Carbon stock assessment of large leaf mahogany (Swietenia macrophylla King) and dipterocarp plantations in the Mt. Makiling Forest Reserve [Philippines]

Results showed that the large leaf Mahogany stand has a total biomass production of 605.25 tons/ha while the Dipterocarp stand amounted to 563.93 tons/ha. Converting the biomass accumulation to total carbon stored, it resulted to 542.05 tons C/ha and 639.81 tons/ha for large leaf Mahogany and Dipterocarp stands, respectively. Based on the three carbon pools investigated, the results are as follows: for the large leaf Mahogany stand: above-ground, 246.63 tons C/ha; ground biomass, 20.02 tons C/ha; and below-ground biomass, 275.40 tons C/ha. While the Dipterocarp stand, the results are as follows: above-ground, 248.08 tons C/ha; ground biomass, 20.46 tons C/ha; and below-ground biomass, 371.27 tons C/ha. Out of the three carbon pools studied, the below-ground biomass has the highest carbon deposits primarily contributed by its soil component. Both plantations exhibited the same order in terms of the amount of C stored in its different carbon sinks. Specifically, the actual amount of C stored per carbon pool for large leaf Mahogany and Dipterocarp stand, respectively, were determined to be in the following order: SOC [soil organic carbon] (253.36 tons C/ha: 326.61 tons C/ha, tree biomass (245.48 tons C/ha; 245.51 tons C/ha), roots (22.04 tons C/ha; 44.66 tons C/ha), ground litter (18.35 tons C/ha; 17.39 tons C/ha), CWD [coarse woody debris] (1.67 tons C/ha; 3.07 tons C/ha), understorey/herbaceous vegetation (1.15 tons C/ha; 2.57 tons C/ha). Results of the study further showed that both plantations exhibited higher carbon content compared to a natural forests, a secondary forest, some fast growing plantations and agroforestry farms based on previous studies conducted in the country. On the average, the amount of carbon stored from both plantations is equal to 590.93 tons C/ha as against that of a natural forest (392.96 tons C/ha), secondary forests (ave. of 337.68 tons C/ha, fast growing plantation (ave. of 253.89 tons C/ha) and agroforestry systems (ave. of 106.94 tons C/ha)