanization emerged as a positive driving factor for reducing agricultural carbon emissions. The results of this study highlight the complexity and regional variability of agricultural carbon emissions in Guangdong Province. The integration of local spatial autocorrelation and RF algorithms provides a robust analytical framework for understanding these dynamics. In addition, this study offers valuable policy insights and quantitative tools for regional agricultural carbon emission reduction and promotes green and low-carbon development strategies. Overall, our findings underscore the importance of targeted region-specific policies to address the unique challenges and opportunities within different areas of Guangdong Province. By leveraging advanced analytical techniques and comprehensive datasets, policymakers can better understand and mitigate the factors driving agricultural carbon emissions, paving the way for sustainable and environmentally friendly agricultural practices.

     

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