Exploring the Volume Paradox: Comparing Different Formulas for Estimating the Wood Volume of Trees and Logs in Nepal

Accurate estimation of tree and log volume plays a pivotal role in a wide range of applications within the field of forestry, especially in biomass assessment and forest management. The effectiveness and applicability of formulas for volume estimation have recently become a topic of extensive deliberation among forestry officials and a diverse array of stakeholders. This study conducts a comparative analysis between the Huber and allometric equation with the Quarter girth formula and a formula based on form factor to estimate the volume of standing trees and logs. Field measurements of 168 felled trees in coupes and randomly selected 1192 logs were examined in this study. The findings of the study revealed a decrease of approximately 0.8% in timber volume and a substantial increase of 78.6% in firewood volume while adopting the allometric equation when compared to the formula based on form factor. Similarly, the application of Huber's formula resulted in a 27.34% increase in volume compared to the Quarter girth formula. ANOVA demonstrated highly significant differences in the average volume per tree among the four formulas (p value = 0.00004) for both standing tree and log volume, and further analysis using Tukey's HSD indicated that the Quarter girth and form factor-based formula for standing trees differed significantly from the allometric equation for standing timber, while other formula combinations did not show significant differences. Timber losses in the felling and bucking stage with the Quarter girth and Huber formula were 37.06% and 19.86%, respectively. Moreover, paired t-test at 5% level of significance revealed that there was a significant loss in both tree felling using both formulas.