Carbon storage and biomass patterns of tree species in Girnar hills, Gujarat

This study assessed tree diversity and quantified carbon storage and biomass patterns in the Girnar Hills, Gujarat, a semi-arid forest ecosystem for which quantitative baseline carbon data remain limited. Vegetation sampling was carried out using a quadrat method along two stairway routes (old and new stairways). A total of 90 quadrats (10 × 10 m), together covering approximately 0.9 ha (90 × 100 m 2 quadrats), were established at 70 m intervals, and all trees with a diameter at breast height (DBH) ≥ 10 cm were enumerated. In total, 528 individuals representing 52 species and 22 families were recorded. Tree girth and height were measured in the field, and biomass was estimated using a generalised allometric equation for tropical dry deciduous forests. Below-ground biomass was derived using a fixed conversion factor (0.26), and carbon stock was calculated assuming 50% of total biomass as carbon; plot-level values were summed and divided by the total sampled area to derive a stand-level, hectare-scaled estimate. Applying the standard conversion factor (3.6663) to the estimated carbon stock, the cumulative CO₂ stock of all sampled individuals was 82,812.71 kg, equivalent to 92.01 t ha −1 . The highest cumulative contributions were recorded for Tectona grandis (12,600.54 kg), Lannea coromandelica (6522.70 kg), Ficus racemosa (5941.93 kg), Ficus arnottiana (4952.42 kg), and Diospyros melanoxylon (4691.06 kg), reflecting the summed contribution of all individuals of each species across the study area. At the family level, Moraceae and Fabaceae showed the highest carbon contributions, accounting for approximately 14.3% and 13.9% of the total stock, respectively. DBH showed a strong positive relationship with carbon stock (R 2 = 0.90); however, because biomass was estimated using a generalised allometric equation applied without independent, site-specific validation, this relationship should be interpreted as an internally consistent model fit rather than a fully validated predictive capacity, and it carries residual model uncertainty. Intermediate DBH classes (1030 cm) accounted for the largest share of the cumulative carbon stock. These findings provide baseline carbon storage estimates for Girnar forests and demonstrate the applicability of simple dendrometric models for rapid carbon stock assessment, supporting future conservation and climate mitigation planning. Given the vulnerability of semi-arid dry deciduous forests in Western India to both moisture stress and anthropogenic pressure, this baseline stocks offer a reference point for prioritising high-biomass species and intermediate size classes in forest management and restoration planning across similar hill ecosystems in the region.