Allometric biomass models for bark of Cinnamomum tamala in mid-hill of Nepal

Allometric bark biomass models for Cinnamomum tamala (one of the important commercial non-timber forest product tree species) have been developed using bark biomass and tree dimension data with thirty destructively sampled trees from the natural population in the mid-hill of Nepal. Diameter at breast height (D) alone and both D and total height (H) as independent variables and bark biomass (W) as dependent variable were used for modelling. The models were evaluated on the basis of numerical fit statistics, graphical appearance and biological logic. Among eighteen different models tested, the model of the form: W = DH/(b1 + b2DH) accounted for the largest proportion of bark biomass variations ( R adj 2  = 0.92; RMSE = 3.67 kg) for individual C. tamala tree, and showed relatively better graphical appearance and biological logic. Reliability of the model would be higher when it is applied to various sizes of C. tamala trees growing in the site and stand conditions similar to the basis of this study. Further work on re-calibration and validation of proposed model with data from a larger geographic area, wider range of tree sizes, site and stand conditions is recommended.