Abstract:
Growth and yield models are generally used to predict the temporal development of forest
stands. These models are affected by environment, genotype, and management practices.
Growth and yield potential of J. procera were not well developed to inform decision-makers
and enterprises in the forest sector. Therefore, the study was aimed at developing growth and
yield models and comparing growth and yield performance of 16 year provenances. The study
was carried out in a randomized complete block design. The plot size was 100m
xii
2
with 2.5m by
2.5m spacing. Data was taken on diameter at breast height (DBH), height and cross-sectional
diameter at a 1-meter interval of standing trees of the sample. SPSS version 25 and Microsoft
excel 2013 was used to analyze the data. The regression technique was used to develop the
model and analysis of variance was performed for yield comparison. The result showed a
variation of coefficient of determination ( R
2
) and root mean square error (RMSE )on eleven
provenances of growth and yield models. All developed models were significant and had good
performances (R
2
>50) except DBH-height relation models. The combined variable models had
better accuracy. Provenances of J. uniperus procrea plantation had also a significant effect on
growth and yield performances (p = 0.05). DBH (cm) and basal area (m
2
ha⁻
1
) did not show
significant variation among provenances of sixteen year J. procera plantation (p = 0.05).
However, the highest and the lowest values were recorded in the provenances of Kolobo
(16.2cm) and Khatasa (14.7 cm) respectively. There was significant variation in height growth,
the form of the tree, and volume and biomass production of sixteen-year J. procera plantation
among eleven provenances. The highest Kolobo (11.35m) and lowest Khatasa (9.67m) value of
mean heightwas obtained. Volume, and trunk biomass were obtained in provenances of Kolobo
(10.12 m
3
ha⁻
1
, 5491.6 kg ha⁻
1
) and Hirna (6.92 m
3
ha⁻
1
, 3738.4 kg ha⁻
1
).respectively. On the
other hand, the highest and lowest Leaf and branch biomass were obtained in the Provenances
of Khtasa (5491.6 kg ha⁻
1
) and Hirna (2716.2 kg ha⁻
1
) respectively. The highest and lowest
form factor was obtained in provenances of Gaint (0.43) and Hirna (0.32) respectively. The
generic form factor is 0.4. Provenance specific and combined variable models had better
accuracy which resulted significant variation on growth and productivity of J. procera. The
best provenance of growth and trunk yield was Kolobo so that it should be promoted for further
plantation. On the other hand, Provenance Khatasa was best in leaf and branch biomass, which
should be, promoted for restoration purpose. Lastly, using these developed models for J.
procera provenances will enhance efficiency and accuracy interested bodies
