Estimation of biomass and carbon storage potential in agroforestry systems of north western Himalayas, India

The estimation of carbon stock in agroforestry is crucial for curbing the global climate crisis. In this study, biomass production and carbon storage potential of the prevalent agroforestry systems along an altitudinal gradient in the Chamba district of Himachal Pradesh was carried out during 2019-2021. Agroforestry practices were categorized into eight land use systems viz., agrisilviculture, agrihorticulture, agrosilvohorticulture, agrohortisilviculture, hortiagriculture, silvopastoral, pastoralsilviculture and hortipastoral systems and were divided into four altitudinal ranges viz., <1000 m above sea level (m asl; Z-I), 1000-1500 m asl (Z-II), 1500-2500 m asl (Z-III) and > 2500 m asl (Z-IV). Results revealed that biomass production and total carbon storage (vegetation + soil) were significantly affected by the land use type along the altitudinal gradient. Among the different agroforestry systems, maximum aboveground biomass (47.48 Mg ha-1) and belowground biomass (12.20 Mg ha-1) were recorded for agrohortisilviculture. Biomass production was positively correlated with altitudes and increased with an increase in altitudes. Soil carbon density was the maximum (35.77 Mg ha-1) under silvopastoral showing a decreasing trend along the altitudinal gradient. The total carbon storage potential was observed the maximum (59.76 Mg ha-1) under silvopastoral system followed by agrohortisilvicuture > agrosilvohorticulture > agrisilviculture > pastoralsilviculture > hortiagriculture > hortipastoral > agrihorti-culture. Along the elevation gradient, total carbon stock ranged from 43.99 to 51.13 Mg ha-1 with the maximum carbon stock corresponding to Z-III and the minimum for Z-IV. This study offers a useful approach for selecting different land use systems and vegetation patterns to maximize thecarbon stocks in a cost-effective manner, which will further help to mitigate global warming issues in other fragile Himalayan catchments.