Tree growth characteristics, stand productivity and carbon storage in age series indigenous species demonstration plantations in Forest Research Institute of Nigeria

Forest plantations are important in meeting national and global demand for industrial wood due to their fast growth rate and high productivity. They can produce 3–10 times higher biomass than natural forests, making them important for climate change mitigation. We examined the growth characteristics, productivity and carbon storage of age series Nauclea diderrichii and Terminalia ivorensis plantations at Forestry Research Institute of Nigeria. Tree growth variables were measured in 25 m x 25 m temporary sample plots selected from 6 to 24 years plantations of the two species. Biomass data were obtained through non-destructive means. Mean diameter at breast height (DBH) ranged from 13.3 cm (6 years) - 37 cm (24 years) in T. ivorensis and 18.3 cm (13 years) - 22.4 cm (14 years) in N. diderrichii stands while mean total height varied from 10.1 m - 21.2 m and 16.5 m - 17.8 m in respective plantations of the two species. Both species demonstrated a high degree of merchantability, with no difference between them (66.5 - 81.4% in T. ivorensis and 77.0 - 77.2% in N. diderrichiii). Mean basal area, volume, biomass and carbon stock in T. ivorensis stands were: 9.4 - 19.4 m2/ha, 63.5 - 252 m3/ha, 48.8 t/ha - to 188.6 t/ha and 24.4 t/ha - 94.3 t/ha, respectively while they were 12.0 m2/ha - 12.1 m2/ha, 118.4 m3/ha - 195.8 m3/ha, 187.0 t/ha - 214.6 t/ha and 93.5 t/ha - 107.3 t/ha in N. diderrichii plantations. The two tree species have a good growth rate and productivity when compared with some tropical plantation tree species. The productivity, merchantability, biomass and carbon stock of N. diderrichii and T. ivorensis stands are indicating their suitability as candidates for good quality timber, carbon sequestration and climate change mitigation.