Carbon stock assessment and carbon credit potential of tree plantations at Navsari agricultural university campus in Gujarat

Accurate quantification of carbon sequestration in institutional plantations is critical for advancing both climate mitigation and carbon finance. This study estimated above-ground biomass (AGB), below-ground biomass (BGB), soil organic carbon (SOC), and total carbon stock across six major species–Mangifera indica, Manilkara zapota, Tectona grandis, Gmelina arborea, Casuarina equisetifolia, and Ailanthus triphysa–planted at Navsari Agricultural University, Gujarat. A 15% random sampling intensity was applied across 6.98 ha of plantation blocks, and tree volume was calculated using species-specific volumetric equations. M. indica exhibited the highest per-tree biomass (266.4 kg), while C. equisetifolia recorded the lowest (47.4 kg). Total biomass-derived carbon stock was 161.8 t and SOC analysis revealed significantly higher concentrations in surface soils (0–15 cm) compared to subsurface layers (15–30 cm). Two-way ANOVA confirmed significant effects of species (F (5,24) = 1078.5, p < 0.001), depth (F (1,24) = 7300.5, p < 0.001), and their interaction (F (5,24) = 730.9, p < 0.001). M. indica recorded the highest SOC (1.49% at 0–15 cm), while T. grandis and C. equisetifolia consistently showed lower values. The total carbon stock across plantations was 257.1 t (63% biomass, 37% SOC), equivalent to 941.1 tCO₂-e. Valuation under multiple carbon markets projected potential revenues ranging from 4705 USD (voluntary price, 5 USD/CER) to 65,870 USD (EU ETS, 70 USD/CER). Institutional plantations can contribute measurable carbon stocks and have potential to generate modest carbon revenues under specific market scenarios. Integrating such landscapes into carbon markets can enhance the sustainability opportunity.