According to the International Panel on Climate Change (IPCC), agriculture and land-use change account for about 24% of the world’s greenhouse gas emissions.
Climate change will also have strong impacts on food security in the long-term. Therefore agriculture needs to reduce its climate footprint. But a recent study of XU Jianchu’s group from Kunming Institute of Botany, Chinese Academy of Science (KIB/CAS), World Agroforestry Centre (ICRAF) and a team of researchers from various institutions in Africa, Asia and Europe have shown that the potential to reduce greenhouse gas emissions from crop and livestock production is limited. At the same time, large forest areas, primarily in the tropics, are still being converted into agricultural land to feed the world’s growing population. For these reasons, agricultural practices that can significantly reduce carbon emissions are in high demand.
Remote sensing data show that in 2010, 43% of all agricultural land globally had at least 10% tree cover, up from eight percent in the preceding decade,” said Robert ZOMER from ICRAF, lead author of the study. “Given the vast amount of land under agriculture, agroforestry may already significantly contribute to global carbon budgets.”
However, regional differences in the trend are significant. The distribution of tree cover on agricultural land depends on climatic conditions in different parts of the world. High tree cover is found in humid areas such as South East Asia, Central America, eastern South America, as well as central and coastal West Africa. Tree cover on agricultural land was moderate in south Asia, sub-humid Africa, central and western Europe, the Amazonia and mid-west North America. On the other hand, low tree cover was found in east China, northwest India, west Asia, the southern border of the Sahara Desert, the prairies of North America and southwest Australia.
“Study results show that existing tree cover makes a major contribution to carbon pools on agricultural land, demonstrating the potential to add to climate change mitigation and adaptation efforts,” said Prof. XU Jianchu of the KIB/CAS. “If tree cover is accounted for, the total carbon stock is over four times higher than when estimated using IPCC tier 1 estimates alone.”
The study entitled “Global Tree Cover and Biomass Carbon on Agricultural Land: The contribution of agroforestry to global and national carbon budgets” has been published on Scientific Reports:http://www.nature.com/articles/srep29987
This study was supported by National Basic Research Program of China (Grant No. 2014CB954100)
Global map of average biomass carbon per hectare on agricultural land in 2000 and 2010, and the change in average biomass carbon from 2000 to 2010 (tC ha-1). Maps were produced based upon a spatial analysis using ESRI ArcGIS software (version 10.3)
Key Laboratory for Plant Diversity and Biogeography of East Asia, CAS
Kunming Institute of Botany
Prof. Dr. XU Jianchu