Interannual Variations of the Carbon Footprint and Carbon Eco-efficiency in Agro-ecosystem of Beijing, China

• Main Authors: TIAN Zhi-hui, MA Xiao-yan, LIU Rui-han
• Format: Article
• Language: zho
• Published: Agro-Environmental Protection Institute, Ministry of Agriculture 2015-12-01
• Series: Journal of Agricultural Resources and Environment
• Subjects: Beijing; agro-ecosystem; carbon footprint; carbon eco-efficiency; carbon source; carbon sink
• Online Access: http://www.aed.org.cn/nyzyyhjxb/html/2015/6/20150614.htm

Suburban farmland ecosystems are known to be affected by intensive land use/cover change (LUCC) during the process of urbanization in Beijing. We investigated inter-annual changes in carbon sequestration, source, footprint, and eco-efficiency from 2004 to 2012 in the agro-ecosystem of suburban Beijing. Our findings indicated that: (1) Carbon sink increased 2.8 percent annually and the average annual carbon storage amount was 1 058 200 t, with food crops constituting the highest proportion at 80.4% of carbon storage in farmland ecosystems, of which maize contributed 68.5% as the largest constituent; (2) Carbon emission in the system showed a gradually decreasing trend, with agricultural chemicals as significant contributors. The annual average carbon emission was 276 000 tons in the Beijing farmland ecosystem, and decreased approximately 1.3 percent per year. The largest amount of carbon emissions came from agricultural chemicals at 85.4%, of which nitrogen fertilizer was the biggest contributor at 83.7％; ( 3) The carbon footprint also showed a decreasing trend along with an ecological surplus of carbon. The average carbon footprint was 5.71 hm2 in the Beijing farmland ecosystem with decreasing rate at 5.5% annually; however, the carbon surplus showed a downward trend due to reduction in the amount of arable land; (4) Finally, the increasing carbon sink capacity led to higher carbon eco-efficiency, with an annual average of 3.854 kg C·kg-1 CE, carbon sequestration was greater than the amount of carbon released. In summary, the agro-ecosystem in suburban Beijing has sustained a relatively high carbon eco-efficiency, and agricultural production continues to have high sustainability potential.