Effect of Spacing Regimes on Growth and Carbon Storage of Tectona grandis, Gmelina arborea and Terminalia ivorensis in a Nine Year old Forest Plantation in the Transition Rainforest of Sierra Leone

Abstract

The study was conducted to investigate the effect of spacing on growth and carbon storage of Tectona grandis, Terminalia ivorensis and Gmelina arborea in a nine year old Plantation Forest experimental plots at Njala University, Sierra Leone. The aim was to assess the effect of four different spacings (1.8m x 1.8m, 2.0m x 2.0m, 3.0m x 3.0m and 4.0m x4.0m) on tree growth and carbon storage in tree biomass of the three species. The species were planted in square plots consisting of four different spacings with a split plot design in three replications. Measurements of DBH, height, volume, biomass and carbon percentage of biomass were taken and the data was subjected to analysis of variance (ANOVA). The results showed that spacing had significant effect on DBH, height, biomass, carbon percentage and volume. The 4.0m x 4.0m spacing had the highest DBH, biomass, carbon percentage of biomass and volume whilst the highest height was recorded at 2.0m x 2.0m. Gmelina arborea dominated among the three species selected followed by Tectona. Terminalia was poor in most parameters except for height and volume. Strong positive relationships were observed between tree DBH and biomass (r2 = 0.79) DBH and carbon percentage of biomass (r2 = 0.89) and DBH and volume (r2 = 0.95). The results indicate that 4m x 4m spacing and Gmelina arborea can be recommended for afforestation and reforestation programmes aimed at wood and timber production for fast growth and higher carbon sequestration.