Quantification and economic valuation of carbon sequestration from smallholder multifunctional agroforestry: a study from the foothills of the Nilgiris, India

Agroforestry is widely recognized for its role in climate change mitigation and adaptation. However, carbon sequestration and a marketable carbon value of smallholder agroforestry systems in India are poorly documented. Therefore, the present study was carried out to quantify carbon stock in a circular-shaped multifunctional agroforestry (MFA) divided into four equal quadrats. It comprises 24 different tree species and 8 intercrops, mainly established to provide daily income to small and marginal farmers. A nondestructive method was used to assess biomass carbon stock. Soil core samples collected from 0 to 60 cm depth were analysed to quantify soil organic carbon (SOC) stock. Results revealed significantly higher biomass and carbon stock in the following order: Neolamarckia cadamba Melia dubia > Lagerstroemia parviflora > Dalbergia latifolia > Tectona grandis. Duncan's multiple range test revealed significant differences in the multi-utility circles (P < 0.001). The total change in SOC stock was 11.55 Mg quadrat(-1), but the difference was insignificant in different soil depths. The results indicated that the total carbon sequestration and CO2e from vegetation were 2.23 and 9.23 tonnes respectively. Similarly, CO2e from the soil were 42.37 Mg quadrat(-1) respectively; the highest contributions were from quadrat II and quadrat IV of MFA. By taking into account profitability and incentives to smallholder farmers, the total marketable carbon revenue of MFA was calculated as US$ 206.40.

Automated summary

This study quantified carbon stock in a multifunctional agroforestry system in India and found that different tree species and soil depths had significant impacts on carbon sequestration. The findings contribute to our understanding of carbon fixation and soil organic carbon stock in agroforestry systems in India and have implications for climate change mitigation.