Global tree cover and biomass carbon on agricultural land: The contribution of agroforestry to global and national carbon budgets

Agroforestry systems and tree cover on agricultural land make an important contribution to climate
change mitigation, but are not systematically accounted for in either global carbon budgets or national
carbon accounting. This paper assesses the role of trees on agricultural land and their significance
for carbon sequestration at a global level, along with recent change trends. Remote sensing data
show that in 2010, 43% of all agricultural land globally had at least 10% tree cover and that this has
increased by 2% over the previous ten years. Combining geographically and bioclimatically stratified
Intergovernmental Panel on Climate Change (IPCC) Tier 1 default estimates of carbon storage with
this tree cover analysis, we estimated 45.3 PgC on agricultural land globally, with trees contributing >75%.
Between 2000 and 2010 tree cover increased by 3.7%, resulting in an increase of >2 PgC (or 4.6%) of
biomass carbon. On average, globally, biomass carbon increased from 20.4 to 21.4 tC ha?1. Regional
and country-level variation in stocks and trends were mapped and tabulated globally, and for all
countries. Brazil, Indonesia, China and India had the largest increases in biomass carbon stored on
agricultural land, while Argentina, Myanmar, and Sierra Leone had the largest decreases