TITLE:
Variation in Stem Straightness and Wood Basic Density of Tectona grandis Provenances at Longuza Forest Plantation, Tanzania
AUTHORS:
Anthony P. Opiyo, Japhet N. Mwambusi, Shabani A. O. Chamshama, Revocatus P. Mushumbusi
KEYWORDS:
Tectona grandis, Provenance Trial, Wood Quality, Tanzania
JOURNAL NAME:
Open Journal of Forestry,
Vol.16 No.4,
October
19,
2026
ABSTRACT: Stem straightness and wood basic density are crucial characteristics influencing the wood quality, commercial value, and utilization of Tectona grandis (Teak) timber, yet variation in these traits among provenances remains poorly studied, particularly in Tanzania. This study assessed wood quality based on stem straightness and basic density variation across 12 Teak provenances established on the same site in 2011 at Longuza Forest Plantation, Tanzania. The trial was laid out in a randomized complete block design with 8 replications, each plot containing 6 trees. Stem straightness was measured non-destructively using a scoring method (1 = best, 4 = worst), while basic density was determined through standardized laboratory testing of extracted core samples. Statistical analysis was performed in SAS® 9.4, using mixed models with provenance fitted as a fixed effect and replicate block and family nested within provenance fitted as random effects, to account for the trial’s design structure. Stem straightness did not vary significantly among the 12 provenances (F (11,29) = 1.56, p p −3) significantly denser than CSIRO Thailand (0.469 ± 0.053 g cm−3; Tukey-adjusted p −3. These findings show that, at 11 years of age, provenance level differences in stem straightness are modest relative to tree to tree variation within families, while basic density shows a more defensible, if still limited, provenance level signal. Given the modest and uneven replication across provenances, selection decisions should be made cautiously, with re-assessment recommended as the trial matures.