Above-ground biomass estimation of Acacia mangium Willd. in revegetation area of coal mining.
Acacia mangium Willd. is categorized as an invasive species in the revegetation area of coal mining. The presence of A. mangium causes a shortage the organic matter in the revegetation area. The abundance of A. mangium biomass could be used as a source of organic material for soil enhancer to improve soil fertility. The objective of this study was to develop allometric models of Acacia mangium and to estimate the potential above-ground biomass of A. mangium in PT Wahana Baratama Mining (PT WBM). This study was conducted in February-April 2019. A. mangium population and distribution were collected through vegetation inventory with 0.5% sampling intensity. The allometric models were established using a destructive method. The above-ground biomass allometric model for the four diameter classes are as follows: seedlings (B = 0,002002 - 0,02469D + 0,07322D2 with R2(adj)= 99,38%), saplings (B = 2,754 - 1,742D + 0,4093D2 with R2(adj) = 99,89%), poles (B = -9,16 - 1,153D + 0,5007D2 with R2(adj) = 99,96%), and trees (B = 0,134741D2,38 with R2(adj)= 96,94%). The allometric models were used to estimate the above-ground biomass potential total of A. mangium by using inventory data. The inventory result showed that the mean density of A. mangium is 13.187 individuals/ha with a mean diameter of 5,64 cm. The potential above-ground biomass of A. mangium in PT WBM revegetation area is estimated at up to 51.022,59 tons. The above-ground biomass of A. mangium has potential value to be utilized as a soil enhancer as well as meet the needs of organic material for the whole PT WBM revegetation areas.