Allometric Equation for Biomass Estimation of Pouteria adolfi-friederici
(Engl.) Baehni in Gerba Dima Forest, South western Ethiopia
Abstract
Abstract: This study was conducted in Gerba Dima Forest, South Western
Ethiopia to formulate allometric equations for Pouteria
adolfi-friederici. Prior to collecting data for tree allometry, the
study forest was stratified into 3 forest strata based on altitudinal
variation. By employing semi-destructive technique, 30 individuals were
systematically selected and sampled for measuring biomass along the
three forest strata. Based on the data collected, several equations were
developed. Before establishing the allometric equation, scatter plots
were used to see whether the relationship between independent and
dependent variables was linear. Furthermore, several allometric
relationships between independent and dependent variables were tested.
The best-fit model developed was validated by testing the regression
assumptions. AGB was regressed against the various forms of predictors
(i.e., DBH, H and WD) and three allometric models showed significant
performance (p < 0.05) on their F-test. Among the three
allometric equations which showed significant performance, the selection
of the best-fit model was conducted based on their P-value, adjusted r2,
AIC, RMSE. The two models are nested to the third model and hence the
complete model, lnAGB=1.806+1.419×lnDBH+0.628×lnWD, is selected as the
best-fit model against the other two nested models since the p-values of
coefficients of the complete model are significant (p < 0.05).