中国耕地系统时空演变对陆地生态系统碳收支的影响

Impact of spatial-temporal changes in the cropland system on carbon budget of terrestrial ecosystems in China

为揭示耕地系统时空演变对陆地生态系统碳收支的影响,本研究将耕地资源和耕地利用统一纳入耕地系统,采用InVEST模型、温室气体排放系数核算方法评估1980—2018年市级尺度下中国(统计数据未包含港、澳、台地区。下同)耕地系统时空演变对碳储量、碳排放的影响。研究表明:1)耕地系统时空演变导致碳储量减少3×10^(8)t,碳排放增加1×10^(8)t,因此导致碳收支共损失4×10^(8)t;2)林地、湿地被开垦为耕地是碳储量减少的主要原因,而化肥、农机等农业生产资料投入的大幅增加是碳排放增加的主要原因;3)耕地系统时空演变对碳收支影响的空间差异明显,东南沿海、西北地区的城市碳收支出现提升,而东北地区的城市碳收支损失严重。因此,应重视从“人类-自然”耦合系统视角剖析耕地系统变化的碳效应;未来既要对耕地侵占林地、湿地等生态用地进行科学合理的管控以减少碳储量损失,还需要提高化肥、农药等农业生产资料的利用效率,促进耕地由传统集约利用模式向可持续集约利用模式的转型。

This study aims to reveal the impact of the spatial-temporal changes in the cropland system on the carbon budget of terrestrial ecosystems.The resources and utilization of cropland were integrated into the cropland system.InVEST model and greenhouse gas emission factor method are adopted to assess the impact of spatial-temporal changes of the cropland system on carbon storage and carbon emissions in China(The data do not include those of Hong Kong,Macao,and Taiwan regions.The same below)between 1980 and 2018 at the municipal scale.The results show that:1)The spatiotemporal changes in the cropland system led to a decrease of 3×10^(8)t in carbon storage and an increase in carbon emissions of 1×10^(8)t,resulting in a total loss of 4×10^(8)t in the carbon budget.2)The reclamation of forest and wetlands for cropland was the main reason for the reduction of carbon storage,and the increase in the input of agricultural materials such as fertilizers and machinery was the main reason for the increase in carbon emissions.3)The spatial-temporal changes in the cropland system in the impact of the carbon budget showed a significant difference.The carbon budget of cities in the southeast coast and northwest China increased,but the loss of the carbon budget in Northeast China was massive.Therefore,more attention should be paid to the carbon effect of changes in cropland systems from the perspective of a“humannature”coupling system.In the future,it is not only necessary to carry out scientific and reasonable control of cropland encroachment on natural lands such as forests and wetlands to reduce the loss of carbon storage but also necessary to improve the utilization efficiency of agricultural materials such as fertilizers and pesticides in order to promote the transform of cropland utilization mode from traditional intensive utilization mode into sustainable intensive utilization mode.