Modeling the bole mass of beech (Fagus Orientalis Lipsky) through allometric equations within Hyrcanian forests

Biomass Measurement is one of the prominent procedures for estimating carbon storage and/ or carbon dispersion in atmosphere following global warming. This research aims at modeling the various & different applicable equations in order to increase the accuracy of dry biomass measurement of beech species in natural Hyrcanian forests. This research was backed by natural resources organization so that 21 beech trees could be cut. After cutting and converting the trees, each part of bole which had been converted, was weighed and one disc with 2 cm thickness from the 2-5 m end part of the bole was taken. Then, the samples were taken to lab and they were oven-dried at 105ْ C to obtain moisture content and constant special gravity. For multiple modeling three variables such as diameter at breast height, bole height and dry wood density were used. The results showed that the combination of height and square of diameter (DBH² ×H) as explanatory variables would induce the best allometric model. As well, among the whole models presented in this study, the power function just having diameter at breast height (R²adj = 0.922; SEE = 0.241) and log-transformed model having combined variables (DBH²× H) were the best models (R²adj = 0.993; SEE = 0.072) so that they could demonstrate the best goodness of fit. At the end, the ultimate model to estimate the bole biomass of beech in the case study was Y = exp [-3.436 + 0.977 ln (DBH²×h)]. Consequently, this height prediction on the original scale is multiplied by correction factor (CF = 1.002) to correct the underestimation.