Allometric equations for estimation of tree biomass from plantation residues of Gmelina arborea Roxb. and Tectona grandis L.f. in Guanacaste, Costa Rica

The use of thinning residues and the final harvests of plantations of Gmelina arborea and Tectona grandis for energetic purposes has become a financially viable activity in the most recent years; however, in most cases neither the producer nor the buyer has an estimate in generated biomass. For the purpose of facilitating the commercialization of biomass, it is necessary to have allometric equations that facilitate an estimation of the biomass produced. In this paper, the objective was to generate and validate allometric equations to calculate the aerial forest biomass from the residues of Gmelina arborea and Tectona grandis plantations; the study was developed with three plantations of T. grandis and two plantations of G. arborea with different ages; harvesting individuals and calculating the amount of biomass produced. Nine alometric models were analyzed and a decrease ratio of the percentage of residues was found as the diameter of the individuals of both species increased. For T. grandis the best model was B= 7,35(0,16)*(d) with a R-2 of 0.75 and an average square error of 85.51; with G. arborea the best model was B= 5,40(1,24)*(d) with a R-2 of 0.82 and an average square error of 100.54. The feasibility of using these models is to estimate the crop residues of non-timber plantations, since multiple studies show the functionality of the models including the use of wood.