Models for estimating volume of Tectona grandis at Longuza and Mtibwa forest plantations in Tanzania
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Date
2025
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Publisher
Tanzania Journal of Forestry and Nature Conservation
Abstract
This study aimed to develop and validate
allometric equations for estimating total and
merchantable volumes of teak (Tectona
grandis L. f.) trees in two major statemanaged
forest plantations in Tanzania,
Longuza in the Tanga Region and Mtibwa
in the Morogoro Region. It addresses the
existing gap of the absence of accurate
volume models required for the reliable
estimation of total teak tree volume, which
is critical for effective forest management
and planning. A total of 177 destructively
sampled trees were used to fit non-linear
regression models incorporating diameter at
breast height (D) and total height (H) as
predictor variables. Site-specific and general
models were developed and evaluated.
Models that included both D and H
outperformed those based solely on D,
providing more unbiased volume estimates
across diameter classes and sites. The bestperforming
models exhibited high
explanatory power (R² ≥ 0.96) and low
prediction errors (PE% < 3%). The H-D
relationship reveals differences in tree
allometry between the two sites, with taller
trees on average in Longuza than in
Mtibwa. The site-specific H-D and volume
equations are recommended where
available. In the absence of such models, the
generalised equations developed herein
provide a reliable alternative across teak
plantations in Tanzania.
Description
Journal Article
Keywords
Volume equations, Teak forest plantations, Non-linear model, Tree diameter and height relationship, Lunguza and Mtibwa