Carbon stock measurements of a degraded tropical logged-over secondary forest in Manokwari Regency, West Papua, Indonesia

Several studies have been conducted in the past on carbon stock measurements in the tropical forests of Indonesia. This study is the first related research conducted in the New Guinea Island. In a degraded logged-over secondary forest in Manokwari Regency (West Papua, Indonesia), carbon stocks were measured for seven parts, i.e., above-ground biomass (AGB), below-ground biomass (BGB), under-storey biomass (B _u), necromass of dead leaves (N _l), necromass of dead trees (N _t), litter (L) and soil (S) using appropriate equations and laboratory analysis. Total carbon stocks were measured at 642.8 tC·ha⁻¹ in the low disturbance area, 536.9 tC·ha⁻¹ in the moderate disturbance area and 490.4 tC·ha⁻¹ in the high disturbance area. B _u, N _l and N _t were not significant in the carbon stock and were collectively categorized as a total biomass complex. The carbon stock of litter was nearly equal to that of the total biomass complex, while the total carbon stock in the soil was eight times larger than the total biomass complex or the carbon stock of the litter. We confirmed that the average ratio of AGB and BGB to the total biomass (TB) was about 84.7% and 15.3%, respectively. Improvements were made to the equations in the low disturbance logged-over secondary forest area, applying corrections to the amounts of biomass of sample trees, based on representative commercial trees of category one. TB stocks before and after correction were estimated to be 84.4 and 106.7 tC·ha⁻¹, indicating that these corrections added significant amounts of tree biomass (26.4%) during the sampling procedure. In conclusion, the equations for tree biomass developed in this study, will be useful for evaluating total carbon stocks, especially TB stocks in logged-over secondary forests throughout the Papua region.