Uji Kemampuan Sekuestrasi Karbon Vegetasi Target Pemulihan pada Cagar Alam Goa Nglirip Kabupaten Tuban

Abstract

Goa Nglirip Nature Reserve (GNNR) in Guwoterus Village, Tuban Regency, has experienced ecosystem degradation associated with phosphate mining, with documented loss or reduction of vegetation previously recorded in the area. Restoration activities have been initiated, but the recovery documents used in this study indicate that replanting has not covered all target vegetation types. This study estimated aboveground biomass, carbon stock, and CO₂ equivalent stored in individuals belonging to target vegetation types historically recorded in the reserve documents and identified types showing relatively high carbon-stock values as one consideration for restoration species selection. Primary data comprised diameter at breast height (DBH), age, and wood density from 13 trees representing four species: preh (1 tree), tamarind (5 trees), jamblang/duwet (4 trees), and jackfruit (3 trees). One branch sample was collected from each tree to determine wood density. Aboveground biomass was estimated nondestructively using the allometric equation of Ketterings et al. (2001). Carbon stock was calculated using an approximately 46% carbon fraction following Hairiah and Rahayu (2007) and converted to CO₂ equivalent. The asam jawa individual (c) showed the highest estimated biomass at 1,499.31 kg, corresponding to 689.68 kg C and 2,528.84 kg CO₂e. Because the sample size was small and unbalanced and the individuals were sourced outside the reserve, the results are treated as descriptive estimates for the observed individuals rather than annual sequestration rates or statistical species-level comparisons. From a carbon-storage indicator perspective, tamarind and jackfruit may be considered candidates for further restoration assessment alongside ecological suitability and conservation objectives.