ALLOMETRIC EQUATIONS FOR ESTIMATING MERCHANTABLE WOOD AND ABOVEGROUND BIOMASS OF COMMUNITY FOREST TREE SPECIES IN JEPARA DISTRICT

Understanding the essential contribution of community forests for industrial development or climate change mitigation principally requires the accurate measurement of merchantable wood and aboveground biomass. However, the quantification of those parameters using the destructive method requires high cost and time consuming. To anticipate these constraints, allometric equations development has a potential contribution to facilitate a more efficient estimation of wood and biomass production without disturbing forest regeneration capacity. Therefore, this study aimed to develop allometric equations for quantifying merchantable wood and aboveground biomass of community forest tree species. The destructive sampling was carried out on 45 trees from three species (15 trees each), namely Swietenia macrophylla King, Falcataria moluccana (Miq.) Barneby et J.W.Grimes, and Tectona grandis L.f. Furthermore, three general allometric equations were examined using some predictor variables, i.e. diameter at breast height (D), quadrat diameter at breast height combined with tree height (D2∙H), as well as D and H separately. The results showed the highest average of merchantable wood and aboveground biomass recorded in S. macrophylla (0.41 ±0.10 m3; 0.33 ±0.07 t), followed by T. grandis (0.20 ±0.07 m3; 0.18 ±0.06 t) and F. moluccana (0.16 ±0.05 m3; 0.06 ±0.02 t). Meanwhile, the relative contribution of foliage biomass to total aboveground biomass gradually declined along with the increasing diameter classes. In contrast, a fluctuating trend was observed in the stem and branch. Also, equation ln Y = lna + b∙lnD was best in quantifying the wood and biomass. The addition of H as a predictor variable in the equations did not show a meaningful influence to increase accuracy estimation in the species. Based on these results, it was concluded that the development of allometric equations was reliable to facilitate more efficient estimation of merchantable wood and aboveground biomass for community forest tree species with over 95 accuracy. © 2021 Lesotekhnicheski Universitet (University of Forestry). All rights reserved.