Abstract:
Eucalyptus globulus (Tasmanian blue gum) belongs to the family of flowering plants known
as Myrtaceae and the origin of south eastern Australia. The introduction of Eucalyptus
species in Ethiopia at the begging of the 20
xii
th
century.This study involved the development of
Stem volume estimation model and form factor function of smallholder Eucalyptus globulus woodlot
plantation in the Farta district. The study kebeles were selected based on resources available and in
each woodlot plantations were selected purposely. Random sampling method was used for
establishing plots in woodlot plantation sites for measuring tree parameters. The plot size was 200 m
2
,
the data was taken on uncoppiced and coppiced woodlot plantation by destructive and non
destructive method by measured the tree parameters, A total of 120 destructed sample trees were used
in different diameter class distribution for yield estimation and model development. The data was
randomly divided into equal sizes for equation development and validation. Data were analyzed using
descriptive statistics& regression analysis by using Microsoft Excel and SAS software statistical
analysis. Model fitting and validating statistics were assessed using coefficient determination (R
2
),
root mean square (RMSE), Absolute mean deviation (AMD) and paired t-test were used to evaluate
the performance of equation. The yield of standing stem volumes first coppiced high yield of
production than uncoppiced woodlots per heactare was recorded. For estimated stem volume
combined variable models had better accuracy than single variables. Among the different equations,
the Islam and Chowdhury function of the form V= a+bD+cH+dD
2
H (model 6) is the best performed
and fitted model. pollanschuz’s function was the best fitted model in estimating the form factor of
Eucalyptus globulu tree species. is the best performance and fitted. The form factor of Eucalyptus
globulus of uncoppiced was 0.436±0.03 for the DBH class of (4.5-23.5 cm) and first coppiced
0.4503±0.045 was for the DBH class of (4.5-34.9 cm) and for aggregating data 0.443±0.039
correction factor recommended for estimated stem volume of Eucalyptus globulus with a DBH range
(4.5-34.9) and seven (7) years of woodlot plantation in the study site. Model validation for stem
volume and form factor showed that no significant difference between observed and predicted models
for the best -selected and fitted model(p>0.05)
