Thinning compliance and its effects on growth, yield and stem quality of pinus patula at sao hill forest plantation,Mufindi district, Tanzania
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Date
2023
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Sokoine University of Agriculture
Abstract
This study assessed the thinning compliance, effects of thinning on the growth, yield and
stem quality of Pinus patula at Sao Hill Forest Plantation. Data were purposely collected
from 285 circular plots of 0.03 ha (9.78 m radius) distributed randomly in 19 thinned
compartments with the same site class and age. Fifteen plots were established in each
purposely selected compartment where the adequacy of thinning for thinned
compartments was determined by calculating the remaining number of stems per hectare
and the deviation from scheduled values expressed in percentages. Thinning timing were
obtained by deducting the age the compartment was supposed to be thinned as indicated
in thinning schedule. One sampled t-test was used to compare if there were a significant
difference between the number of remaining stems after thinning and those indicated in
the thinning schedule. To assess the effect of thinning on growth, yield, and stem
quality, three thinned and three unthinned compartments were purposely selected based
on their compatibility in terms of site class and age. The height of three fattest trees,
diameter at breast height (Dbh), and stem quality of all trees in a circular plot of 9.78 m
were measured and recorded. An independent t-tests were used to test for significant
difference between stand paramenters and Mann-Whitney U test were used to test stem
quality between thinned and unthinned stands. A Mann-Whitney test was performed to
assess if the stem quality of the thinned stands differs significantly from unthinned
compartments. Thinned compartments were significantly overstocked and all
compartment were not thinned on time as recommended in the thinning schedule.
Thinning increased growth and yield of Pinus patula. Thinning improves stem quality
by 9% resulting in trees having straight and good stem. Thinned stands have higher
volume than unthinned stands. Therefore, this study recommended that pine plantations
should be timely thinned as per used thinning schedule to ensure that more volume is
attained.
Description
Masters Dissertations
Keywords
sao hill, forest plantation, mufindi district, pinus patula, stem quality