陕北农田作物生产碳源/汇及碳足迹空间特征

农作物生产过程既是碳源,也是碳汇。研究作物生产过程中碳吸收、碳排放特征对区域农业碳减排具有重要意义。以陕北区域为例,采用高分辨率遥感数据,结合GEE遥感云平台和随机森林算法,获取了作物种植分布信息,并建立碳吸收排放测算模型,分析了陕北地区2021年农田作物的碳源/汇效应、碳足迹及其空间分布格局。结果表明:①陕北种植的粮食作物主要为玉米、稻谷、薯类、豆类,经济作物主要为蔬菜、苹果、枣树,这七类作物集中分布在延安南部河谷区域和榆林西北部区域。②除枣类外,陕北地区其余作物的碳吸收量均高于碳排放量,以碳汇功能为主,其中,玉米和苹果分别对该地区碳吸收、碳排放的贡献率最高,碳吸收、排放量分别达到了189.74×10⁴ t和11.41×10⁴ t,苹果、薯类和枣类碳足迹较高,分别达到了9.92×10⁴ hm²、8.77×10⁴ hm²和21.65×10⁴ hm²,其余作物碳足迹处于0.26-1.49×10⁴ hm²之间。③从空间上看,研究区单位面积农田碳吸收量呈现西北高、南部低的分布格局,而碳排放量、碳足迹分布正好相反,南部高、西北低。④研究区可通过培育高产品种、优化施肥量、控制农膜农药用量、调整作物种植结构等措施,提高作物固碳效应,促进农业生产碳减排。

Carbon source/sink and carbon footprint estimation for field crop production and spatial characterization in northern Shaanxi Province

Crop cultivation is a source as well as a sink of carbon emissions. It is necessary to investigate and measure the characteristics of carbon uptake and carbon emissions of crops during the production process in order to reduce carbon emissions in regional agriculture. In this study, the GEE remote sensing cloud platform was utilized to simulate the distribution of agricultural planting by using high-resolution remote sensing data and a random forest algorithm model. An analysis of the carbon source/sink effect, carbon footprint, and spatial distribution pattern of field crops in northern Shaanxi was conducted in 2021 using a carbon uptake carbon emission calculation model based on this assumption. The results were as follows: ① The primary grain crops cultivated in northern Shaanxi were maize, rice, potatoes, and beans, while the main cash crops were vegetables, apples, and jujube trees, according to the findings. These seven crops were concentrated in Yan''an''s southern valley and Yulin''s northwestern region. ② Except for jujubes, the remaining crops in northern Shaanxi absorbed more carbon than they emitted, and the carbon sink function was dominant. Maize and apples contributed the most to carbon uptake and emissions in the region, with carbon uptake and emissions totaling 189.74×10⁴ t and 11.41×10⁴ t, respectively. Apples, potatoes, and jujubes had greater carbon footprints, reaching 9.92×10⁴ hm², 8.77×10⁴ hm², and 21.65×10⁴ hm², respectively, whereas the rest of the crops had carbon footprints in the 0.26-1.49×10⁴ hm². ③ Carbon uptake per unit area of agriculture in the research area was spatially distributed as high in the northwest and low in the south, but carbon emissions and carbon footprints were distributed in the other direction, high in the south and low in the northwest. ④ By cultivating high-yielding varieties, optimizing fertilizer application, controlling the amount of agricultural film and pesticide, and adjusting crop planting structure, the study area can improve crop carbon sequestration and promote carbon emissions reduction in agricultural production.