BIOMASS EQUATIONS FOR RUBBER TREE (HEVEA BRASILIENSIS) COMPONENTS IN SOUTHERN THAILAND

The rubber tree (Hevea brasiliensis) is cultivated for latex production, but its timber is used in industry and its logging residues can be used for power generation. The reliable estimation of biomass is basis for operational calculations. In this study, allometric biomass equations for fresh and dry biomass of the above- and belowground non industrial tree components of mature rubber tree (leaves, branches <3 cm in diameter, branches 3-5 cm in diameter, stumps with roots, stem) at the clear-cutting phase were developed. The models were based on 18 sample trees of clone 600 harvested in Songkhla province, southern Thailand. Diameter at breast height (DBH), height (H) and their combination ((DBHH)-H-2*) were tested as independent variables. In the models, easily measurable DBH gave a considerably higher coefficient of determination than H. Combining both DBH and H in the models did not improve the equations. The equations provided logical biomass predictions and they had high coefficient of determination. Fresh mass equations can be used in predicting the value of trees in local markets and dry mass equations for estimating the amount of residual biomass in mature rubber tree plantations in southern Thailand.