The paper below was cited in the report of the FAO/IPCC Expert meting on land use, climate change and food security: 23-25 January 2017: http://www.fao.org/documents/card/en/c/d5400b77-1533-4c37-86a7-4945c320ea8d/
Description of the underpinning research
Noponen, M.R.A., Healey, J.R., Soto, G. & Haggar, J.P. (2013). Sink or source – the potential of coffee agroforestry systems to sequester atmospheric CO2 into soil organic carbon. Agriculture, Ecosystems & Environment, 175, 60-68.