Quantifying carbon stocks and sequestration potential in agroforestry systems under divergent management scenarios relevant to India’s Nationally Determined Contribution

Abstract

In many countries including India, perennialization of agricultural lands, afforestation and reforestation have often been proposed to address land degradation and mitigate climate change. Among the various perennialization options, agroforestry holds a great potential for creating carbon (C) sinks and mitigating emissions from agriculture, while also increasing adaptive capacity. However, information is scanty on the C sink potential of agroforestry in the different climatic and altitudinal zones of India that are suitable for agroforestry. Therefore, the objectives of this analysis were to (1) quantify variations in biomass C and soil organic carbon (SOC) stocks in the major agroforestry practices along climatic zones and altitudinal gradients, and (2) provide projections of the C sequestration potential in areas that are highly suitable for agroforestry in India. Biomass C stocks were higher in agrosilvopastoral (73.4 Mg C ha-1) than in agrisilvicultural (42.6 Mg C ha−1) and silvopastoral systems (42.7 Mg C ha−1). Similarly, SOC stocks were higher in agrosilvopastoral (53.0 Mg C ha−1) than in agrisilvicultural (44.1 Mg C ha−1) and silvopastoral systems (33.5 Mg C ha−1). Agroforestry systems in humid zones had significantly higher total biomass C stocks (97.9 Mg C ha−1) and SOC stocks (51.8 Mg C ha−1). SOC stocks were significantly higher under agroforestry in medium (51.2 Mg C ha−1) than in high (46.7 Mg C ha−1) and low (32.7 Mg C ha−1) altitudes. Assuming no significant change in area under agrisilvicultural, agrosilvopastoral and silvopastoral systems, the total C sequestered by 2050 was projected to be 4.2, 4.5 and 1.5 Pg CO2 eq, respectively. With an increase in 5% of current area at 5-years intervals, the total CO2 eq sequestered by 2050 was estimated at 5.4 Pg in agrisilvicultural, 5.8 Pg in agrosilvopastoral and 1.9 Pg in silvopastoral systems. It is concluded that expansion of the area under agroforestry by a mere 30% has the potential to offset significant proportions of India’s total emissions by 2050. Therefore, we recommend the inclusion of agroforestry in the Nationally Determined Contribution of India.