生态文明建设下中国种植业温室气体排放时空演变特征

New spatiotemporal characteristics of greenhouse gas emissions from China′s crop farming under the construction of ecological civilization

农作物种植在保障国家粮食安全的同时,也是农业领域重要的温室气体(GHG)排放源之一,在我国农业“双碳”目标实现路径中具有显著地位。基于多源统计数据,分别在国家尺度和省域尺度上,定量分析了1978—2020年我国种植业GHG排放的动态变化与空间分异格局。结果表明:(1)1978—2020年我国种植业GHG排放总量整体呈显著增加趋势(P<0.01),但其在1997—2003年和2012—2020年间出现了两次较为明显的下降,且下降的成因并不相同,使得GHG排放强度(即单位粮食产量的GHG排放量)在这两个时段表现出相反的变化过程。其中,2012—2020年间出现GHG排放减少而粮食产量增加的态势,GHG排放强度降幅接近20%,已呈现出粮食增产和碳减排目标的协同实现。(2)1978—2020年省域尺度上种植业GHG排放量呈现出“南高北低、东高西低”的空间差异,总体格局与粮食产量的均值分布存在较好的对应关系。但在2012—2020年间,全国大部分地区粮食产量增加,同时这些地区GHG排放强度都出现了不同程度的下降,主要得益于化肥和农药使用量的减少。研究结果体现了在确保我国粮食安全的前提下,生态文明建设政策的实施为种植业实现“双碳”目标做出了积极的贡献。

Crop farming,along with ensuring national food security,is also an important source of greenhouse gas(GHG)emissions in the agricultural sector,and therefore acts as a crucial role in global warming.As the world′s leading agricultural producer,China feeds 20%of the global population with only 7%of global croplands through constantly improvement of agricultural practice including the increased input of fertilizers and pesticides over the past decades.With the implementation of the Sustainable Development Goals of the United Nations and China′s carbon neutral strategy,accurate estimation of GHG emissions from crop farming has a significant position in the path of realizing the carbon peaking and carbon neutrality goals in China′s agriculture.However,a comprehensive,long-term,and spatially-precise profile of GHG emissions from crop farming is still lacking in China.In order to accurately understand changes of historical emissions and their implications for future mitigation,this study quantitatively analyzed the dynamic changes and spatial differentiation patterns of GHG emissions in China′s crop farming from 1978 to 2020 based on multi-source statistical data at the national and provincial scales,respectively.The results showed that the total GHG emissions from China′s crop farming showed a significant increasing trend from 1978 to 2020(P<0.01).However,there were two significant decreases from 1997 to 2003 and 2012 to 2020.Furthermore,the reasons for these decreases were not the same,so that the GHG emission intensity(i.e.,GHG emissions per unit of grain production)showed opposite changes in these two periods.Particularly in the period from 2012 to 2020,there was a decrease in GHG emissions and an increase in grain production,which resulted in a decrease in GHG emission intensity of nearly 20%.This finding showed a synergistic realization of the goals of increased grain production and GHG emission reduction.From 1978 to 2020,GHG emissions from crop farming at the provincial scale showed a spatial difference of higher in the south and east while lower in the north and west,and the overall pattern corresponded well to the distribution of the mean value of grain production.However,grain production increased from 2012 to 2020 in most regions of China,whereas the GHG emission intensity decreased in these regions to different degrees,which mainly due to the reduction of chemical fertilizer and pesticide use.Specifically,the application of nitrogen fertilizers and pesticides declined to different degrees from 2012 to 2020 in Northeast China,North China,Jianghuai,and Sichuan-Chongqing regions,which did not affect the increase of grain production,but contributed to the reduction of GHG emissions.The results of this study showed that the implementation of ecological civilization construction policies has made a positive contribution to the cultivation industry to achieve the goal of carbon peaking and carbon neutrality under the premise of ensuring China′s food security.