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All Journal MANAJEMEN HUTAN TROPIKA Journal of Tropical Forest Management Jurnal Sylva Lestari
Mwambusi, Japhet Noah
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Agriculture, Biological Sciences & Forestry Earth & Planetary Sciences Energy Environmental Science Materials Science & Nanotechnology

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Growth, Yield, and Stem Quality of Tectona grandis Grown with Different Spacings at Longuza Forest Plantation, Tanzania Samamba, Enos; Chamshama, Shabani Athumani Omari; Mwambusi, Japhet Noah
Jurnal Manajemen Hutan Tropika Vol. 30 No. 1 (2024)
Publisher : Institut Pertanian Bogor (IPB University)

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.7226/jtfm.30.1.138

Abstract

Spacing is a silvicultural practice that affects the growth of trees in forest plantations. However, the yield depends on growth, which is determined by spacing. In addition, spacing influences the quantity of the final crop available for harvesting, specifically in forest plantations for sawlog production. Spacing is also used as a management practice to control the quality of trees, as dense stands are expected to have trees with good stem quality. However, little has been done to address the effects of spacing on the growth, yield, and stem quality of Tectona grandis until final harvesting age. Teak plantations in Tanzania are grown at a rotation age of 20 years. Thus, this study aimed to assess the effect of spacing on the growth, yield, and stem quality of 24-year-old T. grandis in a Longuza Forest plantation in Muheza, Tanzania. Data were collected from a spacing trial using a randomized complete block design with three treatments: 2 m × 2 m, 3 × 3 m, and 4 m × 4 m, with three replications. The growth and yield parameters assessed were diameter at breast height (dbh) total tree height, and stem quality. Data were analyzed to obtain the basal area, volume, and mean annual increment. Statistical analysis was performed using analysis of variance (ANOVA), and multiple comparisons among treatment means were performed using Tukey's honest significant difference test (p-value = 0.05). The results showed that spacing did not significantly affect growth and yield parameters. The stem quality was significantly different in some treatments. The highest dbh and height growth were observed at 4 m× 4 m spacing. The highest values of basal area, volume, and mean annual increment were observed at a 3 m× 3 m spacing. Stem quality differed significantly between the 2 m× 2 m and 4 m× 4 m spacings. Because teak plantations in Tanzania are aimed at sawlog production, it is recommended to continue practising a spacing of 3 m× 3 m, which will ensure a higher mean annual increment with a higher volume at the stand level. In addition, a spacing of 3 m × 3 m ensured a higher percentage of trees with good stem quality.
Effects of Tree Spacing on the Physical and Mechanical Properties of 24-Year-Old Tectona grandis Wood in Longuza Forest Plantation, Tanzania Samamba, Enos; Mwambusi, Japhet Noah; Chamshama, Shabani Athumani Omari
Jurnal Sylva Lestari Vol. 13 No. 3 (2025): September
Publisher : Department of Forestry, Faculty of Agriculture, University of Lampung

Show Abstract | Download Original | Original Source | Check in Google Scholar | DOI: 10.23960/jsl.v13i3.1154

Abstract

This study investigated the effects of initial tree spacing on the physical and mechanical properties of 24-year-old teak (Tectona grandis) in Longuza Forest Plantation, Tanzania. Three spacing treatments (2 m × 2 m, 3 m × 3 m, and 4 m × 4 m) were evaluated using a randomized complete block design with three replications. Physical properties assessed included wood density (D) and heartwood percentage (HWP), while mechanical properties comprised modulus of elasticity (MOE), modulus of rupture (MOR), compressive strength parallel to the grain (CSP), shear strength parallel to the grain (SS), and cleavage strength (CLS). Results showed that spacing had no significant effect (p > 0.05) on most physical and mechanical properties, except for SS and tangential CLS at specific height levels. Although non-significant, D, MOE, MOR, CSP, and CLS tended to decrease with increasing spacing, whereas HWP and SS exhibited variable trends. The highest mean values for D (0.57 g/cm³), MOE (8,588 N/mm²), MOR (90.78 N/mm²), CSP (49.41 N/mm²), and CLS (14.83 N/mm) were observed at a 2 m × 2 m spacing, while the lowest values generally occurred at the widest spacing (4 m × 4 m). The findings suggest that closer spacing may enhance wood quality by promoting higher wood density and strength, although differences were not statistically significant. These results provide insights for silvicultural management of T. grandis plantations, suggesting that a 2 m × 2 m spacing may be preferable for optimizing physical and mechanical wood properties at older stand age. Keywords: heartwood percentage, modulus of elasticity, modulus of rupture, spacing, Tectona grandis, wood density
Co-Authors Chamshama, Shabani Athumani Omari Samamba, Enos